Submerged and transmucosal healing yield the same clinical outcomes with two-piece implants in the anterior maxilla and mandible: interim 1-year results of a randomized, controlled clinical trial

Objectives: To test whether or not transmucosal healing at two-piece implants is as successful as submerged placement regarding crestal bone levels and patient satisfaction. Material and methods: Adults requiring implants in the anterior maxilla or mandible in regions 21-25, 11-15, 31-35 or 41-45 (WHO) were recruited for this randomized, controlled multi-center clinical trial of a 5-year duration. Randomization was performed at implantation allowing for either submerged or transmucosal healing. Final reconstructions were seated 6 months after implantation. Radiographic interproximal crestal bone levels and peri-implant soft tissue parameters were measured at implant placement (IP) (baseline), 6 and 12 months. Patient satisfaction was assessed by a questionnaire. A twosided t-test (80% power, significance level a 0.05) was performed on bone-level changes at 6 and 12 months. Results: One hundred and twenty-seven subjects were included in the 12-month analysis (submerged [S]: 52.5%, transmucosal [TM]: 47.2%). From IP to 6 months, the change in the crestal bone level was -0.32mm (P<0.001) for the S group and -0.29mm (P<0.001) for the TM group. From IP to 12 months, bone-level changes were statistically significant in both groups (S = 0.47 mm, P<0.001; TM-0.48 mm, P<0.001). The mean differences of change in the bone levels between the two groups were not statistically significant at either time point, indicating the equivalence of both procedures. For both groups, very good results were obtained for soft tissue parameters and for patient satisfaction. Conclusions: Transmucosal healing of two-piece implants is as successful as the submerged healing mode with respect to tissue integration and patient satisfaction within the first 12 months after IP.