Half of all tooth-colored restorations, which are made of composite resin, fail within 10 year. 60 % of all operative dentistry involves replacing them, according to research in the Journal of the American Dental Association.
To make a bond, a dentist etches away some of the dentin’s minerals with phosphoric acid to expose a network of collagen. Acid-etching is kind of similar to priming a wall before it’s painted; it prepares the tooth for application of an adhesive to the hybrid layer so that the resin can latch on to the collagen network. Unfortunately, the imperfect adhesives leave spaces inside the collagen that are not properly infiltrated with resin which can cause the bond to fail.
Dr. Franklin Tay is trying to prevent the aging and degradation of resin-dentin bonding by feeding minerals back into the collagen network. With a two year, $252,497 grant from the National Institute of Dental and Craniofacial Research, he will investigate guided tissue remineralization. This approach is a new nanotechnology process of growing extremely small, mineral-rich crystals and guiding them into the demineralized gaps between collagen fibers.
Dr. Tay says. “We’re trying to mimic nature, and we’re learning a lot from observing how small animals make their shells.”
The crystals, called hydroxyapatite, bond when proteins and minerals interact. Dr. Tay will use calcium phosphate, a mineral that’s the primary component of dentin, enamel and bone, and two protein analogs also found in dentin so he can mimic nature while controlling the size of each crystal.
Most crystals are grown from one small crystal into a larger, homogeneous one that is far too big to penetrate the spaces within the collagen network. Dr. Tay will fit the crystal into the space it needs to fill. “When crystals are formed, they don’t have a definite shape, so they are easily guided into the nooks and crannies of the collagen matrix,” says Dr. Tay.
If Dr. Tay’s concept of guided tissue remineralization works, he will create a delivery system to apply the crystals to the hybrid layer after the acid-etching process.
Dr. Tay says “Our end goal is that this material will repair a cavity on its own so that dentists don’t have to fill the tooth.”
Adapted from materials provided by Medical College of Georgia.