Dentoalveolar and Soft Tissue Compensation in Class III Malocclusion

Objectives: Compensatory is a mechanism that preserve a proportional and harmonious facial pattern in patients with Class III skeletal pattern. There are two major treatments for this type of patient which are orthodontic surgery and fixed orthodontic appliances. The objective of this study is to assess dentoalveolar and soft tissue compensation in Class III skeletal pattern in relation to normal occlusion.
Methods: Pre-operative lateral cephalometric radiograph of 30 patients each from Class I and Class III skeletal pattern were selected for this study. The cephalometric parametric such as sagittal jaw relationship, occlusal plane angulation, chin thickness, distance of lips toward aesthetic line, incisors inclination were measured.
Results: The result shows significant difference in DL' (p = 0.019), ANB (p = 0.000), SN-AB (p = 0.004), SN-L1 (p = 0.001), SNB (p = 0.037), L1A (p = 0.000) and DU' (p = 0.001). There are no significant differences in other sagittal jaw relationship,upper incisor proclination, distance of upper lip to aesthetic line and thickness of chin.
Conclusion: In summary, the dentoalveolar compensation in Class III skeletal pattern is by retroclination of the lower incisors meanwhile the soft tissue compensation is achieved by the change of the distance of the upper and lower lips towards the aesthetic line, in response to the inclination of the incisors.