Tuesday, November 2, 2010

How have crown restorations changed over the years?

When a tooth has been damaged in some way that results in a loss of tooth structure, such as a fracture, large cavity, or after a root canal, the indicated treatment is often a crown, or cap. A crown is an indirect restoration, or one that is fabricated outside of the mouth and then cemented over the tooth with a bonding cement. Although they require preparation or reduction of the remaining tooth to place, crown restorations are good for the overall health of the tooth because they strengthen and reinforce the underlying damaged tooth structure.

Back in the 1950's - 1960's, most crowns were fabricated from gold alloys. Although gold is very biocompatible, strong, and long lasting, these crowns were not highly esthetic and were not well accepted in the front of the mouth. Doctors tried to improve their appearance by veneering the front of the crowns with resin materials that were tooth colored, but the results were often unfavorable.

By the 1970's, Ceramic materials were being developed that could be fused to white gold alloys in a furnace. This technology vastly improved crown and bridge esthetics, but limitations still existed. These crowns were more opaque than natural teeth, because the dark gold needed to be blocked out by an opaque porcelain layer, which limited the crowns ability to transmit light. The light would enter the crown, hit the opaquer, and bounce back out, rather than being transmitted through the tooth like a fiberoptic light. This resulted in not only increased opacity, but a loss of color value and a greyish shadow in the gumline beyond the crown margin. In addition, the gold margin where the porcelain ends at the gumline often resulted in the appearance of a dark line at the gumline above or below the crown.

In the 1980's, porcelain technology was taken a step further, and all-ceramic restorations were developed. While this technology eliminated the previously discussed concerns, further problems arose. These early all-ceramic crowns were very weak. They had a high incidence of fracture, and could not be used for bridgework. Also, they needed to be bonded to the underlying tooth for any strength at all and the available bonding agents at the time were very limited. So even though these materials were available, the standard porcelain-fused-to-metal crowns and bridges were the most widely used.

By the 1990's porcelain technology was improving as was the strength and availability of resin bonding cements. Over the next 20 years, several generations of all ceramic restorations were developed, including products of sufficient strength that they could be used for bridgework of small spans in the anterior of the mouth. With these advancements in technology, we were finally able to achieve the esthetic results we had always strived for but fell short, but strength was still an issue. The most recent development in our quest for beauty and strength has been the development of porcelain layered over zirconia restorations. Although these crowns and bridges are more opaque than some of the previous all ceramic restorations, they are much stronger and light years ahead of porcelain-fused-to-metal in terms of esthetics. These days, much of my ceramic work focuses on zirconia. It is the only material so far that allows acceptable esthetics with the strength we need for function.

If you are in need of a crown or bridge, come in to see me and we will discuss all of your esthetic needs and porcelain options as we develop a treatment plan that is right for you.

Tuesday, May 11, 2010

Topical vs Systemic Fluoride: Which is more Important?

Fluoride is an ion of the element fluorine. It occurs naturally in water, rock, soil, and in living tissue. Fluoride does not occur in its free form, but rather is always bound to another element.

How does fluoride work to prevent cavities?

The answer to that question depends on how the fluoride ion is presented, either systemically or topically.

Systemic fluoride is introduced to the body through sources such as fluoridated water. It has been determined that the optimum concentration of fluoride in drinking water to provide cavity prevention safely is in the range of 0.7 - 1.2 ppm. Most municipalities maintain a concentration within this range, but people relying on natural sources of drinking water should test their water to determine if fluoride supplements should be prescribed. Systemic fluoride begins to exert its effects while teeth are still forming. Bones and teeth have an organic matrix, but they actually gain their strength and hardness from an inorganic, crystalline composition known as hydroxyapatite. Cells responsible for tooth and bone formation utilize available calcium and other minerals to form the hydroxyapatite matrix. When fluoride ions are also available, such as occurs when fluoride is ingested, cells will use them to produce an additional compound called fluorapatite. Fluorapatite becomes integrated in the inorganic matrix, resulting in a more durable and acid-resistant substance. This has been shown to have a beneficial effect in reducing the incidence of dental decay.

