Evaluation of biofilm formation, adhesive strength and effectiveness of cleaning protocols on adhesive-containing acrylic resin specimens: An in vitro study.

Background: Denture adhesives promote greater stability and retention of dentures. However, they can also facilitate biofilm formation related to oral diseases.

Objectives: The study aimed to evaluate the influence of 2 adhesives on the microbial load of mixed biofilm and adhesive strength. Additionally, the objective was to assess the effect of 3 hygiene protocols on the microbial load and cell metabolism of this biofilm.

Material and methods: The study compared Corega Ultra Cream (CCA) and OlivaFix® Gold (OFA) adhesives by evaluating the biofilm formation of Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans by colony-forming unit (CFU), as well as adhesive strength. The implemented hygiene protocols included brushing and immersion in water (BW), 0.15% triclosan (BT0.15%), or 0.25% sodium hypochlorite (BSH0.25%). The control groups were either without adhesive (CG) or without any hygiene protocols (CGwH). The one-way and two-way analyses of variance (ANOVAs) with Tukey's post hoc test and a generalized linear model with Bonferroni adjustment were used for statistical analysis (α = 0.05).

Results: The microbial load of C. albicans was higher when OFA was used (p < 0.001). The microbial loads of C. glabrata and S. mutans were similar between adhesives and higher in the CG (p < 0.001). The influence of the adhesives on the microbial load of S. aureus was not statistically significant (p = 0.287). The adhesive strength promoted by OFA was greater and more stable than when CCA was used (p = 0.007). The immersion in sodium hypochlorite led to a reduction in the microbial load of C. albicans (p < 0.001), C. glabrata (p = 0.002) and S. mutans (p = 0.012), independent of the adhesive. For S. aureus, the microbial load was lower with OFA/BSH0.25% (p = 0.022). All hygiene protocols resulted in a decreased cell metabolism when compared to the CGwH (p < 0.001).

Conclusions: Brushing with BSH0.25% solution was the most effective hygiene protocol, resulting in a reduction in the microbial load and metabolism. This protocol may be recommended as a first-line option for the disinfection of dentures.