Effectiveness of bionator therapy for Class II malocclusions

Abstract

The goal of this retrospective study was to examine the effectiveness of isolated bionator therapy in Class II patients both longitudinally and over the long term. We aimed to determine whether skeletal and/or dentoalveolar reactions differ in relationship to the Angle Class (II, Division 1 vs. II, Division 2). A total of 50 juvenile patients with Class II malocclusion (♀ n = 26, ♂ n = 24) were included. A total of 24 patients presented an Angle Class II, Division 1 and 26 an Angle Class II, Division 2. We compared the patients' lateral cephalograms taken at the beginning of treatment (t1: 10.1 years), after active therapy (t2: 13.8 years), and at the end of retention (t3: 16.4 years) analyzing the following cephalometric parameters: SNA, SNB, ANB, ANB(ind), SNPog, Wits appraisal, U1-SN, U1-SpP, L1-MeGo, interincisal angle. Mean and standard deviations of each of the variables were calculated. Differences between t1-t2 and t2-t3 were tested for statistical significance. Changes in the variables were then analyzed biometrically for specific differences in terms of Angle Class (II, Division 1 vs. II, Division 2). Between t1 and t2, SNB (p = 0.000) and SNPog (p = 0.000) increased significantly, as did ANB (p = 0.000), while the difference between ANB and ANB(ind) (p = 0.000) and Wits appraisal (p = 0.000) decreased significantly. The dentoalveolar variables U1-SN, U1-SpP, and the interincisal angle changed significantly in both groups. The inclination of the upper incisors was corrected by retrusion in the Class II, Division 1 and by protrusion in the Class II, Division 2 group. Only marginal changes in all variables between t2 and t3 were observed. A significant skeletal effect (even in long-time stability) through bionator treatment could be confirmed in this study of Class II, Divisions 1 and 2 patients. The desired effect on the upper front teeth was realized, and there was no appreciable dentoalveolar compensation in the mandible.