Tongue brushing and oral probiotics for the treatment of halitosis: a randomized controlled trial

Abstract To evaluate the effectiveness and sustainability of oral probiotics ( Streptococcus salivarius K12), tongue brushing, and their combination in reducing halitosis. The study was a prospective, randomized, placebo-controlled trial. A total of 80 participants were randomly allocated to four groups: control ( n = 20), oral probiotics ( n = 20), tongue brushing ( n = 20), and a combined group of tongue brushing and oral probiotics ( n = 20). Assessments were taken at three time points: at baseline; after a 4-week intervention; and at a 4-week intervention-free follow-up. The outcome measurements included volatile sulfur compound (VSC), self-reported halitosis, organoleptic score, and tongue coating index. After the 4-week intervention, VSC levels were significantly decreased in the oral probiotics, tongue brushing, and combined groups (all p < 0.05), with the greatest reduction observed in the combined group. At the 4-week intervention-free follow-up, the combined group VSC levels remained significantly lower than baseline, despite slight rebounds. Self-reported halitosis scores decreased after intervention and follow-up ( p < 0.05). Organoleptic scores improved only in the combined group post-intervention ( p < 0.01). Tongue coating scores decreased in both tongue brushing and combined groups, but not in the oral probiotics group. Both tongue brushing and oral probiotics were effective in reducing halitosis, with the combined intervention producing the most significant and sustained improvements.