TY - JOUR ID - TI - The effect of orthodontic relapse on the proliferation of fibroblast and epithelial rests of Malassez in periodontal ligament of rat molars (A histopathological study) AU - Munad J. Al-Duliamy AU - Ghada M. Mustafa AU - Omar A. Kader PY - 2013 VL - 25 IS - 4 SP - 114 EP - 119 JO - Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد SN - 18171869 23115270 AB - Background: Relapse of previously moved teeth, is major clinical problem in orthodontics with respect to the goals ofsuccessful treatment. This study investigated the effect of orthodontic relapse on the proliferation of fibroblast andepithelial rests of Malassez cells in periodontal ligament of rat molars.Materials and Methods: Sixteen ten-week- old male Wister rats were randomly divided into four groups composed offour animals each: Group I received no orthodontic force (control). In both Group II and Group III, uniformstandardized expansive springs were used for moving the maxillary first molars buccally for periods of one and threeweeks respectively. The spring initially generated an average expansive force of 20 g on each side. In Group IV thesprings were left for three weeks, until the maxillary first molars moved buccally, after that the springs were removedand the animals were scarified after three weeks of relapse tooth movement. After the humanly scarification ofanimals, each maxilla in all groups was dissected into two halves each half including the three maxillary molars andprocessed for histological examination. The number of both fibroblast and ERM cells in each cluster was counted inthe PDL of the pressure side of the mesio-buccal roots of the maxillary right and left first molars in all groups and thesurface areas of the ERM clusters were also measured in all groups.Results: The number of fibroblast was significantly increased at the end of active movement (Group III) andsignificantly very highly increased during the relapse period (Group IV). Regarding the ERM cells there werestatistically significant increase in both the number of cells in each ERM cluster and the surface areas of the ERMclusters in Group III and highly significant increase in Group IV, while Group II showed no significant differencesregarding all measurements.Conclusions: It was concluded that fibroblast and ERM cells may play an important role during orthodontic relapse

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