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EN
Amelogenesis imperfecta (AI) is an inherited tooth disorder with widely varying phenotypes. The aim of this study was to determine the microhardness and microstructure characteristics of the enamel in AI teeth. The AI phenotypes examined were hypoplastic (pitted and smooth form), hypomaturated, and hypocalcified. Six AI patients were diagnosed according to clinical characteristics. The microhardness of the enamel was measured on axial cuts of AI teeth acquired from the patients. The measurements were done on several sites from the enamel surface towards the dentine-enamel junction using the Vickers scale. Values of microhardness were compared to corresponding control teeth. The microstructure of AI enamel types was evaluated using scanning electron microscopy. The values of microhardness in pitted hypoplastic AI samples were, on average, lower compared to the control enamel and dropped markedly towards the dentine-enamel junction. The smooth hypoplastic enamel was not only extremely thin but also much softer than control enamel. The values for hypomaturated AI fluctuated, but the palatal sites were markedly softer than in the control tooth. Hypocalcified enamel was the softest, with values resembling those of dentin. Microstructural changes varied from altered orientation of enamel prisms in pitted hypoplastic AI to lack of normal prismatic structure and severe porosity in hypocalcified AI. The present results suggest different microhardness profiles and microstructures in each phenotype. Variations among phenotypes are expected with larger case selection in this genetically heterogeneous disease.
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EN
Animal teeth are a common model in studies on dentin adhesive materials. The aim of this study was to compare microstructural parameters (density and diameter of dentinal tubules (DT), peritubular dentin (PTD) thickness, PTD and intertubular dentin (ITD) surface area) and chemical characteristics of canine, porcine, equine, and human root dentin. The middle layers of dentin were harvested just below a cemento-enamel junction from incisors and investigated by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). SEM evaluation of the specimens revealed, that porcine dentin shared most similarities with human dentin. When comparing the density of DTs, canine dentin was also found to be similar to human dentin. Elemental composition of the root dentin did not differ significantly in porcine, equine and human dentin, but in canine dentin higher magnesium value in PTD compared to ITD was found. It is known that microstructural and chemical characteristics affect the strength of the adhesive bonds created among restorative materials and dentin. According to the results of this study, porcine dentin seems to be the most appropriate model to study dental materials to be used in human restorative dentistry.
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