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Published on: January 17, 2025
Effect of uniaxial bending methods on the flexural strength and Weibull analysis of heat-polymerized, CAD/CAM milled,
Abdulaziz Alhotan1, Hanan Al-Johani2, Ahmed Altarazi3
1Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
Objectives:
To compare the flexural strength and modulus of denture base resins manufactured by conventional methods, 3-dimensional (3D) printing, and computer-aided design and computer-aided manufacturing (CAD/CAM) milling using 3-point bending (3PB) and 4-point bending (4PB) methods after simulated aging.
Methods:
Ninety bars (64 ×10 ×3.3 mm) were prepared from heat-polymerized (Lucitone-199), CAD/CAM milled (G-CAM), and 3D-printed (Denturetec) denture base resins (n = 30 per material). After 10,000 thermal cycles, specimens were subjected to either 3-point bending (3PB) or 4-point bending (4PB) (n = 15 per method) to measure the flexural strength (σ3PB and σ4PB) and elastic modulus (E3PB and E4PB) using a universal testing machine. Weibull analysis was performed to evaluate the reliability (m) and characteristic strength (σ0) as a function of 3PB and 4PB. Fractographic analysis was conducted using scanning electron microscopy (SEM). Data were analysed using 2-way ANOVA followed by Tukey post hoc and Student t-tests (α=.05).
Results:
Significant effects of material type and uniaxial bending method on flexural strength and modulus were found (P < .001). Irrespective of the flexural strength measurement approach, CAD/CAM milled resins exhibited significantly higher flexural strength in both methods (σ3PB=125.6 ± 5.2 MPa, σ4PB=110.5 ± 4.5 MPa) and elastic modulus (E3PB=2400 ± 120 MPa and E4PB=2800 ± 150 MPa) compared to 3D-printed and heat-polymerized resins. Irrespective of the denture base resin manufacturing method, σ3PB was significantly higher than σ4PB whereas E4PB was significantly higher than E3PB (P < .001). Weibull analysis exhibited highest reliability for CAD/CAM resins (m=25.24 - 43.83). Considerable microscopic differences were detected.
Significance:
CAD/CAM milled denture base resins exhibited superior flexural properties compared with 3D-printed and heat-polymerized resins.
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