Since subperiosteal dental implants are custom made implants, design and manufacturing must be carried out with great care, solving comprehensive mechanical analyses. In this work, we performed a 3-day fatigue test on a 3D-printed titanium implant in a custom-designed mechanical testing device. After three days of average chewing loading, no residual deformation was observed. Moreover, no cracks or inclusions were observed when examining the CT scans. Nor did the printing defects on the implant cause any problems. The tested implant showed satisfactory results and was considered to be suitable for implantation. With the case study, we also showed that the new experimental methodology developed for the mechanical examination of subperiosteal implants is suitable for fatigue examinations of implants.

During the investigation, the effect of screw tightening torque on the potential loosening of screws under load was examined in the case of custom-made subperiosteal implants. The study focused on the connection screws between the implant components, testing the commonly applied tightening torques of 15 Ncm and 30 Ncm. Mastication was simulated using a custom-designed, PLC-controlled testing device, which allowed for the reproduction of variable numbers, forces, and speeds of bite cycles. With this device, six different scenarios were tested, including 500, 2000, and 10,000 bite cycles, under both constant and variable bite forces. A caliper was used to record potential length changes of the screws, force sensors measured the bite forces, and calibrated torque screwdrivers were used to verify the loosening torques. Based on the analysis of the measured data, it was concluded that for the M1.8 screws tested, a tightening torque of 15 Ncm does not provide sufficient resistance against loosening, whereas 30 Ncm offers adequate stability.