INTRODUCTION

It seems like cracked teeth are becoming a more and more prevalent finding in clinical practice. The ADA News and the New York Times recently published articles on this subject. One reason is people are living longer and are retaining their natural dentition. “Cracked teeth seem to be a result of repetitive stress injury, and so the longer teeth are in use, the more likely they will become cracked. This is a modern epidemic and something we have never before as a profession had to deal with,” said Rob Roda, past president of the American Association of Endodontists. “Cracked teeth are undergoing a time-dependent, load-related, progressive process that, without intervention, results in pain, infection, and splitting of the tooth requiring extraction.”

A cracked tooth can be defined as an incomplete fracture initiated from the crown and extending cervically and sometimes subgingivally, usually directed mesiodistally.¹ The depth and extent of the fracture are usually unknown and may progress to communicate with the pulp and/or periodontal ligament.

A cracked tooth diagnosis can be very perplexing because of the very vague nature of the presenting signs and symptoms. Do we treat, or do we extract? Studies show that the range of treatment for the cracked tooth can vary from conservative treatment modalities to extraction and replacement with implants. When a crack is suspected, guiding the patient to the proper treatment and then following up is paramount. The initial symptoms of a cracked tooth can often mimic those of pulpitis, necrosis, or apical periodontitis while there are clinically and radiographically no signs of caries. Most of the time, the involved tooth is minimally restored or not restored at all, making the diagnosis all the more difficult (Figure 1). The goal of this article is to help the practitioner navigate the complexities of diagnosing and treating the cracked tooth.

COMMON CRACK LOCATION

Mandibular first and second molars are the most susceptible to fracture, followed by the maxillary premolars. The crack is most often found on the mesial or distal marginal ridge or under an existing restoration.^2-4

DIAGNOSING THE CRACKED TOOTH

Understanding the extent of the crack is important as well. A craze line is a small crack that does not extend past the enamel. Teeth with craze lines will not cause any sensitivity to biting or temperature, and no treatment is necessary. Once a crack extends into the dentin, the patient can start to have temperature sensitivity and biting pain. As long as the crack does not extend into the root canal space, the crack can be managed by making a crown to establish complete cuspal protection. This treatment protocol is dependent on the patient’s symptoms.

If a tooth is minimally restored (or not restored at all) and has no caries yet presents with symptoms of pulpitis or necrosis, a cracked tooth should be suspected (Figures 1 and 2). These teeth can be retained if diagnosed and treated in a timely manner. The prognosis drops precipitously if the tooth has become necrotic. This would suggest that the crack has been there for a much longer period of time.⁵

Classic symptoms of a cracked tooth include sharp pain on biting (or release) and unexplained temperature sensitivity. Often, the patient has difficulty pinpointing the offending tooth, which makes reproducing the patient’s chief complaint all the more critical. One of the best ways to diagnose a cracked tooth is by testing each cusp of a suspected cracked tooth with a “tooth sleuth.”⁶ Cotton roll compression is another technique that can be employed.^2-4 Vitality testing is important as well. These tools will help to pinpoint the offending tooth.

Early diagnosis and detection are paramount in the management of the cracked tooth. With early detection, many teeth can be saved. Unfortunately, because the pain is intermittent, and due to the vague nature of the symptoms, there may be a delay in treatment. Many cracks are diagnosed when they have already extended deeply into the root structure, making the prognosis hopeless (Figures 2 and 3). These cracks also provide an avenue for bacteria to invade the pulp space, eventually leading to either an inflamed pulp (pulpitis) or an infected pulp (necrosis/apical periodontitis).^5,7 The cause of the sharp pain on biting is due to the movement of the fractured segments triggering fluid movement within the dentinal tubules. This fluid movement triggers nerve fibers located in and around the dentinal tubules.⁸

Figure 1 The patient in this case had been to multiple dentists over the past 2 years with a vague discomfort on the lower right side. Due to a lack of caries or restorations and the inability to reproduce the patient’s chief complaint, no treatment was rendered. A CBCT scan (Veraviewepocs 3D R100 [J. Morita]) revealed periapical radiolucency, as well as a narrow vertical defect, on the distal aspect of tooth No. 31. This was confirmed with clinical periodontal probing depths of 8 mm. This tooth also tested negative to vitality testing. A diagnosis of a cracked tooth with radicular extension was made, and extraction was recommended. All symptoms subsequently resolved. The extracted tooth revealed a crack running down the full extent of the buccal aspect of the mesial root. There was a second crack (not visualized) on the distal aspect corresponding with the distal bone loss.

