Diastema ClosureA closed gap, in natural proportions.

This page explains what causes a gap between the front teeth, when moving the teeth closes it and when width has to be added, why the design matters more than the material, and what treatment costs.

A diastema is a space between two teeth, most often between the two upper front teeth. In children it is common and often closes as the adult teeth come in. In adults it has a cause, and the common ones are these: teeth that are too narrow for the arch they sit in; lateral incisors that are undersized or missing, which lets the front teeth drift apart; a band of gum tissue, the frenum, attached low between the front teeth; habits such as tongue thrusting; and gum disease, which lets teeth drift as the bone around them is lost.

The causes fall into two groups. Some are about where the teeth sit; others are about how wide they are. That distinction decides the treatment. Gum disease is treated before anything else, and a habit that pushes teeth apart has to stop, or a closed gap can reopen.

Closing a diastema well is a proportion problem, not a filling problem. The two central incisors are already the widest teeth in the smile. Add all of the missing width to them and they become oversized, the most common sign of a poorly planned closure.

The design shares the width out instead. Each tooth across the smile takes a little, so every tooth stays in proportion to its neighbors. In this case, ten upper veneers closed the gap: the central incisors were widened slightly, the lateral incisors and canines in proportion, and the first premolars took some of the width at the corners of the smile. That is why closing a gap is rarely a matter of two veneers.

Width needs length. Widening a short tooth without lengthening it produces a square tooth. Where the gum line sits low, a gum lift comes first. In this case, undersized lateral incisors had let the front teeth drift apart; the gum lift gave the laterals and the central incisors the length to be widened in proportion, and the gap closed without enlarging the two teeth that were already the widest.

The gum between the teeth. Where a gap closes, the small peak of gum between the teeth, the papilla, has to fill the space above the new contact, or a dark triangle can be left. In this case, the gum lift also shaped those peaks for symmetry.

Composite bonding closes small gaps by adding tooth-colored resin to the sides of the teeth, with little or no preparation. It costs less at the start; it also stains and chips more readily than porcelain and typically needs replacing within a few years. For a large gap, where several teeth have to change together, porcelain is more predictable.

Veneers change width, not position. They do not move a tooth, and they do not stop teeth drifting where gum disease or a habit is the cause. A gap too large to share out without making teeth wide needs orthodontics first, to bring the teeth closer, and then veneers for what remains.

Veneers are a commitment. Minimal-preparation veneers remove 0.3 to 0.5mm of enamel, and less at the sides where the gap already leaves space, but enamel does not grow back, and a tooth that has had a veneer will need one again when it is replaced. In return, a closure in porcelain does not depend on a retainer, because the width is in the restorations rather than in the position of the teeth.