Morphological characteristics of the symphyseal region in adult skeletal class III crossbite and openbite malocclusions

Objective: To evaluate the relationship of the morphological characteristics of the symphyseal region of adult Class III malocclusion to the differences in overjet and overbite. Materials and Methods: The basal and symphyseal widths along with the alveolar and symphyseal heights were evaluated using data from the lateral cephalograms of Korean adult male skeletal Class III, divided into crossbite (n = 28) and openbite (n = 41) groups. Korean male normal occlusion samples (n = 32) were used as controls. Results: The width of the symphyseal region including the basal width, point B width, Id width, symphyseal thickness, and pogonion width were similar in adult Class III crossbite and normal occlusion groups, but significantly less in the adult Class III openbite group (P < .001). The alveolar height was similar in the adult Class III crossbite and control groups, but significantly less in the adult Class III openbite group (P < .05). However, the symphyseal height was similar in all three groups. Conclusions: An openbite, rather than a negative overjet, is the major factor influencing the symphyseal morphology in an adult Class III malocclusion.