Research in Focus
NYU Dental Study Identifies Promising New Approach for Treating Tooth Hypersensitivity

Dr. Racquel Z. LeGeros

NYU College of Dentistry researchers have identified a promising new approach for treating tooth hypersensitivity, while simultaneously preventing bacteria from causing further harm.

Tooth hypersensitivity occurs when the dentin becomes exposed, causing dentinal tubules to open up. When open tubules come in contact with cold, hot, sweet, or acidic substances, painful stimuli are transmitted to the pulp. Hypersensitivity can be caused by oral bacteria, which attach to the tooth surface and leave an acidic residue of biofilm and calculus.

Most toothpastes, protective strips, and other treatments for tooth hypersensitivity utilize potassium oxalate to close the tubules. But potassium oxalate cannot prevent a recurrence of tooth hypersensitivity because deposits in the tubules from potassium oxalate treatment are highly susceptible to the effects of acids from biofilm, citrus drinks, and other acidic liquids.

In the NYU dental study, a coating on the tooth surface and deposits in the dentin tubules obtained from a calcium phosphate solution containing fluoride and zinc ions proved effective in preventing the growth of Streptococcus mutans, a bacterium commonly associated with dental caries. The coating not only caused the exposed dentin tubules to close again, but also prevented Streptococcus mutans from causing further damage. The findings were presented on July 17, 2010, at the annual meeting of the International Association for Dental Research in Barcelona, Spain, and part of the study will be published in the February 2011 issue of the American Journal of Dentistry.

Coprinicipal investigators Dr. Racquel Z. LeGeros, Professor and Associate Chair of Biomaterials & Biomimetics at the NYU College of Dentistry, and Dr. Haijin Gu, Chief Dentist at Sun-Yat-sen University Guanghua School of Stomatology in Guangzhou, China (while a Visiting Scholar at NYU College of Dentistry), compared two groups of dentin samples immersed for 24 hours in a solution containing Streptococcus mutans. One group was treated with the calcium phosphate/ fluoride/zinc formulation for eight minutes, while the second group received no treatment. Bacteria multiplied on the untreated samples, but their growth and development were inhibited on the treated dentin. In addition, the treated group had significantly fewer open tubules than the untreated one.

"Because the calcium, phosphate, and fluoride ions formed a solution that occluded the open dentin tubules, and the zinc and fluoride ions inhibited bacterial growth and colonization, our findings suggest that this formulation may represent a tooth hypersensitivity treatment that is less susceptible to the effects of acid compared to treatments made with potassium oxalate," said Dr. LeGeros, who plans additional testing to confirm the findings.

Coinvestigators on the study included Dr. Robert Boylan, Associate Professor of Basic Science & Craniofacial Biology, and Dr. John P. LeGeros, Adjunct Professor of Biomaterials & Biomimetics, both of the NYU College of Dentistry; Dr. Junqi Li, Dean of the Guanghua School of Stomatology; and Dr. Danni Fan, Assistant Professor of Prosthodontics at the Guanghua School of Stomatology.