Agenesis of Maxillary Lateral Incisors in Orthodontic Patients and the Relation to Overall Tooth Size

The maxillary lateral incisor is the second most frequently missing tooth in the dental arch with clinical management requiring a complex and multidisciplinary treatment approach. It has been suspected that teeth could be smaller in the maxillary or mandibular arches in patients experiencing agenesis of the maxillary lateral incisor, making ideal occlusal relationships and space creation for restoration of the lateral incisor difficult to obtain. The purpose of this study is to determine if a tooth size discrepancy exists in orthodontic patients with agenesis of the maxillary lateral incisor(s). Forty sets of dental casts from Caucasian orthodontic patients (19 male and 21 female) mean age 15.9 years were gathered from orthodontists in the Greater Milwaukee area. All casts had agenesis of one or both maxillary lateral incisors but an otherwise full complement of teeth from first molar to first molar. The teeth were measured with a digital caliper at their greatest mesio–distal width and then compared to a control group gathered from Marquette University’s Orthodontic department matched for ethnicity, age and gender. Males in the test group had significantly smaller maxillary posterior teeth when compared to males in the control group, with differences in posterior tooth size ranging from 0.28 –0.78mm. Females in the test group showed significantly smaller maxillary anterior teeth with significant differences ranging from 0.22–0.42mm. The posterior teeth (first bicuspid through first molar), were not significantly smaller in the female test group. Some of the test group’s mandibular teeth for males and females were smaller than normal, but no apparent pattern was observed. The remaining maxillary lateral incisor was also significantly smaller (1.27mm difference) in the male and female unilateral agenesis test groups indicating higher incidence of ’peg’ laterals when compared to the control group. The present study found that agenesis of one or both maxillary lateral incisors is associated with a tooth size discrepancy. Caucasian males experienced smaller than normal posterior maxillary teeth and females showed smaller anterior maxillary teeth. It is important for clinicians to recognize a tooth size discrepancy before creating a treatment plan for a patient experiencing a missing maxillary lateral incisor.