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• Glossary

Fillings

A "filling" is the dental procedure where the decayed part of a tooth is cleaned out and then the tooth is filled with some sort of filling material. The good news about fillings is that today's children need many less than in previous generations. Children have significantly less tooth decay in their primary (baby) and permanent teeth today than they did in the early 1970s. Among children between the ages of six and 18 years, the percentage of decayed permanent teeth decreased by 57.2 percent over a 20-year period. In addition, children between the ages of two and 10 years experienced a drop of nearly 40 percent in diseased or decayed primary teeth.

So what is all the fuss about mercury in fillings? In recent years, people have become more concerned about the health effects and appearance of mercury amalgam fillings. Fortunately, their concerns are largely unwarranted. Mercury amalgam fillings, also called dental amalgams, are quite safe and are very durable.

The Australian Government's National Health and Medical Research Council (NHMRC) have continued to investigate the safety of amalgams used in dental restorations (fillings). However, no valid scientific evidence has shown that amalgams cause harm to patients with dental restorations, except in rare cases of allergic reactions.

The growing debate over the safety of silver-coloured fillings, known as dental amalgam, pits science against emotion, and consumers are caught in the crossfire. The decision about what to use to fill your cavities is a matter best decided by you and your dentist. Yet emotional reports claiming amalgam is responsible for a variety of diseases are confusing and perhaps even alarming people to the point where they will not seek necessary dental care. If you are reading this page, the chances are good that you are among the majority of Australians who have had one or more teeth filled with an amalgam.

Most dental amalgams are silver in colour and are made from a mixture of mercury and an alloy of silver, tin and copper. Mercury makes up about 45-50 percent of the compound. Mercury is used to bind the metals together and to provide a strong, hard, durable filling. Mercury has been found to be the only element that will bind these metals together in the best possible way to manipulate the material into a tooth cavity.

Is mercury in dental amalgam safe?

According to the Australian Dental Association, backed by volumes of research, mercury in dental amalgam is not poisonous. When mercury is combined with other materials in dental amalgam, its chemical nature changes so it is essentially harmless. The amount released in the mouth under the pressure of chewing and grinding is extremely small and no cause for alarm. In fact, it is less than what patients are exposed to in food, air, and water on a daily basis.

Dental amalgam has withstood the test of time, which is why it is the material of choice. It has a 150-year proven track record and is still one of the safest, durable and least expensive filling materials.

Alternative Materials

Advances in modern dental materials and techniques increasingly offer new ways to create more pleasing, natural-looking smiles. Researchers are continuing their often decades-long work developing aesthetic materials, such as ceramic and plastic compounds that mimic the appearance of natural teeth. As a result, dentists and patients today have several choices when it comes to selecting materials used to repair missing, worn, damaged or decayed teeth.

The advent of these new materials has not eliminated the usefulness of more traditional dental restoratives, which include gold, metal alloys and dental amalgam. The strength and durability of traditional dental materials continue to make them useful for situations where restored teeth must withstand extreme forces that result from chewing, such as in the back of the mouth.

Alternatives to amalgam, such as cast gold restorations, porcelain, and composite resins are more expensive. Gold and porcelain restorations take longer to make and can require two appointments. Composite resins, or white fillings, are aesthetically appealing, but require a longer time to place, and have shorter life spans.

Common Alternatives to Dental Amalgams
Composite fillings - Composite fillings are a mixture of acrylic resin and finely ground glass-like particles that produce a tooth-coloured restoration. Composite fillings provide good durability and resistance to fracture in small-to-mid size restorations that need to withstand moderate chewing pressure. Less tooth structure is removed when the dentist prepares the tooth, and this may result in a smaller filling than that of an amalgam. Composites can also be ‘bonded’ or adhesively held in a cavity, often allowing the dentist to make a more conservative repair to the tooth. In teeth where chewing loads are high, composite fillings are less resistant to wear than amalgams. It also takes longer to place a composite filling.

Ionomers - Glass ionomers are tooth-coloured materials made of a mixture of acrylic acids and fine glass powders that are used to fill cavities, particularly those on the root surfaces of teeth. Glass ionomers can release a small amount of fluoride that help patients who are at high risk for decay. Glass ionomers are primarily used as small fillings in areas that need not withstand heavy chewing pressure. Because they have a low resistance to fracture, glass ionomers are mostly used in small non-load bearing fillings (those between the teeth) or on the roots of teeth. Resin ionomers are made from glass filler with acrylic acids and acrylic resin and are sometimes used in place of glass ionomers. Ionomers experience high wear when placed on chewing surfaces. Both glass and resin ionomers mimic natural tooth colour but lack the natural translucency of enamel. Both types are well tolerated by patients with only rare occurrences of allergic response.

Porcelain (ceramic) dental materials – These include porcelain, ceramic or glasslike fillings and crowns. They are used as inlays, onlays, crowns and aesthetic veneers. A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. All-porcelain (ceramic) restorations are particularly desirable because their colour and translucency mimic natural tooth enamel. All-porcelain restorations require a minimum of two visits and possibly more. The restorations are prone to fracture when placed under tension or on impact. Their strength depends on an adequate thickness of porcelain and the ability to be bonded to the underlying tooth. They are highly resistant to wear but can quickly wear opposing teeth if the porcelain surface becomes rough.