Peg Lateral Incisors: Treatment Options and How Orthodontics Can Help

What are peg lateral incisors?

Peg lateral incisors — also described as microdont lateral incisors — are upper lateral incisor teeth that are abnormally small and characteristically cone-shaped or peg-like in form. The tooth is present but significantly undersized, typically less than two thirds the normal mesio-distal width of a lateral incisor. The condition may affect one or both upper lateral incisors. It can occur in isolation or as part of the hypodontia spectrum, where it often exists alongside missing teeth elsewhere in the dentition. A peg lateral is not a missing tooth — it is a malformed one — and this distinction is central to treatment planning.

How common are peg lateral incisors?

Peg lateral incisors are among the most frequently encountered dental anomalies, with reported prevalence of between 1 and 2% of the population. They are more common in females than males. Bilateral peg laterals — where both upper lateral incisors are affected — occur in approximately one third of cases. There is a known association with hypodontia (missing teeth): patients with peg laterals are more likely than average to have missing teeth elsewhere, and patients with missing lateral incisors on one side may have a peg lateral on the other side. A peg lateral is also more common in individuals with a family history of hypodontia.

How are they diagnosed?

Peg lateral incisors are typically identified on clinical examination and confirmed on dental X-rays. Periapical radiographs show the full tooth including root length, which is often shorter than average in peg laterals. A dental panoramic radiograph (OPG) allows assessment of the whole dentition, which is important given the association with hypodontia. Photographs and study models or digital scans are used for treatment planning, particularly when assessing tooth proportions for restorative work. Bolton discrepancy analysis — which measures the combined tooth widths of upper and lower teeth — is performed as part of orthodontic records, and peg laterals create a predictable upper-arch deficiency that needs to be accounted for.

How peg laterals affect bite and aesthetics

The small size of a peg lateral creates spaces either side of the tooth. The aesthetic impact depends on whether there is spacing in the smile zone and how the surrounding teeth have compensated. If peg laterals are present alongside crowding, the appearance may be less obviously abnormal. More commonly, the peg lateral creates a visible gap between the central incisor and canine, and the small tooth itself looks disproportionate. Functionally, the peg lateral may not provide good guidance contact and does not contribute to normal overjet and overbite relationships in the same way as a properly sized lateral. The overall effect is often a smile that looks unbalanced, particularly in close-up photographs.

Treatment planning options — close or open the space

The fundamental treatment planning decision for peg lateral incisors is whether to close the spaces around the small tooth and substitute the canine into the lateral position, or to open and maintain the space and restore the lateral incisor to normal size with a prosthetic tooth. Canine substitution involves moving the canine forward with orthodontics to fill the lateral incisor space, then reshaping and restoring the canine to look more like a lateral, with the first premolar moving into the canine position. Space opening involves orthodontically creating ideal space for the correct-sized crown, followed by composite bonding to widen the existing peg lateral, a veneer, a bridge, or an implant-supported crown. The right choice depends on the existing bite, crowding or spacing, skeletal pattern, and patient preference and age.

Bolton discrepancy and tooth size analysis

A Bolton discrepancy analysis compares the sum of upper and lower tooth widths. Because peg laterals are undersized, the upper arch has a tooth-size deficiency relative to the lower arch. This means that if spaces are simply closed by moving teeth together, a perfect Class I occlusion with ideal overjet and overbite may not be achievable — there is not enough upper tooth material to fill the arch correctly. The Bolton discrepancy quantifies this mismatch and allows the treatment plan to account for it. Commonly the decision is to open space orthodontically and restore the lateral to the correct width, which resolves the discrepancy, rather than close spaces and end up with a compromised bite or residual gaps.

Composite bonding to normalise peg lateral shape

Composite bonding is a minimally invasive way to increase the width of a peg lateral incisor, adding tooth-coloured composite resin to the sides of the tooth to give it normal proportions. It is commonly used as a transitional restoration — particularly in younger patients after orthodontic treatment but before the patient is old enough for an implant — and can also be a definitive treatment if the patient prefers a less invasive approach. Composite bonding typically needs to be renewed every five to ten years as it is susceptible to staining and chipping. It requires no drilling of the tooth and preserves underlying tooth structure. When performed after orthodontic space opening, the dimensions are ideal and the result can be highly aesthetic.

Veneers for peg lateral incisors

Porcelain veneers are a more durable and longer-lasting aesthetic restoration for a peg lateral incisor. A thin layer of porcelain is bonded to the front surface of the tooth, increasing its apparent width and providing a natural, translucent appearance. Veneers require minimal tooth preparation and are usually suitable once growth is complete — in most cases from the late teenage years onwards. They are particularly well suited where the peg lateral has a reasonably adequate root and the space has been orthodontically opened to the correct dimension. Unlike composite bonding, porcelain veneers are highly stain-resistant. The main limitation is cost, and they carry a long-term commitment to repeat work as veneers eventually need replacing.

Implants — timing considerations

A dental implant replacing a peg lateral incisor provides the most lifelike and durable result. However, implants must be placed after skeletal growth is complete — typically not before age 18 in females and 19 to 20 in males — because placing an implant in a growing jaw will result in it becoming infra-occluded as the surrounding bone continues to develop. This is a critical distinction: the space should be opened and held orthodontically, with a transitional restoration such as composite bonding or a removable retainer with a pontic tooth, until growth is complete. CBCT imaging before implant placement confirms that there is adequate bone volume in the space created by orthodontics. Planning between the orthodontist, restorative dentist, and implant surgeon is essential for a predictable outcome.

NHS vs private treatment

Peg lateral incisors in children and teenagers may qualify for NHS orthodontic treatment if the IOTN score is 4 or 5, which is common given the spacing and tooth-size discrepancy involved. However, the restorative component — composite bonding, veneers, or implants — is not available on the NHS for cosmetic reasons, meaning most patients face private costs for the definitive restoration. A combined NHS orthodontics and private restorative plan is entirely possible and is a practical approach for many families. Adults with peg laterals will typically access both orthodontic and restorative treatment privately. The total cost of a comprehensive plan depends on the treatment route chosen and the complexity of the case.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.