[Studies of the resistance of phosphate cements, silicate cements and autopolymer preparations to bacteria].
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Silicate cement was inserted in deep unlined cavities in 70 human teeth; 35 cavities were cleaned with an antibacterial cleanser, and the other 35 cavities in the contralateral teeth were treated with water spray only. In all teeth, invasion of bacteria from the tooth surface was prevented with a surface seal. Histologic examinations after 4 weeks revealed bacterial growth on dentinal walls in 9 of the uncleaned and in 2 cleaned cavities. Only in these 11 teeth was an inflammatory reaction seen in the pulp. Under eight cavities without bacterial growth and with silicate cement placed directly on an exposed pulp, no serious injury and no inflammatory reactions were observed. It was concluded that silicate cement per se does not seriously irritate the pulp. Infection of cavity walls should be avoided, not only by removing grinding debris and antibacterial cleansing, but also by use of a liner to prevent invasion of bacteria from the surface of the tooth.
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Six brands of silicate cements have been characterized by means of optical emission spectrography with respect to the contents of elements in minor or trace quantities in a search for presence of possible toxic elements. Beryllium was observed in two powders at levels of 1.3 and 1.6% Cadmium was found in two powders at levels of 0.02 and 0.03%. Lead was measured in three powders at levels of 0.001-0.003%. Bismuth, boron, copper, gallium, iron, manganese, titanium, tin and zirconium were found in various brands in either powder or liquid at levels of 0.001-0.1%. Upper limits of the amounts of the various elements that might be transferred to the gastrointestinal tract after dissolution of the cement matrix in the oral cavity have been calculated.
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The biologic compatibility of two composite materials (Cosmic, Epstic) based on Bowen's resin and two silicate cements (Frontasil, Silicap) and theirs components were assessed in cell culture. The compounds eluated from the material specimens under physiological conditions affected monolayer cultures of rat fibroblasts and rat epithelial cells (linr RL-19). Silicate cement eluate brings about death of cells due to high concentration of H-ions. Neutralized eluate of freshly prepared Cosmic, Estic and Frontasil caused the same cell damage which was less pronounced following Silicap eluate. The toxicity was markedly reduced following use of an eluate material which had a setting time of 24 hours. After the 2nd and 3rd elution of same specimen the cytoxicity was noticeably weakened, however, it was still demonstrable. The patterns of injury were different following composite material and silicate cement. All tested components soluted in Eagle medium have an irritating effect on the cultivated cells.
Recently, vital pulp treatment (VPT), including direct pulp capping, which preserves pulp vitality and extends the functional lifespan of teeth, has garnered significant attention. The purpose of this study was to evaluate the performance of calcium silicate cement, the gold standard for VPT, alongside hydraulic calcium silicate cement (Pro-MTA), a material with extensive evidence of effectiveness, Bis-GMA resin-modified calcium silicate cement (TH), and a newly developed material, methacrylate resin-modified calcium silicate cement (RM-MTA), in a model of pulpitis induced by caries progression. Additionally, the calcium ion (Ca2+) release capacity of these materials and their comprehensive effects on pulpal wound healing were assessed using RNA sequencing (RNA-seq). In both sound pulp models and caries-induced pulpitis models, RM-MTA and Pro-MTA exhibited similar performances. Unlike TH, they induced significant tertiary dentin formation within the dental pulp beneath the material, without any residual inflammatory cells. Inflammation was specifically assessed with a focus on M1/M2 macrophages. While the timing of Ca2+ ion release differed among the materials, the total amount released was comparable, although the release of calcium ions (Ca2+) from TH was significantly lower compared to that observed for the above materials. Moreover, comprehensive genetic analysis revealed that the expression of cell proliferation-related genes was selectively reduced in TH, suggesting that differences in resin composition may account for these variations in behavior. These findings suggest that RM-MTA induces tertiary dentin and demonstrates biocompatibility comparable to that of Pro-MTA. This makes it suitable for the treatment of both sound and mildly inflamed pulp tissues. Additionally, its resin properties are expected to enhance both mechanical performance and clinical handling.
This study aimed to asses the effect of silicate cement on Copalite -covered cavity walls in extracted human teeth. Class V cavities were prepared in 24 premolars and filled with silicate cement (Bio-Trey). Four cavities were unlined, the rest of the cavities were lined with 1 or 2 layers of Copalite before insertion of the restorations. After 6 months, 70-100 microns thick longitudinal sections of the teeth were studied by polarized light microscopy, microradiography and electron probe microanalysis. When imbibed in water or quinoline, a subsurface zone of altered birefringence was noticed in nearly all cavity walls. Nearly half of the cavity walls in the experimental groups showed a surface zone of increased radiopacity. In a few instances a subsurface radiolucent zone was present. By electron probe microanalysis F (0,4-3% by weight), Zn (1-4%) and Al (0,2-6%) were measured in the outer 10-60 microns of the cavity walls. The study shows that even with a double layer of Copalite, known to prevent microleakage, a desirable uptake of F and Al from silicate restorations into cavity walls can take place. Copalite does not prevent a phosphoric acid effect on the cavity walls.
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