Implant-prosthetic Rehabilitation with and without Platform Switching: A Retrospective Clinical Cohort Study

Abstract

The study aimed to retrospectively compare peri-implant bone loss, prosthetic complications, and patient-reported outcome measures (PROMs) after implant-prosthetic treatment on abutments with platform switch or platform match. Records of patients, who received implant-prosthetic treatment on abutments with/without platform switch in a single dental clinic between November 2015 and November 2018, were retrospectively analyzed. Analysis was restricted to the following patient selection criteria: no need for any bone grafting procedures before/during implant placement, and no serious systemic disease. Implants were conventionally loaded with screwed prosthetic restorations after a healing period of 3 months. Crestal bone loss was measured by digital radiography at implant placement and after at least 2 years under functional implant loading conditions. Patient satisfaction was recorded with the visual analogue scale (VAS) at the time of the follow-up examination. Clinical records of 59 patients were available for analysis. Patients of the study cohort received in total 128 implants with different lengths and diameters according to the manufacturer's specifications. Prosthetic restorations were fixed either on abutments with platform switch (BEGO PS-UNI: n = 74; 57.8%) or platform match (BEGO SUB-TEC Universal: n = 54; 42.2%). No implant was lost and no failure of prosthetic restoration was recorded during follow-up, except for prosthetic screw loosening in 32 implants (25.0%). Abutment type and location (maxilla vs mandible) had a significant impact on peri-implant bone loss (OR = 3.4; 2.8). A significant reduced rate of bone loss was observed at implant sites, provided with abutments according to the platform switch concept (35.1 vs 64.8%). No significant correlation was recorded between less bone loss and a higher patient satisfaction, while loosening of the prosthetic screw was significantly associated with lower satisfaction scores. BEGO PS-UNI abutments with a platform switch design revealed significant less crestal bone loss after a mean observation period of 20.8 months. Abutments with a platform switch design may lead to less peri-implant bone loss. In order to maintain a higher patient satisfaction, clinicians should focus on the quality of the implant-prosthetic connection in screwed restorations.