A New Prediction of Nasal Tip Projection Resulting From Le Fort I Osteotomy by Means of Fuzzy Inference

抄録

In the presurgical work-up of orthognathic surgery, a resultant soft tissue profile is predicted on a lateral cephalogram. Although several hard to soft tissue ratios of linear regression formulas are available to predict a change in the lips and chin, the prediction of nasal change could not be done with linear formulas. Because the change is a non-linear result of the interaction of some factors:elasticity of the nesal cartilage and soft tissue. This paper demonstrates a prediction system for Pronasale by means of the fuzzy rule-based inference. Materials were 20 sets of lateral cephalograms taken before and 6 months after surgery of 20 bimaxillary orthognathic surgery cases. The system outputs showed very high correlation with actual changes (r=0.94) and errors ranged from -0.6mm to 0.5mm with standard error 0.35. Therefore, the fuzzy rule-based prediction system is adovocated for prediction of resultant profile after orthognathic surgery.