What is tooth bonding?

A lot of people have heard about bonding but may not entirely understand what that means. Bonding involves sticking a white filling material to tooth structure. There have been huge advancements in this field especially as more and more people do not want metal fillings in their mouths.

The first bonding that was done, which is still the key to bonding today, involved treating enamel with acid and etching it like one would etch glass. Microscopically the enamel ends up looking very rough. The white resin filling material, which is strengthened with quartz crystals, flows into these microscopic pits and is “bonded” to the tooth. This bond is very strong but a problem would arise if a tooth was so badly damaged that there was very little enamel left. So dental researchers found a way to bond filling material to the inner tooth structure - the dentin.

Dentine is not as strong as enamel and is made of of microscopic tubules with a collagen fibre matrix and these tubules are filled with fluid. White filling material doesn’t like liquid but some brilliant researchers figured out a way of getting the filling material to flow into the dentinal tubules and get entangled in the collagen fibres. Now there was a way of getting a very strong bond to enamel and dentine.

Orthopaedic surgeons discovered a problem when they “bonded” new joints into people. They used the collagen fibres also but found that over time the bond would weaken. They discovered that an enzyme called MMP would slowly cause the breakdown of the collagen fibres. They discovered that they could treat the collagen with a chlorhexidine solution and it would eliminate the enzyme. Dental researchers discovered that this worked in teeth also. They found that chlorhexidine solution could eliminate the enzyme but it could also be eliminated by a solution called HEMA.

What does all this mean? When your dentist gives you a white filling he or she will treat the tooth with acid to prepare it for bonding and then coat the dentine with a solution to eliminate MMP enzyme. After that a bonding solution will be applied to the tooth and then the filling material is added.

The vast majority of bonding solutions and filling materials are light activated. That means that they harden when a blue light is shone onto them. These bonded fillings are excellent but they are time consuming because each step has to be done exactly as the manufacturer specifies. The materials have to be handled precisely and the time that the blue light is applied is also very specific. It must also be kept in mind that the bonding solutions and filling materials are very expensive.

Bonding has revolutionized dentistry.