Comparison of second molar development in subjects with class I, class II-1, class II-2, and class III skeletal growth patterns

Abstract

Class II-2 is a difficult malocclusion to treat. Early treatment is recommended, entailing distal movement of the maxillary first molars, which can result in impaction of the second molars. This could be avoided if the developmental stage of the maxillary second molar were known. Objectives: To compare the ages at which the maxillary second molars reach specific developmental stages for subjects with Class I, Class II-1, Class II-2, and Class III skeletal growth patterns. Methods: Records from the Michigan Growth Study, which contains longitudinal data for over 300 Caucasian subjects of Northern European descent, were searched for subjects having Class I, II-1, II-2 or Class III occlusal patterns, based on their last available plaster casts and cephalometric radiographs. ANB of ≥ 5° was regarded as Class II while that ≤ 0° was considered Class III. An attempt was made to match the Class II–1 and Class I to the Class II-2 and Class III subjects.. All available records for Class II-2 and Class III subjects were included in the study as those were rare. The age at which each of the second molars of each patient reached the development stages described by Demirjian (1973) were established using the serial lateral oblique radiographs which were available. The GLM procedure in SAS was used to compare the data among and within the skeletal patterns. Results: There were no significant differences among the four skeletal patterns as related to the developmental stages of the second molars. However, the developmental stages were reached at significantly different ages. Conclusion: There were no statistically significant differences in the stages of development of the second molars among Class I, Class II-1, Class II-2 and Class III subjects.