Movements of temporomandibular condyles during swallowing.

There have been studies that investigated mandibular movements and positioning during swallowing, but the results were inconsistent, and still the exact position of the condyles during swallowing is unknown. The purpose of this investigation was to study the kinematics of the mandible and the condyles, and to determine the actual movement paths and position of mandible and condyles during the process of swallowing. The study was performed on a sample of 44 dental students. Measurements were done with an electronic axiograph. After non-occlusing attachment was fixed in the mouth, every subject swallowed for five times from the rest position. The final swallowing position of the left and the right condyles was measured in the sagittal plane. The final swallowing position of the sagittal incisal point was measured in sagittal, frontal and horizontal plane, and data was statistically analyzed. The condyles showed average movement toward posterior (left 0.17 mm, SD 0.28, right 0.16 mm, SD 0.25) and superior (left 0.14 mm, SD 0.20, right 0.14 mm, SD 0.23). Anterior and/or inferior position had 20% of participants. The average sagittal incisal point movement during swallowing was toward anterior (0.30 mm, SD 0.53) and superior (0.81 mm, SD 0.84). The mean mandibular lateral movement was 0.1 mm (SD 0.1). The results of the study suggest that retrusion during swallowing is not the rule, although on average there is a slight tendency of condylar movement toward posterior. Swallowing can be used as auxiliary method for determining vertical dimension of occlusion.