People experiencing agony from tooth decay may soon find relief, after two new studies discover how an enzyme in teeth, which is needed to form enamel, can help lessen or eliminate this type of pain.

According to researchers from the University of Southern California, or USC, say that matrix metalloproteinase-20, or MMP-20, form enamel together with other enzymes. Tooth enamel, which is the hardest bioceramic in the human body, is a non-living tissue and cannot rejuvenate. To address this, the team found that an amelogenin-chitosan hydrogel could grow an enamel-like layer that reduces lesions by up to 70 percent.

“Recognising MMP-20’s function in biomineralisation is one of the first steps to learning how dental enamel forms in nature,” said Qichao Ruan, lead author of the study and a postdoctoral research associate in the Center for Craniofacial Molecular Biology at USC. “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.”

With this discovery, people may be able to use an overnight mouth guard or teeth strips saturated with hydrogel to regrow enamel-like substances and reduce teeth sensitivity, according to Janet Moradian-Oldak, a dentistry professor at the Herman Ostrow School of Dentistry of USC.

Moradian-Oldak first discovered the existence and role of MMP-20, which was detailed in the Biomaterials journal last month. With her colleagues, she found that MMP-20 chops up proteins during the crystallisation of enamel. Together with other enzymes, it gets rid of ‘sludge’ so the enamel making cells in the body can add more mineral and make enamel.

To test the new hydrogels’ effectivity, Ruan and his team used wild type mice and MMP-20 null mice in an environment that mimics an oral cavity’s biochemical processes. They found that the gel created a robust attachment, eliminating the threat of secondary cavities in the same spot, Ruan said. The gel could be more effective than traditional crowns, whose adhesion weakens over time, he added.

While products such as toothpaste and mouthwash containing fluoride and casein phosphopeptide-amorphous calcium phosphate promote remineralisation of initial enamel lesions, they need to be used regularly and are more of a tire patch than a real solution, Moradian-Oldak said. The newly discovered gel, however, fills the cracks and holes with an enamel-like substance.

For their next steps, the team seeks to to alter the gel recipe using MMP-20 to create a stronger enamel-like seal to prevent decay from progressing.

Tooth decay is Australia’s most common health problem, according to the Australian Dental Association. It has five times the prevalence of that of asthma among children, and each year sees 11 million newly decayed teeth develop. According to government reports, tooth decay is also the second most costly diet-related disease in Australia, which is all the more concerning given that the vast majority of all dental disease is preventable.

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