Purpose: High crown-implant ratios might affect the biologic and technical performance of a reconstruction. The aim of this study was to assess whether a higher crown-implant ratio of single restorations on 6-mm implants resulted in more peri-implant bone loss and more prosthetic complications during a 1-year followup period. Materials and Methods: A group of 37 patients were provided with 47 single-implant-supported restorations on 6-mm implants. Implants were placed in the posterior mandible or maxilla, where limited bone height was available. The clinical crown-implant ratio was determined on digitized casts. Peri-implant bone changes were analyzed on intraoral radiographs. Prosthetic complications were scored throughout the evaluation period. Results: The mean crown-implant ratio was 2.14 ± 0.42. The mean peri-implant bone loss was 0.13 ± 0.36 mm. No complications occurred. Conclusion: High crown-implant ratios are not accompanied by increased peri-implant bone changes or prosthetic complications during a 1-year follow-up period. Schlagwörter: alveolar bone loss, crown-implant ratio, dental implants, fixed dental prosthesis, prospective study, single-tooth