Development of the measuring system of 3-D force on the tooth and Measurement to an abutment tooth of the partial denture

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The aim of this study was to investigate the modality of 3-D force onto abutment tooth in vivo with a special miniaturized piezo-electric force transducerIn order to clarify the characteristic of a small crystal piezo-electricity formula load sensor, a rigid proofreading equipment, made with steel material, that hate 1 axis variable vice of angle change by 0.05-degree was developed. This was enable to load to the transducer fixed with a brass jig from horizontal direction to vertical direction. When regression analysis between sensor output and the known amount of loads was applied to investigate the linearity, correlation coefficients of X-axis, Y-axis and Z-axis are 0.99999, 0.99999 and 0.99996, respectively. The effect of the hysteresis on sensor output for X-axis, Y-axis and Z-axis were 0.9%, 1.1% and 1.7% at the maximum, respectively. As the effect of temperature on sensor output was examined by 10-degree rise, the increase of output on X-axis, Y-axis, and Z-axis were 0.5%, 0.46%, … More respectively. These results showed the transducer hadquite precision, and was suitable for in vivo measurement of functional loads onto the tooth.A load measuring device that consists of an inner part similar to a metal core, a force transducer and an outer part similar to a tooth crown was manufactured. These were united by a steel screw and set with temporary cement on the tooth, so it enabled to measure the load onto the tooth in vivo.Informed consent was obtained from subjects after explaining the aim of this study. During clenching, force magnitudes and directions in 3-D on tooth crown were recorded. When the bite force increased, the direction of load changed in the mesial palate side in natural dentition. For the abutment tooth of a partial denture which have a removable occlusal rest, when with the occlusal rest, the amount of load became lager than not with the occlusal rest and the direction of load changed in the distal buccal side.Conclusion : this system enables to measure a 3-D functional load onto abutment tooth in vivo. Less