Comparison of Chlorhexidine Gluconate, Sodium Hypochlorite, Neem Extract, and Microwave Radiation for Disinfection of Type IV Dental Stone.

Abstract

Objective:  The present study evaluated the effect of chemical disinfectants and microwave sterilization on the removal of biofilm containing Pseudomonas aeruginosa, Streptococcus mutans, and Candida albicans from type IV dental stone.

Materials and methods:  One hundred twenty-eight (N = 128) type IV dental cast stone specimens were prepared, and biofilms of microorganisms were cultured. Dental stone samples were subjected to disinfection protocols, including 0.5% chlorhexidine (CHX), 0.5% sodium hypochlorite (NaOCl), 20% neem extract, and microwave irradiation for 1 to 5 minutes. Colony forming unit (CFU) counts and scanning electron microscopy were utilized to witness changes in the biofilm, pre- and postdisinfection/sterilization.

Results:  For P. aeruginosa, significant (p < 0.05) decrease in CFU counts after 1 minute (from 233 to -215) and 2, 3, and 5 minutes (from 233 to -233) were observed after CHX treatment. After microwave radiation, a significant decrease in CFU counts was also observed after 1 minute (from 233 to -130.3), 2 minutes (from 233 to -229), and 3 and 5 minutes (from 233 to -233). For S. mutans, a significant (p < 0.05) decrease in CFU counts was observed after 1, 2, 3, and 5 minutes (from 212 to -268) after NaOCl treatment and microwave radiation (from 212 to -271 after 1 minute and from 212 to -274.3 after 2, 3, and 5 minutes). For C. albicans, significant (p < 0.05) decrease in the CFU counts (1-5 minutes) was observed after CHX exposure, while NaOCl and microwave radiation demonstrated equal disinfection potency. Neem extract was effective to disinfect the dental stone; however, it was not as potent as the other disinfectants and microwave radiation.

Conclusion:  It was observed that exposure to CHX, NaOCl, and microwave radiation significantly reduced the microbial CFU counts. Although the use of neem extract also significantly reduced these CFU counts, this reduction was not as much as the other three tested materials. Further research exploring other chemical disinfectants with various concentrations is recommended.