Figure 2 The patient in this case presented with severe acute biting pain on the upper right. Tooth No. 4 was extremely tender to percussion and biting. There were no caries or restorations on tooth No. 4. You can see a crack line running mesial to distal on the occlusal table. A 7-mm periodontal pocket was probed on the mesial. A diagnosis of a cracked tooth with radicular extension was made. After the tooth was extracted, you can visualize the crack running from the mesial marginal ridge halfway down the root.

Figure 3 Tooth No. 18: The patient presented with severe pain to biting and continuous throbbing pain on the lower left. A diagnosis of pulp necrosis with symptomatic apical periodontitis was made. CBCT images revealed the cause being a cracked tooth extending in a mesiodistal direction and obliquely to communicate with the PDL on the lingual. The extent and direction of this fracture was not visualized on conventional radiography.

TREATMENT OF THE CRACKED TOOTH

There is a wide range of treatment options for the cracked tooth. Treatment will usually fall into 1 of 3 categories:

1. Crown

2. Root canal and crown

3. Extraction

The treatment depends on the status of the pulp and the depth of the crack. A surgical operating microscope is essential in determining the extent of the crack and the prognosis once the root canal is initiated.

If a cracked tooth is diagnosed with reversible pulpitis (no lingering sensitivity to biting or thermal stimulation), a temporary crown is advised for 6 to 8 weeks. If symptoms resolve, then proceed with a permanent crown. If symptoms don’t resolve, root canal therapy is indicated prior to permanent crown placement.^2-4

If a cracked tooth has a pulpal diagnosis of irreversible pulpitis (a crack that elicits spontaneous or lingering pain) or necrosis (infection) with or without a periapical lesion, then root canal therapy is indicated prior to crown placement (Table 1) (Figures 4 and 5). If root canal treatment is initiated and it’s discovered that the crack extends into the root, then extraction may be indicated.^5,9-13 A recent study showed very promising results when treating a cracked tooth, even when the crack extended into the radicular dentin.¹⁴ The technique employed used intra-orifice barriers placed apically to the apical extent of the crack in the radicular dentin. The goal was to prevent the ingress of bacteria and reinforce cervical dentin.¹⁴

Figure 4 The patient in this case presented with signs and symptoms of a cracked tooth (visualized clearly upon access of the tooth) and irreversible pulpitis associated with tooth No. 3. The patient was motivated to save the tooth with root canal therapy and a crown. The patient was completely asymptomatic after the first visit. The tooth was crowned one month after the root canal was completed. At the 2-year followup, the patient presented asymptomatic. The radiograph revealed no periapical pathology or marginal bony breakdown.

Figure 5 The patient in this case presented with acute biting pain on the lower left. A tooth sleuth revealed biting pain associated with the ML cusp of tooth No. 18. There was a lingering, painful response to vitality testing. Upon access, a crack line was noted running from the occlusal surface down to the level of the ML canal but not into the canal. A cracked tooth was diagnosed. The patient opted to have this tooth endodontically treated and then crowned. Upon the 3-year evaluation, the tooth was asymptomatic with no signs of periapical pathology or periodontal breakdown.

Figure 6 The patient in this case presented with a vague discomfort on the lower right. The gingiva adjacent to tooth No. 31 was inflamed and slightly swollen. The initial diagnosis was a periodontal abscess. Local curetting of the area temporarily relieved the patient’s pain. However, the patient returned with a similar discomfort after a short time. A CBCT scan was recommended and revealed a J-shaped radiolucency on the mesial root of tooth No. 31. A 10-mm periodontal pocket was probed on the mesiobuccal aspect of tooth No. 31. A diagnosis of vertical root fracture (VRF) was made, and extraction was recommended. After the tooth was extracted, a fracture was not only noted on the mesiobuccal, as expected, but surprisingly also along the distal root.

CRACKED TOOTH VS VERTICAL ROOT FRACTURE

A cracked tooth shouldn’t be confused with a vertical root fracture (VRF). VRFs are mostly found in previously endodontically treated teeth. These fractures are initiated at the apical end and progress coronally (Figure 6). They can also be found mid-root adjacent to the terminus of a post. On the other hand, cracked teeth are found mostly in teeth that have not had root canal treatment, and the crack is initiated in the crown and spreads apically toward the root (Figure 7). Cracked teeth can sometimes occur on endodontically treated teeth that have not been properly restored with cuspal coverage. Cracked teeth are often directed in a mesiodistal direction (Figure 8), while VRFs are mostly directed in a buccolingual direction within the root. The classic J-shaped or halo-shaped apical radiolucency, as well as the deep, narrow “isolated” periodontal pocket, is classically associated with VRFs (Figure 6). In contrast, classic symptoms of biting pain and unexplained temperature sensitivity are associated with cracked teeth.^15-18 While cracked teeth are amenable to a range of treatments, VRFs usually have a hopeless prognosis and require extraction and replacement with an implant. If the offending tooth is multi-rooted, it may be possible to resect the root with the VRF and retain the tooth with the remaining roots (Figure 9). Because the pain associated with VRFs may be fleeting and intermittent, the patient often doesn’t seek treatment until significant bone has been lost around the tooth.

