The Ohio State University: College of Dentistry

Newest Projects in Development

Dentin-Pulp Dynamics Change with Age:

Figure 1. America’s aging population Source: censusscope.org

The world is aging at a high rate. Tooth loss is no longer seen as a natural process of aging, and retaining healthy teeth into old age is now a common goal. Like all human organs, teeth decline over time. Dentin increases in thickness due to ongoing dentinogenesis, leading to nerve fiber and odontoblast regression into an increasingly smaller dental pulp (DP) chamber (Figure 2). This reduces tooth sensitivity and injury responses. Arterial degeneration reduces the number of arteries that supply coronal pulp regions with blood for nutrients and hydration. Hypermineralization and dehydration increase the risk of fatigue cracks and decrease the ability of teeth to absorb energy. As a result, almost all people (94-97%) develop dental caries between the ages of 35 and 641. The restorative procedures currently used to treat infected teeth can cause cracks at the dentin-restoration interface that can lead to secondary infections, a reduction in tooth stiffness, and subsequent tooth failure2–8. Painful tooth decay and/or tooth loss can reduce patients’ ability to chew and speak clearly, as well as affect their overall appearance (Figure 3). This discomfort often leads to a soft diet high in saturated fat and cholesterol and low in fiber and nutrients. This poor diet, combined with the social challenges that accompany edentulism, have a direct effect on health and mortality9–12.

Figure 2. Aging tooth structure Source: Pocket Dentistry

With the advent of regenerative medicine and tissue engineering, regenerative dentistry and endodontics has quickly gained attention and has shown promising results in human clinical trials. However, several challenges remain, particularly since the regenerated tissues are not actually dental pulp or tubular dentin, but instead more fibrous or bone-like in nature and lacking sensitivity.

Figure 3. Painting by Leonardo da Vinci

Our laboratory is now investigating how the dentin-pulp complex changes with time. In addition, modern medicine has identified many differences in how aging occurs between the sexes, yet many medical treatments have been developed based on male-only studies. As a result, clinical treatments often fail to perform well in female patients. In dentistry, most clinicians treat dental maladies equivalently between the sexes. We believe addressing sex as a biological factor in tooth aging is crucial to the design of precision-based dental treatments and to help retain natural teeth into old age.

 

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MicroCT of Mouse Molars with Age +/- Hormone Treatment

Oral Bone and Tooth Aging in Mouse Model of Aging

One Set of Extracted Rat Molars

Preparing to Divide Root and Crown Portions of Rat Molars

References:

  1. Dye B, Thornton-Evans G, Li X, Iafolla T. Dental caries and tooth loss in adults in the United States, 2011-2012. NCHS Data Brief. 2015;(197):197. https://www.cdc.gov/nchs/products/databriefs/db197.htm. Accessed March 8, 2021.
  2. Yahyazadehfar M, Ivancik J, Majd H, An B, Zhang D, Arola D. On the mechanics of fatigue and fracture in teeth. Appl Mech Rev. 2014;66(3):0308031. doi:10.1115/1.4027431
  3. Lucas F, Rogers KA, Harrington BK, et al. Eμ-TCL1xMyc: a novel mouse model for concurrent CLL and B-cell lymphoma. Clin Cancer Res. 2019;25(20):6260. doi:10.1158/1078-0432.CCR-19-0273
  4. Winter W, Karl M. Dehydration-induced shrinkage of dentin as a potential cause of vertical root fractures. J Mech Behav Biomed Mater. 2012;14:1-6. doi:10.1016/j.jmbbm.2012.05.008
  5. Lin LM, Skribner JE, Gaengler P. Factors associated with endodontic treatment failures. J Endod. 1992;18(12):625-627. doi:10.1016/S0099-2399(06)81335-X
  6. 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
  7. Kishen A. Mechanisms and risk factors for fracture predilection in endodontically treated teeth. Endod Top. 2006;13(1):57-83. doi:10.1111/j.1601-1546.2006.00201.x
  8. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. J Endod. 1989;15(11):512-516. doi:10.1016/S0099-2399(89)80191-8
  9. Holm-Pedersen P, Schultz-Larsen K, Christiansen N, Avlund K. Tooth Loss and Subsequent Disability and Mortality in Old Age. J Am Geriatr Soc. 2008;56(3):429-435. doi:10.1111/j.1532-5415.2007.01602.x
  10. Hämäläinen P, Meurman JH, Keskinen M, Heikkinen E. Relationship between dental health and 10-year mortality in a cohort of community-dwelling elderly people. Eur J Oral Sci. 2003;111(4):291-296. doi:10.1034/j.1600-0722.2003.00055.x
  11. Abnet CC, Qiao YL, Dawsey SM, Dong ZW, Taylor PR, Mark SD. Tooth loss is associated with increased risk of total death and death from upper gastrointestinal cancer, heart disease, and stroke in a Chinese population-based cohort. Int J Epidemiol. 2005;34(2):467-474. doi:10.1093/ije/dyh375
  12. Shimazaki Y, Soh I, Saito T, et al. Influence of dentition status on physical disability, mental impairment, and mortality in institutionalized elderly people. J Dent Res. 2001;80(1):340-345. doi:10.1177/00220345010800010801