Evaluation of the methods for determining accuracy of fit and precision of RPD framework in Digital (3D printed, milled) and conventional RPDs - a systematic review

Background: The advent of digital technologies has introduced novel methods for RPD fabrication, potentially enhancing the fit compared to the conventional approaches. This systematic review aimed to evaluate the methods to assess the accuracy of fit and precision of the RPD framework fabricated using conventional and digital (3D printed and milled) methods.

Methods: A comprehensive literature search (Registration Number CRD42023459566) was conducted across different electronic databases like PubMed/MEDLINE, Embase, Scopus, Web of Science, and Google Scholar. Studies investigating RPD fit and precision assessment using various techniques (Visual inspection and pressing test using silicone impression material, 3D digital analyses using a software, light microscopy, digital microscope at 50x, superimposition method /surface matching software program, µCT on silicone specimens and direct measurements) in in-vitro studies were included. Data extraction and quality assessment were performed to evaluate the methodological rigour of the selected studies. A narrative synthesis of the findings was carried out to evaluate the methods to assess the accuracy of fit and precision of the RPD framework fabricated through conventional and digital methods due to heterogeneity in study variables.

Results: Out of 413 records, a total of 8 in-vitro studies were included in this review. The key findings of the review suggest that RPD fit accuracy varies across fabrication processes including conventional techniques, resin milling, selective laser melting (SLM), and digital superimposition. Resin milling with polyether ether ketone (PEEK) offers the best accuracy. Among the different methods used in assessing the fit accuracy of the RPD framework silicone-based fit evaluation and superimposition techniques/ surface matching are commonly used methods.

Conclusion: Both traditional (non-computerized) and computerized methods for the assessment of fit and precision of conventional and digital RPD frameworks are used commonly. But still, formulation of a standard method for fit assessment of RPDs is warranted. In future with further refinements, digital methods would completely outperform the traditional methods.