In this issue of Dentistry Today, our editor-in-chief, Damon Adams, DDS, recently led an interview with David Hornbrook, DDS, and his ceramist, Kent D. Kohli, CDT.

First off, thanks to both of you for being willing to share some time with us to discuss the important topics of collaboration and communication within doctor-technician teams. Would you both please give our readers a little background as it relates to your expertise in doctor-technician communication and the interprofessional relationships that serve to bolster excellence with aesthetic and functional outcomes?

DH: I have been in clinical practice for the past 33 years and have experienced much success that can be attributed to good communication between my dental laboratory technicians and me, and the journey included learning from any mistakes made along the way as well. Over my career, I also founded several live-patient aesthetic programs that paired up the attending clinicians with ceramists, teaching and emphasizing a collaborative approach to dentistry. In addition, I have had the valuable experience of being the director of education at Utah Valley Dental Lab for the past 3 years. My role there is to act as a liaison between the clinicians and ceramists. This has allowed me to directly witness the importance of great doctor-technician communication skills and the compromises that can and will occur with poor, little, or even no communication.

KK: I have been in the dental laboratory profession for nearly 30 years. First as an in-house technician, second as an owner/operator of a commercial laboratory for nearly 23 years, then as a general manager, and now as the chief operating officer (COO) of 2 large commercial dental laboratories. In addition to these work experiences, I have taught hands-on courses and given lectures over these past 18 years on ceramics, aesthetics, and the importance of good communication between doctors and technicians to ensure predictable and successful clinical outcomes.

Figure 1a. Zirconia disc (IPS e.max ZirCAD [Ivoclar Vivadent]) after milling and before pre-sintering. After sintering, these restorations will change to white according to their corresponding tooth shade.	Figure 1b. Leucite-reinforced anterior restorations (IPS Empress Esthetic [Ivoclar Vivadent]) on a printed model. The impression was taken using the TRIOS Intraoral Scanner (3Shape).

To achieve consistent and predictable clinical success, do you feel it is important to work with a ceramist who is located near your dental office?

DH: Although, at times, it would be nice to walk next door or across the street to hand a case to my ceramist, I really feel, in this age of digital files and efficient shipping, that having a technician close by is no longer necessary. For many years now, I have not used a ceramist who works in my hometown. I believe that it is more important to find a ceramist who has the same goals, work ethic, occlusal philosophies, and aesthetic eye than one based on location. The bottom line is that the most important aspect of a successful partnership is more about effective communication skills than proximity. Since my ceramist is about 1,000 miles away from me, I rely on texts, emails, and photographs to achieve the desired results for our patients.

KK: This is a great question, and I have experience in both an in-house setting as well as long-distance working relationships with hundreds of clients. While it is nice for the doctor to have a ceramist in an adjoining suite to come over each time one needs a custom shade, it is entirely possible to attain an equally acceptable result via quality intraoral photography, custom light-cured shade tabs, and shade communication software.

Figure 2a. The Freedom Appliance is shown on the maxillary arch. Molars are not covered so that a deprogrammed bite can be taken with the appliance in place. The anterior composite stop only opens the bite to obtain molar clearance.	Figure 2b. With the Freedom Appliance in place, a bite registration is injected over the molars bilaterally; then the patient bites gently into this reproduced physiological bite (in centric relation).
Figure 2c. The Freedom Appliance is then removed, and the patient bites back into bilaterally placed posterior bite registration material.	Figure 2d. Bite registration material is injected into the anterior segment. This “tripod” bite is used by the technician to mount the case.

What advice can you share with doctors that can help them find top-notch dental lab technicians?

DH: Probably the best places to start the search are at certain dental meetings and by reading journals written by technicians. Meetings, such as the ASDA (American Society of Dental Aesthetics) Conference, AACD (American Academy of Cosmetic Dentistry) Scientific Session, and the Chicago Dental Society Midwinter Meeting, are all excellent places to meet dental technicians, see their work, get to know them personally, and even hear them lecture. The LMT Lab Day is primarily for technicians, but I really enjoy going as a clinician to be with and hear from talented ceramists and other laboratory experts who have a wealth of knowledge. Another great way is to note who did the laboratory work for the authors of clinical case report articles, such as those you read every month in Dentistry Today. If you see clinical cases involving lab work that you are impressed with in an article, check the end of the article for an acknowledgment of the dental technician or dental laboratory team.

KK: One need not look much further than the continuing education programs that you attend as clinicians. In addition to meetings like the ones Dr. Hornbrook just mentioned, talented dental technicians can be found attending didactic and hands-on CE programs offered by organizations such as the Pankey Institute, Dawson Academy, Kois Center, Spear Education, Hornbrook Center for Dentistry, and more. As dental technicians, we strive to be like-minded co-professionals who value multi-disciplinary education where each participant checks his or her ego at the door in the pursuit of excellence.

Figure 3. Photos of incisal edges are used to communicate incisal characteristics to both the patient and the ceramist (IPS Empress Esthetic restorations).

What recommendations can you both share regarding impression materials and the types of impressions that should be taken for different scenarios? Where do you stand regarding the use of digital impression techniques?

DH: Accurate impressions, especially related to the capture of margins, is still the No. 1-reported challenge for dental technicians. Before I actually discuss impression types themselves, I’d like to say that bad impressions will always yield bad results. “Garbage in, garbage out,” as the old saying goes. Your patients deserve quality impressions! As for impression materials, most technicians do not prefer a putty/wash impression because there is a higher chance of rebound and distortion if the putty begins to gel slightly before being placed in the mouth. All the technicians I have worked with prefer a heavy-body/light-body wash; this involves utilizing a simultaneous technique where the clinician injects the light-body material around the preps while the dental assistant fills the tray with the heavy-body material. Most clinicians are using vinyl polysiloxane (VPS) materials, although technicians have no problem with polyether impression materials. If traditional physical impressions are being taken, I would absolutely suggest taking a full-arch impression for all your larger multiple-unit cases and any bridge cases. This is because the lab team needs the stability of more teeth in contact to accurately articulate and mount the models. I would also always recommend taking a face-bow with any multi-unit cases. Not only are you going to achieve more accurately mounted models, you are also sending a message to your lab team that you do not compromise and that you expect the same from them. I think quadrant dual-arch or check-bite trays are fine for single units as long as the case does not involve the most distal tooth in the arch. To help prevent impression distortion, I would recommend against the use of a flexible plastic dual-arch for a definitive impression and for the use of a tray that incorporates metal in the design, such as an appropriately sized Bite Relator Tray (Temrex). Also, when taking dual-arch tray or quadrant impressions, be sure to capture the teeth all the way to the canines in the arch; this ensures that the technician can create great occlusal anatomy without introducing working interferences. If the canine is not captured, they will be guessing and will usually design a very flat and inefficient occlusal anatomy.

Figure 4a. Preoperative image of anterior teeth with chemical erosion.	Figure 4b. Postoperative photo of the 4 minimally invasive IPS Empress Esthetic veneers.

Regarding digital impressions, I am personally a huge fan of this technology and how it has continued to evolve, becoming more and more user friendly and efficient and featuring increasingly sophisticated hardware and software. I use the TRIOS Intraoral Scanner (3Shape) in my office and appreciate its accuracy and integration directly into my technicians’ digital design software. The new scanners are faster and more accurate than analog (vinyl) impressions, and if you miss a margin in your scan for some reason, you can see it immediately and need only to rescan over that one area rather than take an entire new impression. The model printers are very accurate and can even print soft-tissue models, which I prefer when doing implants and anterior restorations. I also feel that the accuracy is so high with these scanners and the design software that there is really no need to even utilize models to ensure the desired occlusal and proximal contacts or marginal fit.

KK: I am somewhat of a progressive in my viewpoint on this matter, and I am growing ever more fond of the digital intraoral scanner (IOS) workflow. However, from my long-term experience, I would add here that a high-quality VPS impression, when taken properly, is equal to, or rivals, most digital impressions. Many clinicians are often under the misconception that a digital IOS will overcome all their previous technical challenges found in taking traditional physical impressions, but this is not always the case, as it is still quite necessary to isolate the field and to provide adequate tissue retraction in order to capture all of the necessary details.

How should a clinician communicate the desired materials to be used in specific restorative cases?

DH: Of course, these matters should always be discussed up front with the laboratory team before preparations are ever begun as a part of the treatment planning process. Different materials require different preparations, and poorly designed preparations may limit what materials could, or should, be used. Dental technicians are so knowledgeable on what is available. The materials side of the dental laboratory business is changing so rapidly, especially with regard to all-ceramic dental materials, and I have found that ceramists are usually much more up-to-date on materials than even most clinicians. Ceramists and dental lab teams really want to give you the best restoration possible in terms of aesthetics, fit, and long-term prognosis, so involve them in the decision-making process when appropriate, and take a collaborative approach that will help ensure success. The more educated the clinician becomes on materials, the more input they should provide. With all that is available today, I think it is no longer appropriate to simply request an “all-ceramic” crown on a lab prescription, leaving the material choice up to the lab team to make on its own. We, as clinicians, need to become more familiar with the advantages, disadvantages, indications, and contraindications of different materials so we can thoughtfully request materials and collaboratively discuss options with our lab teams.

KK: Over my many years, I have come to appreciate having a dialogue with my clients rather than simply being told what material to use. Each clinical case presents specific challenges, and, dependent upon the desired aesthetic outcome, patient expectations, preparation design, restorative space provided, material thickness, stumpf (dentin) shade, functional situation, and strength requirements, a suitable restorative material may then be collaboratively chosen.

Figure 6a. The removal of 2 anterior PFMs on maxillary centrals. Numerous photographs were taken to provide characteristics of adjacent teeth to match.	Figure 6b. The all-ceramic crowns on the model.

Figure 6c. The completed IPS Empress Esthetic crowns on the maxillary centrals. All shades and characteristics were transferred to the ceramist via photos.

What materials do you prefer for the majority of your restorative cases, both anterior and posterior?

DH: Based upon more than 25 years of experience with it, I am a huge fan of IPS Empress Esthetic (Ivoclar Vivadent), and I request that all anterior restorations are fabricated using this very aesthetic, leucite-reinforced all-ceramic material. I especially like the way it interacts with light better, compared to any of the other materials. For posterior teeth, it really depends upon my preparation design. For full coverage on molars, I use high-translucency zirconia. The aesthetics are excellent, and studies have shown that this material can be bonded in using resin cements. It also exhibits good wear characteristics. Also, I only need a 1.0-mm minimum occlusal reduction with this material, which is helpful on second molars with short preparations and minimal inter-arch distances. For inlays and onlays on molars, I prefer lithium disilicate (IPS e.max [Ivoclar Vivadent]). All bridges in my office are zirconia frameworks overlaid with either a powder/liquid ceramic or a pressed ceramic. The only time I use metal in my practice is when I restore implants using hybrid abutments.

KK: As I mentioned earlier, each case is a little different. However, if we begin with the end in mind, and if we collaboratively develop a comprehensive treatment plan and put in place specific “fail-safes,” an appropriate material may be selected for each case. While we still do a fair number of IPS Empress Esthetic restorations, and certainly do a large number of lithium disilicate IPS e.max restorations as well, today’s higher translucency zirconia materials afford exceptional aesthetic alternatives, so these should also be considered.

When doing a full-mouth case, what is the first and most important step that you complete prior to a diagnostic wax-up?

DH: There are 2 very essential parts to this question: The first is based on aesthetics, and the second is related to function. The smile must be designed by the clinician before the technician can even begin the wax-up. This design must include the following: (1) the incisal edge position of the centrals, (2) the smile line, (3) incisal edge inclination, (4) the midline position, (5) the profile of the anterior teeth, (6) the buccal corridor, and (7) gingival changes. This is the same list of information needed by denture technicians before the teeth are set, and the final assessment and adjustments are made by the clinician during the wax try-in. With regard to establishing proper function, I take a physiological bite driven by muscles and determine any changes that will be made to the vertical dimension of occlusion (VDO). The technician cannot even begin a wax-up without an accurate restorative bite position. My personal occlusal philosophy is based upon using a midpoint stop appliance, or a deprogrammer, to allow the muscles to determine where the condyle should be placed. This is a physiological bite and is muscle driven, which is why I use what I call a Freedom Appliance. This appliance is designed by opening the bite on an articulator just enough so that we have posterior clearance and then placing a composite platform behind the maxillary central that is in contact with the lower incisors. This composite is then light cured. Next, I remove the maxillary model and take an Essex-like suck-down material and vacuum form it over the model with the composite platform. This Freedom Appliance is then trimmed to the premolars only. The patient wears this for several weeks, and without posterior teeth influencing the seating of the condyles, I can then take a bite with this appliance in place. I realize that I am sharing this as an abbreviated description of a very important, detailed step in achieving success with full-mouth rehabilitations.

