Comparison of Second Molar Eruption Patterns in Skeletal Class I and Class II Malocclusions

The timing and pattern of eruption of second molars are clinically important factors and might be related to different types of craniofacial skeletal morphology and malocclusion.In this cross sectional study the eruptive positions of the second molars in Class I and Class II malocclusion were studied and compared.Pretreatment records including clinical examinations, and radiographs of 99 orthodontic patients, (56 girls and boys with the mean age of 0. years) were evaluated. Approximately 5. % of the patients had skeletal Class I, 5.% had skeletal maxillary Class II, and 9.% had skeletal mandibular Class II malocclusions. The eruptive position in relation to a reference line, as well as, the developmental stages of the patients’ second molars, and the dental ages were recorded using theirs panoramic radiographs. Data were analyzed using ANOVA and Chi- square tests. The mean values of dental and chronologic ages of the subjects were similar. The distribution of various developmental stages in each malocclusion group was similar. There was an association between the type of skeletal malocclusion and dental developmental stage of the second molars (p <0.000). The eruptive position of second molars was more occlusal in the maxilla of patients with maxillary Class II and more apical in the mandible of patients with mandibular Class II (p <0.000). According to the present study, the maxillary second molars erupt earlier in maxillary Class II malocclusion patients, and the mandibular second molars erupt later in mandibular Class II malocclusion compared to other malocclusions.