RELATIONSHIP BETWEEN OCCLUSAL PLANE ORIENTATION AND SAGITTAL MALOCCLUSIONS: STUDY OF AN ORTHODONTIC POPULATION

Objective: The aim of this study was to evaluate the association of the skeletal pattern and angle class with the occlusal plane (OP). This study also examined the effect of orthodontic treatment on this plane. Methods: Lateral cephalometric radiographs of a sample of 135 patients were collected. The angles between the Frankfort horizontal, palatal plane (PP), mandibular plane (MP), and the OP were analyzed and compared between several groups and subsequently before and after treatment. Results: The statistical comparison between 3 skeletal frame groups demonstrates that the cant of the OP showed a major difference. This difference was greater in class III subjects. Examination revealed that the OP was not meaningfully affected within the Angle classification. Statistically, a significant correlation was found between OP steepness and the vertical skeletal pattern. A significant rise of OP/sella-nasion (SN) for class I (p=0.019) and II (p=0.015) after orthodontic treatment. In addition, patients treated with elastics showed a significant decrease of OP/MP (mandibular plane) in Angle class III and considerable increase of OP/SN and OP/PP in Angle class II. Observations of the group treated with bimaxillary extractions showed that OP/SN (sella nasion line) and OP/PP differ in a meaningful way. Conclusion: This study confirms the association between the skeletal pattern and the OP inclination in adults. Concerning the Angle classification, there was no significant difference between the groups. Orthodontic therapy had an influence on the inclination of this plane for the different malocclusions. Premolars extraction in class I cases significantly modified the OP. For class II and III malocclusions, the OP inclination was mainly altered by the use of intermaxillary traction elastics