Figure 7 The patient in this case presented with extreme pain on the entire right side of his face, extending into his ear. The patient reported on and off biting pain and temperature sensitivity over the prior 2 months. The pain had recently became unbearable. A clinical exam revealed that tooth No. 31 had pain on biting as well as a 7-mm probing depth on the distal. There was no response to vitality testing. A cracked tooth with radicular extension was diagnosed, and the tooth was planned for extraction. The extracted tooth revealed a crack running from the distal marginal ridge deep into the root structure.

Figure 8 The patient in this case presented with a chief complaint of on and off biting discomfort on the lower left. Tooth No. 19 was very sensitive to percussion and cotton roll compression. The cold test was inconclusive. A CBCT scan revealed PDL widening at the apex of the mesial and distal roots. Tooth No. 19 was planned for “exploratory” root canal therapy and a crown. After the amalgam was removed, a crack (cracked tooth) was seen running from the mesial to the distal. Once access was made into the pulp chamber, the full extent of the crack could be visualized running on both the mesial and distal aspects of the crown but not down to the pulpal floor. The patient returned for the second visit, reporting that all symptoms had subsided. The root canal was completed, and the patient was referred back to her dentist for the crown. The patient returned for the 10-month re-evaluation with a core buildup and permanent crown (no post). The tooth was completely asymptomatic, and the radiograph revealed no signs of periapical pathology or periodontal breakdown.

Figure 9 The patient in this case presented with a previously endodontically treated tooth No. 3. The chief complaint included a dull discomfort around the apical region of tooth No. 3. Radiograph examination revealed a periapical breakdown around the apex of No. 3. The J-shaped radiolucency around the MB root was strongly indicative of a VRF. The patient was very motivated to save this tooth, and a root resection was planned. Upon flap reflection and removal of granulation tissue, a VRF was clearly visualized. The MB root was resected.

ETIOLOGY OF THE CRACKED TOOTH

Cracked teeth are the result of repetitive stress to the dentition. They can also be the result of sudden stress on a vulnerable tooth. Repetitive stress would result from parafunctional habits such as bruxism and clenching, whereas a sudden stress injury could be the result of biting on ice, nuts, hard candy, etc.

CRACKS WITH AGE

Older patients have a more brittle dentin structure, and as such, their teeth are more prone to fracture. Rarely do we see classic cracked tooth symptoms in children or adolescents. One study found that the dentin is 50% weaker in those above 55 years old in comparison to those younger than 35 years old.¹⁹ It seems that the fatigue resistance of human dentin decreases with age.²⁰

PREVENTING CRACKS

One of the best ways to prevent cracking a tooth is to have the patient wear a nightguard if clenching or grinding is a habit.

A patient with a history of a cracked tooth should be evaluated for full-coverage restorations on teeth vulnerable to fracture in the future. It is very common to see a patient have a tooth removed due to a crack, only to return a short time later with a crack on another tooth because the edentulous space was never restored. The lack of a restoration after the loss of a tooth puts more stress on the remaining teeth, thus leading to greater vulnerability for fractures on the remaining teeth.

CONCLUSION

Diagnosing and treating the cracked tooth can be a complex endeavor. Many factors contribute to the proper diagnosis and treatment of the cracked tooth. With a better understanding of cracked teeth, more of these teeth can be saved than previously thought.

A chart outlining a few classic studies associated with cracked teeth and vertical root fractures is available here.

ACKNOWLEGEMENTS

The author wishes to thank Dr. Charles Solomon and Dr. Leslie Elfenbein for their valuable input.

REFERENCES

1. Rivera EM, Walton RE. Cracking the cracked tooth code: detection and treatment of various longitudinal tooth fractures. In: Colleagues for Excellence. Chicago: American Association of Endodontists; 2008

2. Cameron CE. The cracked tooth syndrome: additional findings. J Am Dent Assoc. 1976;93:971–5. doi:10.14219/jada.archive

3. Krell KV, Rivera EM. A six year evaluation of cracked teeth diagnosed with reversible pulpitis: treatment and prognosis. J Endod. 2007;33(12):1405–7. doi:10.1016/j.joen.2007.08.015

4. Kahler W. The cracked tooth conundrum: terminology, classification, diagnosis, and management. Am J Dent. 2008;21(5):275–82.

