A Prospective Cohort Study Assessing the Impact of Fixed Orthodontic Appliances on Saliva Properties and Oral Microbial Flora

Purpose: Orthodontic treatment may introduce a risk to the integrity of enamel due to plaque accumulation and colonisation by oral microbes. This prospective cohort study observed the effect of fixed, self-ligating orthodontic appliances on saliva properties and oral microbial flora. Materials and Methods: Thirty adolescent patients were recruited (13 female, 17 male, mean age 13.97 +/- 2.07 years). Saliva samples were collected before placement of fixed orthodontic appliances (TO), and 4 (T1) and 12 (T2) weeks later. Salivary pH, flow rate and buffering capacity were recorded. All saliva samples were cultured on agar plates for 2 days. Salivary prevalence of Neisseria spp., streptococci, Staphylococcus aureus, coagulase-negative staphylococci and Candida albicans were assessed. Results: High buffering capacity was reported in 21 patients at TO, 22 patients at T1 and in 28 patients at T2. Saliva flow rate also increased over time (7.08 ml/5 min at TO, 7.93 ml/5 min at T1 and 8.35 ml/5min at T2). Mean pH was 7.63 at TO, 7.67 at T1 and 7.78 at T2. There was no evidence that either pH or the number of colonies of any of the microbial species changed over time. Conclusion: The increased buffering capacity of saliva as well as the salivary flow rate after initial bonding might be protective against the development of dental caries. Current microbial findings indicate that initiation of orthodontic treatment may not be associated with significant changes in oral microbial flora.