Flexural Strength, Fatigue Behavior, and Microhardness of Three-Dimensional (3D)-Printed Resin Material for Indirect Restorations: A Systematic Review

The purpose of this systematic review was to evaluate three mechanical properties of 3D-printed resins for indirect restorations according to published scientific evidence. This systematic review was conducted according to the PRISMA statement (preferred reporting elements for systematic reviews and meta-analyses). The search was performed by two investigators, (DD) and (VB), and a third (AC) resolved disagreements. Articles were searched in four digital databases: PubMed, EBSCO, Lilacs, and Science Direct, starting on 18 February 2024. As 3D-printing technology has shown significant advances in the last 5 years, the review was conducted with a publication year range between 2019 and 2024, in English language and included in vitro articles on the mechanical properties of flexural strength, fatigue behavior, and microhardness of 3D-printed materials for temporary or definitive restorations. MeSH terms and free terms were used for the titles and abstracts of each article. Finally, the QUIN tool was used to assess the risk of bias. In the main search, 227 articles were found, of which 20 duplicates were excluded, leaving 207 articles; of these, titles and abstracts were read, and 181 that did not meet the eligibility criteria were eliminated; of the remaining 26 articles, 1 article was eliminated for not presenting quantitative results. Regarding publication bias, 6 of the 25 articles had a low risk of bias, 18 had a medium risk of bias, and 1 had a high risk of bias. It may be concluded that 3D-printed resins have lower flexural strength, fatigue behavior, and microhardness than other resin types used for the fabrication of temporary and permanent restorations. The type of 3D printer and polymerization time could be factors that significantly affect the flexural strength, fatigue behavior and microhardness of 3D-printed resins. Based on existing evidence, it should be considered that additive technology has promising future prospects for temporary and permanent dental restorations.