An Evaluation of the Frankfort Mandibular Plane Angle Bisector (FMAB) Wits Appraisal in the Assessment of Anteroposterior Jaw Relationships in Class II Individuals

Accurate diagnosis and treatment planning are of vital importance to practicing orthodontists. The purpose of this longitudinal study was to evaluate the reliability and validity of the Frankfort Mandibular Plane Angle Bisector (FMAB) reference plane in the assessment of anteroposterior discrepancies in a sample of Class II Division 1 individuals. Comparisons were made between the FMAB, ANB angle, and maxillo-mandibular Bisector (MMB) in both treated and control samples of Class II Division 1 patients. The data was collected from pre-treatment (T0), immediate post-treatment (T1) and two year post-retention (T2) lateral cephalograms of 40 female and 36 male Class II Division 1 subjects. Patients were treated non-extraction with fixed orthodontic appliances in conjunction with cervical or straight pull headgears and Class II elastics. Cephalometric data were compared to an untreated control group of 15 female and 15 male Class II Division 1 subjects. The data was evaluated using independent samples t-tests and ANOVA statistical tests to determine statistical differences between groups (p \u3c 0.05). The FMAB was determined to be a highly reproducible reference plane which mimics the ANB angle in the changes seen with growth and treatment. The FMAB-Wits had a mildly higher correlation with the ANB angle than the MMB-Wits. A good correlation (r \u3e 0.80) was found between the FMAB-Wits and MMB-Wits appraisal measurements in both the control and treatment groups for all time periods, indicating that the use of either of these measures may be indicated in cephalometric analysis