A congenitally missing lateral incisor: canine substitution, an implant or a resin-bonded bridge

In dentistry this is called lateral incisor agenesis. The tooth has not been lost later on; the bud never formed at all, at a very early stage of development. Because there is no permanent tooth to dissolve the baby tooth's root and take its place, the baby lateral incisor often stays in the mouth, and some people carry it into their thirties. That is why the situation is usually noticed not through pain but on an X-ray.

How common it is has most often been measured by the meta-analysis published in Community Dentistry and Oral Epidemiology in 2004. With wisdom teeth left out, the frequency of missing teeth comes out at 4.6% in men and 6.3% in women in Europe, 5.5% and 7.6% in Australia, and 3.2% and 4.6% in North America. The frequency in women is 1.37 times that in men. In the same meta-analysis the most commonly missing tooth is the lower second premolar, with the upper lateral incisor second and the upper second premolar third. In 83% of people with a missing tooth only one or two teeth are missing, so for most people the subject concerns a single site rather than the rest of the mouth.

There are data from Turkey too. When the panoramic X-rays of 3,341 orthodontic patients at Atatürk University were reviewed, the frequency of missing teeth excluding wisdom teeth came out at 4.6%, and the most commonly missing tooth in that group was the upper lateral incisor. The lateral incisor has one further feature: while with most teeth the absence is on one side, with the upper lateral incisor both sides being missing at once is more common. So when one side is found to be missing, the other side is looked at carefully; if there is a tooth there, it is most often smaller than normal or has stayed pointed at the tip. That small tooth is a milder form of the same tendency.

The hereditary share is high. In missing teeth that do not come alongside a syndrome, five genes stand out today: PAX9, MSX1, EDA1, AXIN2 and WNT10A. All of them work in the pathways that govern the formation of the tooth bud. Seeing the same picture within a family is common. But it is not passed on by the simple rule of a single gene: within the same family, one person can be missing two teeth while another has nothing more than a pointed lateral incisor. The honest statement is this: the probability goes up, the outcome is not known in advance.

One reason the lateral incisor is a subject of its own is its effect on its neighbour. The theory runs that the permanent canine, as it comes down on the palatal side, uses the lateral incisor's root as a guide. Studies measuring what happens when that root is absent do not give a single answer: in a 2025 meta-analysis bringing together 17 case-control studies and 10,155 patients, a missing lateral incisor was found to be associated with disturbed eruption of the canine. The association was strongest with displacement of the tooth and weaker with it staying impacted; the review itself marks the quality of the evidence as low. In practice two separate pictures emerge. If the canine has erupted towards the gap, you get the situation families describe as the canine having come there anyway, and the first option in the treatment discussion is born here: since the tooth has come there, should it be left there? If the canine has lost its way or stayed impacted in the palate, the picture is different from the start; surgically uncovering that tooth and drawing it into place with orthodontics comes onto the agenda, and the plan is built accordingly.

The first knot in the whole plan is this question: will the gap be closed, or opened to the right width and completed with a tooth? On the closing route the canine is moved into the lateral incisor's place, its incisal edge and corners are reshaped, and if needed composite or a veneer brings its shape and colour closer to a lateral incisor; the premolar behind it then takes on the canine's role. On the opening route, orthodontics brings the gap to the right size and makes the neighbouring roots parallel at root level as well as crown level; the gap is then filled with an implant or a resin-bonded bridge. The decision is made by the orthodontist together with the prosthodontist or restorative dentist, and it has to be made before the brace goes on.

The details that decide are concrete: how the lower and upper molars sit relative to one another, whether there is crowding in the jaw, the colour and size of the canine, the height of the gum margin, how much gum shows when you smile, and whether the absence is on one side or both. If the upper teeth stand forward and there is crowding, the closing route becomes sensible on its own, because space had to be gained in any case. If the bite sits well and there is no spare space in the upper jaw, closing the gap can disturb the relationship between lower and upper.

For anyone wanting to hand the choice over to the data, there is bad news: there is no randomised trial comparing them. The systematic review published in Cureus in 2026 screened 1,244 records and narrowed them down to 19 studies; 18 of these were retrospective and only one was prospective. The results run as follows: on aesthetics, space closure was mostly found acceptable both by patients and by observers who were not dentists; the gum measurements were close to one another in the two groups, with more plaque-retaining areas reported on the prosthetic side; at the jaw joint, neither method showed more problems than the other. In most of the studies the risk of bias is moderate or serious, and the overall certainty of the evidence is low. The seven-study review published in Stomatologija in 2021 had arrived at the same place: there seems to be a difference, but it is not statistically significant.

