Aim: To determine the differences of morphological and morphometric characteristic of periodontal ligament in young and adult rats at 14 days of Tooth Movement (OTM).
Materials and methods: All procedures were performed in Bioterium of Faculty of Pharmaceutical Sciences.. U. de Chile. Standardized orthodontic appliances were installed in right hemimaxilar in 2 groups of 7 rats, of 16 and 46 weeks of age. Eeuthanasia by intracardiac perfusion at 14 days. 7um cuts were stained with H & E and TRAP immunohistochemical stain. 40x microphotographs (Micrometrics SE Premium) were analyzed, in bone: the lacunae resoprtion number, osteoclasts, osteocytes, osteoplast, growth lines and Sharpey's fibers insertion. In Periodontal ligament (PL): hyaline zones, fibroblast-like cells and collagen organization. In the tooth surface: cementoblasts, odontoclasts, resorption areas in cement and Sharpey's fibers insertion. Differences between groups were analyzed by Wilcoxon test and chi square.
Results: In adults, in bone, at strain areas, osteoplast number was significantly higher, on pressure side the number of osteocytes was significantly lower (p = 0.03), fewer Sharpey fibers inserted and desorganized, less osteoclasts and osteoblasts than in young rats. In PL, the number of fibroblasts was significantly lower (p = 0.001) on both sides, there were more hyaline zones and disordered fibers, mainly in pressure side. On tooth surface, there were significantly less odontoclasts on both sides (p = 0.0004 pressure, tension, p = 0.023), and Sharpey fibers were fail inserted in cement at stressed pressure side.
Conclusion: Adult rats after 14 days of OTM showed significant differences compared to younger rats, with higher number of empty bone lacunae, more hyaline zones, disordered collagen fibers, fibroblasts and less odontoclasts.