The lateral incisors are the second teeth from the center of the upper jaw, positioned directly next to the two large central front teeth. A noticeable variation in the size and shape of these teeth is quite common and can be a significant cosmetic concern for many people. These smaller-than-average teeth can create visible gaps or an asymmetrical appearance in the smile. Understanding the biological reasons behind this variation is the first step toward exploring available solutions to achieve a more uniform smile.
Defining the Condition: Peg Laterals and Microdontia
The clinical term for teeth that are unusually small is microdontia. This condition is most often localized, meaning it affects only one or a few teeth, with the upper lateral incisors being the most commonly involved teeth after the wisdom teeth. The specific manifestation of localized microdontia in the upper lateral incisors is often called a “peg lateral.”
A peg lateral is a permanent tooth that has not developed to its full size and instead has a characteristic conical or pointed shape, resembling a small peg. This developmental anomaly can occur on just one side of the mouth (unilateral presentation) or it can affect both upper lateral incisors (bilateral presentation). Although this size difference is largely an aesthetic issue, it can sometimes lead to functional problems like improper spacing or bite alignment.
The Primary Cause: Genetics and Developmental Timing
The primary reason for the development of small lateral incisors is genetics, as the condition is overwhelmingly hereditary. It is frequently passed down through families, often following an autosomal dominant inheritance pattern, meaning a person only needs to inherit one copy of the gene to express the trait. The expression of this trait, however, can vary significantly, which explains why one person might have a fully missing tooth while a relative only has a slightly smaller one.
This dental variation is rooted in the process of tooth formation during embryonic development. The lateral incisors are generally the last of the front teeth to begin forming, making them susceptible to disruptions in the developmental pathway. This late timing means that slight genetic or environmental fluctuation during tooth bud formation can alter their growth more easily than the larger, earlier-developing central incisors.
Specific genes, such as MSX1, have been identified as having a role in the development and patterning of teeth. Variations in these genes are strongly associated with dental anomalies, including the complete absence of teeth (agenesis) and the development of undersized teeth like peg laterals. The condition often occurs as an isolated trait without being associated with a major systemic syndrome.
Solutions for Small Lateral Incisors
Patients seeking to correct the appearance of small lateral incisors have several well-established restorative and cosmetic options available. Treatment often begins with orthodontics, using braces or clear aligners to position the teeth correctly and create the precise amount of space necessary for the subsequent restoration. Proper spacing is a necessary preparatory step that ensures the new restoration can be the correct size and shape.
Composite Bonding
One of the most conservative and least invasive treatment options is composite bonding. This procedure involves applying a tooth-colored resin material directly to the small tooth and sculpting it to the desired size and shape. Composite bonding is typically completed in a single dental visit and is cost-effective, though the material is less durable and may require repair or replacement after several years due to staining or chipping.
Porcelain Veneers
A more durable and aesthetically superior solution involves placing porcelain veneers. A veneer is a thin, custom-made shell of porcelain that is permanently bonded to the front surface of the tooth, completely covering the existing structure. This option requires the dentist to remove a small amount of the tooth’s enamel to ensure the veneer fits seamlessly, but it offers excellent color stability and longevity, often lasting ten to fifteen years or more.
Dental Crowns
For cases where the tooth is severely undersized, misshapen, or compromised, a dental crown may be recommended. A crown is a full-coverage restoration that encases the entire visible portion of the tooth above the gum line, restoring it to its ideal size, shape, and strength. While this option requires more tooth preparation than a veneer, it provides the maximum level of structural support and protection for the underlying tooth.