Peg Laterals: How Aligners and Bonding Work Together

The two teeth immediately either side of the upper front teeth are the lateral incisors. In most people they are slightly narrower and shorter than the central incisors — that proportional difference is part of what makes a smile look natural rather than uniform.

In some people, one or both lateral incisors develop much smaller than expected, often narrowing towards the tip into a cone or peg shape. These are peg laterals, and they are one of the more common developmental variations in tooth form.

Treating them is an interesting problem, because a peg lateral is rarely a purely restorative issue or a purely orthodontic one. It is usually both, and the sequence in which those two elements are addressed makes a substantial difference to the outcome.

Peg laterals are a form of microdontia — a tooth that is smaller than the normal range for its type. The cause is developmental and largely genetic. The lateral incisor is, in evolutionary and developmental terms, one of the more variable teeth in the human dentition, and it is also one of the teeth most commonly missing altogether.

There is a recognised association: families in which peg laterals occur frequently also see congenitally absent lateral incisors. It is not unusual to see a patient with a peg lateral on one side and no lateral incisor at all on the other.

Peg laterals are not a disease. They are not caused by anything the patient did or failed to do, they are not a sign of poor oral health, and in many people they cause no functional problem whatsoever. Many patients live with them entirely comfortably and never seek treatment. Others find them noticeable in the smile and wish to address the proportion.

The instinctive solution to a small tooth is to make it bigger. Composite bonding can add material to a peg lateral, building it out in width and length to match the size of its counterpart on the other side.

Sometimes that is exactly the right treatment and nothing else is needed. But there is a frequent complication, and it is a spatial one.

When a lateral incisor develops small, the teeth on either side tend to drift towards it over the years, closing down the space it occupies. By the time the patient seeks treatment, the gap available may be considerably narrower than a full-sized lateral incisor requires — and it is often unevenly distributed, with more space in front of the peg tooth than behind it, or the reverse.

If you simply build the peg tooth out to fill the available space, one of two things happens. Either the tooth ends up too narrow, because the space was never wide enough, or it ends up the right width but positioned off-centre, sitting closer to the canine than to the central incisor. Neither reads as natural.

There is also the question of contour. A peg lateral is not just narrow — it is often positioned slightly palatally, rotated, or tipped. Adding material to a badly positioned tooth means adding it unevenly, which produces a bulky result on one surface and a thin, fragile margin on another.

This is where orthodontic treatment earns its place. The purpose of aligner treatment in a peg lateral case is generally not to straighten teeth in the conventional sense — it is to distribute space correctly.

Specifically, aligners can be planned to:

Create the right amount of space. Using the golden proportion of the smile and the size of the opposite lateral incisor as a guide, a target width is established, and the teeth are moved to open exactly that much space.

Distribute it evenly. Rather than leaving all the space on one side of the peg tooth, aligners can be planned to position the peg lateral centrally within its allocated space, so that material is added symmetrically to both sides during bonding.

Correct the tooth's position. Rotation, tipping and palatal displacement can be addressed before any restorative material is placed, meaning the bonding is applied to a well-positioned tooth and can therefore be applied evenly and at an appropriate thickness.

Level the gum line. A small tooth frequently sits with its gum margin higher than its neighbour's. Some vertical repositioning during aligner treatment can improve gum symmetry, which matters a great deal in the appearance of the finished result.

Our page on clear aligner treatment sets out how these movements are planned and monitored.

The order of treatment is not arbitrary.

Assessment and planning first. Photographs, digital scans, radiographs and measurements. Crucially, the restorative endpoint is designed before the orthodontic treatment starts — the final width and shape of the lateral incisor is decided, and the aligner plan is then built to deliver exactly the space that design requires. Planning the orthodontics without knowing the restorative target is how cases end up with the wrong amount of space.

Health first. Any decay, gum inflammation or other active disease is addressed before teeth are moved. Our dental hygiene appointments are usually part of the preparation.

Aligner treatment. Space is created and distributed, tooth position is corrected.

Retention immediately. Space that has been opened will close again given the opportunity. Retention is not optional in these cases — it is essential, and it must be in place from the moment active movement finishes.

Bonding. With the space correctly established and stable, composite is added to build the lateral incisor to its planned dimensions. Our page on composite bonding explains what this involves.

Final retention review. The retainer is often remade or adjusted after bonding, because the tooth is now a different shape.

Some patients ask whether whitening should be included. If it is planned, it needs to happen before the bonding, because composite does not lighten in response to whitening gels. Our teeth whitening page covers the sequencing.

Once space is correct, the tooth can be built up in composite resin or restored with a porcelain veneer or crown. Both are legitimate.

