Purpose: The aim of this study was to assess the radiographic and clinical outcomes of extra-short implants either alone or in conjunction with osteotome sinus floor elevation and to compare these with regularsized implants in the posterior atrophic maxilla. Materials and Methods: Systemically healthy, nonsmoker individuals having at least one tooth gap in the posterior maxilla were included in the study. When the residual bone height was 4 mm, an extra-short implant (4 to 6 mm) in conjunction with osteotome sinus floor elevation was placed; when the residual bone height was between 4 and 7 mm, an extra-short implant alone was placed; and when it was ≥ 8 mm, a regular implant (8 to 10 mm) was placed. The implants were uncovered at 4 months, and porcelain-fused-to-metal crowns were fabricated. Crestal bone level, change in the crestal bone level, crown-to-implant ratio, and residual bone height were measured at baseline and 6 and 18 months postloading. Results: Thirty patients (15 men, 15 women, age range: 30 to 73 years) received 80 implants. One implant in the extra-short implant (n = 27 implants) and regular implant (n = 24 implants) groups and two implants in the extra-short implant with osteotome sinus floor elevation group (n = 29 implants) failed before loading. Crestal bone level was significantly higher in the regular implant group compared with the extra-short implant with osteotome sinus floor elevation group at 18 months (P .028). Crestal bone level change between 6 and 18 months was significantly lower in the extra-short implant + osteotome sinus floor elevation group compared with the regular implant group (P = .003). There was no correlation between the crestal bone level, crestal bone level change, and prosthetic and implant characteristics (P > .05). Conclusion: Extra-short implants placed either in native bone or in conjunction with osteotome sinus floor elevation may provide similar clinical and radiographic outcomes that are comparable to those obtained with regular implants. Both extra-short implant placement methods can be promising noninvasive treatment options for the posterior maxilla, and implant dimension, crown length, crown-to-implant ratio, and residual bone height may not affect the crestal bone level change, at least in the short term. Schlagwörter: dental implants, maxillary sinus floor augmentation, minimally invasive surgery