Effects of functional versus bisected occlusal planes on the Wits appraisal

Lateral cephalometric radiographs of 35 males between the ages of 11 years and 24 years, all of whom had Class II, Division 1 malocclusions, were traced and Wits appraisals were completed with the use of two occlusal planes: the functional occlusal plane and the bisected occlusal plane. These two values were then statistically related to two dental parameters (overjet and incisor angulation [1 to 1]) and one skeletal parameter (angle ANB) by means of the Pearson product-moment correlation with a predetermined level of statistical significance at p < 0.05. The findings demonstrated that Wits values for both occlusal planes were significantly correlated to both skeletal and dental parameters. Each Wits value also shared variance with the Wits value for the other occlusal plane. Both Wits measures seem to vary to the same degree when compared to the other measures, as demonstrated by the r values. From the results of this experiment, three conclusions can be drawn: (1) either occlusal plane can be used in the calculation of the Wits appraisal to aid in the diagnosis of the severity or degree of anteroposterior jaw disharmony, (2) the bisected occlusal plane Wits appraisal value showed a higher relationship to dental measures than the functional occlusal plane Wits appraisal value, and (3) the functional occlusal plane Wits value shared slightly more variance with skeletal measures (i.e., angle ANB).