Effect of 8% arginine toothpaste on Streptococcus mutans in patients undergoing fixed orthodontic treatment: randomized controlled trial

OBJECTIVE: To assess the effect of toothpaste containing 8% arginine on Streptococcus mutans (S. mutans) in dental plaque around orthodontic brackets, and to draw a comparison with a regular fluoride toothpaste. TRIAL DESIGN: A single-center, parallel-arm, triple-blind, randomized controlled trial was conducted. METHODS: The clinical trial was conducted at the Orthodontic Clinic, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Seventy-two patients (age range: 15-30 years) who required fixed orthodontic treatment were recruited and randomly assigned to arginine and fluoride groups. Randomization was performed using RANDOM.ORG online software, and the participants were divided into two parallel groups, with a 1:1 allocation ratio. Patients were requested to brush their teeth twice daily for 30 days with an experimental toothpaste. Plaque sampling was performed at two intervals, namely at the beginning of the study (T(0)) and 30 days later (T(1)). Real-time PCR was used to assess plaque samples in terms of the number of S. mutans surrounding stainless steel brackets in orthodontic patients. A triple-blind design was employed. RESULTS: The baseline characteristics (age, sex, and the relative number of S. mutans) between the groups were similar (p>0.05). Only the arginine group showed a significant decrease in the relative number of bacteria between T(0) and T(1) (p=0.02). CONCLUSION: Arginine is an important prebiotic agent in maintaining healthy oral biofilms, and prevent dental caries during fixed orthodontic treatments. TRIAL REGISTRATION: The trial was registered at the Iranian Registry of Clinical Trials (IRCT20181121041713N2), https://en.irct.ir/user/trial/42409/view.