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.