Composite bonding is additive, meaning little or no natural tooth needs to be removed. It is completed in a single appointment, it can be adjusted and added to over time, and it can be repaired if it chips. It is not as resistant to staining or wear as porcelain and will need maintenance and eventual replacement. For a young patient, or for anyone who wants to keep options open, the reversibility is a significant advantage.

Porcelain veneers offer better colour stability and surface durability, but generally require some preparation of the tooth surface and are made in a laboratory over two or more appointments. On a very small peg tooth there may be relatively little surface area to bond to, which is a technical consideration. Our page on porcelain veneers discusses when they are appropriate.

For most peg lateral cases, particularly in younger patients, composite bonding is the more common first choice, with porcelain considered later if and when it becomes appropriate.

A few points worth stating plainly.

Composite bonding on a peg lateral is a maintained restoration, not a permanent one. It will stain at the margins over time, it can chip, and it will need polishing, repair and eventually replacement. The factors that influence how quickly it wears are covered in our article on what makes composite bonding wear faster.

The two sides may not end up perfectly identical. If one lateral is peg-shaped and the other is normal, matching the built-up tooth to a natural neighbour in colour, translucency and surface texture is technically demanding. A close match is a realistic aim; an indistinguishable one is not always achievable, particularly at the incisal edge where natural enamel is translucent in ways composite struggles to reproduce.

Gum symmetry has limits. Orthodontic movement can improve an uneven gum line, but where the discrepancy is substantial, gum contouring may need to be considered as a separate step. Our gum contouring page explains that procedure.

Retention is lifelong. This bears repeating because it is the most common cause of disappointment years later. Space that was created orthodontically will close if retention lapses, and a closing space around a built-up tooth produces crowding, pressure on the bonding, and an unstable result.

Can peg laterals be bonded without any orthodontic treatment first?

Sometimes, yes — where the existing space is already close to the correct width and the tooth is reasonably well positioned. In that situation bonding alone can produce a good result in a single visit. The difficulty arises when the space has closed down or is unevenly distributed, because building the tooth to fill an inadequate or off-centre gap will not look right. An assessment with measurements will tell you which situation applies to you.

How long does the combined treatment take?

The aligner phase is the longer part and depends on how much movement is required — this can range from a few months for minor space redistribution to considerably longer for more complex cases. The bonding phase is usually completed in one or two appointments once space is stable. Your treatment plan should set out an estimated timeframe, though these estimates can change if teeth respond more slowly than anticipated.

Will the built-up tooth feel different?

Most patients adapt within days. The tooth will be wider than it was, so there is an initial awareness of it, particularly with the tongue. Speech is very rarely affected by changes to lateral incisors. If the bonding feels rough initially, this can often be improved by polishing, and our article on whether rough bonding settles explains what to expect.

Is bonding on a peg lateral more likely to chip than bonding elsewhere?

It can be, for two reasons. The composite is often adding significant bulk rather than a thin surface layer, and the front teeth take shearing forces when biting. Nail biting, opening packaging with the teeth, and grinding are the most common causes of chipping. Where grinding is present, a night guard is usually recommended to protect the restorations.

Can peg laterals be left untreated?

Absolutely. Peg laterals do not cause disease, do not compromise function in most cases, and do not need to be treated for health reasons. Treatment is entirely elective and driven by whether the appearance concerns you. Some patients regard them as a distinctive feature and have no wish to change them, which is a perfectly reasonable position.

Do peg laterals run in families?

There is a recognised hereditary pattern. Peg-shaped lateral incisors and congenitally absent lateral incisors tend to appear in the same families and are considered to be variations of the same developmental trait. If a peg lateral has been identified in a child, it is worth mentioning at family dental appointments, and our children's dentistry page covers how developing dentitions are monitored.

If peg lateral incisors are something you would like to address, the first step is an assessment that establishes how much space is currently available, how much is needed, and therefore whether bonding alone will achieve a proportionate result or whether space needs to be created first.

That assessment involves measurements and photographs rather than opinion, and it will give you a clear picture of what each approach could realistically deliver.

You can contact our team to arrange a consultation at our Wimpole Street practice. Our cosmetic dentistry pages set out the treatments available, and pricing explains how fees are structured.

This article provides general information and does not constitute individual dental advice. Suitability for aligner treatment, composite bonding or veneers depends on individual factors including tooth position, available space, gum health and bite, and can only be determined following clinical examination. All restorations have a finite lifespan and require ongoing maintenance and eventual replacement. Orthodontic treatment carries risks including relapse, root shortening and gum recession, which will be discussed with you before treatment. Wimpole Dental is regulated by the Care Quality Commission, and our clinicians are registered with the General Dental Council.

Next review due: 11 September 2027