A Comparision Of Three Superimposition Method In Evaluating Skeletal And Dental Changes Contributing To Sagittal Molar Correction In Skeletal Class II Malocc-Lusion Treated With The Herbst Appliance

Objective: The purpose of this investigation was to compare the reliability of three different cephalometric superimposition method , including Bjork's structural,Pancherz and Pitchfork methods, for evaluating skeletal and dental changes contributing to sagittal molar correction by Herbst appliance treatment. Methods: The material consisted of 15 pairs of cephalogram obtained before and after Herbst appliance treatment (8 males and 6 females ,skeletal maturity stage MP3:FG-G).Each pair of cephalograms were superimposed and traced by three different methods to quantitatively evaluate the sagittal molar occlusal change, including dental and skeletal changes. The cephalometric data before and after treatment were analysed statistically. Rusults: 1. With a approximately no total rotation, and no rotation between anterior cranial base and SN plane, there was statistically significant difference in skeletal and dental changes of maxillary molar between the Bjork's structural and the Pancherz method, but statistically no difference in skeletal and dental changes of mandibular molar. 2. With a approximately no total rotation, and no rotation between anterior cranial base and nasal line, there was no statistically significant difference in the skeletal and dental changes contributing to sagittal molar correction between the Bj?rk's structural and the Pitchfork method . 3. There was statistically significant difference in the skeletal changes of maxillary molar, and no statistically significant differ -ence in the changes of mandibular molar and dental changes of maxillary molar between the Pancherz and the Pitchfork method . Conclusion : 1. Three methods,which varied on superimposition and measuring, when analysed on the skeletal and dental changes contributing to sagittal molar correction in cases treated with the Herbst appliance, might resulted in the identical or different effect. They were as follows: first,the measurements of the maxillary molar by the Pancherz method differ from the those by the Bj?rk's structural method ,but a conform -ity in the measurement of mandibular molar between them,secondly the analysed result of the Pitchfork method confirm to the Bj?rk's structu -ral method's and thirdly, with difference in skeletal changes of the maxillary molar, there were the conformity in measurement by the Pitch -fork method and the Pancherz method, not only in the dental changes of the maxillary molar, but in the skeletal and dental changes of the mandibular molar. 2. The Pitchfork method and the Pancherz method is comparatively direct and distinct on quantitatively evaluating skeletal and dental changes of molar correction of treatment with the Herbst.