ASSESSMENT OF CHIN SURGERY BY A COORDINATE FREE METHOD

A quantitative description of the changes and stability after geniopla sty in a cross-sectional sample of 19 patients who had advancement gen ioplasty is presented. Euclidean distance matrix analysis (EDMA) of fi ve cephalometric landmarks was used to assess these changes. During th e first 6 months after surgery, bone deposition occurred at B point an d pogonion, with bone resorption at the superior and posteroinferior a spects of the advanced segment. The genial segment rotated slightly an ticlockwise. The authors believe this to be due to the action of the m entalis muscles. The stability of the advanced segment was excellent w hen assessed 1 year after surgery. The Euclidean distance matrix metho d can be used to assess shape changes and does not require cephalograp hic superimposition. It can also distinguish repositioning from remode lling and the changes of genioplasty from those of concomitant orthogn athic surgery.