Association between interdental plaque acidogenicity and caries risk at surface level: a cross sectional study in primary dentition

Background. In schoolchildren the most commonly decayed primary teeth are molars affecting proximal adjacent surfaces especially. Aim. To determine whether a more acidic plaque in response to sucrose challenge is detected in children with more carious lesions. Design. Plaque pH measurements, using the microtouch technique, were carried out in interproximal spaces between primary molars, in 157 high caries risk children (314 sites and caries status of the 628 proximal surfaces recorded). The area under the curve (AUC5.7 and AUC6.2) was analyzed. Results. The AUC5.7 and the AUC6.2 showed a statistically significant difference between plaque adjacent to proximal surfaces with or without caries. Differences for AUC5.7 and AUC6.2 were recorded between one decayed surface compared to two decayed surfaces (P < 0.01) whereas a statistical significant difference was only observed for AUC5.7, when the areas under the curve were obtained near one decayed surface compared to two sound surfaces (P = 0.04). Conclusions. The higher acidogenicity of the dental plaque found in presence of a proximal carious lesion in primary maxillary molars represents an additional risk factor for the adjacent surface. This finding may help clinicians in treatment decisions.