Frequently Asked Questions About Restoring Teeth

• What filling material choices do I have?
• Which filling material is for me?
• How long do fillings last?
• Should my extracted teeth be replaced?
• What options are there to replace lost teeth?

• Biting force applied to the area to be restored
• Depth and extent of the cavity
• Importance you place on having a tooth-coloured restoration
• Cost — indirect restorations cost more than direct restorations
• Longevity of each type of restoration

Discuss the choice of the materials used with your dentist. To help you make an informed decision, a brief summary of the features of each type of filling material is described below:

Silver amalgam

Silver amalgam has proven its durability and has been in use for over a century as a filling material to restore cavities in teeth. It is a combination of mercury and a silver alloy which when initially mixed becomes a plastic mass that can be adapted into the cavity before it sets hard.

Now and again, some groups have raised health concerns regarding the use of mercury in silver amalgam fillings. Numerous health authorities around the world (including an independant scientific review by the Life Sciences Research Office, USA, 2004) have examined the available scientific evidence and all have unanimously concluded that silver amalgam is safe to use.

• Very durable
• Good wear resistance
• Not technique-sensitive
• Cost-effective

Disadvantages:

• Colour — does not match teeth. Therefore, usually used for posterior teeth only
• Requires mechanical retention to stay in position
• May conducts hot/cold sensation to teeth in deep cavities
• Environmental concerns with use of mercury
• Allergy in a extremely small percentage of the population

Composite Resins

and opacities to match teeth (rollover figure left). They can be used for use both anterior and posterior teeth.

Advantages:

• Excellent colour match possible
• Adheres to tooth structure
• Cavity shape conserves tooth
• Does not transmit heat/cold to the tooth

Disadvantages:

• Technique sensitive
• Does not last as long as silver amalgam in posterior teeth
• Discolours after many years
• Allergy in a small percentage of the population

Glass-ionomer

This is another tooth-coloured restoration, consisting of fine glass particles in a matrix. However, it is less esthetic than composite resins, as well less resistant to wear than the others. Therefore, it is usually used to restore cavities in non-load bearing areas like the root surfaces of teeth (rollover figure below).

Advantages:

• Acceptable colour match
• Adheres to tooth structure
• Cavity shape conserves tooth
• Leaches fluoride which is anti-cariogenic
• Doesn't transmit heat/cold to tooth

Disadvantages:

• Quite technique sensitive
• Insufficient strength to use on the biting surfaces of teeth
• Surface stains more easily than composite resin
• Surface dehydrates in smokers and mouth breathers, causing surface break down

Porcelain/Ceramic

Requires to be fabricated or milled in the laboratory, hence will usually require two visits. Can be used for fillings, crowns (rollover figure below)and short span bridges (fixed partial dentures). Is cemented to the tooth.

Advantages:

• Excellent match possible
• Stable colour
• Wear resistant
• Doesn't transmit heat/cold to tooth

Disadvantages:

• Brittle — weak in tension. May chip or crack.
• Potentially it could wear opposing teeth if the porcelain/ceramic surface is rough

Gold and Base Metal Alloys

Like porcelain, it requires to be fabricated in the laboratory, hence will usually require two visits. These very versatile restorations need to be cemented to the tooth. Gold and semi-precious alloys are easier to work with but their price swings with the vagaries of the global economy. They wear at approximately the same rate as tooth enamel. While base metal alloys are more economical, they are harder, consequently, they tend to wear down the opposing tooth.

Advantages:

• Very durable
• Strong — can be used in thin sections
• Gold alloys wear at same rate as tooth enamel

Disadvantages:

• Does not match tooth colour
• Gold alloys are relatively expensive
• Base metal alloys are hard and wear away opposing teeth
• Nickel containing base-metal alloys may cause allergic reactions in some people

Porcelain Fused to Metal

This combines the strength of metal with the esthetics of porcelain. Usually used for crowns and bridges that are cemented to the tooth. This is probably the most commonly used type of crown.

Bridge

Also known as a fixed partial denture. The replacement tooth is most commonly anchored in place on opposite ends by a crown, which is cemented onto the teeth on either side of the gap. This usually takes two visits to complete. The disadvantage is that the teeth that anchor the replacement tooth has to be shaved to provide space for the porcelain and/or metal of the bridge. Long term, replacement cost of the bridge is higher than implant-retained crowns as the bridge will need to be renewed.

Implant Retained Crown

A titanium implant that integrates with bone, is placed into the space. A crown is then cemented or screwed into the implant. The treatment is more complex and the placement cost is higher than a conventional bridge. The advantage is adjacent teeth are not involved, and therefore, over the long term, replacement cost for the single unit crown is lower than a bridge.

Acrylic denture

This removable option is the most economical method. As the plastic plate that holds the replacement teeth has to be sufficiently thick to prevent breakage, it intrudes into the tongue's space, which initially may affect speech. Most people, however, are able to adapt with time. Food tends to get between the denture and the gums, therefore, the denture will need to be removed after meals to clean out the food particles. Wires to hold it in place may sometimes be visible.

Cobalt-chromium denture

As this base metal is far stronger than acrylic, the plate that holds the replacement teeth can be thinner and less extensive, providing more flexibility in design. Consequently it is more comfortable to wear. Like the acrylic denture, food tends to get between it and the gums, therefore, the denture will need to be removed after meals to clean out the food particles. Wires to hold it in place may sometimes be visible.