RESUMO
Aim: Bimaxillary protrusion is a common condition observed irrespective of race and ethnicity and is a chief concern for patients who seek orthodontic treatment. The aim of this study was to compare and evaluate changes in soft tissue structures and incisor positions in class I bimaxillary protrusion subjects undergoing orthodontic therapy when friction and frictionless mechanics were used. Methods: Two groups with a total of 40 patients aged 1830 years diagnosed with class I bimaxillary protrusion treated by extracting first premolars were considered for this study. Patients treated with friction mechanics were included in Group 1 and those treated with frictionless mechanics in Group 2. The digital lateral cephalograms were calibrated and analyzed using Nemoceph software. Selected landmarks were marked on pre- and post-treatment cephalograms and assessed for intra- and inter-group soft tissue and incisor position changes. Student's t-test was used to analyze the collected data using SPSS 20 software. Result: Intragroup comparison revealed significant changes in both groups. Inter-group comparison of the selected parameters between groups 1 and 2 showed differences but without any statistical significance, except for the inter-incisal angle. Conclusion: Pre- and post-treatment comparison analysis revealed significant soft tissue changes in both groups. However, the comparison between friction and frictionless mechanics showed no statistically significant changes
