Avaliação estereologica ultraestrutural das densidades volumetricas dos fibroblastos e do colageno do ligamento periodontal do incisivo de rato em condições funcionais alteradas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The volume density of periodontal ligament structures was determined in rat lower incisors submitted to altered oclusal forces. Nine adult male rats had their left incisors sectioned at the level of the interdental papilla every second day, during 7 days. These teeth erupted unimpeded and thus were hypofunctional, while their contra lateral right incisors erupted impeded and are considered hyperfunctional. The lower incisors of three rats, used as controls, remained normofuncional. Ultrathin sections stained with uranyl acetated and lead citrate were photographed at the magnification of 5000x. Three electronmicrographs (final magnification 10.875x) of the tooth-related and alveolar bone-related compartments from 3 regions at the mesial face of the periodontal ligament were selected. Region 1 was the one close to the alveolar crest; regions 2 and 3 were at level of the 1 st lower 3rd lower molar respectively. By point-counting volumetry, using a square grid with 100 intersection points, the volume density of fibroblasts, their cytoplasmic processes and of collagen (fibrils plus interfibrilar substance) was determined. In tooth-related compartment there was no significant differences between the relative volume of fibroblasts, in each region, between the three functional conditions. In each condition, this volume was larger in the most apical region as compared to the two other more incisal regions. The volume density of collagen decreased in the incisal-apical direction and also there was no significant difference between functional conditions. However, under hypofunction, this decrease of collagen density was more marked, being the difference between the three regions statistically significant. The volumetric density relation between fibroblasts and collagen, when compared to the normal function, increased in the hiper and mainly in the hipofunctional conditions being significant the differences in regions 1 and 3 . Similar results, although not so regular, where found in the connective tissue of the alveolar bone-related compartiment. As for the fibroblast cytoplasmic processes their relative volume increased in the incisal-apical direction in normofunctional teeth while in the altered conditions their volume density was smaller and almost invariable in the three regions, being the differences in region 5 significant. No such differences were found in the alveolar bone-related compartment. The volumetric alterations observed, some of which were common to the hyper and hypofunctional conditions, could not be related to the increase in the rate of eruption which occurs only in the unimpeded teeth

ASSUNTO(S)

estereologia morfologia dentes deciduos - erupção dentes - tratamento ligamentos microscopia eletronica

ACESSO AO ARTIGO

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