5. Berman LH, Kuttler S. Fracture necrosis: diagnosis, prognosis assessment, and treatment recommendations. J Endod. 2010;36(3):442–6. doi:10.1016/j.joen.2009.12.018

6. Türp JC, Gobetti JP. The cracked tooth syndrome: an elusive diagnosis. J Am Dent Assoc. 1996;127(10):1502–7. doi:10.14219/jada.archive.1996.0060

7. Ricucci D, Siqueira JF Jr, Loghin S, Berman LH. The cracked tooth: histopathologic and histobacteriologic aspects. J Endod. 2015;41(3):343–52. doi:10.1016/j.joen.2014.09.021

8. Brannstrom M. The hydrodynamic theory of dentinal pain: sensation in preparations, caries, and the dentinal crack syndrome. J Endod. 1986;12(10):453–7. doi:10.1016/S0099-2399(86)80198-4

9. Kang SH, Kim BS, Kim Y. Cracked Teeth: Distribution, Characteristics, and Survival after Root Canal Treatment. J Endod. 2016;42(4):557–62. doi:10.1016/j.joen.2016.01.014

10. Rivera EM, Walton RE. Longitudinal fractures. In: Torabinejad M, Walton RE, eds. Principles and Practice of Endodontics, 4th ed. Philadelphia: Saunders; 2009: 108–28.

11. Tan L, Chen NN, Poon CY, et al. Survival of root filled cracked teeth in a tertiary institution. Int Endod J. 2006;39(11):886–9. doi:10.1111/j.1365-2591.2006.01165.x

12. Sim IG, Lim TS, Krishnaswamy G, et al. Decision making for retention of endodontically treated posterior cracked teeth: a 5-year follow-up study. J Endod. 2016;42(2):225–9. doi:10.1016/j.joen.2015.11.011

13. Krell KV, Caplan DJ. 12-month success of cracked teeth treated with orthograde root canal treatment. J Endod. 2018;44(4):543-548. doi:10.1016/j.joen.2017.12.025

14. Davis MC, Shariff SS. Success and survival of endodontically treated cracked teeth with radicular extensions: a 2- to 4-year prospective cohort. J Endod. 2019;45(7):848-855. doi:10.1016/j.joen.2019.03.015

15. Tsesis I, Rosen E, Tamse A, et al. Diagnosis of vertical root fractures in endodontically treated teeth based on clinical and radiographic indices: a systematic review. J Endod. 2010;36(9):1455–8. doi:10.1016/j.joen.2010.05.003

16. Fuss Z, Lustig J, Tamse A. Prevalence of vertical root fractures in extracted endodontically treated teeth. Int Endod J. 1999;32(4):283–6. doi:10.1046/j.1365-2591.1999.00208.x

17. PradeepKumar AR, Shemesh H, Jothilatha S, et al. Diagnosis of vertical root fractures in restored endodontically treated teeth: a time-dependent retrospective cohort study. J Endod. 2016;42(8):1175–80. doi:10.1016/j.joen.2016.04.012

18. Tamse A, Fuss Z, Lustig J, et al. An evaluation of endodontically treated vertically fractured teeth. J Endod. 1999;25(7):506–8. doi:10.1016/S0099-2399(99)80292-1

19. Yan W, Montoya C, Øilo M, et al. Reduction in fracture resistance of the root with aging. J Endod. 2017;43(9):1494-1498. doi:10.1016/j.joen.2017.04.020

20. Seo DG, Yi YA, Shin SJ, et al. Analysis of factors associated with cracked teeth. J Endod. 2012;38(3):288–92. doi:10.1016/j.joen.2011.11.017

ABOUT THE AUTHOR

Dr. Stern is a Diplomate of the American Board of Endodontics. He is the director of endodontics at the Touro College of Dental Medicine and lectures frequently on the subject of clinical endodontics. He has lectured at many local county dental societies, the New Jersey Dental Association Annual Session in May 2019, and the Greater New York Dental Meeting in 2020. He maintains a private practice, Clifton Endodontics, in Clifton, NJ. He can be reached at jstern5819@gmail.com.

Disclosure: Dr. Stern reports no disclosures.

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Researchers at the University of Zurich said they have mapped the first complete atlas of single cells that make up human teeth. They also said that their research shows that the composition of human dental pulp and periodontium very greatly, opening up new avenues for cell-based dental therapeutic approaches.

The researchers used advanced single-cell sequencing technology to distinguish every single cell that is part of the dental pulp and periodontium.

“Our study provides an unprecedented understanding of the composition of these two tissues, which are subject to tooth-specific and bacterially linked pathologies such as caries and periodontitis,” said coauthor and senior researcher Pierfrancesco Pagella of the Institute of Oral Biololgy at the university.

“Both the dental pulp and the periodontium contain stem cells that possess a great regenerative potential,” Pagella said.

