Congenitally missing lateral incisors: which option, and when

How common it is, and why it happens

The lateral incisors are the smaller teeth right beside the two upper front teeth. Being born without one or more adult teeth is called hypodontia. Upper lateral incisors are missing in roughly 1.7% of people; both sides may be affected, or one may be missing while the other stays small and pointed. It is often genetic, so other people in the family may have missing teeth too.

It is usually noticed in the mixed dentition years, when baby and adult teeth are in the mouth together: the baby tooth does not loosen when expected, the canine comes through right next to the front tooth, or gaps are left. A panoramic X-ray shows whether the adult tooth is there. A baby lateral incisor with nothing underneath can stay for years, but its root may gradually dissolve, so it cannot be relied on in the long run.

Three routes: close the gap or keep it

The first question is whether the gap will be closed, or kept and filled. That gives three options:

• Closing the gap: braces move the canine into the lateral incisor's place, and it is reshaped to look like one.
• Keeping the gap for an implant: braces open a space of the right width, and once growth has finished an implant with a crown goes into it.
• Keeping the gap for a bonded (Maryland) bridge: a false tooth is held by a thin wing glued to the back of a neighbouring tooth.

When the canine takes the lateral incisor's place

In space closure, orthodontic treatment (moving teeth with braces) brings the canine into the lateral incisor position and the premolar into the canine position. A canine is bulkier, has a pointed tip and is often slightly darker, so its tip is smoothed, tooth-coloured filling material (composite) may be added to reshape it, and the gum levels are taken into account.

The advantage is that there is no false tooth to renew over the years, and treatment can finish in the teens. In studies, gum health after space closure was similar to that of natural teeth, and people who were not dentists often liked the result as much as an implant. Most of these studies are small and retrospective, though, so the certainty of the evidence is low.

If the gap is kept: bridge or implant

A bonded bridge is held by a thin wing bonded to the inner surface of the neighbouring tooth, which usually needs little or no drilling. It can be fitted in a few visits and does not rule out an implant later. It can come unstuck from time to time, which seems to depend largely on design, technique and case selection; in suitable cases these bridges are reported to do well for many years.

An implant needs both bone and space. With less than 7 mm at crown level or between the neighbouring roots, an implant is usually not possible, so the orthodontist straightens the roots as well as opening the space. Where space is tight, a narrow-diameter implant (about 3–3.5 mm) is considered. These sizes are well documented for single front-tooth gaps, although the studies are mostly of low quality. A narrow-diameter implant is not a mini implant, which is thinner and mainly used to hold dentures.

Why an implant waits until growth has finished

Natural teeth keep erupting as the jaws grow, whereas an implant fuses with the bone and stays put. An implant placed during growth therefore falls behind its neighbours over the years: the crown looks short and a step appears in the gum line. Patients often describe this as the implant having “sunk”. It is hard to correct and sometimes means redoing the crown or the implant.

So an implant is placed once growth is complete, which for most people means the early twenties; a bridge may be possible in the late teens. Growth is judged to have finished when height has stopped increasing, sometimes confirmed by comparing X-rays taken some time apart. As the face keeps changing slowly in adult life, a small difference can still appear over the years.

What is worn while waiting

If the braces come off in the teens, several years may pass before an implant. The space has to be held open in that time, or the teeth drift and treatment may need repeating. The usual solution is a removable retainer carrying a false tooth; a good design has small wire stops that hold the neighbouring teeth even if the false tooth breaks off. An easily removable temporary bonded bridge is another option for some teenagers. A healthy baby tooth with nothing beneath it can also serve as a natural space holder.

This content is for general information only and does not replace an examination.