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Dental Materials (dental + material)
Selected AbstractsAntibacterial activity of silver inorganic agent YDA fillerJOURNAL OF ORAL REHABILITATION, Issue 4 2004S. Ohashi summary, YDA filler is an antibacterial agent that is currently in commercial dental use. In this study, we attempted to determine whether it exerts an antibacterial effect on human saliva bacteria, and to determine whether it can be used in dental materials. CFUs in 1 mL stimulated human saliva were examined using blood agar and mitis salivarius agar after immersion, with or without YDA filler. The antibacterial effect was compared with that of Ketac-Silver. Dental materials containing 5% wt YDA filler were prepared for in vitro testing on S. mutans and A. viscosus. Furthermore, we examined the in vitro cytotoxicity of experimental MMA resin containing YDA filler on HeLa cells. Human saliva bacteria and mutans streptococci showed reduced viability following exposure to YDA filler after 12 h. The concentration of silver ions released by YDA filler was below 1 ppm after 12 h. Two tested strains showed reduced viability following exposure to dental materials containing YDA filler. In another experiment, MMA resin containing YDA filler did not show cytotoxicity on HeLa cells after 24- and 48-h exposure. Thus, YDA filler may help in the development of antibacterial dental materials, such as composite resin, glass,ionomer or temporary cement. [source] Dental gold alloys and contact allergyCONTACT DERMATITIS, Issue 2 2002Halvor Möller Contact allergy to gold as demonstrated by patch testing is very common among patients with eczematous disease and seems to be even more frequent among patients with complaints from the oral cavity. There is a positive correlation between gold allergy and the presence of dental gold. Gold allergy is often found in patients with non-specific stomatitides as well as in those with lichenoid reactions or with only subjective symptoms from the oral cavity. The therapeutic effect of substituting other dental materials for gold alloys is conspicuous in casuistic reports but less impressive in larger patient materials. The amount of dental gold is correlated qualitatively and quantitatively to the blood level of gold and the effects if any of circulating blood gold are unknown. There is clearly a need for prospective studies in the field and gold sodium thiosulfate is considered an important item in the dental series for patch testing. [source] The biocompatibility of modified experimental Portland cements with potential for use in dentistryINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2008J. Camilleri Abstract Aim, To evaluate the biocompatibility of a group of new potential dental materials and their eluants by assessing cell viability. Methodology, Calcium sulpho-aluminate cement (CSA), calcium fluoro-aluminate cement (CFA) and glass,ionomer cement (GIC; Ketac Molar), used as the control, were tested for biocompatibility. Using a direct test method cell viability was measured quantitatively using alamarBlueÔ dye, and an indirect test method where cells were grown on material elutions and cell viability was assessed using methyltetrazolium (MTT) assay as recommended by ISO 10 993-Part 5 for in vitro testing. Statistical analysis was performed by analysis of variance and Tukey multi-comparison test method. Results, Elution collected from the prototype cements and the GIC cured for 1 and 7 days allowed high cell activity after 24 h cell exposure, which reduced after 48 h when compared to the nontoxic glass,ionomer control, but increased significantly after 72 h cell contact. Elutions collected after 28 days revealed reduced cell activity at all cell exposure times. Cells placed in direct contact with the prototype materials showed reduced cell activity when compared with the control. Conclusions, Cell growth was poor when seeded in direct contact with the prototype cements. GIC encouraged cell growth after 1 day of contact. The eluted species for all the cements tested exhibited adequate cell viability in the early ages with reduced cell activity at 28 days. Changes in the production of calcium hydroxide as a by-product of cement hydration affect the material biocompatibility adversely. [source] Microhardness and fracture toughness of dental materials by indentation methodJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Aylin, akar-Deliormanli Abstract The main objective of this study was to measure the fracture toughness of the human teeth enamel using the microindentation technique and to compare the results calculated from the equations developed for Palmqvist and radial-median cracks. Vickers microhardness measurements of dental ceramic (alumina) and human teeth were performed using indentation fracture method. The fracture toughness of enamel was calculated using different equations reported in the literature. Vickers microhardness of the sintered alumina specimen (98.8% theoretical density) was measured to be 14.92 GPa under 9.8N indentation load. Three equations based on the radial-median cracks were found to be applicable for the fracture toughness determination of the enamel. Results show that indentation fracture method is adequate to measure microhardness and fracture toughness of dental materials. However the calculation of fracture toughness depended on the nature of the cracks and also on the location of the indentation. Therefore, it is necessary to identify the crack profile and to select the appropriate equation for accurate fracture toughness values. