Denture base materials: An in vitro evaluation of the mechanical and color properties

This study aimed to compare the physical and mechanical properties of four denture base materials: Polyan IC (PA), milled polymethylmethacrylate (PMMA), three-dimensional (3D)-printed resin (3DP), and SR Ivocap (SR).

Ninety-six samples were prepared and divided into four groups as follows. Group A consisted of 3DP (Asiga DentaBASE, Asiga) fabricated using a manufacturer-recommended 3D printer (Asiga Pro 4k, Asiga). Group B comprised milled PMMA (MP) (Ivotion Base, Ivoclar Vivadent). Group C included PA (BredentSenden), meanwhile, group D involved SR (Ivoclar VivadentSchaan). Cuboid samples (65 mm x 10 mm x 2.5 mm) were used for biaxial flexure strength testing in a universal testing machine (UTM). Cylindrical samples of 20 mm x 40 mm were used for compressive strength testing in a UTM. Additionally, cuboid samples (65 mm x 10 mm x 2.5 mm) were used for Vickers surface hardness testing in a microhardness tester. disk samples (10 mm x 2.5 mm) were employed for color stability testing both in a coffee solution and Coca-Cola, using a digital spectrophotometer. Statistical analyses were performed using one-way analysis of variance and Tukey's post hoc analysis (α=0.05).

MP demonstrated superior compressive strength (p = 0.002) and color stability compared to that exhibited by 3DP (p < 0.001) while displaying similar flexure strength (p = 0.336) and hardness (p = 0.708). MP and PA displayed similar compressive strength (p = 0.081), flexure strength (p = 0.159), and color stability in coke (p = 0.071). However, MP had reduced hardness (p < 0.001) and color stability in coffee (p < 0.001). Moreover, MP demonstrated a higher compressive strength (p < 0.001) than that displayed by SR. However, the flexure strength, hardness, and color stability were similar (p > 0.05). Furthermore, 3DP exhibited comparable compressive strength (p = 0.334) to that of PA but demonstrated significantly lower flexure strength (p = 0.005), hardness (p < 0.001), and color stability (p < 0.001) compared to PA. In comparison to SR, PA had a higher compressive strength (p < 0.001), hardness (p = 0.001), and color stability in coffee (p < 0.001), although they demonstrated similar (p > 0.05) flexure strength and color stability in coke.

The MP and PA demonstrated superior compressive strength than that exhibited by the other materials tested. The tested materials had similar flexure strengths, except for PA which demonstrated superiority over the 3DP. Among all tested materials, PA exhibited the highest hardness, while the 3DP was the least color-stable.

Considering the mechanical properties and color stability, Polyan and milled polymethylmethacrylate are preferred for complete denture fabrication. However, the limited repairability and complex handling of Polyan should be considered.