Patterns of Congenital Missing Teeth in South Korea with Non-Syndromic Oligodontia: A Retrospective Study

This study aimed to analyze the types, distribution, symmetry, and patterns of congenitally missing teeth (CMT) in patients with non-syndromic oligodontia who visited 11 dental university hospitals in South Korea. Between 2001 and 2024, a multicenter study was conducted on 136 patients aged more than 7 years who had a congenital absence of six or more permanent teeth, excluding third molars. The Tooth Agenesis Code (TAC) was calculated for each quadrant to assess the CMT patterns and symmetry. The analysis showed that the average number of CMT was 9.48, with eight missing teeth being the most common. Significantly more teeth were missing in the maxilla than in the mandible (p < 0.0001), with no significant difference by gender. The most commonly missing tooth was the maxillary second premolar. TAC analysis revealed that the highest frequency of missing first and second premolars (TAC = 24) was found in all quadrants. Bilateral symmetry (52.9% in the maxilla, 56.6% in the mandible) was higher than antagonistic symmetry. In addition, the highest single-tooth symmetry was observed for the second premolars. This is the first study in South Korea to analyze the types of CMT in patients with non-syndromic oligodontia using the TAC concept. The findings may serve as a valuable foundation for future diagnosis and treatment planning.