Posts for tag: fillings
Over the last century and a half millions of people have had a tooth cavity filled with “silver” amalgam. Perhaps you’re one of them. The use of this effective and durable filling has declined in recent years, but only because of the development of more attractive tooth-colored materials.
At the same time there’s another issue that’s been brewing in recent years about this otherwise dependable metal alloy: the inclusion of mercury in amalgam, about half of its starting mixture. Various studies have shown mercury exposure can have a cumulative toxic effect on humans. As a result, you may already be heeding warnings to limit certain seafood in your diet.
So, should you be equally concerned about amalgam fillings — even going so far as to have any existing ones removed?
Before taking such a drastic step, let’s look at the facts. To begin with, not all forms of mercury are equally toxic. The form causing the most concern is called methylmercury, a compound formed when mercury released in the environment combines with organic molecules. This is the form certain large fish like salmon and tuna ingest, which we then ingest when we eat them. Methylmercury can accumulate in the body’s tissues where at high levels it can damage various organ systems.
Dental amalgam, on the other hand, uses elemental mercury. Dentists take it in liquid form and mix it with a powder of other metals like silver, tin and copper to create a pliable paste. After it’s placed in a prepared cavity, the amalgam hardens into a compound in which the mercury interlaces with the other metals and becomes “trapped.”
Although over time the filling may emit trace amounts of mercury vapor, it’s well below harmful levels. You’re more likely to encounter “un-trapped” mercury in your diet than from a dental filling. And scores of studies over amalgam’s 150-year history have produced no demonstrable ill effects due to mercury.
Although it now competes with more attractive materials, amalgam still fills (no pun intended) a necessary role. Dentists frequently use amalgam in less visible back teeth, which encounter higher chewing pressures than front teeth. So, if you already have an amalgam filling or we recommend one to you, relax — you’re really in no danger of mercury poisoning.
It takes a lot of skill, experience, talent and artistry to create tooth restorations that look so natural that no one can tell them apart from the originals. To do so requires understanding of the normal anatomy of a tooth as well as of the interactions of light and color.
How the anatomy of a tooth determines color
The color that we perceive when looking at a tooth results from the combined appearance of the tooth’s center core (dentin layer) and its covering enamel. Going from the outside in, the enamel is made of tightly packed crystals of calcium, which cause it to be one of the hardest substances naturally produced by animals. The crystals are also responsible for a tooth’s brilliance and translucence. The dentin is more like bone, a porous living tissue composed of microscopic tubes, interspersed with more calcium crystals. In the very center of the tooth is a central chamber containing the pulp and nerves.
Each of these layers has its own physical and optical properties. Since the enamel is translucent and the dentin is more opaque, most of the tooth’s color comes from the dentin and is transmitted through the enamel layer. Factors that affect this transmission include the thickness and age of the enamel as well as external tooth whitening.
If the enamel is more translucent, more of the color of the dentin shows through. If it is more opaque, the enamel absorbs and reflects light so that less color is visible and the enamel looks brighter.
The language of color composition and reflected light
Color means the whole spectrum in the rainbow. The spectrum is made up of the three primary colors — red, blue, and green. When all are combined, they create white light.
Hue refers to the brightest forms of the colors. The color we perceive depends on the dominant wavelength of light that is reflected by an object.
Value refers to a color’s lightness or darkness. A brighter color has a higher value.
Chroma is the amount of identifiable hue in a color. An achromatic color (without hue) appears gray.
Saturation is a measure of a color’s intensity.
This terminology of color is used not only by dentists and dental technicians, but also by a wide range of artists. It implies expertise and understanding of how colors work, how they vary and change and affect one another.
Contact us today to schedule an appointment or to discuss your questions about bonding to repair chipped teeth. You can also learn more by reading the Dear Doctor article, “Artistic Repair of Front Teeth with Composite Resin.”