Development of a Three-dimensional Occlusal Force Sensor

The aim of this study was to develop a three-dimensional small occlusal force sensor which could be set up inside the crown of the tooth and measure both the three-dimensional occlusal force and the tooth displacement path during function at the same time in vivo. The measurement error of this occlusal force sensor was 11.9%, 8.7%, and 5.9% at maximum in the mesio-distal, bucco-lingual and colono-apical directions, respectively. The subject was a Japanese male who had good periodontal conditions and an acceptable centric occlusion. After this occlusal force sensor and tooth displacement transducer were set up at the upper left first molar, the three-dimensional occlusal force and the tooth displacement were measured simultaneously during clenching at the intercuspal position and biting a ready-made monoaxial occlusal force meter. During clenching at the intercuspal position, the tooth displaced toward the palato-disto-apical direction and this was almost the same direction in which the occlusal force acted. The difference between the values measured by this sensor and a ready-made monoaxial occlusal force meter was about 9.5% at maximum. This three-dimensional occlusal force sensor is able to reveal how occlusal force is diffused.