KK: From a laboratory technician’s perspective, I want the patient to be deprogrammed and the muscles to be in a relaxed state so that the condyles are seated in their most optimal positions and, ultimately, that any occlusal prematurity or interference may be eliminated to provide a stable joint and an optimal functional situation. By abiding by these principles, I know that when we choose the appropriate maxillary incisal edge position and develop the envelope of function around it, our restorations will not only be highly aesthetic but will also service the patient well for the long term.

What information or variables are required to obtain a functional and aesthetic wax-up from your lab technician?

KK: In addition to the information Dr. Hornbrook just shared, first and foremost, we need a maxillary incisal edge position for teeth Nos. 8 and 9. If there is a new VDO, then we need that information as well. Additionally, a bite record of the current situation; a stick bite; and, finally, the 12 recommended AACD photos will provide us with the necessary information to develop the new smile design.

How important is it to deprogram the muscles and to identify occlusal prematurities and interferences prior to establishing a new VDO?

DH: In my opinion, anytime we see anterior wear of teeth, deprogramming or taking a muscle-driven physiological bite is mandatory. Changing the VDO requires this step as well. If I am restoring a smile, and there is no tooth wear, then there really is no need to take a deprogrammed bite.

KK: In my opinion, it is paramount, as mentioned previously.

How do you convey subtle nuances in incisal characteristics to your ceramist?

DH: Always take and share photos! I have created a library of different incisal edges that I can first show my patient and get his or her approval and then send directly to my ceramist to match. Ceramists are all very visual individuals, and if you send a photo, they can match it. I think the best source of information is to fill your library with photos of cases that you have done and, even better, photographs of natural, unrestored anterior teeth taken of patients in your practice.

KK: We have a unique working relationship with our clients. Each client has full access to his or her cosmetic ceramist, and as a natural consequence of getting to know one another and each other’s preferences, we develop specific smile styles, mamelon characteristics and corresponding translucency, and subtle color nuances that will serve as the standard for restoring smiles going forward. Some of our clients also prefer to draw pictures to communicate some of these details.

When you and your ceramist approach a cosmetic case, how much artistic freedom is allowed? What parameters are within this approved arena of creativity?

DH: Other than subtle shape characteristics, I do not give them much creative license. This is because I need to discuss all the variables with my patient during my smile design consultation and then transfer these variables to the ceramist to match. I am always open to discussing any suggestions that my ceramist has and will often incorporate them back into my smile design. This comes into play most often with changes to provisionals when the ceramist sees the photos and suggests changes in things like the buccal corridor, length, embrasures, etc.

KK: As I mentioned earlier, our clients develop a very unique and specific preference for their smile design cases, and while they still afford us some artistic freedom, once we arrive at a “look” that serves their clientele well, we tend to stick with that signature.

What do you feel is the most important detail you can provide the lab technician when creating a new smile on a worn dentition case?

DH: The most important detail is the final maxillary incisal edge position! A talented ceramist can usually design a reasonably nice case if he or she knows where the incisal edges need to be. Without this vital information, the ceramist is lost.

KK: I totally agree! It’s definitely the new maxillary incisal edge positions of teeth Nos. 8 and 9. Even a crude mock-up in the mouth and a photo and measurement of the incisal edge positions are incredibly helpful!

Why is the maxillary incisal edge position so critical for a technician, and how is this information used?

DH: Because the position of every tooth in the mouth is determined by the incisal edge position of the maxillary central incisor. Think dentures! As the denture is designed, the first thing the clinician determines in the wax rim is where the maxillary incisal edge will be placed.

KK: The maxillary incisal edge position governs and frames the smile. With this detail, everything else will fall into place. From observing natural smiles that we find attractive, we then begin to work from the front of the mouth and move posteriorly, not only developing the elements of aesthetics but also the envelope of function, which will guard and protect the posterior teeth. Inter-incisal embrasures progressively open as one moves distally, and by the time one completes the canines, the buccal corridor begins to fill in, and the smile can then come to life. Dr. Hornbrook likes to say that “Aesthetics drive the case, and function completes it.”

Acknowledgments:
Dr. Hornbrook and Mr. Kohli would like to acknowledge Josh Walker, Phil Nebeker, and Taylor Salinas, ceramists at Utah Valley Dental Lab in Lindon, Utah, for the work performed in the images accompanying the cases in this article.

Dr. Hornbrook graduated from the University of California, Los Angeles School of Dentistry and maintains a private practice in San Diego focused on adult restorative and functional aesthetic dentistry. He is the clinical director of education at Utah Valley Dental Lab in Lindon, Utah. He can be reached via email at david@hornbrook.com.

Disclosure: Dr. Hornbrook is director of education at Utah Valley Dental Lab.

Mr. Kohli is COO and director of operations at Utah Valley Dental Lab. He can be reached at kent@uvdl.com.

Disclosure: Mr. Kohli is an international instructor for Kuraray Noritake. He did not recieve compensation for this article.

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HOW TO COMMUNICATE SHADE  TO THE LABORATORY

Figure 1. VITA 3D shade guide (Vident) demonstrating color orientation of the guide.	Figure 2. Step 1: selecting the appropriate value on the VITA 3D shade guide.
Figure 3. Step 2: selecting the appropriate chroma on the VITA 3D shade guide.	Figure 4. Step 3: selecting the appropriate hue on the VITA 3D shade guide.

Shade selection can be simplified with a shade guide that is arranged based on value, chroma, and hue, allowing the dentist to quickly determine the base shade for the tooth. The VITA 3D shade guide (Vident)  (Figure 1), with groupings based on hue and then value and chroma, has been developed to replace the popular original VITA shade guide and other shade guides that are arranged in a more traditional manner.
It is important that shade selection be performed before the tooth dries, as a dry tooth will appear lighter in value than a moist tooth. First, we need to determine the value of the patient’s teeth. How light or dark are the teeth? Holding the shade guide at arm’s length next to the patient’s mouth determines which group on the shade guide has the correct value. Starting with the right side of the shade guide, the darker value groups determine which of the 5 groups on the shade guide is closest to the tooth to be matched. For example, the value of the tooth best matches group 3 (Figure 2).
Next, we need to determine the tooth’s chroma. Each of the 5 shade groups on the guide has a middle (M) group. Take the M group for the group you selected previously based on the value, and spread the 3 tabs apart and select which saturation level matches the saturation of the tooth being matched. In our example, we determine that the chroma best matches the middle tab of the 3M group (3M2) (Figure 3).
The final step is determining what hue best matches the tooth being matched. Groups 2, 3, and 4 consist of 3 groups each. Groups 1 and 5 only consist of an M group. The group to the left of the M group—the L group—is more yellow than the M group, and the group to the right—the R group—is more red than the M group. Determine if the tooth looks more yellow or red than the M group. The tab that is selected is the base color for the restoration to be done, which in our example we determine that the 3L1.5 is the best match based on the value, hue, and chroma (Figure 4).

COMMUNICATING WITH THE LABORATORY

Selecting a shade tab that meets the criteria of value, hue, and chroma does not mean that the restoration will blend with the surrounding teeth. We need to have a way to communicate the nuances of the tooth to be matched, such as incisal translucency, craze lines, surface texture, and maverick colors. Maverick colors refer to spots of intense color in the tooth that stand out from the surrounding enamel.
Unfortunately, how one person would interpret a written description of what the tooth looks like often is not how another will interpret the same information. As it has been said, “a picture is worth a thousand words.” Photographs assist in communicating what we are seeing chairside to the lab, but the human eye is much more precise in interpreting the information than a camera. The value, hue, and chroma shown in the photographic image are not only affected by the particular camera and its settings, but also by the ambient light present when the image was taken. Additional factors that will affect these color factors are the printer and the monitor. Different printers will render colors differently, so printing the photographic image to send to the lab may not provide accurate value, hue, and chroma of what was seen clinically. This is also an issue when images are emailed to the lab, as different monitors will render different degrees of color for the same image. What you see in your office on your monitor will not be the same value, hue, and chroma that the lab sees on their monitor.

Figure 5. Photograph of the shade tab selected as matching the patient’s native shade shown adjacent to the patient’s tooth.	Figure 6. Photograph of the shade tab selected as matching the patient’s native shade shown with the incisal of the tab contacting the tooth’s incisal edge to help communicate incisal-to-cervical shading.

Digital images are an effective method of communicating with the lab. When photographing a shade tab intraorally, it is best to take 2 views of that tab to aid the lab in how it coordinates with the patient’s tooth color. Typically an image is taken with the shade tab adjacent to the tooth being matched. It has also been recommended that a photograph be taken with the shade tab’s incisal portion contacting the incisal of the tooth being matched, to help communicate gradations from the incisal to the cervical as they relate to the shade tab. These photographs aid the lab in seeing shade comparisons but can be deceptive in communicating the nuances in the tooth (Figures 5 and 6).

SIMPLIFYING SHADE COMMUNICATION

Figure 7. Sopro 717 intraoral camera (Acteon).	Figure 8. SoproShade on the Sopro 717 camera (Acteon).
Figure 9. Sopro 717 control switch with the 3 image positions; full image, left half, and right half.	Figure 10. SoproShade adaptor on a Sopro 717 camera capturing image intraorally.
Figure 11. A patient’s tooth demonstrating incisal translucency and a halo effect in the enamel; craze lines are also evident.	Figure 12. Conversion of the full-tooth image to gray scale assists the lab in seeing texture and light reflection on the tooth’s surface.
Figure 13. Inversion of the full-tooth image gray scale assists the lab in seeing texture and light reflection on the tooth’s surface.	Figure 14. Patient’s tooth captured on left half of image.
Figure 15. SoproShade on the Sopro 717 camera capturing the shade tab.	Figure 16. A patient’s natural tooth depicted on left half and Vita 3D shade tab on right half demonstrating shade comparisons.

Figure 17. A patient’s tooth showing enamel craze lines and a more uniform color variance from cervical-to-incisal.

The SoproShade and Sopro 717 (Acteon) are intraoral camera aids in this communication by providing detailed images quickly and easily. The SoproShade allows the room’s ambient light to be blocked from the image of the tooth being matched while controlling the illumination of the tooth (Figures 7 and 8). The Sopro 717 camera is set with the control switch in the top position to capture a full-tooth image, the SoproShade guide is placed on the tooth with the incisal edge in the holder, and an image is taken (Figure 9). This image will communicate incisal translucency, maverick colors, texture, imperfections within the enamel and gradations across the tooth surface. To aid in communication of areas of light reflection and surface texture, this image can also be converted to a gray scale im-age which will aid the lab in developing a more natural blending restoration. It may be of additional benefit to the lab to also send an inverted image of the gray scale of the full tooth, as this provides more information on surface texture and areas of light reflection than a 2-D image of the 3-D object can provide. The conversion to gray scale and the inverted image can be accomplished with Adobe Photoshop, ACDSee, Paint Shop, or any image editing program (Figures 10 to 13).
Next, the control switch is clicked to the middle position and another image is taken of the same tooth. This will capture the left half of the tooth. The control switch is then moved into the bottom position, the shade tab selected previously is placed in the Sopro-Shade, and the right half of the shade tab is captured adjacent to the left half of the tooth. This will communicate how the base shade relates to different areas of the tooth (Figures 14 and 15).
Additionally, by capturing different shade tabs around the one that was selected intraorally we can confirm which tab best matches the value, hue, and chroma of the tooth. In the example illustrated in Figure 16 we see that the 4M1 tab best matches the tooth’s base value, hue, and chroma.

