Mechanical performance of high-impact 3D-printed denture base resins subjected to thermomechanical aging

Studies on the mechanical performance of high-impact 3-dimensionally (3D)-printed denture base resins (DBRs) after thermomechanical aging are limited. This in vitro study assessed the flexural strength (FS), flexural modulus (FM), Vickers microhardness (VHN), and fractographic patterns of high-impact 3D-printed DBRs.

Four 3D-printed DBRs were evaluated in conventional (Tera Harz Denture Base [TH] and Denturetec [DT]) and high-impact (Freeprint Denture Impact [FI] and Printodent GR-14.2 Denture HI | MSI [PT]) formulations (n = 80). Standardized bar-shaped specimens were designed, fabricated, polished, and subjected to thermomechanical aging (10,000 loading cycles at 5 Hz; 10,000 thermocycles between 5 °C and 55 °C). FM and FS were determined using a 3-point bending test in a universal testing machine, and VHN values were measured using a microhardness tester. Fractographic analysis was performed using a scanning electron microscopy. Measurements were obtained at baseline and after thermomechanical aging. Data were analyzed using a generalized linear model and Bonferroni corrected post hoc tests (α = 0.05).

Resin type, aging condition, and their interaction significantly affected FS, FM, and VHN values (p < 0.001). DT and PT exhibited significantly higher FS values than TH and FI (p ≤ 0.007). The highest FM values were observed in DT materials (p ≤ 0.004), whereas the highest VHN values were found in PT (p < 0.001). Thermomechanical aging resulted in a significant decline in all outcomes (p ≤ 0.042). Distinct fractographic differences were identified among the DBRs.

All tested 3D-printed DBRs met ISO requirements for flexural strength and modulus after thermomechanical aging. However, the notable reductions in flexural and hardness outcomes among some materials suggest the importance of appropriate material selection based on clinical indication and regular monitoring during clinical service.