[Comparing of the results obtained from distalization of the upper molar teeth by applying extraoral forces to permanent and removable appliances].

The purpose of the present study is to compare the experimental and clinical results of permanent and removable appliances on headgears. 3 dimensional photoelastic models were used in the experimental work. On these models, forces applied to face bows which were attached to permanent and removable ancher units. After the experiment sagittal sections prepared and analyzed under polaroscope. The results of the 8 case with removable ancher units and 7 case with permanent ancher units were compared by cephalometric processes. As a result, there was no significant difference between permanent and removable headgears.