Scanning electron microscopy of unused and used manual toothbrushes

A scanning electron microscopic study of the brushing surface of 17 different types of commercial toothbrushes with natural and nylon bristles was conducted on new unused brushes as well as on 65 brushes used from 1 month up to 1 year, once, twice or three times a day, with various brushing techniques. Natural swine or wild boar toothbrushes, even when new, had filaments of irregular length and diameter with deficient and irregular ends. These defective surface conditions became worse with used. Unused soft and hard nylon toothbrushes were made of tufts with bristles of the same length and diameter with cut or rounded ends. The surface of the bristle ends was generally flat but various surface defects were observed. The contours of the bristle ends of both types of nylon toothbrushes improved with use, becoming smooth and rounded. Deteriorations of the brushing surfaces of both soft and hard nylon brushes were observed at time intervals varying from one subject to another, but hard nylon bristles wore best. Soft nylon brushes wore out more rapidly.