Scientists find way to grow tooth enamel, reduce pain linked to decay

Hydrogel developed at USC created a stronger seal on teeth than traditionally used caps.

By Stephen Feller

LOS ANGELES, Nov. 17 (UPI) -- In two recent studies, researchers at the University of Southern California found an enzyme in teeth important for the formation of enamel and a way to motivate it to help regrow enamel -- which may help reduce the pain of tooth decay more effectively than a cap.

Matrix metalloproteinase-20, or MMP20, is found only in teeth, working with other enzymes to organize the crystals that make up enamel. Because the tooth-protecting bioceramic, the hardest found in the body, is non-living tissue and does not actually grow, researchers have found a way to grow an enamel-like substance nearly as strong as the naturally-occurring version.


Cavities are usually treated with drilling the affected area of a tooth, and placing a cap on the the tooth to protect it. The seal that keeps these caps in place can weaken over time, leading researchers to search for a better way to reduce the pain associated with cavities.

"Recognizing MMP-20's function in biomineralization is one of the first steps to learning how dental enamel forms in nature," said Dr. Qichao Ruan, a postdoctoral research associate at the University of Southern California, in a press release. "The findings regarding MMP-20 not only help us to further understand the mechanisms of enamel formation but also can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair."


The researchers first discovered the existence and function of MMP-20, detailed in a study published last month in Biomaterials. Having learned how enamel forms, and using the protein, which prevents unwanted organic material to form in enamel crystals and guides their growth, researchers started looking a way to repair enamel.

In the second study, also published in the journal Biomaterials, researchers tested the hydrogel in a simulated model of an oral cavity's biochemical processes and on human molars without the lesions that lead to cavities.

Researchers sliced teeth into three or four blocks, created artificial tooth decay on them, and then cycled them through samples of artifical saliva of varying acidity.

Supersaturated calcium and phosphate ions, similar to mouthwash, produced an enamel-like substance but the disorganized structure of crystals formed what researchers said is a weaker bond. The hydrogel, however, reduced the depth of lesions by 50 to 70 percent after a week of hydrogel application.

The researchers now are working on a solution that will form a stronger enamel as the conduct pre-clinical trials to test its future use with humans.

"We create a protective cover on enamel," she Dr. Janet Moradian-Oldak, a dentistry professor at the Herman Ostrow School of Dentistry of USC. "We restore the structure of enamel, and it will prevent decay from progressing."


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