The Research Of The Method Of Dental Implant Torque Measurement

In recent years, a new bone support denture technology which is called DentalImplants has been developed in the field of dental restoration. Implant denturetechnology can not only fully dig for the potential of mandible as transfer mode of itsjaw force is closer to natural teeth, but also has a wide range of indications. Thedevelopment of implant denture provides a new direction and effective means thebreakthrough of oral clinical bottleneck. The combination of Implants and bone couldbe affected by many factors, so using the stability of the implant to commonly reflectthe combination of implant and bone in clinical. The higher of the stability of thecombination of Implants and bone, the higher success rate of implant planting. Inoperation of implant denture, it is necessary to regularly test the stability of the implantso as to determine the combination of implant and bone, so that the doctor can take theappropriate measures. Therefore, studying a high precision, convenient and accuratemethod for the test of implant’s stability is great importance.At present, the resonant frequency method and torque measurement method are themethods that people are more concerned about in all methods for implant stabilitytesting. The resonant frequency method has been used in clinical testing, such asOsstell instrument. Although it can measure the resistance lateral force of the implant,but it cannot judge the non-bone integration between the implant and the bone.Although the present method mainly measure the implant’s spin torque and insertiontorque which can accurately reflect the ability of the implant anti-rotational force, butthey are destructive and cannot be used for the clinical intervention. In view of currentsituation of implant stability detection, this paper hopes to measure the torque onimplant using the SAW resonator to judge the stability of the implant. This paper focuson the research of SAW resonator measurement of torque on the shaft.The purpose of this paper is to use high sensitivity, high stability, small size andgood linearity surface acoustic wave(SAW) resonator(433.92MHz) to measure thetorque on shaft. The basic principle of torque measurement of the SAW resonator is asfollow: the shear stress on the rotary shaft will change when the shaft torsionaldeformation, which will make the resonant frequency of the SAW resonator change.The related information of torque on the shaft can be obtained through measuring theresonant frequency of the SAW resonator, and then the shaft torque measurement can be achieved. This paper mainly involves the following aspects:(1) The theory betweenthe shear stress gradient field and the resonant frequency of SAW resonator is proposed,and it is simulated by ANSYS software. And the theoretical formula of relationshipbetween the torque on Shaft and the resonant frequency of SAW resonator is built.(2)Atest system for the measurement of shaft torque is designed based on surface acousticwave resonator.(3)The SAW signal acquisition and processing circuit and FPGA-baseddigital frequency meter are designed.(4) The resonant frequency of SAW resonatorunder different torques is measured by torque test system, and then the shaft torque iscalculated through the relationship between the resonant frequency of SAW resonatorand torque.The results of the ANSYS Simulation show that there is a linear relationshipbetween the resonant frequency and Shear stress of SAW resonator, which is consistentwith the theory and shows that SAW resonator can be used to measure the shaft torque.The changes are of the same between the measured torque and the applied torque fromthe results of the torque measurement experiment. So the SAW torque measuringsystem designed in this subject can achieve the qualitative measurement of the shafttorque. However, there are a deviation between the calculation and the measurement ofthe torque. The above deviation is mainly caused by the roughness of the experimentaldevice. On the one hand, the piezoelectric substrate stiffness of SAW resonator does notmatch that of the metal shaft. On the other hand, the measurement device exist a largemoment loss. These two aspect makes the torque exerted on the rotating shaft do notfully convert to the torque in the rotary shaft. So this technique applied needs manyimprovements to achieve the measurement of torque on the implant.