Development of patient simulation system: Influence of the headrest tilting

Objectives: The lower jaw movement pathway and the head movement during maximal opening and the maximal opening distance were recorded to evaluate the influence of the head position at home (horizontal) position dentistry for a realistic simulation system of dental education. Methods: A total of 20 Japanese females and males were studied. The maximal opening distance and the pathway were measured at different tilting angles of the headrest during home position dentistry using 3D motion capture system (ProReflex, Qualisys Ltd.). The measurement points set on the surface of the face of the subject. It was assumed the motion of the tip of nose as the head movement and the motion of chin (mentium) as the lower jaw movement. Results: The mean value of the maximal opening distance at the head position bended forward group was decreased than the mean value at the head position standard group and the head position bended backward group. There were a statistically significant change between bended forward group and all the other groups by paired t-test (P<0.05). The lower jaw closing pathway at the head position bended groups inclined to trace rear side of the opening pathway. Conclusion: The maximal opening distance decreased at the head position bended forward and there was not significant change between the head position bended backward and the head position standard. The lower jaw movement pathways inclined to be complicated at the head position bended forward and backward. It was suggested that the setting of the headrest tilting should not be over bended at the maximal opening during home position dentistry for jaw function. (This study depends on the grant in 2007 by Ministry of Education, Culture, Sports, Science and Technology in Japanese government.)