AbstractsBiology & Animal Science

The purpose of the present study was to compare a sample of patients with borderline mandibular crowding of 4 to 8 mm (measured on electronic models) that could benefit from extraction therapy or nonextraction therapy. Sixty patients treated by orthodontic residents at The University of Alabama School of Dentistry Department of Orthodontics were evaluated. Thirty patients were treated with nonextraction, and 30 patients were treated with extraction of premolars (17 second premolars and 13 first premolars). Geodigm emodel software was used to compare mandibular width dimensional changes from pretreatment to after orthodontic treatment among the nonextraction, extraction of mandibular first premolar, and extraction of mandibular second premolar treatment groups. In addition, pretreatment and posttreatment cephalograms of the treatment groups were traced with Dolphin Imaging software and compared by evaluating the angle of the mandibular incisor in relation to the mandibular plane. Results of the study showed more intercanine expansion in the extraction sample than in the nonextraction sample. However, the nonextraction sample had a large increase in incisor mandibular plane angle, whereas the extraction samples showed a decrease. The measurements that were statistically significantly different in the extraction and nonextraction groups were as follows: 1. Intercanine width measured at the gingival margin: the extraction sample showed more expansion than the nonextraction group did. 2. Second premolar width in nonextraction patients and first premolar extraction group: nonextraction sample showed expansion in the second premolar width, whereas the first premolar extraction sample showed constriction. 3. Intermolar width change in nonextraction and extraction groups: the nonextraction group showed slight expansion in the intermolar width, whereas the extraction groups showed constriction. 4. Incisor mandibular plane angle changes in nonextraction and extraction samples: the nonextraction group had a large increase in incisor mandibular plane angle, whereas the extraction samples showed a decrease. M.S. viii, 64 p. : ill., digital, PDF file Orthodontics Dentistry Intercanine Incisal Position Nonextraction Extraction Expansion Borderline Crowding UNRESTRICTED