Crowns and Bridges

A crown is a restoration that covers a tooth completely, taking the place of tooth structure lost to decay, fracture or wear. A bridge applies the same principle to a missing tooth: crowns are fitted to the natural teeth on either side of the gap, and a replacement tooth is joined between them. Crowns and bridges are both fixed in place and are not taken out by the patient.

When a crown or a bridge is used

A crown is considered when what remains of a tooth is no longer strong enough to hold a filling, after a large cavity, a fracture, heavy wear, or root canal treatment, which leaves a tooth more brittle. A bridge is considered once a tooth has been extracted and the teeth on either side of the gap are sound enough to carry it. Both are made from a range of materials, among them metal, ceramic, resin and zirconia.

The two parts of a bridge

• The abutments. These are the crowns that fit over the natural teeth on each side of the gap, and they carry the bridge. They use the same materials as a single crown: all ceramic, all metal, or ceramic bonded to metal.
• The pontic. This is the replacement tooth. It rests on the gum ridge and links the two abutments, so that chewing is shared across the row again. A bridge has no clasps and no artificial gum, which is what makes it sit like the teeth around it.

How the treatment works

The dentist shapes the tooth first, removing a thin layer so that the crown fits over it rather than standing proud of it. An impression or a digital scan records the prepared tooth and the way the teeth meet, and a temporary restoration protects it while the permanent one is made. At the following visit the fit, the contacts and the bite are checked before the restoration is cemented.

Recovery and aftercare

The tooth may be sensitive to hot and cold for a short period after cementation, and the bite can feel unfamiliar at first. A crown itself cannot decay, but the tooth beneath it can, and the margin where the two meet is where that begins. Cleaning between the teeth matters as much as brushing, and under a pontic in particular, where a floss threader or an interdental brush reaches what a brush cannot.