Efficacy Analysis of Denture Cleansing Chemicals on Microbial Flora – An<i> in vitro </i>Study

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The cleansing chemicals were handed over to the person who prepared the solutions. The solution was coded as solution ‘A’, ‘B’ and ‘C’ so that the operator and the microbiologist would not know which cleansing chemicals the bottle contained. The contents of the different groups of bottles were recorded in a register by the person who had bottled the solutions, and this person otherwise didn’t participate in the study to avoid potential bias.

2 grams of denture cleansing tablets `A’ were weighed in a digital electric balance and suspended in 200ml of distilled water in a sterilized bottle and the bottle was labeled as solution ‘A’. Similarly done for 2grams of tablets `B’ and powder `C’.

2.7. Microbiological Procedures
2.7.1. Asepsis

Throughout the study, an effort was made to work aseptically; a standard barrier technique was used with sterile latex gloves, facemask and head cap. All laboratory procedures including plating of agar plates were carried out in a laminar air flow cabinet hood.

2.7.2. Microbiological Evaluation of Antibacterial Activity against Staphylococcus aureus

The test group commenced by placing 20 samples of sterilized acrylic resin blocks into the Brain Heart Infusion (BHI) broth inoculated with Staphylococcus aureus standard strain. Sterilized pointed forceps was used to introduce acrylic blocks into the bottle containing inoculated (BHI) broth and incubated at 37⁰C aerobically for 18 to 24 hours. After incubation, 5 samples of acrylic blocks were transferred from BHI broth to 5 different test tubes containing solution ‘A’ aseptically. 5 samples of acrylic blocks to 5 different test tubes containing solution ‘B’. Likewise 5 samples to 5 different test tubes containing solution ‘C’. All the test tubes containing cleansing solution with test samples were kept in the test tube rack inside the laminar air flow cabinet hood for 7 hours.

All the test samples present in solution ‘A’, ‘B’ and ‘C’, after 7 hours immersion in the cleansing solution were individually used to make the primary inoculums onto the agar plate. Then an inoculating wire was used to streak rest of the plate and incubated at 37⁰C for 18 to 24 hours aseptically for the growth of the bacteria.

Remaining 5 samples present in the BHI broth which would serve as the control were directly used to make the primary inoculums onto the BHI agar plate.

Staphylococcus aureus colonies were counted from BHI agar plates once the desired incubation period was achieved, samples treated with cleansing solution ‘A’, ‘B’, and ‘C’ as well as untreated samples for (control) samples using colony counter unit.

2.7.3. Microbiological Evaluation of the Denture Cleansers for Antifungal Activity against Candida albicans

In case of Candida albicans, 20 samples of sterilized acrylic blocks were immersed into the Brain Heart Infusion Broth inoculated with Candida albicans of standard strain which were incubated at 37⁰C for 24 to 48 hours in an incubator. After incubation, 5 samples of acrylic blocks were transferred to 5 different test tubes containing solution ‘A’. Similarly 5 samples each were immersed in test tubes containing solution ‘B’ and solution ‘C’. After completion of 7 hours immersion, all the test samples were retrieved from the test tube and individually used to make the primary inoculums onto the Sabouraud dextrose agar plate. An inoculating wire was used to streak rest of the plate and incubated at 37°C for 24 to 48 hours in the incubators to see the growth of the fungus.

Remaining 5 samples present in the BHI broth which will serve as control were directly used to make the primary inoculums into the Sabouraud dextrose agar plate and streaked with the help inoculating wire to the rest of the plate and incubated at 37°C aerobically for 24 to 48 hours in an incubator.

The fungal colonies were counted both in treated acrylic blocks with cleansing solution and untreated acrylic blocks using colony counter unit once the desired incubation period was achieved.

3. Results

The present study was conducted to evaluate the effectiveness of three commercially available denture cleansing chemicals in reducing cultured microorganisms Candida albicans and Staphylococcus aureus known to cause frequent infections among denture wearers.

The denture cleansers used in this study were commercially available chemicals with different chemical compositions. All the denture cleansers used in this study were alkaline peroxide based denture cleansing chemicals but each cleanser to be studied contained different amount of sodium perborate in them.

All the readings so obtained from both the groups were tabulated and statistically analyzed (1 to 4)

All the analysis was done using SPSS version 14. Mean cfu/ml at baseline and post treatment with various cleansing solution for Staphylococcus aureus and Candida albicans groups were compared using Wilcoxon signed ranks test. Multiple comparisons within the Staphylococcus aureus and Candida albicans groups at post treatment were compared using ANOVA followed by Post hoc Tukey’s HSD test. The cut-off level for statistical significance was taken at p ₌<0.05.

Table 1. Representing cfu/ml of Staphylococcus aureus on BHIA

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Table 2. Representing cfu/ml of Candida Albicans on SDA

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Table 3. Wilcoxon Signed Ranks Test: Non Parametric Test

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Table 4. ANOVA Followed by Post Hoc Tukey Test

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