Influence of Platform Switching, Abutment Design and Connection Protocols on the Stability of Peri-Implant Tissues. A Systematic Review.

PURPOSE To appraise the effect of abutment factors namely platform switching, design and connection protocols on the stability of peri-implant tissues. MATERIALS AND METHODS An electronic and hand search were conducted. Randomized control trials and controlled prospective studies of at least one-year follow-up, published in the last 12 years, were included. RESULTS Initial electronic database search generated 3054 studies, while individual journal and hand searching resulted in 232 articles. Sixty-three publications were selected for full text analysis based on inclusion and exclusion criteria. Nineteen articles investigated platform switching. Fourteen studies reported positive influence of platform switching while five studies did not find a significant difference in bone loss compared to platform matched abutments. Two articles reported on concave abutments and found no advantage over conventional abutments. Seven studies investigated "one-abutment-one-time protocol", two found comparable results to multiple abutment disconnections while five studies suggested better soft and hard tissue maintenance. The risk of bias was unclear or high in most studies. CONCLUSION Platform switched abutments may reduce crestal bone loss during the first year. There is insufficient evidence to suggest better clinical outcomes of concave abutment. There is insufficient evidence to indicate the superiority of 'one abutment-one-time protocol'.