New approach for tooth hypersensitivity

Aug. 20, 2010
New York University College of Dentistry researchers note approach while simultaneously preventing bacteria from causing further harm.

New York University College of Dentistry researchers have identified a new approach for treating tooth hypersensitivity while simultaneously preventing bacteria from causing further harm.

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In the NYU dental study, a coating made from fluoride and zinc ions in a calcium-phosphate matrix proved effective in reversing damage to the tubules caused by Streptococcus mutans, a bacterium commonly associated with tooth decay.

The coating not only caused the exposed tubules to close again, but also prevented Streptococcus mutans from causing further damage. The findings were presented July 17 at the 2010 annual meeting of the International Association for Dental Research in Barcelona, Spain.

Tooth hypersensitivity occurs when the dentin, which lies just below the surface of the tooth, becomes exposed, causing tubules--tiny structures that transmit stimuli to the tooth nerve--to open up. When open tubules come in contact with cold, hot, sweet, or acidic substances, painful stimuli are transmitted to the tooth nerve.

Typically, hypersensitivity is caused by oral bacteria, which attach to the tooth surface and leave an acidic residue of tartar and plaque.

Most toothpastes, protective strips, and other treatments for tooth hypersensitivity use potassium oxalate to close the tubules. But potassium oxalate cannot prevent a recurrence of tooth hypersensitivity because it is highly susceptible to the effects of acids in tartar, plaque, citrus drinks, and other liquids.

Co-prinicipal investigators Dr. Racquel Z. LeGeros, professor and associate chair of niomaterials & niomimetics at the NYU College of Dentistry, and Dr. Haijin Gu, chief dentist at Sun-yat-sen University Guanghua School of Stomatology in Guangzhuo, China, 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 was 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 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 than 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 .

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