Effects of maxillary second molar extraction on dentofacial morphology before and after anterior open-bite treatment: a cephalometric study.

The purpose of the present study was to probe into the effects of maxillary second molar extraction on dentofacial morphology by the use of cephalometric radiographs taken before and after anterior open-bite treatment. The subjects were 30 Japanese patients who had received multiloop edgewise archwire therapy without premolar extraction. They were divided into two groups. Group 1 consisted of 15 patients who had their maxillary second molars removed. Group 2 comprised 15 patients who had been treated without extraction of maxillary second molars. Lateral cephalograms were taken before and after treatment. Seventeen angular and 31 linear measurements were obtained from the lateral cephalograms. Paired and unpaired t tests were used to determine the significance of differences in measurements. The retrusion and extrusion of the maxillary incisors, the distal movement of the maxillary first molars, and the uprighting of the maxillary first premolars and the mandibular first molars were greater in group 1 than in group 2. Moreover, the maxillary first molars intruded significantly in group 1 but extruded insignificantly in group 2. Extraction of maxillary second molars, as well as nonextraction, can be an effective operating procedure for open-bite correction of the permanent dentition.