Accuracy of compensating distance during transferring orientation relation with ear Bow

In transferring relationship of jaws to opening axis of articulator by earbow earpiece of face bow is adapted on ear pin of articulator. So this study was done in order to compare position of earpiece representing external auditory meatus and ear pin of an articulator. This descriptive study was done on 30 students (15 males, 15 females, 20 to 25 years of age) with functionally acceptable occlusion. Kinematic center of rotation was located and maxillary cast was transferred to the Hanau articulator (Medular-196). In the next step, ear-bow is used to register orientation relation of maxilla and after positioning the fork on maxillary cast which was mounted in preview step, the position of center of earpiece of ear-bow was marked on graphs paper which were attached on two round aluminum plate positioned to condylar part of articulator. The last step was to compare registered points to ear pin position of articulator. Kolmogorov-Smirnov and t test were used to examine difference between genders and left and right sides at a significant level of P<0.5. Positions of earpieces in 66.7% of the samples in the left part of the face and 70% in the right part were located upper and more forward as the current ear pin of the condylar compartment. There were no significant differences between both sides and difference based on gender. Considering all achieved results in this study, the current locations of the ear pins in mentioned articulator are not suitable for our samples and some changes must be considered in mounting of casts.