CONCLUSION

Communication is the key for the dentist and lab in developing ceramic restorations that blend with the surrounding dentition. Selecting an appropriate shade is only the first step in getting the restoration to match adjacent teeth. As teeth are not uniform in coloration from cervical to incisal, they have imperfections such as spots of color and craze lines, and translucency gradients vary from patient to patient. It is important to be able to communicate those nu-ances to the lab (Figure 17). The Sopro-Shade and Sopro 717 camera allow transmission of this information in a method different from traditional cameras or other intraoral cameras.

Acknowledgement

The author would like to thank Dr. Mark Murphy for his assistance with imaging accompanying this article.

Dr. Kurtzman is in private general practice in Silver Spring, Maryland. He has lectured both nationally and internationally on the topics of restorative dentistry, endodontics, and dental implant surgery and prosthetics. He can be reached by email dr_kurtzman@maryland-implants.com.

HOW TO COMMUNICATE BRIGHT

So, how do we communicate bright? First, let’s look at how the laboratory works with porcelain. We get porcelain in a powder form, mix it with liquid, and we’re good to go. Unlike zircon blocks that are carved from outside in, where you cannot affect the internal color, porcelain is being built up incrementally (well..when it’s done right). This way you can layer, segment, and embed different color effects. Many commercial laboratories use a method of building based on body porcelain, which should represent the dentin, and incisal porcelain at the incisal third, which should represent the enamel. But this method is similar to the zircon block that is made with one color and simply carved; in other words, it is monochromatic and thick looking, does not allow light penetration, and does not reveal any depth. As a result, our eyes see only the outside material, like looking at white plastic. Even if the ceramic is not that opaque, because of it’s uniformity of color from the internal mass to the outside surface, it is not giving the appearance of depth.
So, let’s look at what we’ve seen so far: no depth, uniformity of color, no light penetration. This is just the opposite of a tooth, which is described as follows: filled with light, iridescent, radiant, luminous, brilliant, glowing.

Figure 3. Value level (brightness level) equivalent to A2 (VITA Lumin Shade Guide [Vident]).

A monochromatic, dull appearance can be enough to destroy a smile, even if the white level is not that exaggerated. However, some dental professionals use the whitest opacious dentin they can find, and it really does look fake. We have some good porcelain companies available to us, providing a good variety of porcelain shade effects and appearances. It is up to us as laboratory technicians and dentists to understand which effects can be achieved and how to use these porcelains properly.
I have noted that restorations can be too opaque, and therefore appear fake. But what about translucency and transparency? These can provide depth and are surely penetrable by light, but the oral cavity is dark, and a translucent material with a dark background shows darkness and an appearance that is too gray. So, what is the answer? If one is too opaque, and the other is too gray/translucent, should we mix the two?

No. We need the opacious porcelain in some areas, and the translucent one in others. It’s a combination, and the magic word really is layering. If you look at dissected teeth you will see layers, and of course the tooth color is coming from the inside, showing through the enamel. When a restoration is being fabricated we use the opacious dentin porcelain to give the layer underneath a masking effect, whether masking the opaque on a metal-ceramic restoration or masking a very white zirconium coping. In addition, a slightly stronger color than the one that was originally chosen is used, because the bright incisal layers on top, which result in color, diminish.
The dentin body porcelain, which is neither translucent nor opacious, does not have the ability to mask the underlying layer. Not having translucency, it produces no beneficial effect without the opacious dentin underneath it and a layer of translucent porcelain covering it on top. Incisal porcelain (which provides the higher value) by itself is too pale looking and colorless, and does not appear translucent.

So, let’s review. Translucent porcelain by itself is too gray in the oral cavity. Dentin body porcelain by itself is too opaque looking compared to natural teeth, but not opaque enough to mask a substructure. Opaque dentin porcelain by itself is too opacious to resemble a natural tooth, but has good masking ability. Incisal porcelain by itself is too opacious and pale looking and has no color (at least not visible color), but appears as high value.
The essence of bright is a layered combination of these abilities. The opacious dentin is masking the substructure and providing stronger basic chroma; the dentin body is giving the resemblance of natural tooth dentin; the incisal porcelain is providing the value; the translucent porcelain is covering the structure, allowing the understructure to be visible, and at the same time projecting its appearance of translucent mass without resulting gray, having a nontranslucent structure layered underneath. These are the basics.
There are a lot more porcelains and more involved build-up techniques, but what I’ve described is the A-B-C of porcelain build-up technique. The natural tooth is layered, and so must a porcelain restoration be if it is to appear natural and bright.
After understanding all of this, the best tool to communicate with your technician is to tell him to read this article. Or, you could definitely ask for masking the substructure enough so no reflection of opaque is appearing, and you could definitely ask for translucent porcelain to be the overall covering for the restoration. You can ask for depth in the restoration by asking that the strength of the color be inside, not stained on the outer surface as it would be on a carved block.
To resemble the patient’s natural teeth translucency, on my lab prescription I have at least 3 levels of translucency: low, medium, and high.
Understanding basic layering is understanding how bright can be achieved. (See Figures 1 to 5 for examples of brightness level.)

Acknowledgment

The author thanks the dentists who worked with him on these cases: Dr. Barry Goldman, director of the prosthetic department at Nova Southeastern University (Florida), Dr. Elizabeth Piela (New Jersey), Dr. Derrick Bullock (New Jersey), Dr. Elo Adibe (Pennsylvania/NewYork), Dr. Robert Berg (New York), and Dr. Richard Kraut, chairman of the dentistry department and director of oral and maxillofacial surgery at Montefiore (New York).

Mr. Davidashvilly graduated dental technology school in Israel (1987), followed by a 3-year apprenticeship. After leading European Ceramic Masters, throughout the years he developed techniques and ways of his own. He graduated from New York University, (American Society of Master Dental Technologists) in 2000, and since 2004 has been working closely with Mr. Vincent Alleluia, MDT, TFNGS (Technical Fellow Northeastern Gnathological Society), as an instructor in this program. He has worked at labs in Israel and New York and managed Monte-fiore Hospital’s lab (New York) in the prosthodontic department. Today, he gives lectures, presentations, hands-on courses, and writes articles. Mastering gnathology, morphology, aesthetics, and ceramics has enabled Mr. Davidashvilly to perform with superior excellence. He owns Art & Science Dental Lab in Farmingville, NY, and can be reached at (631) 285-1112, mmdt100@gmail.com, or BennyDavidashvilly.com.

MODEL WORK CHALLENGES AND SOLUTIONS

If doctors do their own model and die work, sending it directly to an ALMC, then they must take responsibility for certain related challenges that may affect the quality and timeliness of the CAD/CAM work being requested (Figure 1). The type of stone used, the model base design, the quality of model pours, and any subsequent in-office die trimming are all sources of potential problems for the ALMC if one does not know exactly how to perform these tasks specific to a CAD/CAM zirconium oxide system. Also, as with the outsourcing labs previously discussed in Part 1, if the dental office team improperly packs models and dies for CAD, then the risk is much higher that they will arrive in a damaged condition.
All model work completed in the dental office should be done according to the Lava All-Ceramic System Laboratory Preparation technical guidelines bulletin (3M ESPE). Doctors and their dental office team must ensure that all model work is then properly packed for shipment. Before packing and sealing the case box, a trained team member should perform a careful inspection. Time should be taken to check that all model work has been performed properly and that the prescription is both legible and complete.

PREPARATION CHALLENGES AND SOLUTIONS

According to feedback from ALMCs, preparations are the main source of technical challenges they receive from their doctors. ALMCs report that they frequently observe a variety of preparation problems that can make it difficult to move the work through the scanning, design, and milling process efficiently. Problems range from knife-edge margins and J margins to undercuts and dimensional challenges. At the very least, preparation problems often require unnecessary phone calls to the doctor and/or the outsourcing laboratory. In some cases, because of the seriousness of some of these challenges, the quality of the case can be compromised, and returning the case for re-preparation may sometimes be the only option. Ironically, iatrogenic preparation errors, as seen in the laboratories and reported in this article, are almost always preventable or repairable at the initial operative stage prior to taking the final impression.

Figure 1. This die was sent in with numerous bubbles. The ALMC must pour a new model before scanning and design can begin.	Figure 2. Note the knife-edge margin evident around the buccal aspect (right side) and lingual aspect of this otherwise nicely done preparation.
Figure 3. An example of beautifully prepared chamfer preparations. Well-defined, 0.7-mm to 1.0-mm (360?) chamfer margins are ideal for scanning and CAD. They will result in milled copings/frameworks with sufficient room for the layering porcelains, natural emergence profile, and optimal aesthetics in the cervical areas.	Figure 4. A model cut with ideal chamfer margins can be a valuable visual aid. Whether creating a beautiful sculpture or an exceptional preparation, beginning with the final form in mind positively affects the final outcome.
Figure 5. Note the undercut areas that are evident circumferentially on the die in the cervical one-third. This over-reduction was a result of utilizing a round bur to create a chamfer margin depth cut. It must be blocked-out with wax prior to scanning.	Figure 6. A chamfer of a predetermined depth is developed by carefully cutting the margin at one-half the tip width of the bur. Shown is an 856-018 chamfer bur that has a tip width of 1.45 mm and will create a 0.7 mm chamfer when used properly.

Knife-edge margins are contraindicated for any type of all-ceramic restoration including aluminum oxide or zirconium oxide systems. (This style of margin is only appropriate for certain metal applications.) The knife-edge margin can be created unintentionally by using a bur that is too small in diameter to cut an adequate chamfer or when the preparation is prepared too conservatively (Figure 2). This can create problems in identifying and scanning the margin. It also tends to lend itself to exaggerated contours in the cervical one third, since there is not enough room for both the coping thickness and an adequate thickness of layering porcelain. The resulting bulkiness can lead to improper food deflection and possible periodontal problems down the road for the patient.
The chamfer is the ideal margin design for zirconium and aluminum oxide coping system restorations. When adequate tooth structure is available, the ideal minimal chamfer depth is 0.7 mm to 0.8 mm to allow room for the underlying coping and adequate layering porcelain (Figures 3 and 4). It is interesting to note that a well-executed chamfer seems to be a difficult design for many practitioners to master. This can be confirmed if one critically examines cases entering our dental laboratories. Some noted educators, having observed this as well, have recommended utilizing a modified shoulder design in lieu of a chamfer preparation. While a modified shoulder design will work for these porcelain systems, it is a less conservative margin design compared to a properly executed chamfer. Others have advocated utilizing a round bur technique to make a circumferential depth cut to establish a chamfer margin. This technique can lead to circumferential undercuts when not done carefully (Figure 5). Still others have advocated the use of gingival curettage diamonds, known as K-type diamonds (eg, 878K Axis Dental or Brasseler USA), probably with the intention of preventing the J margin. These burs have tips that are pointed instead of bullet-shaped like the 856 chamfer bur series. Unfortunately, when used in what have turned out to be the most popular sizes (014 and 016), these K-type burs create shallow chamfers in the range of 0.3 mm to 0.5 mm. Although less severe than in the case of a knife-edge margin, this can also lead to overcontouring issues and aesthetic problems, as referred to in Figure 2. However, it is important to note that when preparing small teeth such as mandibular anteriors or maxillary peg laterals, very shallow chamfers may be the only choice. In these cases, a K diamond might be a good bur to use, and our dental technicians must simply deal with the contour and aesthetic challenges that result as best they can.
When a tapered 856 bur is used to prepare a chamfer margin, the cut should be made to one-half the tip width of the bur. The depth of the chamfer margin thus becomes dependent on the size of the bur used (Figure 6). Manufacturers can supply the bur dimensions upon request, or burs can be accurately measured with digital calipers.

Figure 7. This is a dramatic example of a J margin created by overpreparation with a chamfer bur. Even if a CAD/CAM coping is designed here, there will be significant challenges for the ceramist and potential for margin damage of the die and solid model. (Also note the circumferential undercut in the cervical one-third and sharp line angles at the occlusal aspects.) Diplomatic technician-doctor feedback resulting in a prep revision is the best solution here.

Figure 8. An end-cutting bur can be used to correct a J margin by removing the outer ìlipî quickly and without damage to the tissue or further reduction of the axial walls. (An M839 Axis Dental bur is shown here. This bur type is usually used to refine and smooth a shoulder for pressed ceramic preps.)

