The Effect of patient position on Recording the Centric Relation of Occlusion by Tracing the Gothic Arch in Dentulous patients

Centric Relation (CR) is the most important recording procedure of maxillamandibular relation in prosthodontic. We investigated the influence of patient's body position in CR recording by extra-oral tracing method. In this analytic cross-sectional study, 18 dentulous subjects were selected randomly. After patient education, the extra-oral tracing device attached to acrylic stents; Then the Gothic arch tracing was accomplished in supine, semisupine and upright positions. The CR achieved by bimanual manipulation method was also recorded. Four points were recorded in four transparent sheets; also, the vertical (Y) and horizontal (X) axis were measured for each point.Then the horizontal, anterior- posterior and straight distances of each point to point that achieved by bimanual manipulation were calculated. Data were analyzed using the one-way ANOVA and ttest with the significant level of I = 0.05. There was no significant difference between horizontal distances of points registered in various body positins and of point registered in Dawson method, but with a view to ant-post and direct distance, the point registered in supine and semisupine positions were significantly nearer to Dawson manner, rather than the points registered in upright position. No correlation to sex and age was obtained between distances of registered points in various body positions and registered point in Dawson method. In dentulous subjects, in comparison to upright position, the obtained CR in supine and semi-supine positions by extraoral tracing method had significant similarity to bimanual manipulation.