BLIS M18 probiotic cleanser: effects on color and surface properties of conventional, milled, and 3D-printed PMMA

Polymethyl methacrylate (PMMA) denture base materials are routinely exposed to chemical cleansers during daily use, yet the material effects of unconventional agents, such as oral probiotics, remain unclear.

This study investigated the effects of experimental exposure to a BLIS M18 oral probiotic solution and conventional denture cleansers on the color stability and surface properties of conventionally processed, milled, and 3D-printed PMMA during simulated denture care for up to 90 days.

One hundred and twenty PMMA discs were fabricated using conventional processing, CAD/CAM milling, and 3D-printing, and were then immersed in distilled water, an effervescent tablet cleanser, 1% sodium hypochlorite, or BLIS M18 oral probiotic solution (experimental). Color change (ΔE₀₀), surface roughness, and Vickers hardness were measured at baseline (T0) and after 90 days (T3), with additional color and hardness measurements at 30 (T1) and 60 (T2) days. Surface morphology was examined using scanning electron microscopy. Data were analyzed using mixed repeated-measures ANOVA with Bonferroni post hoc tests (α = 0.05).

Manufacturing techniques significantly influenced baseline and post-exposure material properties, with 3D-printed PMMA exhibiting higher roughness and lower hardness than milled and conventionally processed materials (p < 0.001). Simulated denture cleansing increased surface roughness Ra, with post-exposure values ranging from 0.31 to 0.46 μm and reduced hardness (5.8-30.7%) over time, whereas cleanser-related effects were statistically significant but small. Color changes remained limited for all groups (0.50-1.73). Experimental exposure to BLIS M18 resulted in minimal changes in color, roughness and hardness compared with conventional cleansers.

PMMA surface integrity is primarily determined by the manufacturing technique rather than the cleanser chemistry. Under simulated denture care conditions, experimental exposure to BLIS M18 demonstrated compatibility with PMMA denture base materials without compromising surface properties or color stability.