Struys et al. Journal of Medical Case Reports 2010, 4:328 http://www.jmedicalcasereports.com/content/4/1/328 C A S E R E P O R T JOURNAL OF MEDICAL CASE REPORTS Open Access Proliferation of epithelial rests of Malassez following auto-transplantation of third molars: a case report Tom Struys1*, Joke Schuermans2, Livia Corpas3, Constantinus Politis2, Luc Vrielinck2, Serge Schepers2,4, Reinilde Jacobs3, Lambrichts Ivo1 Abstract Introduction: Auto-transplantation of third molars is frequently undertaken in order to restore a perfect occlusion and to improve mastication following a substantial loss of molars. However, little is known about the precise role of the periodontal membrane during this procedure. Therefore, we investigated if the epithelial rests of Malassez persist in the periodontal ligament of auto-transplanted teeth and, if so, whether these may show signs of a neuro- epithelial relationship. Case presentation: We report a case of a 21-year-old Caucasian woman who underwent an auto-transplantation of two third molars. After two years, renewed progressive caries of the auto-transplanted teeth led to the removal of the auto-transplanted elements. The periodontal ligament was removed and studied with a light and transmission electron microscope. Conclusion: In this report we examined the ultrastructure of the periodontal ligament after auto-transplantation in order to see if the periodontal ligament recovers completely from this intervention. We observed fully developed blood vessels and a re-innervation of the epithelial rests of Malassez which were proliferating following auto- transplantation. This proliferation might be critical in the remodelling of the alveolar socket in order to provide a perfect fit for the transplanted tooth. In order to minimalise the damage to the epithelial rests of Malassez, the extraction of the tooth should be as atraumatic as possible in order to provide an optimal conservation of the periodontal ligament which will be beneficial to the healing-process. Introduction The periodontal ligament (PDL) is the dense fibrous con- nective tissue which connects the cementum-covered surface of the root with the alveolar bone [1]. Its main function lies in preventing damage to the dental tissues during mastication. It consists, in part, of thick collagen bundles, called Sharpey’s fibers, that run from the alveo- lar wall into the cementum and are responsible for resist- ing the displacing masticatory forces. Other functions which are addressed to the cells in the PDL are the for- mation, maintenance and repair of the alveolar bone and cementum. It has already been described that the alveolar bone can adapt its shape according to the needs during * Correspondence: tom.struys@uhasselt.be 1Biomedical Research Institute, Hasselt University, Campus Diepenbeek, Diepenbeek, Belgium Full list of author information is available at the end of the article root development [2]. This is an important feature when looking at auto-transplantation where this process will be responsible for remodelling the new alveolar socket to the shape of the transplanted tooth. Furthermore, the periodontal ligament has rich sensory innervations [3] and a close relationship with the mechanoreceptors and the epithelial rests of Malassez (ERM) has been detected [4]. ERM are the remnants of the epithelial root sheath of Hertwig (ERSH), a fold of the outer and inner enamel epithelium formed during tooth development. Once root formation is completed, the ERSH becomes penetrated by several collagen bundles of the PDL, resulting in a fenestrated network that surrounds the tooth. The pre- cise function of the ERM is not known yet, but it is believed that they are involved in preventing root resorp- tion and maintaining the width of the periodontal liga- ment, thereby preventing ankylosis [5]. As it is reported © 2010 Struys et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.