What follows is not for selecting patients; it is so that you can see which feature of your own mouth pulls the discussion in which direction. None of it stands in for an examination, and the last word belongs to your orthodontist.

This work is usually spread over years, and its order changes from person to person. The backbone below shows the steps that are common to every route.

1. 1

   Taking records and measuring

   A panoramic X-ray shows which tooth is missing, but it is not enough on its own. An intraoral scan or an impression, photographs, an analysis of the bite and, where needed, a CBCT scan are added. The CBCT scan's real contribution is not showing the width of the gap but showing the thickness of the bone and the true position of the neighbouring roots.

2. 2

   The route decision: close it or open it

   The orthodontist and the prosthodontist make the decision together, before the brace goes on. Changing direction later usually means building the treatment again from scratch, because the teeth will have been moved one way. This is also the easiest moment at which to get a second opinion.

3. 3

   Orthodontics

   Treatment usually takes a few years. If the gap is to be opened, the job is not simply separating the crowns: the neighbouring roots have to be moved apart and made parallel too. Movements that press the roots into the bone are avoided, because they can reduce the bone the implant needs.

4. 4

   Showing that growth has stopped

   What is looked at here is not age on the calendar but measurement. In the Gothenburg study that followed implant outcomes in adolescents for ten years, growth was tracked with height measurements, an assessment of skeletal maturity, and the superimposition of profile X-rays taken one after another. In practice that means: no change should be left between two records taken months apart. Growth finishes later in boys.

5. 5

   The interim period

   Waiting does not mean living with a gap. An artificial tooth added to the retainer, a single-wing resin-bonded bridge or a small removable denture covers this period. If there is a baby tooth still holding firm, that is usually the best temporary solution of all; it preserves both the gap and the bone beneath it.

6. 6

   The permanent solution and digital planning

   Once the CBCT scan, the intraoral scan and the smile photographs are brought together in a single file, the implant's position is chosen inside the planned tooth rather than in the bone. The same file is useful on the closing route as well: the reshaped form of the canine can be tried out on screen and shown in the mouth as a temporary try-in.

None of them is a better version of another. Each asks you to give up something different, and what is given up varies from person to person.

What follows are not rare mishaps but pictures that come up regularly in studies with long follow-up. Even if knowing about them does not change the decision, it puts the expectation in the right place.

Here, healing is not a matter of a week but a follow-up spread over years. Whichever route is chosen, what is monitored is clear, and the timescale is roughly the same.

1. The first year

   With a resin-bonded bridge the margin of the wing is checked, with an implant the fit of the crown and the gum line, and on the closing route the edges of the composite that was added. Whether the retainer is being worn as instructed is monitored too; a gap that has been opened can narrow in a short time if the retainer is not worn, and that wear continues for years.

2. The first five years

   Most of the debonding in resin-bonded bridges is reported in this period; the five-year debonding rate in the review is 15%. It is reported that success begins to drop after the sixth year in single-wing bridges made of glass ceramic, while zirconia and glass-infiltrated alumina frameworks hold up better, to ten and fifteen years.

3. Ten years and beyond

   The implant tooth falling behind its neighbours usually becomes visible in this period. The most practical way of monitoring it is to compare photographs taken from the same angle across the years. If the difference reaches a level that bothers you, the answer is usually to renew the crown rather than the implant.

With a congenitally missing lateral incisor, what is being discussed is not a single procedure but years that follow one another. These are the main items that set the scope:

The route chosen

Closing the gap finishes within the orthodontics and leaves no artificial part in the mouth. Opening the gap adds a separate restorative stage on top of the orthodontics.

The scope and length of the orthodontics

A limited movement aimed at the gap alone and a correction involving both jaws are very different plans, and they take different lengths of time.

The waiting period

If growth is being waited out, the interim period can last years. Which temporary solution is used during it, and how many times it is reworked, is a separate item in the plan.

The state of the bone and the imaging

If the bone ridge is narrow, building it up may be needed; whether a CBCT scan, an intraoral scan and a surgical guide are used also changes the scope.