A number of micro-organisms are present in our mouth. Bacteria are commonest among them. Enzymes produced by these bacteria convert all foods-especially sugar and starch into acids.

Bacteria, acid, food debris, and saliva combine in the mouth to form a sticky substance called plaque that adheres to the teeth.

Plaque that is not removed from the teeth becomes a hard substance called tartar. Plaque and tartar irritate the gums. The acids in plaque can dissolve the enamel surface of the tooth and create holes in the tooth (cavities).