The Rest Cells in Periodontal Regeneration - a Review

The major goal of periodontal therapy is periodontal regeneration including regeneration of alveolar bone, cementum and periodontal ligament fibres. Recapitulation of embryology shows the importance of Hertwig's epithelial root sheath (HERS), involved in cementogenesis and root formation. The remnants of these cells are found in normal periodontal ligament as the epithelial cell rests of Malassez (ERM). The cells of ERM are known to retain the functions of HERS by expression of various proteins and growth factors. These cells have stem cell characters and known to express stem cell related genes and thus lead to the hypothesis that they can contribute to true periodontal regeneration. This article reviews about the embryology and morphology of ERM. It intends to describe the functional roles of ERM not only in maintaining the periodontal ligament homeostasis but also in contributing to periodontal regeneration.