Methods: After approval by the local ethics committee, 20 participants undergoing fixed orthodontic treatment and 20 control counterparts were enrolled and had their whole saliva assessed for flow, pH and buffer capacity. According to a crossover layout, participants imbibed orange juice (15mL, pH 3,6) and water added of 5% sucrose (control beverage, 15mL, pH 6,0) in alternate arms. Participants spitted saliva-beverage mixture immediately after, every each 15s intervals up to 1min, then after every 30s up to 5min and finally after 6 and 7min. pH of such collected samples was measured with a calomel pH microprobe.
Results: No difference was found between salivary flow, pH and buffer capacity of participants wearing or not wearing orthodontic appliance as shown by Student’s t tests. Three-way ANOVA for repeated measures and Tukey’s test demonstrated that regardless of the time elapsed from the water imbibement, salivary pH was similar for both orthodontic appliance wearers and non-wearers. Among the latter, salivary pH was significantly reduced by the orange juice intake throughout 60s (remaining 30s under critical pH of hydroxyapatite), while in participants wearing orthodontic appliance pH was significantly lower up to 210s (remaining 60s below critical pH of hydroxyapatite).
Conclusions: Salivary pH recovery after acidic beverage intake is slow in fixed orthodontic patients, which may put them on higher risk of dental erosion.