You and Your Dentist:
Choosing the Dental Materials That Are Right For You
One of the things your dentist looks for during your regular dental check-up is tooth decay. If you have decay, and require treatment, you can choose from a number of different dental materials and treatment options to restore your teeth to good health. Your dentist can advise you on the type of dental materials that will work best in your particular case, and inform you about the esthetic and cost implications associated with each one. But the final decision in which dental material is placed in your mouth belongs to you.
Before you decide on a treatment plan, it is important to inform your dentist if you are taking any medications, or if there have been any changes in your health status since you last updated your medical history. Various health conditions may influence the range of treatment options available to you. Your dentist is aware of these considerations, and can advise you of any known concerns. Remember, it is your responsibility to inform your dentist of your current medical condition, or if you are pregnant.
If you have any questions about dental materials and procedures described in the pamphlet, talk to your dentist. Your dentist can explain the advantages and disadvantages of each option and material, relative to your specific needs and personal circumstances.
Although your dentist also uses restorative materials to repair broken, stained, missing or damaged teeth, they are most often used to treat caries, which appear on your teeth as brown or black spots. These spots are actually areas of diseased tissue. Left untreated, caries can penetrate through the tough outer layer of your teeth, known as the enamel, into the more sensitive inner layer, or dentin. This can lead to pain, discomfort and, if left untreated, tooth loss.
Your dentist treats caries by carefully removing all traces of diseased tissues, or decay, from the affected tooth. Once the decay is removed, your dentist shapes the resulting cavity and fills it with a suitable restorative material.
Restorative Materials
Restorative dentistry has undergone a virtual revolution in the past 20 years with the introduction of a wide range of new materials and techniques.
Today, four main types of restorative materials are available: metals, composite resins, ceramics and glass ionomers. Each material offers unique advantages and disadvantages, depending of your own specific circumstances and needs.
In addition, there are two main classifications of dental materials, direct and indirect.
When direct materials are used, your dentist can often restore your decayed tooth in a single appointment. these materials are placed directly into the cavity your dentist has prepared, and harden quickly.
Indirect materials usually require a minimum of two appointments to place, because they must be fabricated before they are inserted into the cavity. In most cases, indirect restorations are fabricated in a dental laboratory. Once they are fabricated, they are cemented into place by your dentist.
Dental amalgam is the best known direct material. Although cast gold alloy may be the most durable indirect material, ceramics are increasing in popularity because of their longevity relative to other tooth colored materials.
To choose the treatment plan that's right for you, ask your dentist to explain the risks and benefits, advantages and disadvantages, and the costs, of the different alternatives which could be used to treat your specific problem.
Materials
Dental Amalgam
Dental amalgam is a mixture of various metals, but is primarily composed of mercury, silver, copper and tin. Used in dentistry for more than 150 years, this material offers a number of important advantages. For example, it is inexpensive, highly durable , and easy to place. A decayed tooth can be treated in a single visit to the dentist in most cases.
A possible disadvantage of dental amalgam is its silver color. Some Canadians want their teeth to look completely natural. If this is a concern to you, talk to your dentist about alternative restorative materials.
Dental amalgam restorations release minute amounts of mercury vapor, especially with chewing. Some of this mercury may be absorbed by the body, reach various organs and, in pregnant women, cross the placenta.
The body also absorbs mercury from other sources, including air, water, soil and food.
For the vast majority of Canadians, the small amount of mercury released by dental amalgam is not cause for concern. Despite more than 150 years of observation and investigation, scientists have found no sustainable evidence that dental amalgam causes illness.
Health Canada, which is the government body responsible for regulating the sale of medical services and materials in Canada, considers dental amalgam to be a safe, efficacious dental material for the vast majority of Canadians. this scientific assessment is shared by most medical and dental researchers around the world.
A small number of people are allergic to dental amalgam, in much the same way that individuals are allergic to dairy products or bread. If you are concerned about allergies, talk to your dentist.
Your dentist may also suggest an alternative material, or possibly delaying treatment, if you are pregnant.
