Abstract
Additive manufacturing has emerged as a disruptive technology in prosthodontics, facilitating the rapid and precise fabrication of complete and removable partial dentures. However, maintaining microbial control without compromising the physical-mechanical integrity of 3D-printed photopolymer resins remains a critical clinical challenge. This in vitro study evaluated the effects of various chemical disinfection protocols on the flexural strength, flexural modulus, and surface topography of a commercial 3D-printed denture base resin. Bar-shaped specimens (64 × 10 × 3.3 mm) were printed via digital light processing (DLP) and randomly allocated into four groups (n = 15 per group): control (distilled water immersion), 0.5% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX), and alkaline peroxide effervescent tablets. Disinfection was simulated daily over a simulated 180-day exposure period. Mechanical properties were assessed using a three-point bending test according to ISO 20795-1:2013 standards, whereas surface roughness (Ra) and surface topography were characterized using optical profilometry and scanning electron microscopy (SEM). One-way ANOVA and Tukey’s post-hoc tests (α = 0.05) revealed that 0.5% NaOCl induced a statistically significant reduction in flexural strength (81.42 ± 4.18 MPa) compared to the control (94.15 ± 3.82 MPa, p < 0.001), while concurrently increasing surface roughness beyond the clinically acceptable threshold of 0.2 μm (Ra = 0.24 ± 0.03 μm). In contrast, CHX and alkaline peroxide treatments caused minor, non-significant alterations in flexural performance, maintaining values well above the ISO minimum of 65 MPa. These findings demonstrate that chlorhexidine and alkaline peroxide represent safer hygiene protocols for 3D-printed denture bases than sodium hypochlorite.
