Dental plaque pH in predicting caries relapse after general anaesthesia – an exploratory study

Objectives: Numerous caries risk assessment tools have been proposed in the literature, with few validated in preschool children especially those receiving oral rehabilitation under general anaesthesia (GA). Past caries experience, the best predictor thus far, may not be a reliable indicator after effective clinical intervention. Hence, this longitudinal study was aimed to explore the potential role of plaque pH in predicting future caries incidence after GA among preschool children. Methods: Oral examination, plaque pH measurements and questionnaire survey were performed, among pre-schoolers indicated for GA, at baseline (n = 92), 6-month (6M; n = 83), 12-month (12M; n = 79) and 24-month (24M; n = 66) recall visits after GA. Multivariable logistic regression and receiver-operating characteristic analysis were performed to evaluate the predictive value of models with plaque pH and past caries experience. Results: Individuals with low resting plaque pH at 6M and 12M were shown to be at high risk of 1-year caries incidence at 12M [relative risk (RR) 1.41, 95% confidence interval (CI) 1.09–1.48] and 24M (RR 1.61, 95% CI 1.22–1.73) recall visit, respectively. Moreover, plaque pH demonstrated a statistically significant predictive value in the 12M and 24M models (12M/24M: 85%/77%) compared with past caries experience, which was not a significant predictor in both models (both P > 0.05). Conclusions: Plaque pH may be a promising prognostic and predictive marker for early identification of high-risk children undergoing oral rehabilitation under GA.