Assessment of mechanical, physical, and antimicrobial properties of tissue conditioners incorporated with plant extracts

This study aimed to assess the antimicrobial effects of Mentha piperita, Thymus vulgaris, and Salvia officinalis extracts at varying concentrations (1%, 3%, 5%, and 10% by volume) against S. mutans and C. albicans, as well as to evaluate mechanical and physical properties, such as tensile bond strength, tear resistance, and surface roughness, after incorporating these extracts into acrylic-based tissue conditioners. The samples were prepared for the antimicrobial evaluation, comprising a negative control group (pure tissue conditioner), a positive control group (chlorhexidine digluconate and fluconazole), and test groups with plant extracts at different concentrations. The minimum inhibitory concentration (MIC) and agar disk diffusion methods were employed. Mechanical tests were conducted on samples containing the determined MIC. Antimicrobial test results were evaluated using Kruskal-Wallis and Mann-Whitney U tests, while mechanical properties were assessed by one-way ANOVA. A statistically significant difference in minimum inhibition zone diameters against S. mutans and C. albicans among the plant extracts at different concentrations was found (p < 0.001). However, no significant differences were observed between the groups in terms of tear resistance, tensile bond strength, and surface roughness (p = 0.198, p = 0.123, p = 0.094, respectively). 5% and 10% concentrations were found to be the most effective for positive control groups. 10% concentration of Thymus vulgaris demonstrated antimicrobial activity at a similar level to the 1% chlorhexidine digluconate for S. mutans. Additionally, incorporation of plant extracts at MIC level did not alter the tensile bond strength, tear resistance, or the surface roughness of the tissue conditioner.