Plaque-pH and Tooth Surface Status in High Caries Risk Schoolchildren

Objective: The relationship between plaque-pH and tooth surface status in a group of Sardinian high caries risk schoolchildren was assessed in an in vivo study. Methods: Plaque-pH was measured, using the microtouch technique, in 157 schoolchildren (74 M/83 F) aged 9-11 years. Measurements were carried out in the interproximal areas between the first and second deciduous molars on the left and right sides of the upper jaw. Three hundred and fourteen sites were examined and the caries status of the 628 interproximal surfaces was recorded as sound or decayed. Plaque-pH was assessed at six different time points: at baseline (0 min) and 2, 5, 10, 15 and 20 minutes after a one-minute mouthrinse with 10 mL of 10% sucrose. The area under the curve (AUC5.7 and AUC6.2) was recorded. Instrument reliability was measured assessing the intraclass correlation coefficient (ICC). Results: Statistical analyses revealed significant differences for AUC5.7 and AUC6.2 when assessed near one decayed surface compared to two decayed surfaces (p<0.01). The acidogenic potential of the interproximal plaque was gradually enhanced according to caries status, i.e. from two sound, one sound + one decayed and two decayed approximal surfaces. A high intraclass correlation between the values obtained in one and the same site was found (range 0.82-0.91). Conclusion: The present data suggests a correlation between plaque-pH and tooth surface status as well as a high reproducibility for the microtouch technique used.