BackgroundThe inclusion of herbal antibacterial agents in the composition of toothpastes is becoming increasingly popular, due to lower side effects. The present study intended to investigate the antibacterial efficacy of a herbal toothpaste containing Bamboo salt on cariogenic oral bacteria.MethodsThe present double-blinded parallel randomized controlled clinical trial was conducted on 60 dental students (age range: 18–30). Following the baseline saliva sampling, the participants were randomly assigned into the case and control groups, to use the Bamboo salt herbal toothpaste and conventional non-herbal toothpaste, respectively. They were instructed to brush their teeth twice a day using the Bass technique. Saliva sampling was repeated after four weeks. The salivary counts of Streptococcus mutans and Lactobacillus at baseline and 4-week follow-up were determined and presented as the logarithm of colony-forming units per milliliter (log CFU/mL).ResultsA significant decrease in salivary Streptococcus mutans and Lactobacillus was observed using both toothpastes (*P < 0.001). The difference between the antibacterial efficacy of two toothpaste types on Streptococcus mutans and Lactobacillus was not statistically significant (P = 0.530, and P = 0.137, respectively).ConclusionDue to the comparable efficacy of the investigated herbal toothpaste with conventional toothpaste, it potentially qualifies as a complementary agent for self-care oral hygiene procedures.Trial registration: This trial was registered in the “Iranian Registry of Clinical Trials” (IRCT20210414050964N1) on 21/06/2021.