Cytotoxicity of a trial resin composite liner containing TiK2F6 on rat dental pulp cells.
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The aim of this study was to assess the toxicological responses of a resin composite containing TiK2F6 and NaF in rat dental pulp cells. Trial resin composite liners were made, containing 3 wt% fluorides (TiK2F6 or NaF). These specimens were immersed in 5 ml of cell culture medium supplemented at 37 degrees C for 24 hours. The eluates were used for the experiments. We judged the cytotoxicity of the samples by the cell viability. The original elute solution was serially diluted and then the medium was exchanged for the dilute medium. The cell viability at 1, 2 or 5 days after commencement of re-culturing was calculated. The viability of cells in the eluate from the resin composite liners containing TiK2F6 and NaF decreased with time. The cytotoxicity of TiK2F6 was weaker than that of NaF at all times. (+info)
Evidence for bacterial causation of adverse pulpal responses in resin-based dental restorations.
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The widespread use of resin and resin-monomers for bonding of dental restorations to dentin has occurred because of a fundamental shift in the view that injury to the pulp is induced by restorative procedures. While, for many years, the toxic effects of restorative materials were thought to be of crucial importance in the development of adverse pulpal responses, the key role of bacterial leakage at the restoration-tooth interface is now well-recognized. Consequently, if optimal conditions for the preservation of pulpal health are to be ensured, dental restorations should provide an impervious seal against the surrounding tooth structure. However, polymerization shrinkage and contraction stresses induced during setting, as well as a variety of technical difficulties encountered during the clinical operation, often produce less than perfect results. Therefore, modern restorative procedures involving resin and resin-bonded restoratives must still rely on the ability of the pulp to cope with the injurious elements to which it may be exposed during and after the procedure. This review examines factors that may govern the pulp's response to restorative procedures that involve adhesive technologies. An assessment is made of the risks involved as far as the continued vital function of the pulp is concerned. It is concluded that an intact, although thin, wall of primary dentin often enables the pulp to overcome both toxic material effects and the influences of bacterial leakage. In contrast, the pulp may not do equally well following capping of open exposures with resin composites. A dearth of controlled clinical studies in this area of dentistry calls for confirmation that pulpal health prevails over the long term following the use of total-etch and resin-bonding techniques. (+info)
Testing a degradable topical varnish of cetylpyridinium chloride in an experimental dental biofilm model.
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Dental biofilms are highly associated with the development of dental caries. Novel drug delivery systems are being developed in order to eliminate cariogenic bacteria from the dental biofilms. We formulated two degradable sustained release varnishes, based on acrylic resin, with cetylpyridinium chloride (CPC) as the active agent. These formulations were tested in a dental biofilm model. The retention of CPC in the biofilm was dependent upon the pharmaceutical additives of the varnish. Both varnishes decreased bacterial adhesion, while also demonstrating marked antibacterial properties against the bacteria in the biofilm. (+info)
Thermal coefficients of paste-paste type pulp capping cements.
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Thermal coefficients of four kinds of commercially available paste-paste type pulp capping cements were examined. Control reference samples were made of dentin. A thermal coefficient analyzer was used, heating specimens for a few nanoseconds by a xenon flash bulb and measuring thermal changes by using a thermocouple. Thermal coefficients were examined by this non-steady state method. Thermal conductivities of all cements were almost the same or lower than that of dentin. Therefore, when each cement was heated, the penetrating energy was almost the same or lower than that of dentin. The thickness of the cements was converted into that of the dentin by using the obtained thermal conductivity. The 1-mm thickness of the examined cements were equal to between 0.97-mm and 2.10-mm thicknesses of lost dentin. The use of a pulp capping cement provided better pulp protection from thermal stimuli than did the same thickness of dentin. (+info)
Possibility of allergic reaction to dentin primer--application on the skin of guinea pigs.
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We studied the allergic reaction of guinea pigs to glyceryl methacrylate (GM), hydroxyethyl methacrylate (HEMA) and meso-erythritol methacrylate (EM), which are used as dentin primers. On the 18th day of the application test, when macroscopic investigation revealed an inflammatory reaction, the methacrylic acid-treated group showed marked eschar formation in comparison with the control group. In each of the dentin primer groups, a slight degree of skin redness was noted, but there were no serious symptoms. On the 25th day, the applications were resumed macroscopic inspection on the 32nd day found eschar in the methacrylic acid group only. Therefore, this experiment with dentin primers suggests a delayed allergic reaction. Local irritability test showed a more severe reaction than the application test. In this test, all experimental dentin primers and methacrylic solution promptly showed inflammation, and the chemical compound, methacrylic acid was a factor in inflammation. (+info)
Remineralization of carious dentin. I: in vitro microradiographic study in human teeth capped with calcium hydroxide.
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The objective of this in vitro study was to evaluate a possible remineralization of human carious dentin by calcium hydroxide. Thirty-nine freshly extracted human permanent and deciduous carious teeth were split into two halves. One half was used as control and the other as experimental. In the latter, a cavity was prepared and the remaining bottom layer of demineralized dentin capped with chemically pure calcium hydroxide. The experimental samples were stored at 37 masculine C. Time intervals were 2, 4, 6, 8, 10 and 12 weeks. All tooth halves were sawed and ground to plano-parallel sections with a thickness varying from 75 to 117 microm. Qualitative microradiographs showed a qualitative increase in radiopacity of the calcium hydroxide treated samples. Quantitative microradiography showed a statistically significant increase in total mineral content in the experimental samples compared to the control samples. These results indicate an in vitro remineralization of carious dentin by calcium hydroxide. (+info)
Thermal properties of dental materials--cavity liner and pulp capping agent.
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We studied the thermal properties of cavity liners that included calcium phosphate as inorganic filler, in contrast to the conventional pulp capping agents. Therefore, thermal diffusivity, specific heat capacity, and thermal conductivity were measured. In addition, thermal conductivity results were compared with those of restorative materials and human dentin to examine thermal insulation effects. The thermal conductivity of cavity liners ranged from 0.23 to 0.28 W m(-1) K(-1), and that of pulp capping agents ranged from 0.44 to 0.48 W m(-1) K(-1). Test results indicated that the thermal conductivity of cavity liner was lower than those of human dentin, pulp capping agent, cast alloy, and composite resin for restoration, hence suggesting that cavity liner has a good thermal insulation effect. (+info)
Remineralization of carious dentin. II: In vivo microradiographic and chemical studies in human permanent teeth capped with calcium hydroxide.
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The main aim of this in vivo study was to evaluate a possible remineralization of human carious dentin by means of chemical and microradiographic studies. Eighty-six samples of carious dentin were removed from 36 permanent teeth of 24 patients. These were divided into untreated (control) and chemically pure calcium hydroxide-capped (experimental) samples and analyzed at intervals varying from 10 to 120 days. They were classified according to depth of caries and degree of dentin softening and evaluated in relation to weight, phosphorus concentration, qualitative and quantitative microradiography and absolute values of total mineral content. One of two halves of each sample was selected for chemical studies and the other for total content of mineral salts. Experimental samples were examined with a light microscope and the results obtained showed a qualitative increase in radiopacity. Quantitatively, it was observed that, in the case of samples analyzed for phosphorus concentration, the average mean of differences in percentage increase after treatment was 9.6%, while for the samples evaluated microradiographically for total mineral content, it was 22.29%. In both cases, the differences were statistically significant. (+info)