Platform switching and marginal bone-level alterations: the results of a randomized-controlled trial

Objectives: This randomized‐controlled trial aimed to evaluate marginal bone level alterations at implants restored according to the platform‐switching concept, using different implant/abutment mismatching. Material and methods: Eighty implants were divided according to the platform diameter in four groups: 3.8 mm (control), 4.3 mm (test group1), 4.8 mm (test group2) and 5.5 mm (test group3), and randomly placed in the posterior maxilla of 31 patients. After 3 months, implants were connected to a 3.8‐mm‐diameter abutment and final restorations were performed. Radiographic bone height was measured by two independent examiners at the time of implant placement (baseline), and after 9, 15, 21 and 33 months. Results: After 21 months, all 80 implants were clinically osseointegrated in the 31 patients treated. A total of 69 implants were available for analysis, as 11 implants had to be excluded from the study due to early unintentional cover screw exposure. Radiographic evaluation showed a mean bone loss of 0.99 mm (SD=0.42 mm) for test group1, 0.82 mm (SD=0.36 mm) for test group2 and 0.56 mm (SD=0.31 mm) for test group3. These values were statistically significantly lower (P