Immunohistochemical localization of epithelial rests of Malassez in human periodontal membrane

The aim of the present study was to describe the localization and extension of epithelial rests of Malassez (ERM) in the periodontal membrane (PDM) in normal human third molars. The material consisted of 24 normally developed human third molars surgically removed from patients with an age range from 15 to 27 years (six females and six males). The root lengths were developed from close to half-length to complete apex closure. The extracted teeth were fixed in 10 per cent neutral-buffered formalin, decalcified in ethylene diamine tetra acetic acid EDTA, paraffin embedded and cut sagittaly in 5 microm serial sections. Immunohistochemistry was performed using polyclonal rabbit anti-bovine cytokeratin (wide-spectrum screening, WSS) and the EnVision+ dual link system. The results were based on the visual comparison of WSS in the tissue sections using a light microscope. It was demonstrated that the ERM cells were distributed in the PDM in a network-shaped manner along the root surface and in the furcation region. The distribution of ERM was more prominent in teeth with incomplete root formation. The ectodermal tissue layer might influence not only the morphology of the tooth but also tooth eruption. The reaction of this epithelial layer in connection with ankylosis and orthodontic tooth movement may be of future interest.