An In vitro Comparative Evaluation of Disinfectants on Standard and Clinical Microbial Strains on Heat Cure Resins.

INTRODUCTION: Oral cavity is colonised by numerous micro-organisms that form a biofilm on the acrylic resin. Hence, routine hygiene is essential to prevent oral mucosal inflammation and lesions. Knowledge of appropriate disinfecting agents for acrylic resins is crucial in this context.

AIM: To compare and evaluate the effectiveness of four commercially available disinfectants on heat cure acrylic resin specimens contaminated with standard and clinical strains of two micro-organisms commonly inhabiting the oral microflora.

MATERIALS AND METHODS: Two hundred acrylic resin specimens (n=200), 10 in each group were contaminated in vitro with 1x10(6) cells/ml suspensions of standard and clinical strains of micro-organisms (Candida albicans and Streptococcus mutans) and were immersed in four disinfectants (1% sodium hypochlorite, 2% chlorhexidine digluconate, 2% glutaraldehyde and 3.8% sodium perborate) for 10 minutes. The control group was not subjected to any disinfection process. For collection of clinical strains, oral swab was passed over the buccal mucosa and grown on blood agar culture media. Organism confirmation was done by growing them on selective culture media. Final counts of micro-organisms per ml were performed by plating method for evaluation of microbial level reduction. Results obtained were subjected to ANOVA and Tukey's test.

RESULTS: Standard strains of Candida albicans (C) and Streptoccocus mutans (S) subjected to various disinfectants showed varied mean Colony Forming Units per ml (CFU/ml) from <10,000 to 25,000 and <10000 to <50,000 respectively. Clinical strains and of Candida albicans (C) and Streptococcus mutans (S) subjected to various disinfectants showed varied mean CFU/ml from <10,000 to 50,000 and from 10,000 to 50,000 respectively. Control groups showed maximum mean CFU/ml (>10(5)). All intergroup comparisons were highly significant (p<0.001; HS) and intragroup comparisons were significant (p<0.05; S) except the comparison of clinical strains of Streptococcusmutans subjected to 2% chlorhexidine digluconate and 2% glutaraldehyde which was found to be non significant (p>0.05; NS).

CONCLUSION: Almost 1% sodium hypochlorite was found to be the most effective disinfectant for both Candida albicans and Streptococcus mutans. The least effective disinfectant being: 3.8% sodium perborate.