The study identified great cellular heterogeneity in the dental pulp and the periodontium. Unexpectedly, the researchers said, they found that the molecular signatures of the stem cell populations were very similar.

“We think their different behavior is possibly brought about by their distinctive microenvironment,” said Pagella.

The findings suggest that the microenvironmental specificity is the potential source of the major functional differences of the stem cells located in the various tooth compartments, the researchers said.

The study also demonstrates the complexity of dental tissues and represents a major contribution to a better understanding of the cellular and molecular identity of human dental tissues, the researchers said.

“Single-cell approaches can help us understand the interactions of dental pulp and periodontal cells involved in immune responses upon bacterial insults,” said last author Thimios Mitsiadis, professor at the Institute of Oral Biology. “Therefore, single-cell analysis could be useful for diagnostic purposes to support the early detection of dental diseases.”

The findings then open up new avenues for cell-based dental therapeutic approaches, the researchers said. These advances in dental research also can lead to more appropriate therapies, successful regeneration of damaged parts of the teeth, and even more precise diagnostic tools in dental pathologies, Mitsiadis said.

“These innovations are the consequence of the fusion between bioinformatics and modern dentistry,” Mitsiadis said.

The study, “A Single Cell Atlas of Human Teeth,” was published by iScience.

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There’s a surprising amount of information stored in the hardened plaque, or calculus, between teeth, according to an international team of researchers. And if that calculus belongs to the remains of a person who lived in ancient times, they added, the information could reveal new insights about the past.

Tiny samples can be difficult to work with, though, prompting the researchers to apply a new method to this analysis that finds more proteins than traditional approaches.

The human mouth is full of interesting molecules, the researchers said, such as DNA and enzymes in saliva, proteins and lipids from bits of food stuck between teeth, and the bacteria of the oral microbiome. Under the right conditions, these molecules can be preserved in dental calculus for thousands of years.

Identifying the biomolecules preserved within ancient plaque provides clues about how our ancestors lived, what they ate, what diseases they had, and more, the researchers said. But there’s only so much plaque that can be scraped off old teeth, according to the researchers, so it’s important to apply methods that can extract the most information from miniscule samples.

No gold-standard method for calculus analysis exists, the researchers said. Filter-based techniques often are used, but they can be time-consuming and can introduce contaminants. The researchers, then, examined whether single-pot, solid-phase enhanced sample preparation (SP3) could improve the number and complexity of protein fragments that could be analyzed from preserved plaque.

The researchers applied SP3 to the analysis of calculus from 153 ancient individuals dating between the first and fourth century BCE. With SP3, functionalized magnetic beads grabbed onto protein fragments, making them easy to analyze by mass spectrometry.

SP3 reliably increased the number of unique protein fragments the researchers could identify in samples, including smaller peptides that two other methods, ultrafiltration and acetone precipitation, missed. SP3 also was easy to perform and less likely to introduce contaminants than the other methods. Using this approach, the researchers identified fragments of dairy proteins from the subjects’ diets as well as bacterial proteins that could shed light on ancient diseases.

The study, “Comparing the Use of Magnetic Beads with Ultrafiltration for Ancient Dental Calculus Proteomics,” was published by the Journal of Proteome Research.

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Conventional wisdom says that diet affects oral health. But people begin to disagree on the details, and there are many widely held misconceptions. DentaVox recently surveyed 1,715 respondents from around the world about 10 popular beliefs about diets and teeth to see if they matched what the experts had to say.

First, 48% of respondents said that intermittent fasting may reduce the risk of cavities, and the experts agree. Eating only within an 8-hour window each day, followed by 16 hours of fasting, reduces exposure to food acids and gives teeth a break from fighting cavity-causing bacteria.

Next, a fourth of respondents said that the vegan diet is always dangerous for oral health, but the experts called this a myth. Though vegans don’t eat milk, cheese, and yogurt, which are good for oral health, vitamins such as B12, D, A, and K and elements like calcium, potassium, phosphorous, and arginine are widely available in other foods.

Third, 56% of respondents correctly said that the coffee diet, which includes a cup of black coffee after every meal as well as before bathing and exercising, can lead to enamel erosion, bad breath, and yellow teeth. Doctors suggest that people who partake in the coffee diet also drink plenty of water to protect their teeth from acid and stay hydrated.

According to the survey, more than half of the respondents said that the alkaline diet is helpful in improving pH levels, which is a fact. The pH level in your mouth should be between 6.2 and 7.6 to keep your teeth and gums healthy, and the alkaline diet restricts acidic foods like grains, sugar, dairy, fish, and meats and relies on alkaline foods like fruits and vegetables.

