The Natural Beauty of Tooth Colored Fillings
Bonding — Nature Influencing Art, Art Mimicking Nature
Scientific discovery and ingenuity have led to the successful bonding of composite resins to enamel, now in use for many years. The startling discovery of the nature of the interface (join) between dentin and enamel of teeth, paved the way for the principles employed in adhesive dentistry.
Successful bonding to dentin has required more research and understanding. Ultimately it has been achieved by a process in which the dentin surface is specially “prepared” and then “sealed.” “Immediate Dentin Sealing” (also called “resin coating”) creates an intimate physical and mechanical bond which is not only very strong, but also overcomes the tendency of the composite resin to shrink. Importantly, it also keeps the tooth and therefore you — comfortable. This technique forms the base to which further composite can be added for rebuilding lost tooth structure.
Restorative Dentistry's Challenge — Rebuilding Teeth
The restoration or rebuilding of back teeth from “the ground up” so to speak is dependent upon successful bonding to both enamel and dentin — the foundation of adhesive restorative dentistry. The goal of restorative dentistry is to return all of the destroyed or lost dental tissues of the teeth to full form (shape) and function — allowing biting stresses to pass through them. These adhesive techniques maximize preservation of tooth structure with minimal preparation (drilling) and allow the maintenance of their vitality and natural appearance.
Major advances in this area have also resulted from the study and understanding of how the crowns of teeth actually flex or give under biting force and how dental restorative materials can be used to greatest effect. These newer materials have been developed to actually fuse with natural tooth material and match its behavior, both stabilizing and strengthening the restored tooth thereby reducing the rate of premature failure from fatigue or fracture. They also recreate very natural looking teeth.
How Modern Dentistry Mimics Nature
Choosing which material to restore or rebuild teeth is a critical one based on scientific understanding and the experience and clinical judgment of your dentist.
Proper tooth restoration is a lot more than just filling holes. It is a unique art applied with scientific understanding. It is the shapes and location of the back teeth, the “premolars and molars” that allow their specialized function — chewing and breaking down food. A tooth's internal shape and structure is the guide to how it must be rebuilt in order to be successfully restored. Older restorative concepts were based on the development of excessively strong and stiff materials (such as gold alloys) unable to yield and therefore contributed to failures of the remaining tooth substance around restorations (e.g. decay or cracking). Newer concepts tend to get away from the “stronger and stiffer is better” concept, and rather have moved towards safety principles using materials that mimick the properties of natural tooth structure.
Matching the Behavior of Teeth
Immediate Dentin Sealing — involves the formation of a resin coating which both seals and protects the dentin surface against bacterial leakage and sensitivity. Most importantly it keeps the tooth and you the patient comfortable. This is also the first layer of a sandwich-like structure known as a “hybrid layer” (resin coating) to which composite resin is bonded to rebuild tooth structure.
Dentin Build-up — following its sealing the dentin forming the core of the tooth can be rebuilt with composite resin, adding small layers at a time to fill voids or “undercuts.”
A disadvantage of the older amalgam (silver looking fillings) is that they require a special shape called “undercuts” to be cut into the tooth to hold them in. However, this can involve removal of healthy tooth structure. Too much undercutting can undermine and weaken a tooth resulting in less resistance under biting forces possibly leading to fatigue fractures and cracked tooth syndromes.