The impact of the type and configuration of abutments and their (repeated) removal on the attachment level and marginal bone.

PURPOSE The quality and stability of the soft tissue-implant interface is most likely of paramount importance for the preservation of marginal bone and for the long-term prognosis of oral implants. The aim of the present review was to screen existing data in the literature concerning the influence of transmucosal components' composition, type, design and disconnection on peri-implant tissues. RESULTS The influence of the type of implant system (one-piece or soft tissue level implants versus two-piece or bone level implants) has been poorly studied in humans, and data from animal studies are controversial; both concepts demonstrated comparable long-term stability of peri-implant tissues. The chemical composition of abutments has been mostly studied in animals, with the conclusion that only a few materials (namely titanium, aluminium and zirconium oxides) allow the proper formation of a soft tissue interface. However, there is a severe lack of information about the clinical impact of this parameter, as well as of surface contamination of abutments. Mobility of transmucosal components has been shown to increase marginal bone loss in animals, while the influence of abutment disconnection is more controversial. Only one clinical study suggests that a 'one abutment-one time' technique preserves marginal bone. Studies investigating the influence of platform switching suggest that using an abutment narrower than the implant's platform could have a positive effect on the fate of marginal bone. But those studies are extremely heterogenous and their results controversial. CONCLUSION There is still a severe lack of information about the clinical impact of implant type, of implant/abutment connection, and of abutment composition and stability on peri-implant bone remodelling.