Biofilm management with oral probiotics in patients with fixed orthodontic appliances

Abstract

Introduction: The risk of biofilm formation in orthodontic patients is even higher than the general dental population due to the presence of microniches and increased surface area provided by orthodontic brackets and appliances. If left untreated, oral biofilm can cause white spot lesions, gingivitis and halitosis. Traditional mechanical and chemical methods of managing biofilm formation all have limitations, which warrants the search for novel ways of biofilm management. Probiotics have shown to be beneficial in the oral health of general dental patients. Therefore the aim of this study was to investigate the efficacy of the oral probiotic Streptococcus salivarius M18 in managing biofilm formation in patients wearing fixed orthodontic appliances and to assess its effects on the oral microbiome of these patients.

Methods: The study was designed as a prospective, randomised, triple-blind, two-arm parallel-group, placebo-controlled trial. Sixty-four patients undergoing fixed treatment consumed 2 lozenges daily of probiotic (n = 32) or placebo (n = 32). The outcome measures were plaque index (PI), gingival index (GI) and halitosis-causing volatile sulphur compound (VSC) levels. Oral microflora was analysed utilising next-generation sequencing of the bacterial 16S rRNA gene.

Results: No significant differences in PI and GI scores were found between probiotic group and placebo-control group (p > 0.05). The level of VSCs significantly decreased in both probiotic group (VSC reduction = -8.5%, p = 0.015) and placebo group (-6.5%, p = 0.039) after 1-month. However, after the 3-month follow-up, VSC levels of the placebo-control group returned to baseline levels whereas those of the probiotic group decreased further compared to baseline readings (-10.8%, p = 0.005). The next-generation sequencing showed that the oral ecology of both groups was similar and that there was a significant increase in the abundance of streptococci in both the probiotic and placebo group over time.

Conclusion: Oral probiotic S. salivarius M18 reduced the VSC levels in patients with fixed appliances but did not decrease their plaque or gingival indices. The influence of probiotic S. salivarius M18 on oral microflora seems to be minimal. A longer intervention and follow-up period are needed.