J Prosthet Dent. 2026 Feb 27:S0022-3913(26)00097-1. doi: 10.1016/j.prosdent.2026.02.013. Online ahead of print.
ABSTRACT
STATEMENT OF PROBLEM: Additively manufactured (AM) polymethyl methacrylate (PMMA) crowns exhibit limited color stability, suboptimal surface texture, and insufficient strength. The development of effective reinforcement strategies is essential to overcome these shortcomings.
PURPOSE: The purpose of this in vitro study was to evaluate the effects of incorporating silica (SiO₂) and titanium dioxide (TiO₂) nanoparticles on the fabrication trueness and the optical, surface, and mechanical properties of AM PMMA crowns.
MATERIAL AND METHODS: Mandibular first molar AM PMMA crowns (N=80) were fabricated using 4 materials (n=20 per group): unmodified PMMA (control; FREEPRINT), PMMA with 1 wt% SiO₂ (S), PMMA with 2 wt% TiO₂ (T), and PMMA with a combination of 1 wt% SiO₂ and 2 wt% TiO₂ nanoparticles (ST). Fabrication trueness was evaluated as the root mean square (RMS) surface deviation of the marginal and intaglio surfaces (µm) and their total. Color stability (ΔE₀₀) was assessed using spectrophotometry, and surface roughness (Ra) was measured via noncontact optical profilometry. Wear was assessed by occlusal RMS (µm) after thermomechanical aging; fracture resistance was recorded as peak load to failure (N) on a universal testing machine. Statistical analyses were performed using 1-way ANOVA followed by Bonferroni-adjusted post hoc tests (α=.05).
RESULTS: Fabrication trueness differed among groups (marginal, intaglio, and total RMS; all P<.001), ranking ST<T<S<Control. ΔE00 differed (P=.004): T highest, ST lowest; Control, S, and T exceeded the 0.8 perceptibility threshold, and no group exceeded the 1.8 acceptability threshold. Ra differed (P=.001): Control highest; T higher than S and ST; S and ST not different. Wear differed (P<.001) with the hierarchy Control>S>T>ST; qualitative joint evaluation technique (JET) heatmaps showed the same pattern. Fracture load differed (P<.001): T and ST were higher than Control and S, with no significant difference between T and ST.
CONCLUSIONS: Incorporating SiO₂ and TiO₂ nanoparticles into PMMA formulations synergistically enhanced the overall performance of AM crowns.
PMID:41764005 | DOI:10.1016/j.prosdent.2026.02.013