Yet 47% of respondents believe the myth that diet soda is better than regular soda for oral health. It’s more than the sugar in soda that damages teeth. Soda also is highly acidic regardless of the sweetener used, and over time, sugar-free drinks can cause just as much erosion and cavities as sugary drinks.

Also, 65% of respondents were correct in believing that fast food harms teeth. Added salt and sugar are highly acidic and cause cavities. The fizzy drinks served with fast food can wear down tooth enamel. And, fast food increases the risks of diabetes and gum disease.

A gluten-free diet, though, does not help absorb calcium better, even though 53% of the respondents think so. Celiac disease requires a gluten-free diet and often leads to calcium deficiencies, but non-celiac gluten deficiencies do not compromise calcium absorption.

The Paleo diet, which primarily means whole-food and plant-based meals while allowing for lean meats and fish, restricts sugary and starchy foods so it is good for oral health. But since it limits grains, it could mean more fruits, which can cause sticky teeth. DentaVox said its respondents had a variety of opinions with no real consensus.

Almost 60% of respondents were correct that olive oil, which is prominent in the Mediterranean diet, prevents bacteria from sticking to teeth. In fact, people who live near olive oil manufacturing plants have low incidences of gum disease, DentaVox said.

Finally, 42% of respondents were correct when they said that the keto diet, which cuts down on carbohydrates, leads to bad breath. By burning fat instead of carbs, the body develops ketones, which in turn leads to bad breath. Drinking plenty of water or chewing gum can help people restore their breath.

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Researchers at the University of Illinois at Chicago (UIC) have determined, for the first time, how materials come together at the molecular level to form bones and other hard tissues like teeth and enamel.

The researchers captured high-resolution, real-time images of the mineralization process in an artificial saliva model and discovered distinct pathways that support bone and teeth formation, or biomineralization.

Until now, these pathways, particularly at the early stages when molecules are first starting to organize into a structure, have not been understood clearly,” said Reza Shahbazian-Yasser, PhD, professor of mechanical and industrial engineering at the UIC College of Engineering and corresponding author of the paper.

The researchers observed that both direct and indirect formations of hydroxyapatite crystals, the foundation of hard tissues, can be achieved by local variation in energetic pathways for nucleation and growth.

“The control over the dissolution of amorphous calcium phosphate affects the assembly of hydroxyapatite crystals into larger aggregates,” said Shahbazian-Yasser.

“Using technology developed at UIC, we found evidence that these pathways coexist simultaneously, explaining why different groups had reported seemingly different or opposite results,” he said.

“In addition, we now understood how hydroxyapatite materials nucleate and grow on amorphous calcium phosphate templates. The control over the nucleation and growth of hydroxyapatite will aid in developing new drugs and medical treatments to heal lost or broken bone faster or cure tooth cavities,” he said.

To capture the images, the researchers said they used a unique microdevice that made it possible to use electron microscopy with a liquid model. Using this method, the researchers were able to monitor chemical reactions in the model on the smallest scale.

“Our study provides clear, new evidence of how minerals organize and grow into bone materials, and this finding has many important implications for further research on bone or teeth healing,” said Shahbazian-Yasser.

“By better understanding these pathways, scientists are one step closer to engineering ways to better treat dental diseases and bone injuries, like those from traumatic injuries, or prevent medical conditions that can develop when normal mineralization processes in the body go awry,” he said.

Medical conditions caused by dysfunctional mineralization in the body can include everything from a tendency to develop cavities to osteoporosis.

“In the next step, we would like to learn how molecular modifiers can affect the process of biomineralization, which is important to develop effective drugs,” Shahbazian-Yasser said.

The study, “Revealing Nanoscale Mineralization Pathways of Hydroxyapatite Using in Situ Liquid Cell Transmission Electron Microscopy,” was published by Science Advances.

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March is National Nutrition Month, which DentalPlans.com calls an excellent time for seniors to evaluate their food choices and dental health. The online marketplace for dental savings plans also advises oral health professionals to speak with their older patients about strategies for preserving their oral and systemic health. 

For example, older adults need more calcium and vitamin D to help keep their teeth and bones healthy. They should consume three servings of fat-free or low-fat milk, yogurt, or cheese each day. Lactose-intolerant patients should try lactose-free or calcium-fortified soy beverages.

Also, many older adults need fewer calories than they did in their younger years. They should prioritize nutrient-dense foods like lean proteins, vegetables, and legumes when making meal choices. To avoid serving oversized portions, try using smaller plates, bowls, and glasses.

Older adults should drink water instead of sugar-sweetened beverages as well. Staying hydrated is an important way to combat a dry mouth, which can be caused by medications commonly taken by seniors and is associated with dental decay.

Phosphorous, which is found in eggs, fish, lean meat, dairy, nuts, and beans is good for strong teeth and bones.

