Effectiveness of Chlorhexidine-Coating in Controlling Bacterial Quantity on Toothbrush Filaments

Date of Award

Spring 2006

Document Type


Degree Name

Master of Science (MS)


Dental Hygiene


Dental Hygiene

Committee Director

Gayle McCombs

Committee Member

Lynn Tolle

Committee Member

Wayne Hynes

Call Number for Print

Special Collections LD4331.D46 T87 2006


The purpose of this study was to determine if a significant difference exists in the effectiveness· of chlorhexidine-coated nylon brush filaments as compared to uncoated nylon filaments in reducing the quantity of bacteria. Methods: An IRB-approved, two-group, double-blind, randomized, post-test only design was conducted. Sixty-four individuals were randomly assigned to two equal groups of 32. After using the control or experimental toothbrushes for 30-days, participants returned the toothbrushes to the researchers in sealed autoclave bags. In the laboratory, microorganisms were detached from the toothbrush filaments by sonification and vortexing, then plated on both selective and non-selective media at various dilutions (10-1, 10-2 , 10-3, 10-4 and 10-5). The inoculated plates were incubated aerobically for 24 hours at 37° C. After incubation, bacterial colony-forming units (CFU) were determined for each sample, from two different media, one selective (Mitis Salivarius) and the other not (TSA Sheep Blood). Data were analyzed using Wilcoxon and Kruskal-Wallis tests. Results: After the thirtyday trial period, 59 toothbrushes were returned; experimental group (n=31) and control group (n=28). Data reported includes only results from the l 0-3 dilution. Data from blood agar (19 control and 23 experimental) resulted in a mean CFU for control of 5.41 x 105 compared to experimental mean CFU of6.28 x 105. Data from MS agar (13 control and 23 experimental) resulted in a mean CFU for control of 4.32 x 105 compared to experimental mean CFU of 4.20 x 105. Conclusion: Results revealed there was no statistically significant difference in the numbers of bacteria surviving on the toothbrush filaments between the groups after the 30-day trial period on both blood and MS agar; however, findings only reflect the number of aerobic bacterial colony-forming units. Data cannot be generalized to include anaerobes or other fastidious bacteria, which may react differently in the presence of the antimicrobial agent. Results are only generalizable to similar populations.


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