Microscopic qualitative evaluation of fixation time and decalcification media in rat maxillary periodontium

The rat model is widely used in periodontal research and the quality of histological sections is essential. The purpose of this study was to evaluate the histological characteristics of periodontal tissues in Wistar rat maxillae, with different times of fixation and decalcified by nitric acid or formic acid (Anna Morse Solution). Fifteen rats were used. Fixation was performed for 24, 48 and 72 hours. The maxillae were hemi-sectioned and each part was decalcified either in nitric acid for 7 days or in Anna Morse solution for 35 days. Two trained and blinded examiners performed the evaluation. Fourty eight hours of fixation and decalcification with Anna Morse solution showed more clear characteristics of the epithelium-connective tissue interface and of the periodontal structures. Mean measurements between the cementum-enamel junction and the bone crest varied in the different experimental times from 176.5 (± 60.45) to 210.94 (± 39.33) pixels on the buccal aspect, and from 199.69 (± 38.33) to 298.55 (± 70.81) pixels on the palatal aspect, with no statistically significant differences (ANOVA, p > 0.05). In the same fixation period, decalcification with nitric acid or Anna Morse solution did not display any statistically significant differences. It may be concluded that for a qualitative histological analysis, fixation should preferably be for 48 hours and the demineralization should be made by Anna Morse solution. For a histomorphometric analysis, the decalcification solution does not interfere in the results.

O modelo rato é extensamente usado na pesquisa periodontal, e a qualidade dos cortes histológicos é essencial. A proposta deste estudo foi avaliar as características histológicas dos tecidos periodontais nas maxilas de ratos Wistar, após diferentes períodos de fixação e descalcificação pelo ácido nítrico ou pelo ácido fórmico (Solução de Anna Morse). Quinze ratos foram usados. A fixação foi realizada nos períodos de 24, 48 e 72 horas. As maxilas foram divididas e parte foi descalcificada em ácido nítrico durante 7 dias e parte com solução de Anna Morse por 35 dias. Dois examinadores treinados e cegos executaram a avaliação. Quarenta e oito horas de fixação e descalcificação com solução de Anna Morse mostraram características mais evidentes da interface epitélio-conjuntivo, assim como das estruturas periodontais. As médias, por vestibular, entre a junção cemento-esmalte e a crista óssea nos diferentes tempos experimentais variaram entre 176,5 (± 60,45) e 210,94 (± 39,33) "pixels", e, na face palatina, entre 199,69 (± 38,33) e 298,55 (± 70,81) "pixels", sem nenhuma diferença estatisticamente significativa (ANOVA, p > 0,05). No mesmo período de fixação, a descalcificação com ácido nítrico ou solução de Anna Morse não mostrou diferenças estatisticamente significantes. Pode-se concluir que, para a análise histológica qualitativa, a fixação deve ser preferivelmente em 48 horas e a desmineralização por solução de Anna Morse. Para a análise histo-morfométrica, a solução descalcificadora não interferiu nos resultados.

Ultrastructural study of the periodontal ligament of dog's deciduous teeth after repeated injections by cadmium chloride

The effect of cadmium administration on the histogenesis of the periodontal ligament [PL] of dog deciduous teeth were studied by light and electron microscopic technique. Ten pregnant female dogs were divided into two groups, 5 animals for each. In group I, the dogs were injected with 0.5 mL of physiological saline and used as control. In the group II, the dogs were injected with cadmium chloride [l0mg/kg body weight] at three times intervals weekly. The periodontal ligament of deciduous anterior teeth of new born, at one month old age, were examined. According to our observations, the cadmium has harmful degenerative effect on periodontal ligament. Followed by regenerative response. The process was divided into two main stages. .1- During the first stage, prominent degenerative events took place in the periodontal ligament fibres. However, the blood vessels and nerves remained intact and were not affected. Phagocytosis and removal of necrotic material were well advanced and followed by marked regeneration of collagen fibres of periodontal ligament. 2- During the second stage, two populations of regenerating collagen fibres, based on the predominant cell type present, were observed in the tissue. One of apparently normal fibres located in areas where blood vessels and nerves were abundant and not affected. The other population of groups of regenerative fibres showing fibrotic tissue and collagen. This second type of fibres was predominant in areas where the number of blood vessels was greatly reduced and affected

Histometric study of periodontal trauma in dental germs to be transplanted - scanning electron microscopy

Dental transplants are of great interest in modern dentistry. Research has been directed toward the study of different techniques and observations of the results. Scientific basis is also to be observed and the aim of this paper is to associate technical with scientific data. Dental germs in different stages of development were carefully removed from their alveolar cavities together with the dental sac. Trauma was observed in some areas resulting from the movements of extraction or of the removal of the dental sac by dissection. It should be noticed that by the trauma produced by removal of the dental sac is very uncommon, since the operation is performed at a mesoscopic level. The material showed that the periodontal collagen net is complex in form and the meshes are wider in the surface. Smaller meshes could be seen closer to the cementum surface. Measures could be taken in order to have a basis of the distribution of collagen material around the dental root in different levels. The results showed that extraction should be performed in a most conservative manner and the movements for extraction should be applied to the crown of the dental germ. The maintenance of the periodontal integrity is very important in order to preserve the vascular barrier created by the dental cementum