And, vitamin C promotes gum health, so seniors should eat plenty of citrus fruits, tomatoes, peppers, broccoli, potatoes, and spinach. They also should rinse their mouth gently with water after eating citrus and wait an hour before brushing their teeth since acidic foods and beverages temporarily softens dental enamel.

“Eating healthy contributes to great dental health, but it’s still critical to see your dentist regularly for checkups and cleanings,” said Jenn Stoll, chief commercial officer at DentalPlans.com.

“And if you experience any pain or difficulties when eating, speak to your dentist right away so you can get the care you need and deserve in order to eat a well-rounded, nutritious diet,” Stoll said.

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As the holidays approach, many folks indulge in more wine than usual—and that could lead to more stained teeth, according to Uchenna Akosa, DDS, head of Rutgers Health University Dental Associates, the faculty practice of the Rutgers School of Dental Medicine. But dentists can give their patients tips for preventing these stains while still enjoying their celebrations.

“When you drink red wine, you’re encountering a triple threat to your teeth’s whiteness: anthocyanins, which are the pigments in grapes that give red wine its rich color; tannins, which help bind the pigment to your teeth; and the acidity found in wine, which etches your enamel, making it more porous and easier for the stain to stick,” Akosa said. 

“The strength of your enamel and how prone you are to plaque buildup is key to how much your teeth might stain,” said Akosa, who offered four tips that dentists can share to help their patients prevent wine-stained teeth:

• Brush before, but no immediately after, drinking. Since plaque can make it look like your teeth are stained, you should brush your teeth 30 minutes before drinking, but not right after since toothpaste can cause more etching.
• Don’t drink white wine before red wine. The extra acid in the white wine will exacerbate the staining.
• Drink water while drinking wine. Swishing your mouth with water, which is neither basic nor acidic, after drinking wine helps to reduce the wine’s acidity and stimulates saliva flow, which is critical in fighting harmful bacteria and maintaining the idea pH in your mouth. 
• Enjoy cheese with your wine. Chewing food also stimulates saliva. Cheese is ideal to pair with wine as it both stimulates saliva and reduces the acidity from the wine.
• Get regular dental cleanings to keep your enamel strong. Cleanings can help remove plaque, which is an acidic substance that damages your tooth enamel. If not cleaned, it can result in cavities.

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The Scandinavian countries’ culture of equality between the sexes may go back a long way, according to researchers at the University of Tübingen who compared the health of men and women from the past thousand years using data gathered from teeth and skeletons.

If the data in a population showed that women had the same or even better health values than men, the researchers assumed that boys and girls had relatively equal access to food and other resources. 

The data from Scandinavia indicated that women in rural areas there were in a comparatively favorable position as early as the Viking Age from the late eighth to the eleventh centuries, and in the medieval period that followed. For the society overall, this greater gender equality appears to have led to long-term positive development, the researchers said.

The study was based on European data from the Global History of Health Project. It incorporates data from studies on human skeletons from more than a hundred European sites from the past 2,000 years. 

The researchers looked especially closely at the information provided by teeth. People who are undernourished or seriously ill in early child have linear enamel hypoplasia, which is permanent damage to the enamel. 

“We hypothesized that if girls and women received less food and care than the male members of society, they would have more such damage,” said Dr. Laura Maravall, an economic historian with the school’s Collaborative Research Center. 

“The extent to which values differ between men and women is therefore also a measure of equality within the population,” Maravall said. 

The close connection between the relative frequency of enamel damage and the general state of health was demonstrated by measurement of the corresponding thigh bones. The length of the femur provides information about height, which is relatively greater in individuals with good health and a good diet.

The detailed analysis of the dental data for Scandinavian men and women in the countryside suggested a high degree of equality even in Viking times, the researchers said.

“Such women in the Nordic countries may have led to popular myths about the Valkyries. They were strong, healthy, and tall,” said professor Jörg Baten, also an economic historian with the Collaborative Research Center, adding that the picture in Scandinavian cities was different. 

“The Swedish towns of Lund and Sigtuna, on the site of today’s Stockholm, and in Trondheim in Norway had developed a class system by the Early Middle Ages. Women there did not have the same equality as their sisters in the countryside,” Baten said.

Equality outside of the cities appears to have been linked to specialization in raising livestock.

“Raising crops was something primarily done by men because it required greater muscular strength. But raising animals enabled women to contribute a great deal to the family income. That probably raised their position in society,” said Baten.

Scandinavian women were also well-off compared to other women in Europe, the researchers said. Women experienced significantly less equality in the Mediterranean region and in Eastern European cities.

“The research has provided us with a great deal of evidence on the relationship between gender equality and a country’s economic development. Gender equality not only increases women’s prosperity, it also has a positive impact on economic growth and development in general,” Baten said. 

