Abstract
We measured three-dimensional movements of a maxillary complete denture during clenching at the centric relation in six totally edentulous patients with a newly developedmeasuring system. And we also investigated what influence a flange length concerning thedenture stability would have on the movements.
1. When either a flange whole or just a buccal flange was shortened, horizontal movementsand rotation of the denture increased. Lack of the flange in the region of the maxillary tuberositydecreased the resistance to horizontal shifting of the denture and denture retention by cheekmuscle. These factors are considered to cause the horizontal movements of the denture duringclenching, especially in lateral directions.
2. Both anteroposterior and up-and-down movements of the denture in the region ofincisors increased by shortening a labial flange. These movements seem to be caused by adecrease in mechanical resistance of the labial flange to the alveolar ridge and the mucobuccalfold.
3. Anteroposterior movements of the denture were increased by shortening the palatalregion. This seems to be caused by an increase in occlusal force per unit area due to the decreasein the denture-base area and by a decrease in stiffness of the mucosa due to incomlete border seal.
