Adhesive restorations: rebuilding while preserving the tooth.

Bonding a restoration means joining it to the tooth through a microscopic grip. The surface of the tooth is first prepared, most often with an acid gel applied for a few seconds and then rinsed off: it becomes finely roughened. An adhesive resin penetrates these tiny irregularities, then hardens: it links the tooth to the restoration.

Bonding is not equally reliable everywhere. On enamel, the hard, highly mineralised layer that covers the tooth, it is strong and well sealed. On dentine, the tissue beneath, which is wetter and richer in fibres, a lasting bond is harder to achieve.

Bonding does not tolerate contamination by saliva or blood. While it is being done, the tooth is isolated, most often with a rubber dam: a thin, flexible sheet stretched around the teeth being treated, which keeps them dry.

Bonding requires a sufficiently sound foundation, and a tooth that can be kept dry. Active decay, inflamed gums or a root that needs treatment come first. Very extensive loss, margins lying deep below the gum or a tooth with almost no enamel left make bonding less predictable: a crown may then remain the safer solution.

Composite has two strengths: it is added to the tooth, most often removing only what is damaged, and it can be repaired locally. It suits limited or moderate loss of tooth structure, and corrections of shape on the front teeth.

When a back tooth has lost more, or its remaining walls are fragile, it is rebuilt with a custom-made restoration that is then bonded. The restoration covers what needs protecting, without extending over the rest of the tooth. Measured in the laboratory, the preparation for a full crown removes between two thirds and three quarters of the part of the tooth above the gum; partial preparations remove considerably less.

Ceramic veneers apply the same logic to the front teeth. A veneer is a thin ceramic shell bonded to the visible surface of a tooth: it is held by bonding, and it is the enamel that keeps it secure over time.

A veneer most often requires a preparation of the enamel that is slight and limited to the area being corrected, but irreversible. Before suggesting one, the examination checks that a simpler solution would not be enough: whitening, orthodontic tooth movement, or composite added while removing little or no tissue. It also checks the available enamel, the gums, the way the teeth meet and whether there is any clenching.

No restoration lasts forever, and no lifespan can be promised. Over time, a restoration can wear, chip, come loose, develop a stained edge, or allow decay to form at its margin.

A damaged restoration does not always need to be completely redone. A composite can often be repaired locally, by adding material to the worn or chipped area; a ceramic restoration sometimes can be too, depending on the defect. Repairing avoids removing healthy tissue again, which a complete replacement often requires.

A bonded restoration is cared for like a natural tooth: brushing twice a day, cleaning between the teeth with floss or interdental brushes, and regular check-ups at a frequency agreed with you. These check-ups make it possible to re-polish, touch up or repair early, before a small defect spreads.