The researchers speculate that Scandinavian women have been able to maintain their strong place in society up to the industrial era and beyond. They also say it may be one reason why Norway, Sweden, Denmark, and Finland are prosperous and economically stable.

The study, “Valkyries: Was Gender Equality High in the Scandinavian Periphery Since Viking Times? Evidence from Enamel Hypoplasia and Height Ratios,” was published by Economics and Human Biology.

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The stem cells in teeth can contribute to the regeneration of non-dental organs, particularly mammary glands, according to researchers at the University of Zurich. Dental epithelial stem cells from mice can generate mammary ducts and even milk-producing cells when transplanted into mammary glands, the researchers reported, noting that these findings could have potential for post-surgery tissue regeneration in breast cancer patients.

The ability of adult stem cells to generate various tissue-specific cell populations is of great interest in the medical and dental research fields, the researchers said. These cells can replace damaged cells and therefore represent a good alternative to classical medical treatments for tissue regeneration, the researchers added, perhaps even allowing the de novo formation of entire tissues and organs in the future.

Dental epithelial cells can generate all epithelial cell types in the teeth, but it was not clear if these cells also could produce non-dental cell populations. The researchers at the Institute of Oral Biology of the University of Zurich, however, have shown for the first time that epithelial stem cells isolated from the continuously growing incisors of young mice can form mammary glands in female mice. 

After removing all cells of mammary origin, the researchers directly injected dental epithelial stem cells and mammary epithelial cells into the areas where the mammary glands normally develop. The researchers used advanced genetic, molecular, and imaging tools that allow for the precise follow-up of the transplanted dental stem cells in the mammary gland fat pad of the animals.

“The results show that the dental stem cells contribute to mammary gland regeneration and are able to generate all mammary cell populations and, even more strikingly, milk-producing cells,” said Thimios Mitsiadis, a professor with the Institute of Oral Biology.

This work demonstrates the exceptional plasticity of dental epithelial stem cells to generate not only dental tissues but also other tissues of the body, the researchers said.

“These findings represent a major contribution to the understanding of the cellular and molecular mechanisms involved in the regenerative capacity of dental stem cells and, furthermore, indicate the clinical potential of these specific stem cell populations,” Mitsiadis said. 

In a second set of experiments, dental epithelial stem cells were injected alone, without mammary epithelial cells. In this case, the dental stem cells also were able to form small ductal systems consisting of branching rudiments. But in some cases, this resulted in the formation of cysts.

“This plasticity might be unique for dental epithelial stem cells, since all other non-mammary epithelial cells examined so far have never shown the ability to generate mammary ducts without the support of mammary epithelial cells,” said study coauthor Pierfrancesco Pagella of the Institute of Oral Biology. 

One of the most severe pathological conditions is breast cancer, the researchers said, which is often treated with surgery. 

“Our discovery that dental epithelial stem cells are able to replace cells from the mammary gland opens up new paths for developing stem cell-based therapies that could be used for breast regeneration in the future,” said Mitsiadis. 

The study, “Dental Epithelial Stem Cells As a Source for Mammary Gland Regeneration and Milk Producing Cells in Vivo,” was published by Cells.

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About two out of every three people (65%) frequently use their teeth for tasks other than eating and drinking, putting their oral health at risk, according to a survey conducted by the Oral Health Foundation and Philips as part of National Smile Month. 

The most common misuse of teeth is tearing tape, with 41% doing so regularly. Also 26% of people bite their nails, while 22% use their teeth to carry things when their hands are full. Taking tags out of clothing (20%), chewing pens and pencils (16%), opening bottles (9%), and opening and closing zippers (4%) also are common bad habits.

“Anything from opening bottles to chewing foreign objects can damage existing dental work or cause our teeth to crack,” said Dr. Nigel Carter, OBE, chief executive of the Oral Health Foundation.

“There are also examples of teeth shifting out of place, chipping, and in some cases breaking, due to the pressure and strain. Accidents are also more likely to happen, which could result in invasive and expensive emergency dental work,” said Carter.

“We should stick to using our teeth for what they were designed to do—chewing our food so that it’s more easily digestible. Our teeth also help us to talk and make sounds. They also give our face its shape. Because of this, we shouldn’t be doing anything that could unnecessarily jeopardize them,” Carter said.

Young adults are the biggest culprits when it comes to using teeth improperly, with 85% of 18- to 35-year-olds admitting to performing unusual tasks with their teeth, compared to 70% of 35- to 54-year-olds and 54% of those over the age of 55. 

The survey was conducted as part of National Smile Month, which promotes the benefits of a healthy smile. Its #habits4life initiative encourages everyone to adopt good habits to live healthier, happier, and longer lives.

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