Comparative evaluation of mechanical properties between dual-layer and bonded three-dimensional printed denture base materials: An in vitro study

AIM: The study aimed to compare the flexural strength, fracture toughness, and impact strength of the denture base materials fabricated using dual-layer and bonded 3D printing techniques. SETTINGS AND DESIGN: In vitro comparative study. MATERIALS AND METHODS: Seventy-two bar-shaped samples were fabricated using a digital light processing 3D printer and were divided into 2 groups (n = 36 each). Group I samples were fabricated by dual-layer technique, with the denture base and tooth-colored resins were printed sequentially in a single print cycle. Group II samples were printed separately and bonded with denture base resin. Flexural strength and fracture toughness were tested according to ISO 20795-1:2013, and impact strength was evaluated using ASTM D-256.Statistical Analysis Used: Statistical analysis comprised Shapiro-Wilk for normality, t-test for flexural strength, and Mann-Whitney U-test for fracture toughness and impact strength (α = 0.05). RESULTS: Group I exhibited significantly higher flexural strength (82.78 ± 2.02 MPa) and fracture toughness (89.91 ± 0.53 MPa) compared to Group II (80.01 ± 2.69 MPa and 86.93 ± 2.29 MPa, respectively). Conversely, impact strength was greater in Group II (4.17 ± 0.39 J) than in Group I (3.00 ± 1.04 J) (P < .05). CONCLUSION: The dual-layer printing technique improved the flexural and fracture resistance of denture base materials by eliminating interfacial weaknesses. Although bonded resins exhibited higher impact strength, the structural advantages of dual-printing support its application in clinical prosthodontics.