Definitive abutments placed at implant insertion and never removed: is it an effective approach? A systematic review and meta analysis of randomized controlled trials.

To assess whether repeated abutment dis/reconnections has any impact on peri-implant bone resorption and on soft-tissue healing.

To perform the systematic review and meta-analysis electronic and manual searches were conducted for English articles published up to March 2017. The aim was to identify whether there is a relationship between repeated disconnections of implant abutments (PA group) and prosthetic/implant failures, complications, marginal bone loss (MBL), soft tissue healing and esthetic evaluation (PES), after at least 1 year of function, compared to implants receiving a final abutment at the time of implant placement (DA group). Results: Fourteen articles (535 patients with 994 implants) were selected in the qualitative analysis.

Six of these were included in the metaanalysis. Five prosthesis failed in the PA group and one in the DA group (P=0.1047). Seven biologic complications were experienced in the PA group and six in the DA group (P=0.8121). MBL was statistically lower in the DA group (difference 0.279mm; P=0.000).

Higher buccal recession was experienced in the PA group (difference 0.198mm; P=0.0004). The PES evaluation showed no differences between groups (P=0.289). Conclusions: Repeated abutment dis/reconnections significantly increased MBL and buccal recession. Further studies are needed to confirm these results.