Purpose: To evaluate differences in implant placement accuracy depending upon the presence or absence of metal restorations, as well as between distal extension and tooth-end cases. Materials and Methods: Five experimental groups were designed with mandibular models exhibiting the following dental statuses: six anterior teeth and bilateral second molars, with bilaterally edentulous sites between them (group NN); six anterior teeth (group NDE); identical to group NN, with the six anterior teeth restored with metal crowns (group MN); identical to group NDE, with the six anterior teeth restored with metal crowns (group MDE); identical to group NN, with all remaining teeth restored with metal crowns (group MM). Six implants were placed on the bilateral first and second premolars and first molars; the linear and angular deviations between the preoperatively planned and actually placed implant positions were computed. Results: Implant position errors were 0.55 to 0.87 mm and 0.53 to 0.80 mm at the entry point and apex, respectively, and were 0.35 to 0.71 mm and 2.02 to 3.12 degrees in depth and angular deviations, respectively. Significant differences were observed between groups NN and MM in overall deviations at the entry point (P = .009) and apex (P = .026), as well as in depth deviation (P = .008). Conclusion: The presence of metal restorations on all anterior and posterior remaining teeth resulted in significant differences in linear deviation at the entry point and apex between preoperatively planned and actually placed implant positions, compared with natural teeth without restorations. No significant differences were observed in placement accuracy between distal extension and tooth-end cases. Schlagwörter: cone beam computed tomography, dental implantation, dental models, dental prosthesis, radiation scattering