Although the benefits of systemic fluoride have been well documented, we are now learning that the topical effects of fluoride ions may even be more important. Topically applied fluoride ions can be applied to the teeth through toothpastes, over-the-counter fluoride rinses, and dentist-applied fluoride varnishes or foams. The topically applied fluoride exerts it's effects in several ways. First, it is known to inhibit the ability of bacteria to produce plaque on the teeth by blocking the function of important bacterial enzymes. Secondly, topically introduced fluoride ions lead to reduced demineralization and increased remineralization of tooth structures. Acids from bacterial toxins act by causing loss of calcium and other minerals from the tooth surface. This is the beginning of the decay process. Fluoride acts to slow the process of demineralization and promote remineralization thereby preventing the onset of the carious lesion. It has been shown that the topical effects of systemic fluoride ions which end up in saliva may actually be more important than the effects during tooth formation.

What we need to learn from this discussion is that, to optimally fight cavities, we need to make sure we are providing our families with a fluoridated drinking water source, as well as supplementing that with the use of an ADA accepted fluoridated toothpaste. As an adjuct, all children under the age of 18 should have a topical fluoride varnish application by the dentist every 6 months. If we apply the beneficial effects of fluoride, along with excellent oral hygiene and regular dental visits, we can win the war against tooth decay.

Wednesday, April 28, 2010

Does Bleaching Really Work?

The answer to that question is complicated, because the answer is sometimes.

Discolored teeth occur due to several factors:

1) Teeth are made up of several layers of material. The overlying material is enamel, which is inorganic, consisting of crystalline rods. Enamel is what makes the teeth appear white. The middle layer of the tooth consists of an organic material called dentin. Dentin also makes up the majority of the tooth roots. Dentin is darker and yellower in color than enamel, varies in color due to genetics, and darkens with age or trauma to the teeth. In some patients, the enamel layer is thicker, preventing the darker dentin from showing through. This results in whiter appearing teeth. In other patients, the dentin layer is thinner, and the dentin shows through resulting in a darker and yellower appearance to the teeth.

2) Tooth enamel is crystalline in nature. As a person chews, and subjects the teeth to outside forces such as acids and temperature extremes, small microcracks , as well as small pits and pores, occur in the enamel layer. These cracks and pores accumulate food debris and food stains. This results in not only discoloration, but also blocks the light transmission causing the teeth to appear darker.

This leads us to a discussion of how bleaching agents work. All bleaching agents, whether professionally applied or over-the-counter, consist of peroxide solutions. When applied to the teeth, these peroxides break down into oxygen, which penetrates the tooth enamel and dissolves food debris and stains trapped within the enamel pits, pores, and cracks. This action causes the enamel to appear whiter.

So, will bleaching work for me? It depends. If you have relatively thick enamel and your underlying dentin color is light, you will achieve wonderful results. On the other hand, if your enamel layer is thin, or your dentin color is darkened due to age, trauma, or genetics, bleaching will not be very effective. So maybe I just need to bleach more? Not necessarily, since use of more bleach in situations like this results in the enamel becoming more translucent, rather than whiter. Also, since over-bleaching often results in the enamel layer increasing in translucency, the teeth begin to appear bluish. Bluish, clear enamel is the telltale sign of someone who overused over-the-counter bleaching agents.

If you fall into the category where bleaching will not be as effective, do not be discouraged. You can still achieve the smile of your dreams through the use of ceramic crowns or veneers. Give us a call for a consultation!

Monday, April 26, 2010

How Can Dental Implants Help Me?

Since the mid-1990's, dental implant treatment has changed the lives of thousands of patients. Until that time, replacement of natural teeth required either an invasive treatment such as fixed bridgework, which required removal of all of the overlying enamel on the adjacent teeth, or a removable replacement that did not feel or function naturally.

Now, we have the ability to replace teeth by literally replacing the lost root with an implant fixture. The result feels and functions like a natural tooth.

The process works like this: We prepare the site where the tooth was lost (sometimes we need to add bone to the area), we place the implant fixture in the site, and a few months later we build a new tooth on the fixture.

Implants can also make a tremendous impact on edentulous patients. We can use them to secure removable dentures, or better yet, we can use them to retain a completely implant supported prosthesis to replace some or all of the teeth in an arch.

If you have lost a tooth or have been suffering with loose dentures, don't you owe it to yourself to explore the options that can truly improve your quality of life? Give us a call, and we can set up an individual consultation!