Impact of Implant Abutment Dis-/reconnection on Peri-implant Bone Loss – Preliminary Results of a Randomized Clinical Trial

Objectives: The purpose of this study is to investigate whether the immediate definitive abutment connection to dental implant is effective in preventing marginal bone loss when compared with the conventional treatment with late abutment/implant connection, which include three disconnections and reconnections.
Methods: Twenty-three participants received single implants. After implant placement, each volunteer was randomly allocated to one of the groups: control group (n=12), in which was applied conventional treatment with three abutment disconnections and reconnections at 8, 10 and 12 weeks postoperative; or test group (n=11), which immediately received the prosthetic abutment in a definitive way, without any disconnection. Both groups had their implants activated with provisional crowns at 12 weeks and the prosthetic treatment was completed until 6 months with screw retained metal ceramic crowns. To estimate the gingival margin stability and the long-term success of implant-supported restorations, the peri-implant bone level were assessed as primary outcome through intraoral radiographs at 8 weeks and 6 months, in a perspective of bone maintenance, bone loss or bone gain.
Results: There were no differences between test and control groups at 8 weeks for vertical or horizontal bone loss. After 6 months it was observed significant differences for vertical bone level in the control group (mesial: 0.034± 0.77 mm x 0.513 ± 0.69 mm - p = 0.004; distal = -0.156 ± 0.80 mm x 0.320 ± 0.76 mm - p < 0.001); but not in the test group (mesial: -0.047 ± 0.69 mm x 0.130 ± 0.72 mm - p > 0.05; distal = -0.153 ± 0.44 mm x -0.197 ± 0.69 mm - p >0.05). No statistically significant differences were observed for horizontal marginal bone loss too.
Conclusions: After 6 months, vertical peri-implant bone loss was observed only with the conventional three times abutment dis-/reconnection control group. No significant bone loss was observed with the immediate definitive abutment connection test group.