A problem with the 856 bur design can occur if the tip is carried into the tooth too deeply, causing a J margin (Figure 7). Careful post-preparation and preimpression inspection with a sharp explorer and/or visible inspection with magnification can easily identify the problem before the case is sent to an outsourcing lab or ALMC. This can then be corrected by morphing the J margin into a modified shoulder preparation. This is done by carefully reducing the outer marginal edge adjacent to the gingival collar with a M839-014 or M839-016 (Axis Dental) end-cutting bur. (An equivalent bur from Premier, Brasseler USA, SS White, or another bur manufacturer may be used as well.) End-cutting burs are an ideal choice because they will not harm the gingival tissue as the prep correction is completed (Figure 8).

Figure 9. An axial wall height of 4 to 5 mm interproximally will ensure that there is adequate dimensional room to design and mill the 9-mm, 2-abutment pontic interconnectors required for this posterior bridge.

A final preparation challenge cited by the ALMCs is related to the axial wall height of finished bridge abutment preparations. This problem occurs when there is inadequate room for framework dimensions in the interproximal areas. In designing strong tooth-to-pontic interconnectors, the dimensional requirements are minimal at the mesial and distal surfaces of the abutment teeth adjacent to the pontic. An important part of the solution to this problem is to know what dimensions are required in order to design a strong interconnector that properly supports the layering porcelain and resists the forces of mastication. As a rule of thumb, axial wall height of the prep, or prep and core, at the marginal ridge areas should be 4 to 5 mm minimum (Figure 9). Anterior interconnectors for zirconium oxide are ideally milled at 7 mm², while posterior interconnectors are milled at 9 mm². The Lava CAD system will not allow the mill to create a framework with less than ideal interconnector dimensions. To do other-wise could compromise the strength and/or aesthetics of the final prosthesis.
The doctor should complete a preoperative assessment of the available room in the occlusal-gingival and buccal (facial)-lingual dimension before preparation is begun. Ideal interconnector dimensions should be kept in mind. According to the ALMCs, the vertical height of the interconnector, between the abutment teeth and the pontic(s), is extremely critical to the strength of the beam as it is loaded under occlusal compression in function. In order to gain needed vertical interconnector room for a fixed bridge utilizing a zirconium oxide framework, the practitioner may want to consider placing the margin deeper cervically. However, while the option of placing the interproximal margin deeper to extend the usable axial wall height can be a potential solution, the proper biologic width must always be respected to ensure postoperative gingival health.
If tooth wear and a resulting decrease in available restorative vertical dimension is severe enough to obviate the achievement of proper interconnector dimensions with preparation and margin placement techniques alone, then the most conservative approach should still be considered before proceeding. Despite the added cost and time for the patient, an interdisciplinary approach and diagnosis may be the correct way to proceed.
For example, treatment options such as crown lengthening done by the periodontist can sometimes be a solution as a prerestorative procedure. In still other very select cases, opening the bite (OVD) may be the only vi-able alternative. Any decision to move in this direction, by the nature of the work it necessitates, will radically change and complicate the treatment plan.

CONCLUSION

Ultimately, excellent communication and direct responsiveness in enacting solutions for any identified team challenges will help to ensure success for CAD/CAM systems like Lava. The implementation of consistent teamwork among doctors, outsourcing labs, and ALMCs will yield optimal restorative results, reduce mutual stress, and maximize profits. Laboratory teams should encourage their doctors to fully understand the indications for zirconium oxide copings and frameworks, preparation requirements, and certain laboratory technical requirements. Most importantly, preparations should be designed with the scanning, CAD process, and end product in mind. Finally, an inspection for quality, completeness, and proper shipment preparation of all materials being sent into the ALMC, whether by an outsourcing laboratory or the doctorís office, will be time well spent.

Additional Resources/Reading

Shillingburg HT Jr, Jacobi R, Brackett SE. Fundamentals of Tooth Preparations for Cast Metal and Porcelain Restorations. Hanover Park, IL: Quintessence Publishing; 1987.

3M ESPE. Lava All-Ceramic System Laboratory Preparation. St Paul, MN: 3M ESPE; 2002. http://solutions.3m.com/wps/portal/3M/en_US/3M-ESPE/dental-professionals/products/category/lab-digital/lava-crowns-bridges. Accessed September 24, 2007.

Note: This technical guide regarding LAVA requirements is available for dental laboratories and is also applicable for doctors who prefer doing their own model and die work. The instructions should be reviewed thoroughly and followed exactly to help prevent technical problems or production delays in the milling centers.

Reference

1. Nothdurft FP, Rountree PR, Pospiech PR. Clinical long-term behavior of Zirconia-based bridges (LAVA): five years results. Presented at: IADR Pan European Federation; September 13-16, 2006; Dublin, Ireland. Abstract 312. http://iadr.confex.com/iadr/pef06/techprogram/abstract_85451.htm. Accessed September 24, 2007.

Acknowledgment

The author extends his heartfelt thanks to all the experienced personnel from the Authorized Lava Milling Centers who participated in this project by providing candid information, technical advice, and photos needed to write this article.

Dr. Adams, a graduate of the University of Michigan, is an assistant clinical professor in the Dental Residency Program at the University of Toledo College of Medicine. He lectures internationally emphasizing doctor-technician relationships and techno-clinical perspectives. He also facilitates hands-on preparation workshops designed to optimize the utilization of all-ceramic systems. In addition to his years in private practice, he has had the opportunity to serve as a doctor-technician liaison for many dental laboratories throughout North America for more than 12 years. Dr. Adams is a Contributing Editor for Dentistry Today and is listed in Dentistry Today’s Top Clinicians in Continuing Education (2004 to 2007). In addition, he also serves on the Advisory Board for Spectrum Dialogue (Palmeri Publications). Dr. Adams is a member of the ADA, AGD, AACD, and the National Association of Dental Laboratories. For Dr. Adams’ contact and course information, visit adamsdentalseminars.com.

Disclosure: Dr. Adams has no financial interest in any of the companies referred to in this article.

THE LAVA SYSTEM AND OUTSOURCING LAB-ALMC RELATIONSHIPS

Figure 1. Preoperative photo (No. 30) shows an indirect composite onlay at 5 years requiring a full-coverage restoration.	Figure 2. The completed Lava crown (view of the internal aspect). Note the more opaque appearance of the zirconium oxide coping.

Figure 3. Postoperative photo of the completed posterior Lava crown (No. 30).

Before beginning to discuss the identified challenges and concomitant ramifications for the ALMCs, it is appropriate and helpful to provide a brief review of the CAD/CAM Lava restorative system. We will also briefly examine the various laboratory-ALMC business models that are now actively engaged in the production of these all-ceramic restorations.
In 2000, the Lava system for crown and bridge restorations was clinically introduced in 3M ESPEís experimental operatories in Germany. The first university study began in 2001, with 5-year recall results being published in 2006.¹ Five years ago in 2002, after receiving FDA approval, Lava was first introduced into the United States commercially and has become a widely used all-ceramic system. Lava is a zirconium oxide-based crown coping and bridge substructure system that provides for both underlying strength and aesthetics when veneered according to recommended techniques with the appropriate oven-fired layering porcelains. It can serve as an anterior or posterior all-ceramic alternative to porcelain-fused-to-metal crowns and bridges in many but not all circumstances (Figures 1 to 3). (Contact 3M ESPE or your dental laboratory for a list of Lava indications and contra-indications.) Lava is another example of a lab-fabricated product that goes though the same basic material-data relay loop (doctor to outsourcing lab, to milling center, back to outsourcing lab, to doctor) as described earlier.

Three different business-production models for the CAD/CAM process are available to laboratories fabricating Lava restorations:

(1) The first one is when the dental laboratory owns and houses the CAD/CAM equipment within the same full-service facility. In this model the Lava crowns and bridges are fabricated from start to finish, with the completed product delivered directly back to the doctor for delivery to the patient.

(2) Since many labs do not own their own Lava milling machines due to their physical size, financial abilities, or other reasons of choice, they find it advantageous to outsource the entire CAD/CAM process to an ALMC. Upon receipt of the necessary materials and information from the outsourcing lab, the ALMC scans, designs, and mills the Lava copings and frameworks. The completed millings can then be returned to the original outsourcing laboratory for the addition of layered porcelain and then final delivery to the doctors.

(3) The third business-production model is established when laboratories choose to buy the CAD component only (no milling machine) and become an Authorized Lava Design Center (ALDC). ALDCs are outsourcing labs performing the scanning procedure (CAD) by utilizing Scan ST (3M ESPE) equipment. Scan ST is a remote scanner using the same software as that used by the ALMCs, without the milling component. They then send the data to the ALMC to complete the actual milling process (CAM), thus saving the expense of owning milling machines. This also enables them to have direct control over the designing procedures. It serves to reduce turnaround time and allows them to keep all dental models within their lab. In addition, it gives them the ability to deal directly with any of their doctorís technical issues in a very timely manner.
(Note: 3M ESPE has been offering a choice among these 3 business-production models depending on the particular lab’s goals, needs, and abilities. It allows smaller labs to essentially ìplay on the same fieldî with the larger labs in order to provide their doctors with state-of-the-art materials.)

Figure 4. An example of broken models that an ALMC received from a Lava outsourcing lab. ALMCs stated that this problem happens more frequently than it should.

CHALLENGES PRESENTED TO ALMCS BY OUTSOURCING LABS (WITH SOLUTIONS)

Any problems that occur  before models and/or data entered the ALMC and have not been solved at either the doctor or outsourcing lab level must ultimately be addressed by the ALMC. The outsourcing lab must then contact its doctors if and when it is required. Time and money could be saved if problems, or potential problems, can be caught at the outsourcing lab. Following are the 3 major areas that are most commonly cited by the ALMCs as needing the attention of their outsourcing labs to improve the quality and flow of work both in and out of their facilities.

Broken Models

Figure 5. Note the inability of the shipper to heed the ìFragileî marking on the side of this important package. This points out the need to employ careful packing procedures.	Figure 6. This package shows great protection from all sides. Also note the care in packaging that has been given for all the contents.
Figure 7. An example of an individual case properly packed with the Rx in a separate bag.	Figure 8. When shipping an articulated model it is best to place protection between the teeth.

If models for CAD are inadequately packed, they have a greater chance to arrive broken (Figure 4). Sometimes the shipping company can be less than careful about how it handles even a package marked “fragile” (Figure 5). This results in a valuable loss of production time due to the calls that have to go back and forth among all the involved parties. Unfortunately, it may often mean that the doctor will also have to be called for new impressions. This in turn can result in a loss of trust by the doctor and dental office staff that can reflect on both the outsourcing lab and the ALMC.
Solutions: The ALMCs want their outsourcing labs to ensure that all model work is properly packed for shipment. It is important to individually wrap every model and to secure the wrapping with clear tape or rubber bands. In addition, use only sturdy shipping boxes with ample protection provided by packing materials placed on all sides. (Figure 6). Do not use Fed-Ex Small Paks or other paper or fiber envelopes intended for document shipping. When sending in multiple cases in a single box, each doctor’s individual case models should be individually wrapped and put in separate bags with the prescription enclosed (Figure 7). If articulated models are shipped, place bubble wrap between the teeth as a start to wrapping the model (Figure 8).

Missing Rx Information

Believe it or not, outsourcing laboratory technicians, who themselves complain about receiving prescriptions from doctors who fail to fill them out completely, can be guilty of doing the same thing to ALMCs. Time must be allowed to pay attention to the details in this scripting procedure. Haste and omission will lead to unnecessary calls, wasting precious production time as well as negatively affecting the inter-business (outsourcing lab-ALMC-doctor) relationships.
Solutions: The outsourcing lab needs to remember why it is important for it, the ALMC, and most importantly the doctor, to fill out the ALMC prescription completely. The outsourcing lab should institute and employ a business system that requires a thorough check for completeness and accuracy before the shipping bag/box is sealed. Also, as reported by the ALMCs’ actual experiences, it is important to make certain that the Rx matches the case and model work that is being sent.
With regard to shade information on the Rx, Lava copings and frameworks can be manufactured in different shades to coordinate optimally with the layering porcelain that the outsourcing lab will be applying later. These are known as Frame Shades (3M ESPE), and are numbered from zero to 7, making a total of 8 different shade choices available. (The ìzeroî frame shade is the one most often used for overlying porcelain to be completed in the bleached shade range.) Outsourcing labs need to remember to reference a shade on the prescription to the ALMC so that millings can be shaded to coordinate aesthetically with the subsequently fired veneering porcelains.
With respect to any calls placed regarding the need for more or missing information on the prescription, common courtesy and on-time production requires that all calls should be returned promptly to the ALMC.

