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Tooth Filling Materials
What types of tooth filling materials are available?
Generally, you can have metal fillings (e.g. Amalgam) and tooth-coloured fillings (e.g. Composite Resin, Glass Ionomer Cement). Different filling materials possess different properties and can be used in different situations.

1. Amalgam
What is Amalgam?

Amalgam is a mixture of mainly silver, tin, copper and mercury.

Rationale for Amalgam use

Dental Amalgam is the most frequently used filling material because it is strong and durable and it has been used for more than a century with good results.

Is Amalgam safe?

According to the 1995 FDI/WHO consensus statement, components in dental restorative materials, including Amalgam, may in rare instances, result in local side effects or allergic reactions. There is no scientific literature to indicate that the use of Dental Amalgam is detrimental to health and replacement of Amalgam fillings is not indicated.

The WHO threshold limit value for mercury vapour is 300-500 ug per day. A Swedish Dentist discovered in his research that the measurement of the average daily dose of mercury vapour inhaled from Amalgam restorations was only 1.7ug. This is only 1% of the threshold limit value recommended by WHO. There are a number of sources that contribute to the amount of mercury in our system. In fact, the consumption of fish in our diet has a higher contribution to the body burden of mercury than Amalgam restorations. In comparison, the amount of mercury vapour released from Amalgam restorations is minimal.


2. Composite Resin (CR)
Rationale for CR use

Aesthetic results using tooth-coloured CR filling material are excellent, therefore CR are mainly used for front teeth and small holes in the back teeth when the biting load is not too great, and appearance is crucial. Under suitable circumstances, CR may also be used to change tooth colour, shape and size to improve the smile.

Problems with CR

The tooth filling process with CR is relatively complicated. CR is less durable than Amalgam because it is not as wear resistant. CR may shrink when it sets and so this could lead to a small gap between the tooth and the filling. This gap may cause sensitivity or it could become a potential site for recurrent caries. With time, CR has a potential for being discoloured by picking up stains from food or drinks.


3. Glass Ionomer Cements (GIC)
Rationale for GIC use

GIC are another type of tooth-coloured filling material which are commonly used for baby teeth and fillings close to the gum and root area. It bonds to the tooth structure and releases fluoride to help strengthen teeth and prevent decay. Post-operative sensitivity is rare.

Problems with GIC

GIC are weaker and wear faster than CR and Amalgam. It is not as good as CR in terms of colour.


4. Talk to your Dentist
The information above is only a brief outline of the major types of tooth filling materials available. Please consult your dentist to find out which type of filling material is most suitable for your tooth.


If you have any problems, visit the "Ask a Dentist" section on HKDA Internet Homepage or send us e-mail at or send us your fax to (852) 2529 0755.

Note: "Ask a Dentist" is a free dental advisory service provided by HKDA for dental enquiries.