Prevalence and type of dental abnormalities among patients with different skeletal malocclusion classes in northern Iran

Background: Dental abnormalities are considered important, since they cause aesthetic and functional problems for people. Orthodontic treatment becomes more complicated when craniofacial abnormalities are accompanied with dental abnormalities. Objective: This study aims to compare the frequency and type of dental abnormalities among patients with different skeletal malocclusion classes in northern Iran in terms of age and gender. Methods: Participants were 310 patients (32.9% Class I, 33.9% Class II, and 33.2% Class III). They were evaluated with respect to hypodontia, hyperdontia, impaction, microdontia, macrodontia, and dens invaginatus/evaginatus. Association of the prevalence of dental abnormalities with the type of malocclusion and gender was assessed by Chi-square test and Fisher’s exact test, while independent t-test was used to determine its association with age.   Results: The overall frequency of dental abnormalities was 33%. Class III patients had the highest rate of dental abnormalities (40.8%); however, the difference was not statistically significant (P=0.105). Hypodontia and impacted teeth were the most frequent abnormalities in all malocclusion groups. Occurrence of tooth impaction differed significantly among the three malocclusion groups (P<0.001), where the highest rate belonged to the class III group. Hypodontia was more frequent in males (P=0.040). Tooth impaction and microdontia were the two abnormalities that showed significant association with age (P < 0.05). Conclusions: Dental abnormalities in northern Iran is more prevalent among people with the skeletal class III malocclusion. The prevalence of some dental abnormalities is associated with gender and age.