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Tooth Fillings

Small cavities resulting from tooth decay are repaired reasonably quickly and easily with fillings. Local anaesthesia is usually required to numb the tooth. The tooth is then “prepared” by removing decayed areas with a dental handpiece, leaving as much intact healthy tooth structure as possible in place. The resulting “cavity” is then filled with a dental restorative material – either silver amalgam or tooth coloured composite resin.

Which filing material is best – silver amalgam or composite resin?

For decades, cavities in back teeth have been filled with dental amalgam. Amalgam is a mixture of metals including mercury, silver, tin, and copper. Amalgam has a long track record of success in dentistry due to the following advantages:

  • Ease of placement – Amalgam is simply packed into the cavity in a soft state, carved to the correct shape, and left to solidify
  • Low Cost – Amalgam fillings are less expensive than composite resin fillings, due mainly to their simplified placement.
  • Excellent durability – Amalgam fillings are very durable, sometimes lasting 30 years or more!

However, there are a few key disadvantages to amalgam fillings as well:

  • Unaesthetic – Amalgam fillings range in colour from light silver, to dark gray, to black! Amalgam may also corrode, permanently staining teeth gray.
  • Brittle – Amalgam needs to be at least 2mm thick to be strong enough to withstand chewing forces, so even shallow cavities need to be prepared to at least 2mm in depth. Amalgams that are too shallow will often crack
  • Unbonded – Amalgams are held in place by virtue of undercuts prepared into the tooth. Once the amalgam has hardened, it is “locked” into the undercuts. These undercuts are placed into healthy tooth structure, resulting in a larger preparation than would be needed for a bonded composite resin filling. Tooth structure may also be more prone to fracturing away from an unbonded filling.
  • Amalgam contains mercury – Although amalgam has been used for over a century with no concrete scientific evidence of any ill effects, one must decide whether to opt for a mercury-containing material when there are mercury-free options available.

In recent years, advances in dental technology have given dentists access to excellent tooth coloured composite resin materials. Composite resin fillings address most of the disadvantages of dental amalgam:

  • Esthetic – Composite resin fillings match the colour of natural teeth closely enough to be “invisible” to the casual observer.
  • Thin – Composite resin can be placed in thin layers, unlike amalgam. Therefore there is no minimum preparation depth.
  • Bonded – Composite resin material is bonded into the cavity with very strong dental adhesive. This allows the dentist to remove only the decayed tooth structure and nothing more, sparing as much healthy tooth structure as possible. Bonding may also help stabilize the remaining tooth against fracture.
  • Mercury free

How is a cavity filled?

The goal of a filling is to remove areas of decayed tooth and fill the resulting voids with an appropriate material.

When tooth decay is present in the pits and grooves of a molar, it needs to be removed from the tooth. Local anaesthetic is usually given to numb the tooth. Decay is then removed from the tooth, using high speed and low speed dental handpieces, leaving a cavity.

A dental adhesive is applied to the walls of the cavity, which is then filled with filling material.

Other restorative procedures: Inlay and Onlays | Crowns

 

There are three main options available to restore teeth:

Fillings | Inlays and Onlays | Crowns