Dental amalgam is a material composed mainly of mercury, silver, copper and tin. It has been used in dentistry for over 150 years and remains the filling of choice for less-visible teeth in the back of the mouth.
Dental amalgam has many advantages: it is inexpensive and very durable, and seals the tooth very well, thus reducing the probability of a new cavity. In addition, it can withstand pressure from chewing. The main inconvenience is its silver colour, which may not appeal to everyone.
Dental amalgams release mercury vapours, especially when we chew. Scientific studies have shown that the actual amount of metallic mercury released is well below the toxic threshold.
In fact, we all absorb other forms of organic mercury from the environment every day, from the air, water and some foods, like fish.
Health Canada does not feel that a complete ban on dental amalgam is justified, and neither is the removal of existing sound amalgam fillings. Furthermore, there is no evidence that dental amalgams are causing illness in the general population.
- Good seal
- Durable and abrasion resistant
- Not esthetically pleasing
- Allergic reactions (very rare)
The Ordre des dentistes du Québec does not recommend that patients with sound amalgams have them replaced by other types of fillings.
Enlightened adviceIt is recommended that amalgams not be used for the following patients:
- People with allergies to mercury, although such allergies are rare (less than 1% of people). A skin test and an oral exam can show whether you are allergic to mercury.
- People with kidney disease.
To read Health Canada's position statement: www.hc-sc.gc.ca.
Composite resin is one of the esthetically pleasing materials a dentist can use to restore both back and front teeth, because of its white colour. It is used to correct defects caused by cavities, fractures and faulty tooth positioning. Composite resin consists mainly of a polymer (plastic) and very hard, inert micro-particles.
A more fluid version of composite resin is used as a sealant to prevent the development of cavities in the pits and fissures of the chewing surfaces of the back teeth. Although it is used mainly for children, it is also suitable for adults.
- Composite resin is available in many different shades and therefore offers a good range of colour-matching choices. The final result is very esthetically pleasing.
- Preparing a back tooth to receive a composite filling usually requires a smaller opening than is required for dental amalgam.
- When composite resin is applied to a wide surface on back teeth, it is less durable than amalgam.
- If sealant is lost, there is a higher risk of secondary caries (adjacent to an already restored region).
- Composite resin restorations cost more than dental amalgam.
These photos show examples of restorations of back teeth using composite resin.
Removal of the caries on the upper surface of a molar, leaving a medium-size preparation.
Molar restored with composite resin.
Premolar with a defective amalgam restoration that must be replaced.
Premolar restored with composite resin.
Composite resin is used to replace a broken or lost restoration. It is also used to correct small to medium-sized imperfections due to caries. Composite resin offers adequate long-term resistance to cracking and wear and tear.
Veneers, made of porcelain or composite resin, are very thin shells glued to the visible surface of the tooth.
It normally takes two visits to the dentist to complete this kind of restoration.
The dentist removes a thin layer of enamel from the teeth to be treated, and then makes a mould of your teeth and sends it to a dental laboratory to have customized veneers made. During the second visit, the porcelain veneers are glued to your teeth using resin cement.
Porcelain veneers have an exceptional surface and generally resist stains better than composite resin veneers.
Composite resin veneers
Composite resin veneers can be applied in just one visit, at the dentist’s office.
The dentist removes the visible external layer of the tooth, if necessary, and then applies and shapes a composite resin matching the colour of the natural teeth. A special light is used to harden the composite, which is then adjusted and polished.
Composite resin veneers are less expensive than porcelain ones.
They are generally used to:
- improve one’s appearance, for instance by filling a gap between two teeth
- match up teeth that are slightly out of alignment
- correct the shape or colour of teeth
Inlays and onlays
Porcelain and gold inlays and onlays are restorations made in the laboratory and used to replace conventional amalgam or composite resin restorations.
They are used in cases where the tooth is more fragile, since they protect the tooth better against possible cracking and withstand the pressure exerted by chewing.
The dentist prepares the tooth, makes a mould and sends it to the laboratory, then glues in the inlay or onlay during the next visit. Porcelain is more esthetically pleasing and adheres to the tooth. Gold inlays and onlays are stronger and longer lasting.