Three-dimensional Loads on Implants-supporting Fixed Prostheses in vivo

Objectives: Three-dimensional (3-D) functional loads exerted on dental implants are the essential factors in the biomechanical control of implant-supported fixed prostheses. This study aimed at measuring the functional 3-D loads on the implants supporting fixed prostheses during function and investigating the effect of splinting the superstructures of implant-supported fixed prostheses. Methods: A 66 year-old woman was participated. The 3-D load-measuring device, comprised of a piezo-electric force transducer (Type Z18400, Kistler Instruments AG) and the experimental superstructure, was used for the experiment. The devices were tightened with screws into her implant-fixtures subsisting at the mandibular right second premolar and first molar regions. The 3-D loads during the maximum voluntary clenching (MVC) and biting a piece of paraffin wax (PW) were registered in the case of splinting the superstructures of implant-supported fixed prostheses and in the case without splinting. The magnitude and direction of the recorded loads were analyzed in the spatial coordinates based on her Frankfort and sagittal planes. Results: The sum of load magnitudes exerted on the two implants showed no significant difference between in the case of splinting the superstructures and in the case without splinting regardless of the task. At MVC, the magnitudes and directions of the loads exerted on each implant were significantly different between both cases (Mann-Whitney, p<0.01). The magnitudes of the loads were allocated more evenly to the two implants in the case of splinting the superstructures than in the case without splinting. At PW, the magnitudes and directions of the load on each implant were not significantly different between the cases with and without splinting. Conclusion: The 3-D loads exerted on the implants with fixed superstructures were recorded during function in vivo. The functional 3-D loads on the implants were affected by splinting the superstructures of implant-supported fixed prostheses.