Canadians who suffer from immune system conditions, a neurological condition, or have impaired kidney function, may also wish to discuss alternative materials with their dentist. Although these conditions are not linked to dental amalgam in any way, mercury absorption may be of particular concern to these individuals.
A position statement on dental amalgam, which was released by the Health Protection Branch of Health Canada in August of 1996, recommends that, "whenever possible, amalgam fillings should not be placed or removed from the teeth of pregnant women."
This statement also recommends that "non-mercury filling materials should be considered for restoring the primary teeth of children where the mechanical properties of the material are suitable," and that "new amalgam fillings should not be placed in contact with existing metal devices in the mouth, such as braces."
In a subsequent information sheet, health Canada recognized that "although it is preferable to avoid dissimilar metals in the mouth there may be situations where there is no practical alternative." The sheet also notes that the galvanic effects that may occur when dissimilar metals are used in proximity to one another are usually not severe enough to justify the removal of dental amalgam restorations, if it is necessary to place other metal restorations or devices, such as gold crowns, braces or metal wires, in your mouth.
Dentists also consider a number of factors when they develop treatment plans for children and pregnant women. In many cases, dental amalgam is still the best treatment option available , depending on the location and extent of decay.
Cast Gold
Cast gold restorations have the advantage of long history of clinical use ,in addition to being extremely long lasting. Gold is an inert, biocompatible, highly durable material. Its main disadvantage is its high cost relative to all other dental materials. Gold is a precious metal, which currently sells at between $450 and $550 an ounce on the world market. In addition, cast gold restorations generally require at least two appointments to place. This is true of most indirect restoration materials.
To place a cast gold restoration, your dentist first removes all traces of diseased tissue, or decay, from the affected tooth. The resulting cavity is then shaped to accept the final restoration, and an impression is made. Once the impression is made, your dentist fills the cavity with a temporary filling material and sends you on your way. The impression is then delivered to a dental laboratory, where it is used to create a model of your mouth. This model is used to fabricated the gold alloy restoration, which is then delivered back to your dentist. At your next appointment, your dentist removes the temporary filling material from your tooth, and secures the final restoration in place with an appropriate luting material.
Composite Resins
If you are concerned about esthetics, and want the color of a needed restoration to match the natural color of your teeth, talk to your dentist about the available composite resins. These materials may be an acceptable alternative to dental amalgam, depending on your bite and tooth function.
If your dentist is concerned about the biting forces present on the tooth requiring treatment, dental amalgam, cast gold alloy, or dental ceramic may be recommended to you as preferred alternatives to composite resin.
Although they have the advantage of being tooth-colored, until recently composite materials were not widely used to restore molar teeth. Dentists were concerned about the durability of these materials, their high cost relative to dental amalgam, and the tendency for secondary decay, to develop around composite resin restorations.
However, with the recent introduction of new types and formulations of composite resins, the popularity and usefulness of these materials has increased dramatically.
Most composite materials are pastes when they are first placed in your teeth. Once your dentist has removed all traces of decay from your tooth, and shaped the resulting cavity, he or she will apply a bonding material to the cavity, Composite resin is then placed in the cavity in small layers. After placing each layer, your dentist hardens the composite resin using a special curing light. When the last layer of composite material has been hardened, your dentist finishes the restoration to match the appearance of your natural teeth.
Remember, if you and your dentist choose a composite resin material, it will likely be more expensive than dental amalgam, and the cost of your treatment will be higher. The final cost of treatment will depend on the type of composite resin used, and the size of the restoration that's required.
Current research has identified a possible link between the bonding materials, or sealants, used with composite resin materials, and estrogenicty. In a 1996 study, researchers found that uncured sealant materials demonstrated estrogen-like activity in tissue cultures of breast tumor cells, which stimulated the proliferation of these cells. More studies are needed to determine whether these sealants, or composite resins themselves, which share some of the same components, have the potential to cause adverse health effects in the general population. To date, however, no ill effects have been observed.