Improperly Done Model and Die Work

Figure 9. These dies were trimmed improperly, and the outsourcing lab or doctor outlined the margins in red prior to sending in the case (despite 3M ESPE directions to not mark the dies, which can compromise scanning). Note also that the pontic area is not sectioned and pinned.	Figure 10. A properly trimmed die for Lava scanning. Block-out wax was used where the doctor had used a ìround-bur chamfer techniqueî and produced an undercut above the chamfer margin.

Figure 11. A white indicator spray has been applied to the block-out wax prior to scanning to allow for better data registration. These sprays do not seem to affect the integrity of margins.

ALMCs stated that in some cases dies and model work (including opposing models) are not sent in with the case. Sometimes the model work is received with defects or problems of various kinds (bubbles, voids, sealer on dies) and/or the dies are not trimmed according to Lava specifications. Models for bridge work are sometimes sent into the ALMC that are not set-up correctly (pinned) for scanning (Figures 9 to 11).
Solutions: A light-colored type IV or V die stone (white, beige, buff, or green) without plastic additives (resins) should be used. Attention should be given to ensure that the model bases are smooth and flat with minimal thickness to gain maximum optical accessibility. (A common split-cast system is recommended.) For bridges the model needs to be removable from the articulator and mounting plates because the articulator will not fit in the scanner.

All areas of the model need to be pinned and removable for scanning purposes (Figures 12 and 13). Copings or frameworks for implant abutment posts should also be pinned and removable. For large cases, the ALMC needs study models and diagnostic wax-ups to assist in properly designing the frameworks. When standard copings (only) are requested and single dies are submitted, the labial (buccal) and lingual sides should be marked accordingly to ensure orientation for proper coping design.

CONCLUSION

Excellent teamwork between the outsourcing labs and ALMCs is important to reduce mutual stress and to maximize profits. To serve their doctors better, and to assist ALMCs in providing the quality service that they are being expected to complete in a timely fashion, outsourcing laboratories should perform preshipment checks (QCs) on every case. Inspection and evaluation for completeness, quality, accuracy, and proper shipping preparation of all materials being sent into the ALMC is time well spent.

Reference

Additional Reading

2.  ESPE Dental Products.  Lava All-Ceramic System Laboratory Preparation [Technical Guidelines No. 70-2009-3507-3]. St Paul, Minn; 3M: 2002. Published. PDF: http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs666JM9COrrrrQ-.

Acknowledgment

The author wishes to thank all those experienced personnel from the Authorized Lava Milling Centers who participated in this project by providing candid information, technical advice, and photos.

Dr. Adams, a graduate of the University of Michigan, is an assistant clinical professor in the Dental Residency Program at the University of Toledo College of Medicine. He lectures internationally emphasizing doctor-technician relationships and techno-clinical perspectives. He also facilitates hands-on preparation workshops designed to optimize the utilization of all-ceramic systems. In addition to his years in private practice, he has had the opportunity to serve as a doctor-technician liaison for many dental laboratories throughout North America for more than 12 years. Dr. Adams is a Contributing Editor for Dentistry Today and is listed in Dentistry Today’s Top Clinicians in Continuing Education (2004 to 2007). In addition, he also serves on the Advisory Board for Spectrum Dialogue (Palmeri Publications). Dr. Adams is a member of the ADA, AGD, AACD, ICOI, ICD, and the National Association of Dental Laboratories.

Disclosure: Dr. Adams owns no financial interest in the companies he refers to in this article.

CASE REPORT

Figure 1. This patient’s smile does not match her facial features.	Figure 2. Old crowns are removed and the teeth prepared. Digital photo is taken of the chosen shade.
Figure 3. The Cosmetic Aligner is placed between the patient’s upper and lower teeth after tooth preparation, and is positioned in the correct midline and horizontal plane.	Figure 4. The upper and lower portions of the Cosmetic Aligner are filled with impression material.

Figure 5. The laboratory technician places the Cosmetic Aligner on a master model and marks the midline and horizontal plane.

As seen in Figure 1, this patient’s smile does not match her facial features. The dentition is slightly tilted to her left, and her upper laterals and cuspids do not match symmetrically. The midline and horizontal plane are not aligned properly. She also would like to whiten her smile.
I removed her old central incisor crowns and prepared teeth Nos. 6 to 12 for veneer restorations. A digital photo was taken with the chosen shade to help our lab tech see the entire picture and have a visual of the patient (Figure 2). I will use a whitening procedure to lighten her lower dentition to complement her entire appearance.
At this point the Cosmetic Aligner was used to communicate to our lab tech exactly where we wanted the midline and horizontal plane. The device was placed between the patient’s upper and lower teeth after tooth preparation and was positioned in the correct midline and horizontal plane (Figure 3).
The technique involves brushing the upper portion of the Cosmetic Aligner with adhesive and filling it with quick-set (30 seconds) bite material (Figure 4). Position the Cosmetic Aligner over the prepared teeth where the midline and horizontal planes are desired. The use of facial landmarks such as the eyes, nose, and lips help determine where to position the Cosmetic Aligner. The prepared teeth barely touch the plastic as the material sets. Fill the lower portion of the Cosmetic Aligner with adhesive and quick-set bite material. Reposition the Cosmetic Aligner on the upper prepared teeth and have the patient close down lightly to make an impression of the lower teeth. Allow the material to set without distorting the position of the Cosmetic Aligner. This technique is not used for bite registration. The occlusal bite is taken separately using the same fast bite registration material.
The laboratory technician places the device on the master model and marks the midline and horizontal planes (Figure 5). The final check of the completed crowns or veneers is done by removing the upper bite material and placing the lower impression on the articulated models. This determines if the midline and horizontal planes are correct before returning the case back to the dentist.
Using the Cosmetic A-ligner takes the guesswork out of doing cosmetic cases and does not leave the dentist at the mercy of the lab. You can expect consistently beautiful restorations placed right where you want them (Figure 6). The Cosmetic A-ligner replaces the cumbersome, inaccurate use of the cross stick-bite impression method and is easier, faster, and more economical than other sophisticated articulation equipment. The lab will also find that the number of redo cases is significantly reduced because the technician has the additional information that is not available from models alone. 
As you can see in Figure 7, the Cosmetic Aligner plays a major role in making this patient’s smile fit her face, achieving a beautiful and predictable smile makeover.

Dr. Meulener graduated from the University of Medicine and Dentistry of New Jersey in 1979 and has been in general practice in Little Silver, NJ, for 28 years. He can be reached at (877) 586-7396 or by visiting cosmeticaligner.com.

Disclosure: Dr. Meulener has a patent pending for the Cosmetic Aligner and is president of Cosmetic Aligner.

Case Report

Figure 1. Patient presented with fractured crown on tooth No. 8.	Figure 2. Radiograph revealed no periapical pathology or abnormalities.

The patient was a 30-year-old male with no noteworthy medical conditions, save for an allergy to penicillin, who presented to our office for the first time with a chief complaint of a fractured crown of tooth No. 8 (Figure 1). A small fragment of the crown remained luted to its lingual surface, and the remainder was lost. He related a history of trauma in his mid teens to what had been a virgin tooth, which had necessitated placement of this porcelain jacket crown. It had functioned adequately for more than 15 years until fracturing on a foreign object in food just before his first visit with us. Tooth No. 7 had also suffered some comparatively minor damage at its incisal aspect from this trauma, but the patient and his parents had elected to restore only tooth No. 8 at the time.
On his initial comprehensive examination, the patient’s periodontal readings and occlusal analysis revealed no significant pathology. A full-mouth series of radiographs taken at this time identified no periapical pathology or other abnormalities, including tooth No. 8 (Figure 2). After gathering all clinical records, arriving at a diagnosis, and provision of routine preventive care, restorative treatment planning began. Besides operative treatment of incipient carious lesions at the occlusal and buccal surfaces of tooth No. 31, no other restorative needs were diagnosed at this examination. Vital tooth lightening and restoring the incisal of tooth No. 7 were discussed with the patient in conjunction with the retreatment of tooth No. 8, but he declined these options.
The mesiodistal dimension of the space that remained after the loss of tooth No. 8’s crown was equal to the same dimension of tooth No. 9, thus enabling the new crown’s form to be a mirror image of its natural complement. This in turn would allow for symmetrical contact point positioning and provide for an appropriate soft-tissue architecture, as sounding depths at both aspects of tooth No. 8 were less than 4 mm.² The restoration of tooth No. 8 was now ready to proceed.
Deciding on the appropriate restorative material was the next step in this process. Since the patient exhibited no occlusal discrepancies or parafunctional habits, had a lighter stump shade at this site,¹ and had been functioning acceptably for more than 15 years with a porcelain jacket crown, I decided on IPS Empress (Ivoclar Vivadent) as the material of choice. IPS Empress offers me unsurpassed aesthetics (the most critical factor in this decision), allows me to avoid gingival tissues with the restoration under the right conditions (when desired), and as a pressed ceramic is the easiest material with which to mimic the coronal hard tissues.³ The existing, just slightly supra-gingival preparation design also influenced my choice of materials in this case. In circumstances where occlusal, tooth preparation color,1 or periodontal considerations dictate another material, I would go with Captek (Precious Chemicals Company), as it is a stronger material and displays a higher resistance to the deposits that can cause periodontal disease.⁴ It can also be as aesthetic as any material on the market, as patients in one trial of multiple restorations fabricated for a single upper incisor unanimously chose the Captek units for definitive cementation.⁵
Having chosen the material I would use for this procedure, I then proceeded to redefine the existing crown preparation, removing what was left of the previous crown in doing so. This left the preparation essentially as it was when first cut—chamfered with just barely supragingival margins circumferentially. The final impression was taken in Examix NDS (GC America) along with all shade records before provisionalization, and was sent to the author’s dental laboratory for fabrication of the definitive IPS Empress crown.

Shade information is the most difficult to communicate with a remote dental laboratory,6 and in accurately reproducing the single maxillary central incisor it is absolutely critical. It has been my experience that patients will be less tolerant of a shade deviation in these situations than with any of the other parameters involved. Therefore, the methods used to record shade selection are equally vital, and over the years I have refined my technique from the single shade tab equivalents I was taught in dental school to the utilization of digital shade-matching devices with adjunctive photography to attain the best results. Such devices record and analyze tooth color information in the mouth to produce a computer file detailing the exact porcelain blends necessary to replicate the intended shade according to the Munsell color system parameters of hue, value, and chroma.⁶
Using my modified Olympus CZ3000 camera (Lester A. Dine), I first took digital photos of the different tabs I had chosen for the separate gingival, body, and incisal shades to match tooth No. 9 (Figures 3 to 5). I also took a stump shade photo of the finished preparation, which coincided with the body shade I had taken previously, as I have often found to be the case. These photos served to confirm the readings I would record with my ShadeVision (X-Rite) digital matcher and show the details of tooth No. 9’s surface texture along with any unusual characterizations that might be present. After carefully considering units from several different manufacturers, I found Shade-Vision to be the best combination of both user friendliness (on both ends of the dentist/CDT interface) and accuracy. Since I started using it, I have been able to realize dependably superior shade matches that leave little to be desired. I then took the ShadeVision measurement, attaching the previously obtained digital photographs to the file its software generates, and e-mailed all of this clinical information to the laboratory. After a virtual try-in, as allowed by the ShadeVision software, my office received the definitive restoration.⁷

Figure 6. Excellent shade match, but a small under-texturing on the labial aspect required modification in the laboratory.

