Clinical and Microbiological Changes Following Multi-Strain Probiotic Mouthrinse Use in Dental Students with Halitosis: A Prospective Single-Arm Study

Background: Halitosis is a common oral health condition that negatively affects social interactions, psychological well-being, and professional confidence, particularly among dental students. Conventional antimicrobial mouthwashes, although effective, are associated with adverse effects and disruption of the oral microbiota. Probiotics have emerged as a promising alternative for modulating microbial communities and enhancing oral ecological balance. Quantitative real-time polymerase chain reaction (qPCR) enables detailed assessment of microbiological changes associated with halitosis. Aim: To assess the clinical and microbiological changes associated with a multi-strain probiotic mouthrinse containing Lactobacillus reuteri and Lactobacillus paracasei in dental students with halitosis using qPCR. Materials and Methods: This prospective single-arm study included dental students with clinically confirmed halitosis (organoleptic test [OLT] score ≥ 2). Participants used the probiotic mouthrinse three to four times daily for 14 days. Clinical parameters, including OLT, tongue-coating area (Ta), tongue-coating thickness (Tt), and total tongue-coating score (TCS), were assessed at baseline, day 7, and day 14. Stimulated whole saliva samples were collected at each time point and analyzed using qPCR to assess relative changes in Streptococcus mutans, Lactobacillus salivarius , and Porphyromonas gingivalis . Results: Thirty-four participants completed the study. Significant reductions were observed in OLT, Ta, Tt, and TCS over the 14-day period (p < 0.001). qPCR analysis demonstrated reduced abundance of S. mutans and L. salivarius , with a modest decrease in P. gingivalis . Improvements in OLT were significantly associated with changes in bacterial profiles, particularly S. mutans and P. gingivalis (p < 0.001). A strong positive correlation was consistently observed between TCS and OLT at all time points (p < 0.001). Conclusion: Within the limitations of this study, the probiotic mouthrinse was associated with improvements in clinical indicators of halitosis and favorable shifts in selected oral microbiota. These findings support further investigation through well-designed randomized controlled trials. An infographic on a 14-day probiotic mouthrinse study for halitosis outcomes in dental students.An infographic outlines a study on dental students with halitosis confirmed by organoleptic testing (OLT). The intervention involved using a multi-strain probiotic mouthrinse containing Lactobacillus reuteri and Lactobacillus paracasei, applied 3-4 times daily for 14 days. Outcomes assessed included clinical and microbiological changes. Clinical outcomes showed improvements in organoleptic and tongue coating scores. Microbiological outcomes, measured by qPCR, indicated changes in Ct values and a decrease in the relative abundance of specific bacteria, including Porphyromonas gingivalis, Streptococcus mutans and Lactobacillus salivarius. The study concluded that 14 days of using the probiotic mouthrinse led to significant clinical and microbiological changes in the oral microbiota.