Impact of citric acid and conventional denture cleansers on surface properties and antimicrobial performance of conventionally heat-processed acrylic resin: An in vitro study

Abstract

Statement of problem

Effective decontamination of denture base acrylic resin is essential for biofilm removal but can compromise the integrity of the material. Citric acid has shown promise as a potent antimicrobial agent, though its effectiveness as a denture cleanser is unknown.

Purpose

The purpose of this in vitro study was to evaluate the effect of citric acid on the surface properties and efficacy of biofilm removal on denture base acrylic resin compared with commonly used denture cleansers.

Material and methods

A total of 130 conventional, heat-processed denture base acrylic resin disks were randomly allocated into 1 of 5 groups based on the decontamination solution applied: control 0.9% sodium chloride (NaCl), 0.1% sodium hypochlorite (SH), Periogard (chlorhexidine digluconate), effervescent denture cleansing tablets (Corega Tabs), and 10% citric acid (CA). Surface properties (roughness, hydrophilicity, microhardness, and color stability) were assessed at 3 time points: baseline (T0), after 5 minutes of exposure (T1), and after 1 week of exposure (T2) to the respective solution. A microcosm biofilm was formed on specimen surfaces to evaluate antimicrobial efficacy of the decontamination solution groups, through assessment of microbial viability, metabolic activity, biofilm dry weight, and morphology. A 2-way repeated measures ANOVA was performed for surface properties evaluations and for microbiological analysis, 1-way ANOVA was used (α=.05).

Results

No significant differences in average surface roughness (Ra) were observed between T0, T1, and T2 across all groups (P>.05). CA significantly increased surface hydrophilicity at T2 (P<.001) compared with the other groups. No significant differences in ΔE₀₀ were seen among the groups: all values near the 50% perceptibility threshold. Compared with the control group, all denture cleansers significantly reduced the viability of total microorganisms and Candida species, with no viable colonies detected after treatment (P<.001). However, CA demonstrated a robust antimicrobial effect, with a significant reduction in biofilm dry weight and metabolic activity (P<.001), suggesting superior biofilm disruption compared with the other groups.

Conclusions

Citric acid effectively increased hydrophilicity of conventional, heat-processed acrylic resin without negatively impacting surface roughness, microhardness, or color stability.