Aim: This systematic review of randomized controlled trials (RCTs) aims to answer to the following question: "In patients undergoing dental implant placement, which is the best antibiotic prophylaxis protocol to prevent early failures?" Materials and Methods: The MEDLINE, SCOPUS, CENTRAL and Web of Knowledge electronic databases were searched in duplicate for RCTs up to July 2017. Additional relevant literature was identified through (i) handsearching on both relevant journals and reference lists, and (ii) searching in databases for grey literature. A network metaanalysis (NMA) was conducted, and the probability that each protocol is the "Best" was estimated.Results: Nine RCTs were included, with a total of 1,693 participants. Due to the few events reported, it was not possible to conduct a NMA for adverse events, therefore it was conducted only for implant failures (IF). The protocol with the highest probability (32.5%) of being the "Best" one to prevent IF was the single dose of 3 g of amoxicillin administered 1 hr pre-operatively. Even if the single pre-operative dose of 2 g of amoxicillin is the most used, it achieved only a probability of 0.2% to be the "Best" one. Conclusions:Basing on the available RCTs, the use of antibiotic prophylaxis is protective against early implant failures. Whenever an antibiotic prophylaxis is needed, there is still insufficient evidence to confidently recommend a specific dosage. The use of post-operative courses does not seem however to be justified by the available literature. Prospero registration number: CRD42015029708. K E Y W O R D S adverse events, antibiotic prophylaxis, early failures, early implant failures, implant placement, implant survival, network meta-analysis, penicillins, side effects, systematic review | 383 ROMANDINI et Al.

Even if the insertion protocol does not seem to significantly interfere with the long-term healing process, implant site preparation through the piezoelectric bone surgery technique may allow a reduction of peri-implant bone tissue inflammation and support a more rapid bone tissue healing phase.

The implant-oral environment connection represents a critical step point in crestal bone loss. The amount of marginal bone loss, measured after 30 months of loading (T1-T3), was much less than that reported in the literature, showing that correct loading has a minor impact on the periimplant bone remodeling as compared to surgical implant reopening.