Frequency of hypodontia among high school students in Qazvin

Background: Hypodontia (Congenital tooth agenesis) is the most common developmental dental anomalies in children. As the lack of teeth can cause psychological, aesthetic, and functional problems, knowledge on prevalence of hypodontia could help in diagnosis and prevention of associated complications. Objective: This study was performed to determine the prevalence of hypodontia among high school students in Qazvin. Methods: This was a descriptive cross-sectional study carried out on 2619 high school students of both sexes in Qazvin during 2006-2007. The frequency of hypodontia without considering the third molars in high school children and also the association between the tooth type, sex, upper or lower arch, and the affected side were investigated using interviews, oral study, and cast and panoramic radiographic examinations. Findings: An overall hypodontia frequency of 7.4% was found for the total samples with 7.6% and 7.2% in males and females, respectively. The most frequent missing teeth were the maxillary lateral incisors, mandibular, and maxillary second premolars, respectively. There was no statistically significant difference between the sexes (p>0.05). A higher incidence of missing teeth was observed in maxillary arch compared to mandibular and on the left side rather than the right side (p<0.001). Conclusion: The prevalence of hypodontia regardless of third molars was 7.4% among the high school students in Qazvin, a finding consistent with those reported for European countries. The prevalence of this complication was found to be higher among girls yet the difference was insignificant, statistically.