Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface

Abstract The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP) and relined fiberglass posts (RP) in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10): Group 1 - CP + RelyX ARC; Group 2 - CP + RelyX U200; Group 3 - RP + RelyX ARC; and Group 4 - RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal) of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey's test (α = 0.05). The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001). The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

Estudo eletrofisiológico das propriedades neuronais intrínsicas passivas de CAI em fatias hipocampais de ratos e tecido humano / Electrophysiological study of the intrinsic passive properties neurons of the CAI in slices hippocampal rats and hippocampal human tissue

O presente estudo tem como objetivo verificar a utilização de ratos como controle experimentais para estudos In vitro com tecido hipocampal humano. As fatias obtidas de hipocampo de ratos Wistar machos (espessura de 400 um) e amostras de tecido hipocampal humano (espessura 500um) removidos durante o procedimento cirúrgico para o tratamento de epilepsia de lobo temporal refratária ao tratamento medicamentoso. As fatias mantidas imersas numa cuba com solução de Ringer em temperatura ambiente continuamente oxigenadas e posteriormente transferidas para uma cãmara de interface para registro eletrofisiológico. Registros intracelulares foram obtidos a partir dos neurônios piramidais de CA1 de ratos controles (CR), epilépticos no modelo da pilocarpina (ER) e tecido hipocampal humanos (HHT). Foram avaliadas as propriedades passivas (potencial de membrana, resistência de entrada, constante de tempo) antes e depois da perfusão com o Ringer O-Mg2+. A análise entre CR (n: 40) e ER (n:22) não demonstrou diferenças significativas nas propriedades estudadas. Entre CR e HHT (n:30) não foram observadas diferenças significativas nas propriedades intrínsecas passivas. A análise entre ET e HHT não revelou diferença no potencial de membrana e resistência de entrada, porém a constante de tempo antes da perfusão com o Ringer O-Mg2+ apresentou diferença. Nossos achados sugerem que neurônios hipocampais de CAI de ratos são válidos como grupo controle para estudos experimentais com tecido hipocampal humano