Viscoelastic properties of the periodontal ligament and mucous membrane.

Load deformation studies were carried out on the maxillary arches of three adult Macaca irus monkeys using tooth-borne and tissue-borne plates. By means of an electronically controlled dynamometer, forces with different loading rates, creep, and simulated chewing loads were applied to the plates. The displacement was measured electronically relative to posterior teeth using a linear variable displacement transducer. The six main viscoelastic features noted by other workers for individual teeth under load have been confirmed for the test plates and can be attributed to the connective tissues in the periodontium and in the mucosa. The magnitude of displacement of the tissue-borne plate, however, was appreciably greater than for the tooth-borne plate, and the recovery was far slower. Reducing the part of the plate in contact with mucosa produced greater intrusion, and reducing the number of teeth supporting the tooth-borne plate produced greater displacement.