Measuring Luxation of Dental Implants In Vitro

Loading of dental implants immediately after placement is an important attribute for the patients receiving the implants, but may induce a failure in the osseointegration of the implant. Even though the loading required to induce such failures is currently unknown, it is estimated that the osseointegration may fail if an implant is luxated in bone by more than $50μm$⁠. Therefore, the ability to measure this loading can provide the practicing dentist with critical information in estimating the functional life of a newly placed implant. This paper discusses the design and fabrication of a cost-effective test setup for measuring the amount of horizontal force required to displace a nonosseointegrated implant, and presents the results of our pilot in vitro load measurements for dental implants mounted in a bovine mandible. Although the sample size of our measurements is not statistically significant, the initial data show that the amount of horizontal force required to displace a $4.3×13mm$ implant by $50μm$ is in the order of $150N$⁠, and therefore the implant may fail to osseointegrate for biting forces that are as low as $440N$⁠, which is about half of the typical biting force of an adult in the molar area. One implication of our study is that implants having smaller diameters may move and fail to osseointegrate for even lower biting forces. Furthermore, our work represents the first steps in developing appropriate metrics to correlate the measured biting force generated by a patient with his or her candidacy for immediate functional implant loading.