Background: Given their intraoral service for clinically relevant periods, it is important to clarify whether additive manufacturing parameters influence the surface characteristics of 3D-printed provisional restorations and thereby affect microbial colonization. Methods: This study evaluated the effects of printing orientation and layer thickness on surface roughness, wettability, and Streptococcus mutans biofilm formation of LCD-printed provisional restorations. Disk-shaped specimens were fabricated from a methacrylate-based provisional resin at two orientations (0° and 90°) and two layer thicknesses (50 and 100 µm) (n = 7 per group). Surface roughness (Ra) was measured by contact profilometry, wettability by sessile-drop contact angle analysis, and biofilm formation by crystal violet staining after 72 h. Results: Data were analyzed by two-way ANOVA, aligned rank transform (ART) ANOVA, and correlation analysis (α = 0.05). Orientation alone did not affect Ra (p = 0.992), whereas layer thickness (p = 0.012) and the orientation × layer thickness interaction (p = 0.002, η² = 0.339) were significant. At 50 µm, 90° oriented specimens showed higher Ra than 0° (p = 0.021); this pattern reversed at 100 µm (p = 0.020). Neither parameter significantly affected contact angle or biofilm formation (p > 0.05). Conclusions: Both printing orientation and layer thickness altered the surface microtopography of the specimens; however, no significant differences were observed in short-term S. mutans biofilm formation among the tested groups. Within the limitations of the present single-species 72 h in vitro model, the findings suggest that material-related characteristics may have contributed more prominently to the observed biofilm behavior than the printing-induced surface differences evaluated in this study.

Objective: The objective of this study is to investigate the flexural strength and modulus of elasticity values of temporary fixed prosthetic materials produced with different orientation angles (0°, 45°, 90°).Methods: In this study, bar-shaped specimens (25 mm × 2 mm × 2 mm) with 0°-45°-90° orientation angles were prepared by 3D printing using a temporary restoration resin (Ackuretta Qura Crown Temporary Crown Photopolymer Resin), totaling thirty-nine specimens (n=13). The specimens underwent a twenty-four-hour storage period in distilled water at 37°C, after which their flexural strength and their modulus of elasticity values were measured and subsequently compared.Results: The flexural strength and modulus of the elasticity values of the temporary fixed prostheses produced with different orientation angles (0°, 45°, 90°) exhibited no statistically significant difference (P>.05).Conclusion: The different production angles did not affect the flexural and modulus of the elasticity values of the test specimens produced by the 3D printing. According to the ISO 10477 standards, the flexural strength values meet the criteria (fifty MPa value).Keywords: Temporary fixed prosthesis,flexural strength, elastic modulus, 3D printing