OBJECTIVETo analyze the relationship between inorganic ingredients (Ca, P and F) concentration of plaque residues in the primary teeth and caries status, sugar exposure frequency.

METHODSSubjects were 93 of 3-5 years old children living in Beijing area. According to their caries status, they were classified into two groups: Severe early childhood caries(S-ECC) group and caries free(CF) group. Plaque samples were collected from subjects respectively. Ca, P and F concentration of plaque residues was measured by atomic absorption spectroscopy, spectrophotometer and fluoride electrode respectively. The information of daily sugar exposure frequency of children was obtained from a standardized questionnaire filled by their parents. The relationship between inorganic ingredients (Ca, P and F) concentration of plaque residues and daily sugar exposure frequency was analyzed and the relationship between inorganic ingredients (Ca, P and F) concentration of plaque residues and caries status in the S-ECC group was also analyzed.

RESULTSThe mean values for Ca, P and F concentration of plaque residues were lower in the S-ECC group, but the difference was not statistically significant (P > 0.05). The daily sugar exposure frequency in the S-ECC group was higher than that in the CF group. There were no relationships between Ca, P and F concentration of plaque residues and caries status (dmft, dmfs), sugar exposure frequency in the primary dentition.

CONCLUSIONPlaque residues from CF subjects did not contain a greater pool of calcium, inorganic phosphorus, and fluoride ions than that from S-ECC subjects.