Reliability of Beta-angle in different anteroposterior and vertical combinations of malocclusions

Abstract

PurposeThe aim of this study was to evaluate three-dimensionally the reliability of Beta angle and its validity in different skeletal anteroposterior and vertical malocclusions. Materials and methodsThis is a retrospective cross-sectional study. Two hundred and thirteen pre-treatment Cone-beam Computed Tomography (CBCT) scans (104 males and 109 females) were used in this study. Based on ANB angle, 100 patients were characterized as skeletal Class I (ANB=2.17±1.1°), 62 as skeletal Class II (ANB=5.8±1.47°), and 51 as skeletal Class III (ANB=−2.32±2.42°), and subdivided based on the mandibular plane angle (MP/SN) into normodivergent (MP/SN=32.09±2.31°) and hyperdivergent (MP/SN=40.45±3.71°) groups. All cephalometric indicators were measured on 3D volumetric images using Anatomage software 5.2. Descriptive statistics and Pearson correlation between all variables irrespective of skeletal Class or growth pattern were performed. p Value of <0.05 was considered significant. ResultsThe overall Pearson correlation showed a statistically significant negative correlation (p<0.001) between ANB and Beta angle (0.856). There was no significant (p<0.05) difference in the values of Beta angle, B–X and A–X distance for Class I, Class II and Class III malocclusion with normal and vertical growth pattern. ConclusionsThis three dimensional study interprets the stability of Beta angle irrespective of the difference in craniofacial morphology and growth pattern. Beta angle showed a strong correlation with ANB thus, can be used interchangeably in diagnosis of skeletal malocclusion.