One-time Abutment Placement Versus 4 Times Abutment Removal Around Dental Implants

Introduction: the repeated connection and disconnection of healing abutments during dental implants´ osseointegration has been associated with significant increased peri-implant bone loss, when compared with placing the final prosthetic abutment during implant placement surgery and non-removing it ever again. Previous data from animal studies suggests that the higher the number of removals of the healing abutments, the greater the bone resorption around implants, however the evidence in humans is scarce and heterogeneous. Furthermore, this greater bone resorption has been claimed to be associated to the inflammatory status of the peri-implant soft tissues, which would be greater as a consequence of the repeated disruption of the soft-tissues attachment to the prosthetic abutment, and the hypothetical microbial contamination of the implant-abutment interphase, induced by the repeated manipulation of the prosthetic components. Objective: to evaluate the changes in peri-implant crestal bone levels between two prosthetic protocols, the control being the conventional protocol where healing abutments are placed during surgery and removed four times before the delivery of the final abutment and prostheses, and the test protocol where definitive abutments are placed immediately after implant placement and are not removed ever again. Material and methods: 80 platform switched implants will be placed in the posterior maxilla or mandible of 40 partial edentulous patients. Immediately after implant placement, patients will be randomized to receive the definitive abutment at the moment of implant placement (one abutment-one time protocol), or 12 weeks later, after removing the healing abutment four times during the confection of the final prostheses, following the conventional protocol for implant supported restorations. The day of prostheses delivery, a mucosal biopsy from the implant surrounding tissues will be taken for histomorphometric and immunohistochemical analyses of