The purpose of this study is to compare the CBCT images before and after en-masse retraction in patients with class II division 1 to evaluate the effect of en-masse retraction on the height of alveolar bone and the external apical root resorption. The sample consisted of 15 adult patients with class II division 1 (9 females and 6 males, mean ages of 20.82±2.01) treated with extraction of the first premolars and non-sliding mechanics using metal power arms. CBCT images for each subject were taken before and after en-masse retraction to evaluate external apical root resorption (EARR) and vertical alveolar bone level (VABL). Paired-sample t-tests were used to determine if there were any differences in EARR and VABL before and after en-masse retraction. There was significant root resorption for all teeth during en-masse retraction and significant difference in vertical alveolar bone level on palatal side just for upper incisor teeth. In contrast, there was no significant difference in alveolar bone level on labial side.