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] QUARTZ-TUNGSTEN-HALOGEN AND LIGHT-EMITTING DIODE CURING LIGHTSJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 3 2006Kraig S. Vandewalle DDS Curing lights are an integral part of the daily practice of restorative dentistry. Quartz-tungsten-halogen (QTH), plasma-arc (PAC), argon laser, and light-emitting diode (LED) curing lights are currently commercially available. The QTH curing light has a long, established history as a workhorse for composite resin polymerization in dental practices and remains the most common type of light in use today. Its relatively broad emission spectrum allows the QTH curing light to predictably initiate polymerization of all known photo-activated resin-based dental materials. However, the principal output from these lamps is infrared energy, with the generation of high heat. Filters are used to reduce the emitted heat energy and provide further restriction of visible light to correlate better with the narrower absorbance spectrum of photo-initiators. The relatively inefficient emission typically requires corded handpieces with noisy fans. PAC lights generate a high voltage pulse that creates hot plasma between two electrodes in a xenon-filled bulb. The irradiance of PAC lights is much higher than the typical QTH curing light, but PAC lights are more expensive and generate very high heat with an inefficient emission spectrum similar to that of QTH bulbs. Light emitted from an argon laser is very different from that emitted from the halogen or PAC lights. The photons produced are coherent and do not diverge; therefore, lasers concentrate more photons of specific frequency into a tiny area. With very little infrared output, unwanted heat is minimized. However, argon lasers are very expensive and inefficient due to a small curing tip. LED curing lights have been introduced to the market with the promise of more efficient polymerization, consistent output over time without degradation, and less heat emission in a quiet, compact, portable device. This review evaluates some of the published research on LED and QTH curing lights. [source] Selecting Nanotechnology-Based Composites Using Colorimetric and Visual Analysis for the Restoration of Anterior Dentition: A Case ReportJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2004FRANK J. MILNAR DDS ABSTRACT Currently it is possible to use direct composites and layering techniques to replicate the complex internal structures, visible shape, color, and surface anatomy of natural teeth. To do so, however, requires dentists to understand the principles of nature and the science of dental materials to determine the most suitable restorative material for a specific indication. By incorporating relatively new technologies,colorimetric analysis, which provides computerized shade guide definitions of a tooth and essential information to verify shade mapping, and a new nanotechnology-based direct composite,into composite layering techniques, dentists can more predictably replicate the esthetics of natural teeth. This article presents a case in which both technologies, used in combination with a composite layering technique, contributed to the esthetic and functional restoration of the maxillary central incisors. [source] Curing Dental Resins and Composites by PhotopolymerizationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 6 2000JEFFREY W. STANSBURY PHD ABSTRACT The development and continued evolution of photopolymerizable dental materials, particularly dental composite restoratives, represent a significant, practical advance for dentistry. The highly successful integration of the light-activated curing process for dental applications is described in this review. The basic mechanisms by which the photoinitiators efficiently convert monomers into polymers are discussed along with the variety of factors that influence the photopolymerization process. The conventional camphorquinone-amine visible light photoinitiator system used in most dental restorative materials is illustrated in addition to some alternative initiator systems that have been studied for dental materials applications. CLINICAL SIGNIFICANCE Photopolymerization has become an integral component of the practice of dentistry. A