Retrospective study on the angle of the upper permanent second molars in schoolchildren with normal occlusion

ABSTRACT Objective: The aims of this study were to evaluate the angle of permanent second molars in schoolchildren with a normal occlusion, using panoramic radiographs and plaster models, and to evaluate the correlation between measurements obtained by these two methods. Methods: Thirty Brazilian schoolchildren with a mean age of 14 years and 7 months were selected. These individuals had not previously undergone orthodontic interventions, required a minimum of four of Andrews' six keys of occlusion, with the first key (interarch relation) being mandatory, and significant facial asymmetry was absent. Angulation of the maxillary second molars was measured using panoramic radiographs and plaster models. Results: The mean angulation, according to panoramic radiography, was 105.8º in the distal direction (standard deviation of 5.1º). The plaster models revealed a mean angulation of -5.8º, indicating a distal angulation of the crown. Pearsons' correlation test demonstrated a negative and weak relationship (p = 0.009; r2 = - 0.474), with a greater angle in the panoramic radiographs and a smaller angle in plaster models. This was considered an inverse proportional relationship. Conclusion: Measurements of the panoramic radiographs showed an angulation of 105.8º in the distal direction, while the plaster models revealed an angulation of -5.8º. Therefore, one should consider these angulations in order to personalize the placement of accessories on the upper permanent second molars. Correlation of this angulation using these two methods was negative; however, due to the weak correlation, both methods are needed when evaluating the angle of the upper second molar.