| Research Abstract |
Temporomandibular joint (TMJ) disorders accompanied by disk displacements and/or disk perforations have benn considered to be the results of excessive TMJ loadings. However the precise values for loads acting on TMJ during mastication have not been measured.
In this study in order to measure directly the load acting on the local surface area of the condylar heads of monkeys during mastication the micro pressure-sensor (3mmphi) composed of biocompatible hydroxyapatite (HAP) -piezoelectric Lead Zirconate Titanate (PZT) laminated ceramics was disigned and then fabricated.
First the pressure-sensor was calibrated under the cyclic loading conditions. The reaults of caliblation test showed a linear relationship (r=0.998) between the integrated output of the sensor and the load up to 19.6N.
Subsequently the pressure-sensor was implanted into the anterior and superior surface of the condylar heads of monkeys, and then the loads acting on the sensors and cycle times were recorded during the mastication of hard foods. The maximum loads of 2.05N,0.44N,and 0.32N was measured at the maximum opening of mandible, during chewing movement, and during grinding movement, respectively. Assuming that the load distributed uniformly on the sensor, these maximum loads could be converted into the maximum pressures of 0.29MPa, 0.06MPa, and 0.05MPa, respectively.
And cycle times of 400msec and 180msec was measured at during chewing movement, and during grinding movement.
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