Role of Probiotics in Oral Health Maintenance Among Patients Undergoing Fixed Orthodontic Therapy: a Systematic Review of Randomized Controlled Clinical Trials

The aim was to assess the role of probiotics in oral health maintenance among patients undergoing fixed orthodontic therapy (OT). An unrestricted search of indexed databases was performed until April 2020 using the following Mesh-terms: (1) probiotic and (2) orthodontic. Randomized controlled clinical trials (RCTs) evaluating the influence of probiotic therapy (PT) towards oral health maintenance/improvement in patients undergoing fixed OT were included. Data screening, selection, and extraction were performed; and the risk of bias was assessed using the Cochrane Collaboration’s tool. All evaluations were performed by 2 independent researchers; and disagreements were resolved via discussion. Nine RCTs were included. Eight studies reported that PT improves oral health in patients undergoing fixed OT. Seven studies showed that PT reduces the counts of oral pathogenic bacteria in the oral biofilm and/or saliva. One study reported that PT reduces halitosis in patients undergoing fixed OT. One study found that PT reduces the scores of plaque index (PI) and gingival index (GI); and one study reported that PT has no significant influence on PI and GI in patients undergoing fixed OT. One study reported that PT does not prevent the formation of white spot lesions during fixed OT. Three and 6 studies had a moderate and low risk of bias, respectively. A power analysis was performed in 4 studies. In conclusion, probiotics exhibit antimicrobial activity against oral pathogenic bacteria; however, due to the limitations of the studies assessed, further well-designed RCTs are needed.