Flexural strength of 3D printed posterior dental restorations: A Narrative review of the literature

The objective of this narrative review was to compare and analyze published articles on the mechanical properties of 3D printed fixed dental restorations compared to restorations fabricated with CAD/CAM and/or conventional milled composite and/or acrylic resins and to answer the following research question: Do 3D printed posterior restorations have increased flexural strength compared to restorations made of composite resin and/or acrylic resin? Articles were searched using the following electronic databases: PubMed, GOOGLE SCHOOLAR. This literature review was structured based on the guidelines given by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The PICO/PECO (Participant, Intervention/Exposure, Comparison, Outcome) focused question was: "Do restorations printed on 3D printers (I) for the posterior sector (P) have higher flexural strength (O) compared to restorations made of composite resin and/or acrylic resin (C)?". Of the two hundred and thirty-five titles, which were recognized after a primary search, fourteen articles were included in the analysis. The evidence available after performing this narrative review indicates that 3D-printed posterior fixed restorations have comparable mechanical behavior to CAD/CAM-engineered posterior fixed restorations in terms of flexural strength.