Accuracy of Intraoral Scanner Systems for Fabricating Inlay, Onlay, and Veneer Restorations: A Systematic Review and Meta-Analysis.

Purpose: To evaluate the accuracy of intraoral scanners (IOSs) for fabricating inlay, onlay, and veneer restorations.

Materials and methods: A literature search was completed in five databases: PubMed/Medline, Scopus, Embase, Web of Science, and Cochrane. A manual search was also conducted. Two methods have been used to assess the accuracy of IOSs for fabricating inlay, onlay, and veneer restorations: accuracy of the definitive virtual casts and the marginal and internal discrepancies of inlay, onlay, and veneer restorations fabricated by using IOSs. Included articles were classified into two groups: definitive virtual casts accuracy and restoration fit. Two investigators evaluated the studies independently by applying the Joanna Briggs Institute critical appraisal. A third examiner was consulted to resolve any lack of consensus.

Results: Thirty four articles were included: 17 analyzed the accuracy of definitive virtual casts and 17 assessed the marginal and internal discrepancies. Regarding the accuracy of definitive virtual casts, a trueness of 27.47 μm (p < 0.001) in the inlay subgroup and 64.15 μm (p < 0.001) in the onlay subgroup were found among the IOSs tested. For digitizing inlay preparations, a trueness of 12.29 μm (p < 0.001) in the Primescan, 69.34 μm (p < 0.001) in the Omnicam, 38.39 μm (p < 0.001) in the Trios 3, 52.96 μm (p < 0.001) in the Trios, and 28.90 μm (p < 0.001) in the CS3500 were found. A trueness of 53.00 μm (I² = 99%, p < 0.001) in the Omnicam. Also, a precision of 19.88 μm (p < 0.001) in the inlay subgroup and 19.69 μm (p < 0.001) in the onlay subgroup was obtained. Furthermore, a nonsignificant test result for subgroup differences (p = 0.06) in the marginal discrepancy between conventional and IOS methods was found with a significant heterogeneity (I² = 99%, p < 0.001). However, a significant test result for subgroup differences (p < 0.001) in the internal discrepancy values was found with a significant heterogeneity (I² = 72%, p < 0.001).

Conclusions: IOSs and restoration type influenced the accuracy of the definitive virtual casts. A Better trueness and worse precision was found on the definitive virtual cast of inlay restorations when compared with those of onlay restorations. The impression method used did not impact the marginal discrepancy of inlay and onlay restorations. However, a higher internal discrepancy was found in the inlay and onlay restorations fabricated by using conventional methods, but the discrepancy was not significant. Studies are needed to assess the accuracy of definitive virtual casts for fabricating veneer restorations captured by using IOSs and to measure the fit of the veneer restorations fabricated by using IOSs.

Clinical significance: Intraoral scanners provide a reliable method for fabricating inlay and onlay restorations. The accuracy of IOSs for fabricating veneer restorations remains uncertain.