Glass Ionomer Materials
These tooth-colored materials are easy to use and allow for excellent esthetics. They also have the advantage of containing decay-fighting fluoride, which helps to reduce or eliminate the development of posttreatment decay around the restoration. Their main disadvantage is their low strength and durability.
Glass ionomer materials are suitable for placing low-stress restorations in adults and for treating decay in the primary teeth of children. The main concern with these materials is the lack of extensive clinical data on their longevity. In addition, care must be taken to ensure that they do not come into contact with moisture during the initial stages of setting.
Unlike the composite resins, glass ionomer materials can be placed in a single application, rather than in increments or layers.. One of the main advantages of this material is its ability to bond directly to both enamel and dentin, which decreased the degree of postoperative sensitivity.
New formulations of glass ionomer materials, known as hybrids, may be stronger and more durable than conventional glass ionomer resins. More research is already under way to test the longevity of these materials.
Dental Ceramics
Dental ceramics actually belong to a larger family of materials, ranging from the clay used to make pottery mugs and cups, to the hard ceramic tiles used on the exterior of the U.S. space shuttle.
The ceramic material that dentists use most often is porcelain. Unfortunately, although dental ceramics are often the material of choice when long-lasting esthetic restorations are desired, their poor resistance to fracture limits their use in high-stress areas, such as your molar teeth. In these cases, it may be possible for your dentist to restore your tooth using a porcelain-fused-to-metal crown. These indirect restorations are fabricated in the laboratory by baking porcelain onto a metal frame.
Ceramic and porcelain-fused-to-metal restorations cannot be shaped directly in the mouth. After preparing the tooth to accept the restoration, your dentist makes an impression of your teeth and places a temporary filling in the prepared cavity. Your first appointment ends at this point, and your dentist sends the impression to a dental laboratory. The dental laboratory uses the impression to fabricate a restoration, which is then returned to your dentist to be fitted and cemented to your tooth at a second appointment.
A similar laboratory technique is used to fabricate porcelain-fused-to-metal bridges, which are sometimes used to replace missing teeth.
Because of the additional steps required to fabricate and place ceramic restorations, they are generally more expensive then restorations made from most other direct materials.
Recently, CAD-CAM (Computer Aided Design-Computer Aided Manufacturing) machines have made it possible for dentists to fabricate milled ceramic restorations in the dental office. By taking the dental laboratory out of the equation, these systems usually allow ceramic restorations to be placed in a single appointment. Unfortunately, because the CAD-CAM systems available today are expensive and lack flexibility, they have not lowered the cost of ceramic restorations.
Who Approves Dental Materials For Use?
The Health Protection Branch of Health Canada is responsible for regulating the sale of medical devices and materials in Canada. Manufacturers are required to notify Health Canada when they introduce a new material to the Canadian market, and Health Canada has the authority to stop the sale of any dental material or device that it deems to be unsafe.
Dentists and physicians are encouraged to report to Health Canada any instances where a medical or dental device fails or causes unanticipated ill effects. Health Canada has established a special hotline for this purpose. Depending on the nature of the problem, Health Canada may issue a country-wide alert warning health care providers to stop using the product in question.
There is always an element of risk involved when a foreign substance is inserted into the human body. However, the benefits of using these substances to treat disease or repair damaged tissue should outweigh the associated risks.
Health Canada is currently developing a new process to regulate and approve the sale of medical devices and materials in Canada. The new system will classify all medical devices and materials based on a risk assessment. Health Canada's intent is to ensure that all medical devices and materials are subjected to an appropriate level of approval.
The Canadian Dental Association recognizes and supports Health Canada's mandate to ensure that the dental materials and devices Canadian dentists use to treat their patients are safe and effective. CDA believes that such materials and devices should be subjected to whatever level of testing Health Canada deems to be appropriate.
Remember, your dentist is interested in you and your oral health. If you are concerned about having any particular dental restorative material placed in your teeth, please talk to your dentist and be a partner in decisions about your oral health care.