Purpose: This randomized, controlled, split-mouth trial with a 3-year follow-up was carried out to compare radiologic changes of crestal bone level (CBL) between splinted tissue-level implants restored by platform matching and bone-level implants restored by platform switching. Materials and Methods: Periapical radiographs were taken to evaluate the peri-implant crestal bone changes at baseline (implant restoration), at 1 year, and at 3 years after the definitive restoration. Results: Thirty-five patients requiring a partial fixed dental prosthesis supported by two implants had their sites randomized according to receiving both implant types. Fifty tissue-level implants restored by platform matching, as control implants, and 50 bone-level implants restored by platform switching, as test implants, were placed. For baseline to 3 years, crestal bone changes were 0.18 ± 0.46 mm (P = .043) in the control group and 0.14 ± 0.35 mm (P = .514) in the test group. The mean differences between groups were as follows: baseline to 1 year, 0.07 ± 0.23 mm (95% CI: -0.034, 0.185); 1 to 3 years, 0.01 ± 0.01 mm (95% CI: -0.055, 0.074); baseline to 3 years, 0.04 ± 0.11 mm (95% CI: -0.080, 0.150). No statistically significant differences in CBL at baseline to 1 year (P = .269), 1 year to 3 years (P = .811), and baseline to 3 years (P = .513) were observed. Conclusion: In this trial, CBL changes in the tissue-level control group were statistically significant only between the baseline and 3-year follow-up. Meanwhile, CBL changes in the bone-level test group were not statistically significant in the different times studied. No statistically significant difference in CBL between two implant types was observed. Keywords: bone-level implant, marginal bone loss, platform switching, split-mouth, tissue-level implant