The efficacy of different immersion times in chlorhexidine for reducing the Lactobacillus acidophilus contamination of the toothbrush

Background: Lactobacillus acidophilus is involved in plaque formation and progression of caries, and studies show that it can be transmitted through the toothbrush. Thus, decontamination the toothbrush is necessary for oral health. This study aimed to assess the efficacy of different immersion times in chlorhexidine (CHX) for reducing the L. acidophilus contamination of the toothbrush. Methods: This experimental study was conducted on 84 dental students. Primary saliva samples were obtained from the students, and the salivary count of L. acidophilus was measured. The students were assigned to four groups, and the groups were standardized in terms of primary salivary L. acidophilus count: (I) simple rinse of toothbrush with water, (II) simple rinse of toothbrush with CHX, (III) immersion of toothbrush in CHX for 10 minutes, and (IV) immersion of toothbrush in CHX for 24 hours after use. Saliva samples were collected again from the dental students after 3 weeks of practice. The mean L. acidophilus colony counts of primary and secondary saliva samples were calculated. Also, the mean L. acidophilus colony counts of toothbrushes were compared among the four groups. Data were analyzed using ANOVA and Tukey’s tests. The level of significance was set at 0.05. Results: The mean L. acidophilus colony count of toothbrushes was significantly different between the four groups (P<0.05). Groups 3 (P=0.040) and 4 (P=0.012) showed significantly lower toothbrush microbial count compared with Group 1. No significant difference was noted in the salivary colony count of the four groups after the intervention (P>0.05). Conclusion: Immersion of toothbrush in CHX for 24 hours and 10 minutes was more effective than other methods for the reduction of L. acidophilus count of the toothbrush. In order to prevent corrosion of bristles, 10 minutes of immersion is recommended.