Calcium, matrix polymers and plaque formation.

This study explores the relationship between calcium ions, matrix polymers and the formation of natural plaque on the children's teeth, using direct observation, scanning, transmission and freeze-etching electron microscopy techniques. Plaques were observed either in situ or after removal from enamel with a chelating agent, EDTA. Plaque was not disrupted by EDTA. Matrix polymers in outer plaque were less abundant than in deeper layers of specimens exposed to EDTA before embedding. The several cationic electron-histochemical reagents used generally disclosed more matrix than routine contrasting. The various polymers, other than discrete structures such as fimbriae, may derive from saliva and gingival fluid as well as bacteria. It is concluded that calcium ions are of importance in the early phase of bacterial attachment to the host organic enamel integument, but that calcium plays no part in the formation or maintenance of the strong bonds that link organisms in established plaque.