Impact of oral probiotics on oral health and halitosis in orthodontic patients treated with aligners or conventional fixed appliances vs placebo: two randomized clinical trials.

BACKGROUND

Halitosis is primarily caused by oral microbiota dysbiosis, exacerbated by orthodontic appliances that promote plaque retention. Probiotics offer a potential non-invasive strategy to rebalance oral flora and reduce volatile sulfur compounds (VSCs), but their clinical effectiveness remains largely underexplored in Orthodontics.

OBJECTIVES

The aim of these trials was to determine the effect of oral probiotics containing Lactobacillus salivarius Oral S1 on plaque and gingival indices as well as on halitosis (via VSC) in patients treated with orthodontic brackets or aligners vs placebo.

METHODS

This study was ran as two separate parallel 2-arm trials (fixed appliance trial and aligner trial) in two centers. Each trial included 59 patients randomly allocated to either probiotics or placebo. The intervention was 1 month course of probiotics, compared with placebo. The primary outcome was the modified plaque index (PI-M) and the secondary outcomes were the gingival index (GI) and the VSC levels i.e. H2S, CH3SH, (CH3)2S and their sum (total VSC), all measured at baseline (T0), after 1 month of intervention (T1), and 2 months after discontinuation of the probiotics (T2).

RESULTS

In the aligner group, a significant treatment × time interaction was detected for H2S (P < .001) and total VSC (P < .001), indicating that the changes in these variables over time differed significantly between the treatment groups. In the fixed appliance group, a statistically significant treatment × time interaction was identified for PI-M (P = .01), GI (P < .001), H2S (P = .03), and total VSC (P = .03). Probiotic use was particularly effective in the latter group, with notable improvements in plaque control, gingival health, and halitosis reduction. Partial relapse occurred by T2, suggesting that benefits mostly diminish after intervention cessation.

CONCLUSIONS

Administration of oral probiotics for 1 month significantly improved periodontal health and reduced halitosis in orthodontic patients, especially in those with fixed appliances.