Estudo estereológico comparativo entre os ameloblastos de secreção e de maturação em incisivos de ratos

Ameloblastos são células de origem epitelial, que apresentam funções de síntese, secreção e maturação do esmalte dental. Assim sendo, ameloblastos passam por mudanças morfológicas durante o seu curso de desenvolvimento. Desse modo, cinco ratos adultos Wistar foram utilizados para avaliar a morfologia de ameloblastos da fase secretora e em maturação, usando de métodos estereológicos em microscopia eletrônica de transmissão. Os dados foram analisados pela análise de variância a um critério (ANOVA). Os resultados mostraram que da fase de secreção para a de maturação da amelogênese: a) ocorreu uma redução de 23% no volume absoluto nuclear e o volume absoluto citoplasmático não mostrou diferença estatisticamente significante (p>;0.05); b) o volume total e a superfície total do retículo endoplasmático rugoso (RER) diminuíram 74% e 90%, respectivamente; c) o volume total e a superfície total das mitocôndrias aumentaram 742% e 384%, respectivamente; d) a relação superfície-volume do RER e das mitocôndrias diminuíram 59% e 42%, respectivamente; e) os pequenos grânulos de secreção, dispostos principalmente na área apical, desapareceram junto com o Processo de Tomes e apareceram os lisossomos e vacúolos digestivos principalmente na área supranuclear. Portanto, apesar de ocorrer uma significante adaptação morfológica durante a modulação da fase secretora para a de maturação do desenvolvimento do esmalte, o volume citoplasmático do ameloblasto permanece inalterado.The ameloblasts both in secretion phase and in smooth-ended ameloblasts in maturation phase were studied using stereologic methods in transmission electron microscopy (TEM). From secretion to maturation phase of amelogenesis, the nucleus volume decreased 23% and cytoplasm volume did not show significant changes; the total volume and surface of the rough endoplasmic reticulum (RER) decreased 74% and 90%, respectively, and of the mitochondria increased 742% and 384%, respectively; the surface-to-volume ratio for RER and mitochondria decrease 59% and 42%, respectively; and the predominantly apical secretory granules disappeared joined at Tomes process and lysosomes and phagic vacuoles have appeared principly in supranuclear cytoplasm. Although significant morphologic variation occurs from the secretory to the maturation phase of the ameloblasts, their cytoplasm volume remains unaltered

Ultrastructural and immunohistochemical study of the influence of fluoride excess on the development of rat incisor tooth buds

Little information is available on the pathogenesis of fluorosis during the fetal and initial postnatal period. In the present study, female rats received 0 (control), 7 or 100 ppm of sodium fluoride in drinking water, one week before breeding and throughout gestation and nursing periods. The hemimandibles of the offspring were collected at 0, 7 and 14 days of postnatal life (n = 5) and processed for morphological analyses by light and electron microscopy, immunohistochemical analysis for amelogenin and morphometric study of enamel matrix and ameloblasts of incisors. The results showed a decrease in matrix production at the secretory phase at all study periods for the 100 ppm group. In this same group, the secretory ameloblasts showed reduction of enamel matrix secretion, disorganization of mitochondrial crests, large vacuoles at the apical portion of the cytoplasm, retention of intracisternal material and dilatation of some cisterns in the rough endoplasmic reticulum. In the groups of animals aged 7 and 14 days, analysis of variance showed significant reduction (

Acinar autolysis and mucous extravasation in human sublingual glands: a microscopic postmortem study

Although some morphological investigations on aged human sublingual glands (HSG) found eventual phenomena identified as autolysis and mucous extravasation, the exact meaning of these findings has not been elucidated.Objective The aim of this work is to investigate whether acinar autolysis and mucous extravasation are related to the aging process in human sublingual glands. We also speculate if autolytic changes may assist forensic pathologists in determining time of death.Material and Methods 186 cadavers’ glands were allocated to age groups: I (0–30 years); II (31–60), and III (61–90). Time and mode of death were also recorded. Acinar autolysis and mucous extravasation were classified as present or absent. Ultrastructural analysis was performed using transmission electron microscopy (TEM). Data were compared using Mann-Whitney U, Spearman’s correlation coefficient, Kruskal-Wallis, and Dunn tests (

Healing of root perforations treated with Mineral Trioxide Aggregate (MTA) and Portland cement

Avaliou-se o reparo de perfurações em dentes de cães, tratadas com ProRoot MTA, MTA Angelus e cimento Portland branco. As perfurações foram feitas na região de furca de premolares, superiores e inferiores, com broca STP 58 sob refrigeração com soro fisiólogico. Os animais foram mortos após 90 dias e os dentes foram preparados para análise microscópica pela coloração da hematoxilina e eosina. Os três materiais propiciaram o selamento da perfuração com tecido mineralizado e o teste de Kruskal-Wallis demostrou não haver diferença estatística entre eles.Fourteen root perforations were performed for microscopic evaluation of the repair of interradicular tissue in dogs' teeth. These perforations were accomplished at low-speed with a STP 58 bur at the cervical third of the mesial root toward the furcation under irrigation with saline solution, followed by immediate sealing with ProRoot MTA, MTA-Angelus and white Portland cement. The dogs were killed after 90 days, revealing good results. The Kruskal-Wallis test did not demonstrate any statistically significant difference. It was concluded that the three materials showed good sealing in mineralized tissue, with complete closure, and they were free of inflammation in most teeth

Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate

To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Twenty-four mice (Rattus norvegicus) received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Histologic observation showed no statistically significant difference of biocompatibility (p>0.05) among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s), followed by clinker with 2% calcium sulfate (9.22 s/25.33 s), clinker with 5% calcium sulfate (10.06 s/42.46 s) and MTA (15.01 s/42.46 s). All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinke

Alloxan-Induced Diabetes Triggers the Development of Periodontal Disease in Rats

BACKGROUND: Periodontal disease in diabetic patients presents higher severity and prevalence; and increased severity of ligature-induced periodontal disease has been verified in diabetic rats. However, in absence of aggressive stimuli such as ligatures, the influence of diabetes on rat periodontal tissues is incompletely explored. The aim of this study was to evaluate the establishment and progression of periodontal diseases in rats only with diabetes induction. METHODOLOGY/PRINCIPAL FINDINGS: Diabetes was induced in Wistar rats (n = 25) by intravenous administration of alloxan (42 mg/kg) and were analyzed at 1, 3, 6, 9 and 12 months after diabetes induction. The hemimandibles were removed and submitted to radiographical and histopathological procedures. A significant reduction was observed in height of bone crest in diabetic animals at 3, 6, 9 and 12 months, which was associated with increased numbers of osteoclasts and inflammatory cells. The histopathological analyses of diabetic rats also showed a reduction in density of collagen fibers, fibroblasts and blood vessels. Severe caries were also detected in the diabetic group. CONCLUSIONS/SIGNIFICANCE: The results demonstrate that diabetes induction triggers, or even co-induces the onset of alterations which are typical of periodontal diseases even in the absence of aggressive factors such as ligatures. Therefore, diabetes induction renders a previously resistant host into a susceptible phenotype, and hence diabetes can be considered a very important risk factor to the development of periodontal disease

Papillary cystadenoma of the minor salivary gland of the lower lip

A case report of the papillary cystadenoma from minor salivary gland in lower lip of a 54-year-old man is described