Abstract
Biting force during functional movements applies stress to the teeth, periodontal ligament, mandible and maxilla and produces distortion in all of them. Schöhl (1960), Behrend (1974, 1978), Siebert (1980), Kato (1981, 1982), Miura (1985), and several other researchers have described the significance of the physiological tooth displacement during function and have measured it, which is a very complicated task. To assess such task, the three dimensional tooth displacement transducer type M-3 was developed. It consists of a transducer with three Magnesensors (three pick-up heads and three magnets, a universal joint, a measuring probe and a set-up plate. Its total weight is 48.7grs. The displacement transducer type M-3 is screwed into a paraocclusal splint, which is made up of a 2mm thick aluminium plate and autopolimerizing acrylic resin. This splint is fixed at the labial surface of the anterior teeth with a momentary adhesive. All parts of the transducer -except for the measuring probe- are extraoral, hence the normal masticatory movement, is not altered by its presence and also, the intraoral temperature and humidity do not affect the transducer.
The free end of the 0.3mm diameter measuring probe is attached to the buccal middle surface of the tooth to be tested. Its movement in three directions is accuratory transmitted to the magnets by the universal joint. The displacement transducer type M-3 is contacting type, therefore some measuring pressure is essential, but since this measuring pressure must alternate with the physiological tooth displacement it should be kept as light as possible. As a result of using pivots in the universal joint, the measuring pressure was kept at less than 0.4grs. The linearity error of each transducer was less than 2% within a range of ±200μm. There was a minimum interference among the three transducers.
It became possible to measure the three dimensional physiological tooth displacement during function.
