Surface and microstructural properties of denture base materials: Effects of manufacturing techniques, surface...

Understanding denture base material properties under aging conditions is crucial for assessing their clinical performance and impact on oral health. This study evaluated the behaviour of polymethylmethacrylate (PMMA), dimethacrylate-based polymers (DMA), and polyetheretherketone (PEEK) denture base materials after aging (thermal, mechanical, chemical), based on parameters (surface, mechanical, sorptive, structural) and considering manufacturing techniques (auto-curing, milling, 3D printing).

Disc-shaped specimens (2 mm × 8 mm, n = 10 per group; total n = 500) were manufactured from five denture base materials: PMMA (auto-curing, milling), DMA (3D printing: 90°/45° orientation), PEEK (milling). Standardized rough or fine surfaces were applied. Specimens underwent separate aging protocols: thermocycling, toothbrush abrasion, storage in HCl/NaOCl. Surface and material properties were analyzed prior and after aging. Data were evaluated using non-parametric tests (Kruskal-Wallis, Mann-Whitney U, α = 0.05). Effect sizes were calculated.

Compared to other materials, PEEK showed few significant changes in surface parameters, microhardness, and indentation after aging. All materials exhibited strong effect sizes for water absorption and solubility (r ≥ 0.85∗∗∗). In PMMA, aging significantly reduced surface and mechanical properties, especially in rough-treated specimens. DMA printed with 90° was less affected by aging than with 45°, particularly after fine treatment. Milled PMMA with fine treatment showed the highest aging resistance among PMMA variants. Generally, rough surfaces were more susceptible to aging than fine surfaces.

Aging resistance of denture base materials depends on surface treatment, material, and manufacturing technique. Adequate polishing reduces aging effects on surface and mechanical properties. Milling yields reliable results, while 3D printing requires further optimization.