DENTAL MATERIALS 101

Dentistry is full of old, new, and emerging technology. For example, the different ways to use dental implants over the last 30 years has been a major game changer in the field of dentistry. Likewise, CAD/CAM technology (computer-aided design and manufacturing of dental restorations) has seen steady growth over the same 30 years. Here is a little background on the some of the reasons this technology is here to stay.

Let me start by saying that the best dentistry is NO dentistry. Prevention of decay and other destructive things that happen to teeth is the best line of defense. Having said that, the fact of the matter is, there are many people who need things done to their teeth to preserve them for their lifetime.

Dental amalgam (silver filling) was introduced to dentistry well over 100 years ago. It proved to be one of the major contributors to saving many teeth that were in need of repair. Dental amalgam is a very hard material which can last for many years. However, there are many aspects of dental amalgam that are undesirable. It is ugly, tooth preparation needs to be more aggressive to retain it, the material breaks down over time, and it contains mercury. Dental amalgam is not used in most of Europe and has been dying a slow death in the United States over the last 30 years.

Progressive dentists, who were interested in providing better, longer-lasting dentistry, learned the skill of using gold. Despite the way you feel about gold in your mouth, done well, gold is still one of the best, most biocompatible and longest lasting materials used to protect teeth. Gold has also been dying a slow death mainly due to the fact that patients prefer tooth-colored restorations.

Then composite resin was introduced. It started as a filling material used to fill cavities on front teeth and eventually evolved enough to be used in back teeth. Dental composite, an ultraviolet light-cured resin, is the main direct restorative material used in dentistry today. It has become the amalgam replacement. It is relatively esthetic, chemically bonds to tooth structure, and allows for much more conservative tooth preparation. However, it is much softer than natural tooth structure and therefore has its limitations.

Dental amalgam and composite are what we in dentistry call direct restorative materials. This means that a cavity preparation is made and the material is directly placed in the tooth. This is different than gold or porcelain which are considered indirect materials. These are manufactured and then cemented or bonded to tooth structure.

When a tooth needs a larger filling, specifically one that needs to cover the cusp of a tooth due to fracture, risk of fracture due to cracks, or has undergone extensive destruction due to decay, direct materials like composite are not indicated due to wear factors. Indirect materials are more appropriate and are much longer lasting.

The advantage of CAD/CAM is the ability to provide stronger, esthetic, indirect materials in addition to being more conservative in tooth preparation. Next week I will continue this subject with the specific uses of this technology.

Dr. St. Clair maintains a private dental practice in Rowley and Newburyport dedicated to health-centered family dentistry. If there are certain topics you would like to see written about or questions you have please email them to him at jpstclair@stclairdmd.com. You can view all previously written columns at www.jpeterstclairdentistry.com/blog.