Hypodontia in the Korean orthodontic population: Prevalence and characteristics of a nationwide multicenter study

Objective: To investigate the prevalence and clinical characteristics of hypodontia among orthodontic patients in university dental hospitals in Korea. Methods: A total of 15,422 patients who visited the Departments of Orthodontics at 10 university dental hospitals in Korea between 2021 and 2023 were enrolled as the study cohort. Among these, patients with one or more congenitally missing permanent teeth (excluding third molars) were identified using panoramic radiographs and diagnostic records. The prevalence of hypodontia, number and location of missing teeth, associated dental anomalies, skeletal malocclusion patterns, and treatment methods were evaluated. Results: The overall prevalence of hypodontia was 11.9% (n = 1,835). Younger patients (< 16 years) showed a slightly higher proportion of hypodontia (13.2%) than older patients (11.0%). Most cases involved the absence of one or two teeth (68.7%), while oligodontia occurred in 10.6% of cases. Bilateral cases were more prevalent (56.6%), with 80.8% exhibiting symmetrical patterns. Mandibular second premolars were the most frequently affected (20.7%), followed by maxillary second premolars (14.7%) and lateral incisors (12.0%). Among patients with hypodontia, 37.8% had other dental anomalies, such as impacted teeth and microdontia. A Class I skeletal pattern was the most common overall (40.4%), but a Class III relationship was predominant in patients with oligodontia (42.6%). The most frequent treatments were orthodontic space closure (39.9%), observation (29.5%), and space opening for prosthetic restoration (27.5%). Conclusions: Hypodontia is relatively common among Korean orthodontic patients, especially in younger patients. Accurate diagnosis and individualized, multidisciplinary treatment plans are essential for effective long-term care.