ABSTRACT
Objective:To compare hard tissue morphology by cephalometric measurements between extraction and non extraction orthodontic treatment in borderline cases. Methods: The samples consisted of 33 cases selected as borderline cases by 5 orthodontic specialists. They were divided into 21 extraction cases (including 13 four first premolar extraction cases and 8 second premolar extraction cases) and 12 nonextraction cases by checking patients’ treatment records. Conventional cephalometric analysis was made to compare hard tissue structures before and after orthodontic treatment and the same comparison was made between two different extraction patterns. Results: No statistical difference was found on pretreatment hard tissue morphology between extraction and non extraction groups divided from borderline cases. The SNB angle of the four first premolars extraction group was smaller than that of the four second premolars extraction group by (4.0?1.3)?( P