Purpose: The success of single-tooth implant restorations has resulted in an increased use of nonsplinted implants to replace adjacent missing teeth; however, this may result in excessive force transmission to the implant and bone, causing bone loss. The purpose of this prospective study was to compare the marginal bone level change of adjacent splinted implants and of nonsplinted implants functionally loaded with cemented restorations up to 5 years in maxillae. Material and Methods: Between 2002 and 2004, all patients who received three consecutive adjacent implants in a private office and a university implant dentistry department were included in this study. All implants were placed in posterior maxillae. Maxillary left implants were restored with splinted cemented restorations, and maxillary right implants were restored with nonsplinted cemented restorations. Marginal bone resorption was measured with intraoral radiographs annually for 5 years. The data were analyzed statistically with the Mann-Whitney U test and the two-sample Kolmogorov-Smirnov test to identify differences between splinted and nonsplinted implant restorations. Results: One hundred thirty-two implants were placed in 44 patients. Two subjects (6 implants in total) did not complete the study. Three implants failed at stage-two surgery. Of the remaining 123 implants, 63 were restored with splinted cemented restorations and 60 were restored with nonsplinted cemented restorations. The mean marginal bone level changes at the 5-year recall were -0.7 ± 0.2 mm for splinted restorations and -0.8 ± 0.2 mm) for nonsplinted restorations. Conclusions: Peri-implant marginal bone loss around nonsplinted implants in the present study was statistically equivalent to that observed in splinted implants. Multiple nonsplinted implants can be successfully included in many clinical situations in an effort to optimize esthetics and circumvent the problem of nonpassively fitting frameworks. Keywords: bone level changes, dental implants, implant crowns, implant-supported prostheses, splinting