An ultrastructural evaluation of the relationship between epithelial rests of Malassez and orthodontic root resorption and repair in man.

Contrary to previous reports, epithelial cell clusters with ultrastructural features similar to classically defined epithelial rests of Malassez were found, for the first time, in areas of repairing orthodontic root resorption. These observations were made on the buccal root surface of premolars extracted for orthodontic purposes from adolescent patients who had required rapid maxillary expansion. Ultrastructurally, the epithelial clusters ranged in size from 2-8 cells and were characterized by the presence of true desmosomes (macula adherens) and tonofilaments. Certain ultrastructural features of the epithelial cell clusters indicate that they may be involved in mediating repair cementogenesis subsequent to migration into the resorption bay.