Accuracy of digital implant impressions with intraoral scanners. A systematic review

Aim: The use of intraoral scanners (IOS) for making digital implant impressions is increasing. However, there is a lack of evidence on the accuracy of IOS compared with conventional techniques. Therefore, the aim of this systematic review was to collect evidence on the accuracy of digital implant impression techniques, as well as to identify the main factors influencing the accuracy outcomes. Materials and methods: Two reviewers searched electronic databases in November, 2016. Controlled vocabulary, free-text terms, and defined inclusion and exclusion criteria were used. Publications in English language evaluating the accuracy outcomes of digital implant impressions were identified. Pooled data were analysed qualitatively and pertinent data extracted. Results: In total, 16 studies fulfilled the inclusion criteria: one in vivo and 15 in vitro studies. The clinical study concluded that angular and distance errors were too large to be acceptable clinically. Less accurate findings were reported by several in vitro studies as well. However, all in vitro studies investigating the accuracy of newer generation IOS indicated equal or even better results compared with the conventional techniques. Data related to the influence of distance and angulation between implants, depth of placement, type of scanner, scanning strategy, characteristics of scanbody and reference scanner, operator experience, etc were analysed and summarised. Linear deviations (means) of IOS used in in vitro studies ranged from 6 to 337 µm. Recent studies indicated small angle deviations (0.07-0.3°) with digital impressions. Some studies reported that digital implant impression accuracy was influenced by implant angulation, distance between the implants, implant placement depth and operator experience. Conclusions: According to the results of this systematic review and based on mainly in vitro studies, digital implant impressions offer a valid alternative to conventional impressions for single- and multi-unit implant-supported restorations. Further in vivo studies are needed to substantiate the use of currently available IOS, identify factors potentially affecting accuracy and define clinical indications for specific type of IOS. Data on Data on accuracy OF digital records, as well as accuracy of printed or milled models for implant-supported restorations, are of high relevance and are still lacking. Keywords: accuracy, CAD/CAM, dental implant, digital, impression, intraoral scanner, systematic review Conflict-of-interest and funding statement: The authors state there is no conflict of interest.