A cephalometric evaluation of the vertical changes associated with the BEGG light wire technique

Abstract

Use of the Begg light wire technique in orthodontics har been implicated as causing an increase in anterior facial height. Controversy persists concerning the effects o f this technique on the dentition as well as on the skeletal pattern o f patients. The present retrospective cephalometric study was undertaken to evaluate the vertical changes that occurred during, and after, treatment o f patients with the Begg light wire technique. The lateral cephalometric radiographs o f 31 patients, aged between 11 and 17 years were evaluated before (group A), soon after (group B), and approximately two years after treatment (group C). A series o f angular and linear measurements were performed on each cephalometric tracing, and these data were statistically analysed for changes immediately post-treatment, and approximately two years later. The null hypothesis for this study states that there is no significant change in the vertical facial dimension o f patients treated with the Begg light w i/e technique. Paired / tests were used to test the hypothesis. Stepwise regression analysis o f variance was used to determine which (if any) changes in the independent variables during treatment could predict changes during treatment, and could exert their influence during the retention period. Post-treatment, the SNA angle showed an average decrease o f 1.05° and there was a significant increase in all the linear measurements (N-ANS, ANS-Me, N-ANS(W), ANSM e(W ), S-Go). In the retention period the SNB angle increased significantly by 0.87°, and there was a significant increase in all the linear measurements (N-ANS, ANS-Me, N-ANS(W), ANS-Me(W), S-Go). The mandibular plane showed no significant changes through treatment as well as after two years post-treatment. N-S-Gn angle also showed no significant changes through treatment and following the two year post-treatment retention period. Several variables were evaluated to assess their influence on the changes that occurred. Regression modelling revealed that the initial value o f the following variables, age at the start o f treatm ent, time elapsed between groups A, B, and C, gender, extractions, and skeletal pattern (Class 1,11 and DJ) all influenced the extent o f the vertical changes that occurred in patients treated with the Begg light wire technique. The null hypothesis is retained. There were no significant changes in the mandibular plane angle and the Y axis angle, therefore treatment did not increase the anterior, facial height when "assessed by these two angles. However, changes were noted in angle SNA, SNB, occlusal plane, occlusal to mandibular plane, and palatal to occlusal plane. Significant increases in linear measurements o f anterior facial height were noted, but these may be as a result o f growth.