Effects of composition, finishing, and salivary pH on physicomechanical and biological properties of additively manufactured resin-ceramic composites: An in vitro study.

Objectives To evaluate the effects of composition and finishing on the physicomechanical and biological properties of additively manufactured resin-ceramic composites (AM RCs) for definitive restorations under simulated oral environments with different pH levels. Methods Disk- and bar-shaped specimens were fabricated with 4 AM RCs (Crowntec [CT], Freeprint Crown [FP], VarseoSmile TriniQ [TQ], and VarseoSmile Crown plus [CP]). The specimens underwent either polishing or glazing and were immersed in artificial saliva at neutral and acidic pH levels (37°C, 7 days). Each saliva-conditioned specimen was evaluated for microhardness (HV), flexural strength (FS), protein adsorption (OD), water sorption (WS), and bacterial adhesion (BA). Cell morphology and migration were evaluated. A 3-way aligned rank transform analysis of variance was performed for HV, FS, OD, WS, and BA, followed by Bonferroni-adjusted Mann-Whitney U tests (α=0.05). Results CT showed the highest HV (P<0.001). CT had the highest FS, whereas CP had the lowest (P<0.05). Glazed AM RCs showed lower OD than polished AM RCs in acidic saliva (P<0.001). For WS, FP was the highest in neutral saliva, while TQ was the highest in acidic saliva (P<0.05). BA was significantly affected by salivary pH (P<0.001). Conclusion CT showed superior physicomechanical properties. In acidic saliva, all AM RCs showed lower OD after glazing, whereas BA increased regardless of composition or finishing. Clinical Significances Material composition affects the physicomechanical behavior of AM RCs, while salivary pH influences their biological responses. Under acidic salivary conditions, surface glazing may be beneficial, although it does not effectively reduce bacterial adhesion.