On trying in this unit, I found an excellent shade match whose only flaw was a small under-texturing of its labial aspect (Figure 6) that was not discernible with the virtual try-in. The surface texture of a porcelain restoration has a subtle but definite effect on a patient’s perception of its shade.6 The unit was sent back to the laboratory for reconfiguration of the labial surface, and its new contours were confirmed with digital photography via e-mail prior to its return from the laboratory (Figures 7 and 8).
At the patient’s next visit, this unit was tried in again, and the patient and author found it to be an accurate likeness of its counterpart regarding all essential criteria including shade, contour, proportion, and soft-tissue framework. A minimal enameloplasty was then performed at the mesioincisal of tooth No. 9 to smooth a rough edge. The crown was luted to place with RelyX Unicem  Self-Adhesive Universal Resin Cement (3M ESPE) at the same visit, and a routine semiannual recall revealed a restoration that had satisfied the patient’s aesthetic expectations in full while having satisfactory function and periodontal health (Figures 9 and 10).

CONCLUSION

The aesthetic considerations in restoring any single anterior tooth are challenging,8 and they become even more demanding when that single anterior tooth is the maxillary central incisor.1 The standard in judging restorations of this type is that they should be undetectable when viewed at a conversational distance.9 To achieve this standard, the dentist must satisfy several qualities that depend on careful case selection and favorable clinical conditions. These include correctly recreating the shade, contour, proportion, and soft-tissue framework of the remaining natural upper central incisor. To do this, the dentist must properly evaluate the existing adjacent hard and soft tissues and utilize a suitable tooth preparation design and restorative material. He or she must also employ skilled laboratory technicians and effectively communicate the requisite clinical information to the dental laboratory, if a remote one is used. When this is done adroitly, an outcome will be realized that the vast majority of dental patients will be satisfied with, and that the treating dentist can be proud of.

References

Acknowledgment

The author would like to thank Josh Gall and his team of ceramists at Biotemps Dental Laboratory for their expertise in the fabrication of the restoration depicted in this article.

Dr. McArdle graduated from Tufts University School of Dental Medicine in 1985 and has been practicing general dentistry on the New Hampshire seacoast ever since. He has served on the active medical staff in dentistry of Concord Hospital in Concord, NH, and on the board of directors of Priority Dental Health (prioritydental.com), the New Hampshire Dental Society’s Direct Reimbursement entity. He is a co-founder of the Seacoast Esthetic Dentistry Association (dentalesthetics.com), which is headquartered in Portsmouth, NH. He is the founder of Seacoast Dental Seminars (seacoastdentalseminars.com), also headquartered in Portsmouth. He has authored numerous other articles both nationally and internationally in major peer-reviewed publications. He can be reached at (603) 430-1010, drmcardle@seacoastdentalseminars.com, seda@dentalesthetics.com, or by visiting mcardledmd.com.

Figure 1. Dr. Brian Klym discusses a case face-to-face with one of his dental technicians, Amy Dorman, in Traverse City, Mich.

“Do you really know what to give to your dental technicians in order to get back what you are expecting?” It is a question with a myriad of ramifications (Figure 1).
Despite some positive signs of a growing awareness, I have noticed that very few CE events fully integrate the technical, relationship-based, and interbusiness perspectives of our dental technicians into their curriculum. Our dental technicians are still few and far between at most local, state, and national dental meetings. Most notably, though, the American Academy of Cosmetic Dentistry, the Arizona Dental Association, and the Chicago Dental Society are examples of organizations that have been bringing doctors, staff, and their dental technicians together at meetings to emphasize the importance of the total team concept in achieving optimal results. (There may be others not mentioned here. If so, then they should also be applauded for their efforts in this direction.)
To make a difference in how well we work together as doctor-technician teams, it would be beneficial to see how our dental technicians feel about the CE courses being offered to doctors and their staff. Specifically, and most importantly, how effective is the current curriculum and its impact on our interdependent work?
In order to begin to explore this topic, this article will present feedback from a number of experienced dental laboratory owners and also from the co-executive director of the National Association of Dental Laboratories (NADL). All of these dedicated individuals volunteered to answer questions candidly related to our CE and to offer their opinions on how effective it has been. I believe that their opinions, based on their own valuable experiences, speak for themselves and will give us food for thought the next time we are faced with choosing, designing, or sponsoring CE courses. The first question was posed to all participants, and a compiled list follows. The answers that were repeated most often appear at the top of the list.
In your everyday work experiences with doctors, what would you consider to be the top issues that need to be addressed to obtain the best results possible from your technicians?

• quality and consistency of impressions
• prep design and technique
• more detailed prescriptions that are filled out completely (including future plans for the patient)
• improved communication (more detail) when writing shade prescriptions
• improved doctor-technician communication (ie, the desired result, feedback, returning calls promptly) and stronger professional relationships (more joint CE experiences)
• improvement in the ability to take proper bite registrations
• sharing more photos and preoperative study models
• a working knowledge of the dental material choices and how to handle them post-fabrication (cementation, bonding, occlusal adjustment, polishing, etc)
• understanding the effects of underlying tooth structure, restorative materials, and cements on all-ceramic shades
• proper case protocol with checklists for case requirements (ie, a checklist
  for dentures reminding the doctor to send in trimmed bite rims with the midline marked)
• better knowledge of laboratory procedures for new
  dental graduates and younger dentists
• specific help in how to implement more self-evaluation of work submitted to the lab prior to sending it in (detailed inspections of preps and impressions).

Based on the above collective responses, following are questions concerning CE, with responses from different individuals, whose professional credentials are provided in the Acknowledgment at the end of this article:

Do you feel that CE choices currently available for doctors (and staff) are effective in addressing the aforementioned issues with the majority of cases in your lab?

Robert Wisler, CDT: “No. Either doctors and their staff are not taking the CE that addresses these issues (which is why they are the issues mentioned), or perhaps they are not willing or able to implement the needed changes in their practices.”

Robert Marbach, CDT: “Most CE courses do not address all the major issues involving the relationship between the dentist and the lab, along with the process of creating excellent restorations from preparation to cementation achieved through effective laboratory communication. Many courses are too specific to one topic to address the many factors that will actually improve the final result. Most of these critical steps occur in the operatory, and they should be presented in a chronological series. Many courses consist of too many beautiful before-and-after photos.”

Robert MacTavish, CDT: “Not all the courses are even dental related. There needs to be more personal involvement and hands-on courses.”

John Sebring: “There are plenty of CE courses that address these issues. Whether they are effective, or not, is a key issue. The hands-on courses seem to be the most effective in making changes, especially when they are done with doctor-technician interaction. There has to be a desire by the participants to change or improve that is strong enough to withstand the everyday rigors of business. It is usually easier to go back to what you have always been doing than to break away from the routine.”

If you could wave a magic wand and change, emphasize, or add certain CE topics important to improving the work you do for your doctors, what would be different?

Mr. MacTavish: “I would emphasize courses that would create an environment that would promote the doctor-technician relationship. Over-all, an emphasis on achieving proper preparations and good impressions will make the dental technicians feel better about the case they are working on. It makes dentistry what it should be for all of us-fun!”

Mr. Wisler: “I would have courses that promote a better understanding of prep design and framework design to both doctors and technicians. Also, I would like to see more done on the importance of a step-by-step protocol for each type of case to improve predictability of the end result.”

Mr. Sebring: “I would like to see CE emphasize laboratory communications more; the kind of information that will save the doctor and lab time and money and reduce unnecessary phone calls. For example, far too few doctors send study casts of any kind with their cases. They miss the importance of a preoperative study model when achieving the desired result. They also need to understand the importance of detailed prescriptions (more than “crown #5, shade A3″) and future treatment plans, since there are so many materials from which to choose. Finally, too little importance is placed on returning a call from the lab. If dentists would be willing to set aside a specific time in the morning and/or the afternoon for communication with the lab and their own staff, then the resulting increased efficiency would more than pay for any lost production time. Not to mention that obtaining their desired result the first time, on a more consistent basis, is what every survey says dentists want most from their lab.”

Mr. Marbach: “It would be very helpful to have more courses that offered clinical tips for better restorative results, such as impression troubleshooting, shade-taking, preparation design, and proper bite registration. Also, I would like to see an emphasis on lab communication and the basics of occlusion. We need more courses on new technologies available to the dental team and on implants related to the general practice. We also think that more dentists should attend classes that emphasize the dental laboratoryís perspective. Finally, more courses that would help the doctors select the best restorative materials for their patients would be great. We know that such courses have been helpful to our clients.”

Over the last 10 to 15 years, have you observed any changes in doctors’ responsiveness to CE events that you have sponsored?

Mr. Sebring: “Doctors have become less responsive to CE that we have sponsored in the last 5 years. There was a time when we could not get a large enough room for everyone who wanted to attend! However, these days so many opportunities and courses are available to doctors that it has become much more difficult to fill a course.”

Mr. Wisler: “I have found them to be less responsive in our region. There seem to be too many offerings online, in DVDs, etc, that are competing with live courses.”

Mr. Marbach: “We have noticed a decline in response in the last 5 years or so. There are several reasons. First, more courses are offered in journals and over the Internet. Secondly, many of the CE courses taken by dental professionals are seen as more of a requirement and less as a source of information. As such, many times they attend the courses that are most convenient rather than the ones that have the best content.”

Mr. MacTavish: “Yes, I have noticed changes. They do not think that the particular topics relate to their needs and/or they are too busy to attend.”
Bennett Napier (NADL): “The tried-and-true marketing approaches to entice dentists to participate in laboratory-sponsored CE have changed over the years. The NADL members I speak with on a regular basis who sponsor CE for their clients and dental prospects share that topics and format drive attendance. Topic selection is a key to success. Laboratories that sponsor training on emerging technologies and new materials or information that adds value for practice management can still draw a crowd. Additionally, the format must take into account the busy lives of their doctors, and the events should provide a lot of high-quality content in an abbreviated time frame.”

How do you feel we are doing as an interdisciplinary team (doctors-specialists-dental technicians) in having enough of the right learning opportunities to attend together?

Mr. Wisler: “Very few organizations truly promote doctor-technician courses to attend in which we are taught together. The American Academy of Cosmetic Dentistry leads the field by presenting all the disciplines, including dental technology, on an equal stage.”

Mr. Napier: “We find that a number of our state dental laboratory associations and state dental societies are really working hard to integrate courses at their respective meetings in order to help bridge the gap between dentistry and dental technology. In the last couple of years we have seen an increased awareness that since there are less dental technology schools in the market, and dental schools are not teaching laboratory procedure anymore, it is crucial for CE providers to fill this void.
However, it is still a small percentage of market offerings. The next step is also to include hygienists and assistants in team CE, as they are often performing more and more (expanded duty) functions in different states that directly affect laboratory procedures.”

Mr. Marbach: “We feel like there are several clinician/technician teams available to offer the best CE to the industry. Often, these opportunities are passed up for a more famous ëaestheticí lecturer or for a speaker sponsored by a large dental company.”

Mr. Sebring: “Not nearly enough courses are geared toward doctors and technicians attending together. Tomorrowís technology is already here. As CAD/CAM and other forms of digital scanning/imaging change the way we communicate information and produce restorations, courses taken together involving these types of technologies will be critical to our success as an interdisciplinary team.”

Mr. MacTavish: “We are doing better, but with all that is new lately we need more.”

CONCLUSION

During the last 12 years of my career I have spent a lot of time side-by-side with many dental technicians across North America, either as a doctor-technician liaison or while lecturing or facilitating workshops. I can fully relate to the thoughts of my colleagues who gave their responses for this article. I know many more of us would probably like to add further thoughts to this discussion. I hope that publications such as this will stimulate productive dialogue in each of our respective professions, and, more importantly, between our disciplines. It seems that we have more work to do to address each otherís needs. Despite that we produce a lot of very good dentistry, if you spent any significant time in a dental laboratory you would probably agree that preps, impressions, detailed prescriptions, and the other issues mentioned above (and more) need improvement.
As an industry we have, in fact, begun to make some significant progress related to developing better doctor-technician relationships. However, we have some extraordinary challenges facing our professions in the immediate future. Here are only a few:
1) We will have an everincreasing share of lab work that will be done more inexpensively by offshore workers, and rapidly changing technology with an emphasis to move away from restorations created with human hands not only to improve results, but in fact to compete with foreign workers.
2) A newer generation of dental school graduates that have had little or no exposure to dental laboratory procedures or the value of good relationships with dental technicians.
3) CE that is online, in journals, or on VCR tapes or DVDs, etc, that can indirectly serve to dehumanize further what would otherwise promote the interpersonal relationships that can develop when we have fellowship with one another in and around live courses such as those at dental association meetings.
To continue to find, develop, and retain motivated and talented dental technicians that will serve us conveniently in our own country, we must come together like we have never done before. The best way to stimulate this process is to visit your dental laboratory and begin the process of building a great doctor-technician team. Maybe you will even consider attending some meaningful CE together-the kind of education that begins to address the concerns that were voiced in this article.

