This study was performed to investigate the effect of change of body posture on the rest position and the rotational torque movement of the mandible. Thirty dental students without any signs and symptoms of temporomandibular disorders and with natural dentition were selected for this study. Cervical inclination and the amount of the mandibular movement on protrusion, on left and right excursion, and on tapping in three body postures such as sitting position, supine position without pillow, and supine position with pillow were measured by goniometer, Cervical-Range-of-Motion, and mandibular tracking device, BioEGN with Rotate! program. The data obtained were classified and processed according to body posture and type of lateral guidance with SPSS windows program and the results were as follows:
1. There was significant difference among the three cervical inclinations by body postures.
2. Comparison of mandibular rest positions among body postures showed significant. difference only for
lateral distance in frontal plane, but comparison between before and after swallowing showed significant
difference except for the lateral distance, vice versa.
3. Distance and amount of the rotational torque movement on protrusion and/or lateral excursions didn´t show any difference by body posture. But by both body posture and lateral guidance type, there were slightly significant difference for some items.
4. A significant difference was shown for the rotational torque movement in frontal plane on tapping by body postures, for the lateral distance in frontal plane on sitting position by lateral guidance type, and for the rotational torque movement in frontal plane by both body posture and lateral guidance type.
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