Nonsyndromic Hypodontia Including Bilateral Agenesis of Permanent Maxillary Canines: A Case Report

Permanent maxillary canine agenesis is uncommon, and bilateral absence is particularly rare. When eruption is delayed in the canine region, developmental absence must be distinguished from impaction or ectopic development because the diagnosis changes orthodontic and restorative planning.

A 13-year-old Japanese boy was referred because his permanent teeth had not erupted in the maxillary anterior region. Panoramic radiography showed absence of the permanent tooth germs at FDI 12, 13, 23, and 45. Targeted cone-beam computed tomography confirmed that no impacted or ectopically positioned tooth structures were present at these sites. No ectodermal or craniofacial findings suggested a syndrome. The patient had an Angle Class II first-molar relationship, with 1-mm overjet measured at the maxillary right central incisor and 1 mm overbite. A canine relationship could not be assessed because both permanent maxillary canines were absent. The mother had agenesis of all four permanent second premolars, the sister had bilateral agenesis of the mandibular second premolars, and the father had no dental agenesis. A lateral cephalogram and complete orthodontic records were not available during the diagnostic assessment.

This case represents nonsyndromic moderate hypodontia with an unusual bilateral maxillary canine pattern and variable expression of tooth agenesis within the family. Clinical examination, panoramic imaging, and problem-oriented cone-beam computed tomography established the diagnosis and supported the need for staged multidisciplinary follow-up during growth.