Determination of accuracy of multi implant impressions: A journey through time

Abstract

Introduction: Passive fit is one of the major concerns in implant dentistry as it contributes to the long-term success of the implant treatment. Accurate implant impressions are important for the achievement of passive fit of an implant prosthesis. There is inconclusive evidence on the techniques and types of materials used for making multi-unit implant impressions .In the present article the various parameters affecting the accuracy of implant impression along with impression material and technique are reviewed. Objective: To evaluate the scientific data related to different aspects of multi-unit implant impression accuracy and draw useful conclusions from the review for application in clinical practice. Materials and Methods: Studies from 1990 to 2017 were evaluated. Papers examining implant impression accuracy for two or more implants were selected for review. Case reports, technique articles, and incomplete studies were excluded. Fifty-nine studies were selected for evaluation, three among them clinical and the rest in vitro. Results: Fifteen studies compared polyvinyl siloxane (PVS) and polyether (PE) 11 found no differences between the two materials in terms of impression accuracy. Thirty studies analyzed the splint effect 13 found splinting better and 13 others elicited no differences between splinting and non-splinting. Among the 25 studies examining pickup and transfer impression techniques, 12 favored pickup over transfer and 11 found no differences between the two. Twelve studies assessed effects of various angles of implants and found significant differences in accuracy for 20 to 25degree angle and no differences for 5 to 15-degree angle for most studies, except two. Conclusion: PVS and PE were the preferred impression materials for multi-unit implant impressions. The evidence on splinting was inconclusive and the data supporting splint to non-splint were neutral. Pickup was the better performing technique than transfer, especially with increased num