Effects of postcuring times on the trueness of 3D-printed dental inlays made with permanent resins

ObjectiveThe aim of this study was to evaluate the trueness of 3D-printed dental inlays fabricated using different permanent dental resins and subjected to distinct postcuring times. Materials and methodsA total of 180 inlay specimens were fabricated and divided into nine groups of 20 specimens each. The inlays were first designed using 3D design software (Ansys SpaceClaim) and then transferred to a 3D printer. Using LCD technology, 60 inlays were fabricated from Senertek P-CrownV3 Ceramic (Senertek) resin, another 60 inlays from VarseoSmile Crown Plus (Bego) resin and the final 60 inlays from Saremco Print Crowntec (Crowntec) resin. Each of these three groups was divided into three equally sized subgroups (n = 20) cured with 2,000, 4,000 and 6,000 flashes, respectively, using the Otoflash G171 device (NK Optik, Germany). Then, the specimens were scanned and digitised using an intraoral digital scanner, and their trueness was evaluated by superimposing the digital measurements on the reference design and calculating their root mean squares (RMSs) and total overlap ratios (TORs). MANOVA was used to compare the measurements, and Tukey's test was utilised for the post hoc analysis. ResultsSignificant differences in trueness were observed among the inlays fabricated with different resin types (p < 0.001). The Crowntec resin had the lowest RMS (0.08 +/- 0.018 mm) and the highest TOR (94.59 +/- 2.49%), indicating the best trueness, while Senertek had the highest RMS (0.114 +/- 0.017 mm) and the lowest TOR (80.15 +/- 5.95%), reflecting the lowest trueness. The postcuring time also significantly affected the trueness of the inlays. The 6,000-flashes group had the lowest RMS (0.095 +/- 0.02 mm), and the 4000-flashes group had the highest TOR (89.81 +/- 0.5%). The interaction between the resin type and the postcuring time was significant for the TOR (p = 0.01), suggesting that trueness improvements are material dependent. ConclusionBoth the resin type and the postcuring time significantly influenced the trueness of the 3D-printed dental inlay restorations. The Crowntec resin consistently exhibited superior trueness, and the Senertek resin demonstrated the lowest trueness. The optimal postcuring time varied by material, but 4,000 flashes generally provided favourable trueness outcomes. These findings highlight the importance of selecting an appropriate resin and optimising the postcuring parameters to enhance the trueness of dental inlays, potentially improving their clinical fit and longevity. Clinical relevanceAppropriate resin selection and adherence to optimised postcuring protocols are essential for achieving clinically true 3D-printed restorations, ultimately improving their adaptations in dental applications.