Acknowledgment

The author extends his appreciation and thanks to the following professionals for their willingness to participate in this project: Robert Wisler, CDT, owner of Alpha Dental Studio; Robert Marbach, CDT, owner of Authentic Dental Laboratory; John Sebring, president of Ito and Koby Dental Studios; Robert Mac-Tavish, CDT, owner of MAC Dental Laboratory; and Bennett Napier, co-executive director of NADL, which is the official voice and national support organization for laboratory owners, dental technicians, and Certified Dental Technicians (CDT). The author also commends Dr. Phillip Bonner, editor-in-chief of Dentistry Today, for allowing the recent development of a regular Laboratory section in what had always been essentially a publication for doctors.

Dr. Adams, a University of Michigan graduate, is an assistant clinical professor in the Dental Residency Program at the University of Toledo College of Medicine. He lectures and presents hands-on workshops emphasizing prep design and other related doctor-technician topics internationally for dental organizations and laboratories. In addition to his years in private practice, Dr. Adams has had the opportunity to serve as a doctor-technician liaison for many dental laboratories throughout North America for more than 12 years. He is listed in Dentistry Today’s Leaders in Continuing Education (2004 to 2007) and serves as a contributing editor for Dentistry Today. Dr. Adams is a member of the ADA, AGD, AACD, and NADL. He can be reached at (231) 642-7785 or by visiting adamsdentalseminars.com.

STRENGTH

Most importantly, the choices of materials that can be used with inLab have greater strength than those that can be used chairside. Yttrium-stabilized zirconium oxide (Yz) for high-strength (900 to 1,100 MPa) copings and frameworks is available from 3M ESPE (Lava), Sirona (inCoris ZI), and Vident (inVizion), to mention but a few options. These Yz materials cannot be used to fabricate restorations at chairside. InVizion, with 1,000 MPa of flexural strength, is 4 times as strong and is more durable than other materials used at chairside. In comparison, 2 popular in-office materials have 140 to 200 MPa of flexural strength. However, inVizion also requires a 7-hour cycle, which takes more time and costs more in lab fees than in-office materials.
Using Vident products as an example, other high-strength materials that can be used with inLab CEREC include In-Ceram Spinell (very translucent at 350 MPa); In-Ceram Alumina (good all around, time tested) at 500 MPa; or In-Ceram Zirconia with high strength of 750 MPa. All of these materials are built with VM7 porcelain for the lowest wear on opposing dentition and wear better than any chairside porcelains on the market. A finished inVizion crown with VM9 porcelain is much stronger than a porcelain-fused-to-metal crown.

Figure 1. Preoperative buccal view.	Figure 2. Preoperative occlusal view.
Figure 3. Crown removal begins using a fissure bur on the buccal surface.	Figure 4. Completed crown removal.
Figure 5. Photo-cure of core buildup.	Figure 6. Placement of CompCore AF SyringeMix material for final core.
Figure 7. Completed core.	Figure 8. Retraction using Expasyl.

AESTHETICS AND CUSTOMIZATION

Crowns made with the inLab CEREC system can be made more aesthetically pleasing than chairside alternatives. The ceramist can easily customize the in-Lab porcelain crowns with layering techniques using incisal chroma and opalescent powders, for example.

ACCURACY AND FIT

The impressions and resulting inLab restorations provide for extreme accuracy and great marginal integrity.

CHAIRSIDE EFFICIENCY

Since adjustments can be made more easily on the model than in the mouth, any discrepancies can be corrected before insertion, saving chair time.

VERSATILITY OF PROCEDURES

The new inLab CEREC MC XL (Sirona) is twice as fast and more accurate than previous models. InLab CEREC MC XL with Yz porcelain materials can be used for making cantilevered pontics, veneers, inlay bridges, Maryland bridges, and bridges in a larger milling chamber that can accommodate bridges in excess of 40 mm. Because the sintering procedure necessary for Yz cannot be performed efficiently in the office, the inLab approach provides practitioners with more choices for copings and frameworks.

NO METAL COLLARS, IMPROVED DIAGNOSTICS

Crowns fabricated without metal collars are radiographically translucent, making it easier to detect decay beneath the crown instead of seeing a “big white blob” on the radiograph.

AN EXPANDED ARSENAL FOR DENTIST AND TECHNICIAN

To perform the inLab technique, the model is poured in scannable stone followed by the use of the optical scanner. The design process begins, and the porcelain is then milled to specifications. The next step is either to infiltrate or sinter, which provides more strength than using a chairside technique. The ceramist can now build porcelain, contour, stain and glaze, and return to the clinician a much stronger, more aesthetic, better-fitting and less chair time-consuming restoration. Clearly, the finished restoration using the inLab CEREC technique would be best for the patient in terms of longevity, appearance, and fit.

Figure 19. Completed crown.	Figure 20. Completed crown delivered to patient.

CASE REPORT

A 72-year-old female patient required the replacement of a crown on tooth No. 5, which had previous endodontic treatment. Figures 1 and 2 depict the buccal and occlusal views, showing recession in the darkened root and the stained, worn facing made of acrylic.
Crown removal was begun using a fissure bur on the buccal (Figure 3), and the completed crown re-moval is shown in Figure 4. Bonding for the core build-up using iBond (Heraeus Kulzer) is shown being photo-cured in Figure 5. Placement of the CompCore AF SyringeMix material (Premier) for the final core is shown in Figure 6, and the completed core can be seen in Figure 7. Retraction is being accomplished as Expasyl (Kerr) is being syringed to place in Figure 8. The T-LOC Triple Tray is tried in the mouth in closed position showing proper seating in Figures 9 and 10. A Pentamix 2 automatic mixer (3M ESPE) was used to load the syringe material and load the Triple Tray with the heavier body material. The patient then received the syringe material that was then blown into the sulcus for better adaptation, followed by the seating of the Triple Tray with the heavier body material as shown in Figures 11 to 15.
The impression was sent to the laboratory, where the CEREC system was used to create the dies from the Triple Tray and fabricate the proper porcelain fit, form, and color (Figures 16 to 18). The completed crown as seen in Figure 19 was now ready for delivery to the patient (Figure 20).

Acknowledgment

Photos courtesy of S. Rand Werrin, DDS.

Dr. Goldstein has maintained a private practice in Beachwood, Ohio, for 31 years, focused on cosmetic and implant dentistry. He is a Fellow of the AGD and is currently pursuing his accreditation in the American Academy of Cosmetic Dentistry. He has held teaching appointments at Case Western Reserve School of Dental Medicine and as an attending in the Cleveland Metropolitan General Hospital GPR program. He earned his DDS degree from Case Western Reserve University in 1975 and can be reached at (216) 464-1700 or drjhgdds@aol.com.

Dr. Werrin co-operates a private cosmetic and restorative dental practice in Pittsburgh, Pa, with Dr. Charles J. Miller, his partner of 38 years, and Dr. John W. Gruendel, his partner of 27 years. He is the inventor of and holds patents on 8 Premier Triple Tray designs. As the associate professor for the Department of Continuing Education and Medicine at the School of Dental Medicine of the Univer-sity of Pittsburgh, Dr. Werrin has lectured worldwide and co-authored numerous articles on the subject of restorative dentistry. He earned his DDS degree in 1967 from Temple University and served 2 years after graduation as a general dentist in the US Air Force. He can be reached at (412) 621-0200 or werrin@dentalpgh.com.

ALL-CERAMIC MATERIALS

Over the years several materials have been used for all-ceramic restorations; however, today only 2 types of ceramics are recommended for use with both anterior and posterior crowns and anterior bridges. These categories include the interpenetrating phase composites or glass-infiltrated ceramics, and the polycrystalline ceramics.^3,4
Glass-infiltrated ceramics consist of a product formed by infiltrating molten glass into a partially sintered oxide material (aluminous oxide or alumina-zirconia oxide). Examples of this are InCeram Alumina and InCeram Zirconia (Vident).
Polycrystalline ceramics are materials with densely packed particles containing no glassy components. They cannot be processed to shapes without the use of computer-assisted machinery. Examples of this material include densely sintered, high-purity aluminum oxide, Procera AllCeram (Nobel Biocare), and the yttria tetragonal zirconia polycrystal (Y-TZP) systems. The majority of these systems use CAM of partially sintered Y-TZP blocks, followed by complete sintering of the shaped product for an additional 5 to 8 hours. These systems include Lava (3M ESPE), Cercon (DENTSPLY Ceramco), CEREC InLab (Sirona), and Procera All-Zirkon (Nobel Biocare). The partially sintered or “green state” material is milled to a size that is 20% to 25% larger than the final sintered core to compensate for the shrinkage that occurs during final sintering. As the fit of each final core is deemed to be acceptable, there is no standardization in fit and strength among different manufactured blocks of material because of the differences in the handling of the material by the various laboratories once it has been milled.⁵
A different system, DCS-Zirconium (DCS Popp Dental Laboratory) uses fully sintered Y-TZP blocks to mill fully sintered frames. No shrinkage is involved in the process when the fully sintered material is used, and the core made from totally industrially prepared material is structurally more reliable than the post-sintered green state material. There are questions that the CAD/CAM procedures may induce surface and subsurface flaws that may affects its physical properties.⁶ The use of ultrasonic machining promises to revolutionize the treatment of ceramic material in dentistry, as well as all phases of the industry. This technology greatly minimizes contact of the cutting tool with the material, which significantly reduces friction, heat, and the creation of surface flaws. Furthermore, the process increases the accuracy of the final milled product.⁷
The exceptional physical properties of these CAD/CAM ceramic cores have been described extensively in the literature and are not the focus of this article. This article focuses on the porcelain ceramic that will generate good to excellent aesthetics layered over the CAD/CAM alumina zirconia oxide (AL/ZR) core. The basic fundamental use and qualities for a particular type of porcelain, Initial Zr (GC America), is described.
Initial Zr is one of 6 Initial ceramics in an integrated product line (manufactured by GC Europe) with one color system, which can create metal-ceramic restorations as well as full-ceramic restorations. Each GC Initial ceramic is adapted to meet the needs of its particular fabrication process and frame-work, such as its coefficient of thermal expansion, therefore avoiding stress and fractures. This article focuses on GC Initial Zr, which is designed for layering over CAD/CAM frameworks. GC Initial Zr has an array of unique shades that have been developed for internal layering and external staining, high fluorescence, opalescence, and/or high translucency that allows for very favorable color matching with natural tooth structures.
For simple and promising handling of these high-strength ceramics, it is important for clinicians and lab technicians to consider a few fundamental points.

With zirconium oxide there are 2 variations:

• A white, more or less opaque, milled or sintered zirconium oxide.
• A dyed (in the corresponding shade) sintered zirconium oxide.

Figure 1. Internal aspect of DCS Precifit Zirconium (DCS Popp Dental Laboratory) core with final layers of porcelain. Note the “white” opaque color of the fully sintered core as discussed in the article.	Figure 2. DCS Precifit Zirconium oxide frame or copings ready for porcelain layering.

