Trauma & Critical Care

Biography

Biography: Mai Badreldin Abdelaziz Helal

Abstract

Traumatic occlusion provides a trauma that distresses the whole tooth and its supporting tissues. Epithelial cell rests of Malassez (ERM) are odontogenic epithelial cells located throughout life within the periodontal ligament (PDL) matrix. Recent studies suggested that ERM may have their role not only in maintaining the normal width of the periodontium but also has a significant manner in periodontal regeneration and homeostasis. Aim of Study: The aim of the present study was to investigate the role of ERM in alleviating the deteriorating effect of traumatic occlusion on normal and denervated rat periodontium. Material and methods: Sixty, 7 month old male rats were used in this study. They were randomly and equally divided into five groups. Control, sham, denervated, traumatic occlusion and traumatic-denervation groups. In the latter group, the right inferior alveolar nerve (IAN) was exposed and transected before getting inside the mandibular canal through a 2.5 cm skin incision made along the posterior border of the mandible. Then, after one week recovery, the occlusal surface of the right maxillary first molar was unilaterally raised 1-2 mm with our innovative 7/8 nickel chrome stainless steel crown with free distal surface. Three rats, from each group, were euthanized at 1, 3, 6, and 9 weeks. Half of their right mandibular first molars specimens were dissected, processed for light microscope (LM) and the other half were processed for transmission electron microscope (TEM) using routine and pop-off techniques. Results: Histological observations after one and three weeks, revealed disorganization of PDL fibers of the mandibular first molars of all rats in the denervated and/or traumatic occlusion groups in contrast to those of the control and sham groups, which disclosed normal structured PDL with few clusters of ERM cells throughout the study periods. Remarkably, traumatic occlusion group depicted rise in ERM clusters that disclosed secretory apparatus by EM whereas denervation and traumatic-denervation groups illustrated reduction in size of ERM clusters and cells which revealed apoptotic and karyolitic cells with rarified cytoplasm. On the other hand, after six weeks both traumatic occlusion and traumatic-denervation groups illustrated reorganization of PDL in association with increase in ERM clusters whereas, denervation group revealed further decline in ERM cells numbers and features together with PDL hyalinization and signs of dentoalveolar ankylosis. Interestingly, healing signs were observed after nine weeks in all experimental groups that was marked by the existence of secretory ERM cells. Conclusions: ERM is not a vestigial functionless remnant but it is an active dynamic groups of cells that portray the condition of the periodontium. There are resting ERM in quiescent PDL, apoptotic ERM in traumatized and or denervated ERM and secretory ERM in recovering periodontium.