The former lends itself better to higher-value restorations that are the norm of most patients requesting anterior restorations (Figure 1). The latter definitely offers a more compatible color base for the standard tooth shade buildup, especially for standard layering.8 When using the white zirconium oxide, Initial Zr porcelain lends itself very well to generating the desired aesthetic outcome. The white neutral base of the zirconium oxide allows the applied colors to appear very pure and genuine. The fluorescence missing from zirconium oxide cores or frames must be replaced with a thin coating of liner or frame modifiers to provide the natural fluorescence from inside the restoration. The liners/modifiers can also be individually tinted with the fluorescing Initial stains.⁹
When the clinician prescribes the shade A2, as was done in the case report described later in this article, the laboratory needs to adapt the base chroma in a different fashion than conventional porcelain layering. When making A2 shades, the base chroma should be at least the color effect of A3. With zirconium oxide frames it should be even a warmer tone because the dentin-colored frame material becomes lighter with each firing. The result is that layered restorations without intensified chroma appear too light in the patient’s mouth.⁹
A similar appearance is seen with the white, non-chroma-intensified zirconium oxide restorations. The missing chroma and fluorescence on the frame causes a light, too white/gray appearance. The Initial Zr layering system compensates for this unwelcome addition and standardizes the layering procedure for the laboratory technician.¹⁰
It is not as simple to evaluate the optimal firing of AL/ZR ceramic. Improper firing causes the incorrect shade seen frequently in AL/ZR restorations. Most furnaces fire 20° to 30°C lower, especially in the temperature firing range of zirconium ceramics. All such ceramics, but particularly AL/ZR, react to low firing temperatures with slightly limited transparency and color effects. On the other hand, somewhat higher firing cycles cause no problems and actually support the color and transparency effects. The ceramic firing stability is unusually good, so that in most furnaces raising the end temperature by 10° to 30°C is recommended in order to achieve the best outcome.¹⁰
Incorrectly constructed or layered frames are another reason for aesthetic failures when using white zirconium oxide restorations. In general, the frames should be the same size as the circumference of all the frames and built with light material zirconium oxide. If the frames are of different sizes, then the circumferences of the smaller frames will differ in color, and will appear either gray or too dark and intense in color¹¹ (Figure 2).
When using these AL/ZR frames one must be aware of the aesthetic limits of the material. This material is very difficult to control aesthetically for inlay, onlay, and veneer restorations due to the very white-colored margins. This restorative method lends itself to full-coverage restorations due to the preparation of the tooth structure with circumferential shoulder preparations. The aesthetic effect necessary in veneer, inlay, or onlay restorations is not generally achieved due to the opacious zirconium oxide material blocking light in the enamel of natural teeth, resulting in a color impact along the margin. Therefore, any preparation of the teeth should have a 0.8-mm to 1.0-mm reduction at the margin to prevent this “light-blocking” effect onto the enamel. A shoulder preparation allowing for 0.8-mm to 1.0-mm ceramic material must be provided¹² (Figures 3 and 4).
As a side note, the author has noticed that often in the use of inlay, onlay, crown, or veneer restorations with less than 0.8 to 1.0 mm of marginal reduction, a cut-back of the core is needed and traditional shoulder porcelain is necessary for the optimal aesthetic result. The only problem with this is that this shoulder material is often radiolucent and can show up as open margins or defective restorations to the uninformed clinician when doing follow-up radiographic examination.¹³ Due to this and the aesthetic reasons previously described, the author recommends from experience that another conventional method be utilized if the required amount of preparation cannot be obtained.

PORCELAIN LAYERING

Figure 3. Left maxillary restorations on model demonstrate good aesthetics and light translucency.	Figure 4. Left maxillary restorations cemented demonstrate the disappearance of the restorative gingival margin with the natural enamel of the tooth. (Note fit of zirconium frame and the disappearance of the white gingival line often seen with ZR cores.)
Figure 5. Application of FD-91 for internal copying of dentinal structure.	Figure 6. Bioesthetic layering with modifiers and transparent porcelains.
Figure 7. Restorations after first firing ready for the transparent and translucent porcelains.	Figure 8. Lingual depiction of “color from within” of Initial porcelain. Note the transparency and translucency achieved by the Bioesthetic Layering Method.
Figure 9. Facial aesthetics of restorations with refracted and reflected light demonstrating the “halo effect” desired for optimal aesthetics.	Figure 10. Maxillary premolar demonstrating “color within” without the use of external stains or modifiers. The color mimics natural tooth aesthetics.

With many restorative porcelain layering techniques, technicians learned to build porcelain in the following way: apply opaque, build dentin, layer enamel, and add translucent material. Unfortun-ately, this method has little correlation with a natural tooth. Transparency is found primarily from the inside of all natural teeth, in the transparent dentin. In anterior teeth, abrasion and wear over time cause this transparent layer covering the dentin to appear at the incisal edge. This changes the transparency of natural teeth considerably depending on the angle of light or the angle of incidence. The teeth appear at times lighter, grayer, darker, or even deeper in chroma. The amount of light reflecting through the transparent dentin also changes the perception of depth.
The internal transparent layer of dentin from tooth morphology comes to the surface at the junction of the root and cervical margin, completely covering the root and influencing the value of the gingiva. Therefore, it makes no sense to use opaque marginal materials in this area where nature shows us differently. The use of GC Initial porcelain, due to its highly chromatic and fluorescent INside powders (GC America), imitates the primary dentin and fluorescence that lie imbedded within the teeth. Layering dentin material over the INside material achieves a perfect balance of chroma and value. When one pairs fluorescent, crystal clear transparency with real opalescent enamel, it makes it possible to copy the effect of natural tooth structure.
The layering of Initial porcelain has been described as the Bioesthetic Layering Method. This method is oriented toward copying the light dynamics and transmission of natural teeth. The method begins with the clinician taking the shade. This can be a very complex challenge, as one needs to make allowances for color in natural teeth under different light situations. These variances in color under different light situations are very difficult or almost impossible to achieve utilizing conventional ceramic materials. Even the most talented technicians depend on materials to produce these natural light effects. When the GC Initial materials are layered analogously to the structure of natural teeth, they automatically produce a complete and logical layering process. The natural chroma and fluorescence seen within natural teeth can be transferred to the restoration with the Bioesthetic Layering Method.
This is a method of layering porcelain through incremental layering of porcelains in a systematic manner, unlike the traditional manner described previously. The first step is the use of a fluorescent Fired Frame Modifier, since zirconium frames lack fluorescence. The next step is the application of INside materials to the cervical and proximal areas. Next, the light-reflecting edges are covered with highly fluorescent white dentin (FD-91), and the body is covered with INside material (Figure 5). Next, the dentin body is built, and the enamel table is built over the dentin body with translucent dentin. Next, modifier stains and INside material continue the layering process. The buildup is now covered with a layer of fluorescent transparent material (CLF[GC America]). Next, a cut-back in the incisal area down to the highly fluorescent dentin is accomplished, and FD-91 is again applied. Another layer of INside on the desired internal structure is placed. Next, opalescent enamel is layered (Figure 6). Now the restorations have their first bake in a porcelain oven. Any corrections to shades or colors can now be accomplished with translucent materials and opalescent enamels (Figure 7). The restorations are baked a second time and finished.
Anterior teeth pose a great aesthetic challenge. Incisals of teeth are very sensitive, since all optical light phenomena converge at this small space. Layering porcelain in the incisal table is very critical because the most light is transmitted here. This area will exacerbate the optical differences between felds-patic porcelains and synthetic ceramic frames. A totally different optical appearance can result when dissimilar frame sizes or materials are used side by side. This difference in optical appearance can be neutralized with the high fluorescent dentins and the INside powders (Figure 8).
To achieve the desired natural effect at the incisal angle, Initial porcelain’s different white fluorescent, fluorescent transparent material, and transparent dentin can be utilized to provide the optical phenomenon known as the “mammelon structure” or the “Incisal halo effect” (Figure 9). If there is too much transparency at the incisal edge in the mouth, then this results as an unappealing, unnatural gray and flat effect. The use of the white fluorescent, fluorescent transparent material, and transparent dentin along with the opalescent enamels of Initial porcelain copies natural tooth structure very well (Figure 10). When compared to conventional enamels, the difference aesthetically can be enormous. The use of conventional enamels, dentins, and opaques correlates well with the Vita Lumin shade guide system, but not with the dynamics of light in natural teeth. The opalescent effect on the surface, with fluorescence coming from the inside, creates a highly natural appearance. One needs to utilize the ready-made shade guides as a general reference, but not rely on the shade guide to reproduce the desired outcome.
Communication with the laboratory technician needs to be addressed more explicitly with the design of “shade-mapping.” The clinician must communicate to the technician how and where the porcelain and modifiers are to be utilized so that the maximum aesthetic and optical effects are generated. This can pose a big challenge to the clinician when describing the colors seen to the technician. A thorough understanding of tooth morphology and natural opacious dentins, translucent dentins, and enamels in teeth must be utilized if one is to achieve the optimal effect desired. Initial has simplified this with the Bioesthetic Layering Method described earlier.⁹

CASE REPORT

Figure 11. Preoperative smile view of patient.	Figure 12. Preoperative retracted view of patient’s dentition depicting failing restorations and poor aesthetics.
Figure 13. Dentition evidencing compromised gingival heights, crowding, failing restorations, wear, and overall poor aesthetics.	Figure 14. Preoperative right lateral view.

This patient was very unsatisfied with the anterior aesthetics of his maxillary dentition. He wanted a result that would dramatically change the anterior aesthetics. He was concerned with severe crowding of the anterior incisors as well as the failing restorations that had been present for many years. The patient was presented with a treatment plan involving a complete restoration of his dentition in both the maxillary and mandibular arches. Prior to the restorative dentistry phase he was advised to undergo orthodontic therapy as a method to improve his interdental and intradental relationship. In discussion with the author the patient elected to avoid orthodontic treatment because full-coverage restorations would be necessary to restore his dentition. Gingival concerns were discussed, as the patient was very unhappy with the differing gingival heights in the maxillary anterior segment (Figures 11 to 14).
The treatment the patient wanted to undergo at the operative session was to restore the maxillary anterior segment, periodontally recontour the maxillary anterior gingiva, and recontour the incisal edges of the opposing dentition to aid in incisal guidance. The lower arch was to be restored at a later time. The shade requested as the final shade would be considerably lighter than the patient’s intial shade.

Figure 15. Right lateral view of provisional restorations at corrected vertical and incisal lengths.	Figure 16. GC Fuji Plus single-use dispensing capsule in action demonstrating precise delivery of glass ionomer adhesive material.

The patient was appointed for the initial operative session. The first operative session included a laser-assisted Smile Lift Procedure to accomplish recontouring the gingival architecture to more harmonious and even gingival heights.¹⁴ The teeth were prepared for full-coverage restorations with a 0.8-mm to 1.0-mm circumferential marginal reduction. Tissue retraction, impressions, bite records, and provisional restorations were all accomplished at this session (Figure 15).
Upon completion of the restorations, the second operative session was to be the try-in phase to determine restoration fit, marginal integrity, occlusion, aesthetics, and patient satisfaction. With all these accomplished, the restorations were to be placed with final cement. Zirconium restorations can be easily cemented in the conventional manner with glass ionomer cements or conventional ce-ments. The cement chosen for this case was GC Fuji Plus (GC America). The author utilizes this product due to high fluoride release and high bond strengths.^15-17 This cement is very versatile due to its ability to cement indirect restorations. The material is supplied in a capsule  (Figure 16). It is also available as a Paste-Pak  system (FujiCEM). This ensures the proper mixing ratio every time to achieve the highest compressive, tensile, and bond strengths with the lowest film thickness, and maximum fluoride release.¹⁸

Figure 17. Fully retracted view of final restorations in maxillary arch.  (The higher value restorations that the patient requested will be matched during the mandibular reconstruction phase.)	Figure 18. Final restorations showing translucency and transparency of the zircon frame/Initial porcelain technique.
Figure 19. Preoperative smile view of patient.	Figure 20. Postoperative smile view of patient.

The final results were very aesthetic, and the patient was highly pleased with the results. A third and final operative session was utilized for occlusal accuracy and postoperative evaluation. There was little to no sensitivity during the entire procedure as well as during the provisional and postoperative phase (Figures 17 to 20).

References

Dr. Pinero maintains a private practice in Milwaukee, Wis, where he emphasizes aesthetic, restorative, and laser dentistry. Dr. Pinero lectures nationally and internationally on aesthetic, restorative, and laser dentistry and provides hands-on in-office programs on aesthetic and laser dentistry. He founded The Midwest Institute of Laser and Esthetic Dentistry in Milwaukee, where he holds advanced postgraduate continuum seminars on aesthetic and laser dentistry. In addition to clinical training, Dr. Pinero has helped numerous dentists employ his expertise of patient management to help them propel their practices to be among the top 5% with his Follow the Formula system. He can be reached at (414) 282-2050.

Acknowledgment

The author would like to thank Robert Popp of Popp DCS in Milwaukee, Wis, and laboratory technician Ernest Grabowski of Popp Dental Laboratory for the laboratory phase of this case.