better appreciation of the photopolymerization process as well as its potential and limitations may aid the dentist in the delivery of both esthetic and restorative dental care. [source] Minimum requirements for new dental materials,JOURNAL OF ORAL REHABILITATION, Issue 12 2007I. A. MJÖRArticle first published online: 21 NOV 200 Summary, A brief review of the development of standards for testing and certification of dental materials is presented. The tests employed in the standards are not correlated for the clinical use of the materials, nor to the reasons for failures of the materials. They are, therefore, of limited value for the selection of materials to be used in practice but they are important for quality control of the manufacture of the materials. Previous certification programmes are being discontinued. The responsibility for selecting safe and efficient materials is transferred to the clinicians whereas making safe and efficient materials still is the responsibility of the manufacturers. [source] Comparative radical production and cytotoxicity induced by camphorquinone and 9-fluorenone against human pulp fibroblastsJOURNAL OF ORAL REHABILITATION, Issue 12 2004T. Atsumi summary, Camphorquinone (CQ) is widely used as a photo-initiator in dental materials; however, its cytotoxicity against human pulp fibroblasts (HPF) and particularly the effects of 2-dimethylaminoethyl methacrylate (DMA), a reducing agent and visible light (VL) irradiation on it remain unknown. So we investigated the cytotoxic and reactive oxygen species (ROS)-producing effects of CQ with or without DMA, in the presence or absence of VL on HPF cells. The free-radical production activity of CQ was measured by two different methods [using diphenylpicryl hydrazyl and galvinoxyl]. The phase-transition properties of dipalmitoylphosphatidyl choline (DPPC) liposomes, as a model for biomembranes, induced by CQ were investigated by differential scanning calorimetry. These findings were compared with those of 9-fluorenone (9F), an aromatic photo-initiator with long conjugated groups. Camphorquinone with VL irradiation increased the radical production, whereas 9F with VL irradiation increased ROS production, as well as effecting changes in the DPPC phase-transition properties. The cytotoxicity of CQ towards HPF cells was smaller than that of 9F despite greater radical production. The addition of DMA to the photosensitizer enhanced the free-radical production without increasing the ROS level or the cytotoxicity. Camphorquinone/DMA is a valuable combination for the polymerization of dental resins. [source] Antibacterial activity of silver inorganic agent YDA fillerJOURNAL OF ORAL REHABILITATION, Issue 4 2004S. Ohashi summary, YDA filler is an antibacterial agent that is currently in commercial dental use. In this study, we attempted to determine whether it exerts an antibacterial effect on human saliva bacteria, and to determine whether it can be used in dental materials. CFUs in 1 mL stimulated human saliva were examined using blood agar and mitis salivarius agar after immersion, with or without YDA filler. The antibacterial effect was compared with that of Ketac-Silver. Dental materials containing 5% wt YDA filler were prepared for in vitro testing on S. mutans and A. viscosus. Furthermore, we examined the in vitro cytotoxicity of experimental MMA resin containing YDA filler on HeLa cells. Human saliva bacteria and mutans streptococci showed reduced viability following exposure to YDA filler after 12 h. The concentration of silver ions released by YDA filler was below 1 ppm after 12 h. Two tested strains showed reduced viability following exposure to dental materials containing YDA filler. In another experiment, MMA resin containing YDA filler did not show cytotoxicity on HeLa cells after 24- and 48-h exposure. Thus, YDA filler may help in the development of antibacterial dental materials, such as composite resin, glass,ionomer or temporary cement. [source] New Photocleavable Structures, 4,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2008Acylgermane-Based Photoinitiator for Visible Light Curing Abstract As highly reactive acylphosphine oxide-based photoinitiators (PIs) are limited in the application for dental materials by their absorption behavior, we were interested to prepare acylgermane 1. UV-Vis absorption maximum of the important n,,* transition was red shifted about 30 nm compared to monoacylphosphine oxides. Photo-DSC results with a dental LED lamp showed nearly the same reactivity for 1 compared to camphorquinone (CQ), while monoacylphosphine oxides are not reactive. In broadband irradiation experiments, significantly higher reactivity compared to CQ was found. Application-oriented tests showed sufficient storage stability of the formulation and excellent photobleaching behavior. [source] Metallic dental materials in patient's oral cavity acting as electrodes of electrochemical cellsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2004W. Opydo Abstract The work was aimed at studying of standard potentials of commonly used metallic dental materials and determining of the effect of saliva conductivity and reaction on value of the potentials. The following materials have been examined: gold alloy (a material used for crowns and bridgeworks), chromium-cobalt alloy (for frameworks in removable partial dentures), and silver amalgams (used for fillings) manufactured by three different companies. Taking into account that mucosa makes one of the electrodes existing in oral cavity the rest potentials of mucosa have been in vivo measured in several patients. Their values, converted with respect to NHE, oscillated within the range from + 0.31 V to + 0.47 V. Among metallic dental materials examined in the experiment maximal standard potential was found for the gold alloy, further materials having lower potentials, in decreasing order, were chromium-cobalt alloy, and the amalgams Amalcap Plus, ANA 2000 and Septalloy. Significant differences between standard potentials of examined materials and mucosa indicate spontaneous formation of galvanic cells of electromotive force reaching even about 0.6 V. [source] Burning mouth syndrome: the role of contact hypersensitivityORAL DISEASES, Issue 4 2009R Marino Background:, Burning mouth syndrome is a burning sensation or stinging disorder affecting the oral mucosa in the absence of any clinical signs or mucosal lesions. Some studies have suggested that burning mouth syndrome could be caused by the metals used in dental prostheses, as well as by acrylate monomers, additives and flavouring agents, although others have not found any aetiologic role for hypersensitivity to dental materials. Objective:, To evaluate the extent and severity of adverse reactions to dental materials in a group of patients with burning mouth syndrome, and investigate the possible role of contact allergy in its pathogenesis. Materials and methods:, We prospectively studied 124 consecutive patients with burning mouth syndrome (108 males; mean age 57 years, range 41,83), all of whom underwent allergen patch testing between 2004 and 2007. Results:, Sixteen patients (13%) showed positive patch test reactions and were classified as having burning mouth syndrome type 3 or secondary burning mouth syndrome (Lamey's and Scala's classifications). Conclusion:, Although we did not find any significant association between the patients and positive patch test reactions, it would be advisable to include hypersensitivity to dental components when evaluating patients experiencing intermittent oral burning without any clinical signs. [source] US3 Allergy in dental practiceORAL DISEASES, Issue 2006D Bio, ina-Lukenda Allergy reactions of the oral mucosa comprise an array of clinical manifestations, some of them difficult to differentiate from toxic reactions. Type-I reactions are most frequently seen related to application of polymers in the oral cavity, such as orthodontic bonding and fissure sealant materials. There may also be systemic manifestations such as urticaria. Type-IV reactions may be seen related to most dental materials used, from amalgam and gold to polymers. These reactions appear as chronic reddening and/or ulceration of the oral mucosa. Lichenoid reactions have histopathological characteristics compatible with type-IV allergy reactions and are the most prevalent material-adverse reactions seen in the oral cavity. Recent advances have been made in characterizing the more prevalent allergens on oral mucosa, such as methacrylates, natural rubber latex (NRL) proteins, rubber glove chemicals and disinfectants. This improved understanding has clearly enhanced the success, particularly for type I NRL allergies. Skin patch tests, applying a series of dental materials in non-toxic concentrations on the skin, have been used to identify sensitization. However, the value of those tests can be questioned. Although obvious advances have been made in characterizing dental allergens and understanding potential exposure, improved diagnostic and management techniques are still needed. Corticosteroid therapy is all too often the only treatment. Drug allergy including local anaesthetics, and systemic antibiotics and NSAIDs, may also present in the dental environment, causing life-threatening emergencies specially in 'at risk patients'. The GDP has to know the principles of prevention, diagnosis and management of these situations. [source] Contribution of polymer chemistry to dentistry: development of an impermeable interpenetrating polymer network to protect teeth from acid demineralizationPOLYMER INTERNATIONAL, Issue 2 2008Nobuo Nakabayashi The purpose of this review article is to show how polymer science can contribute to the further improvement of modern dentistry. It has long been believed that the development of strong dental materials is essential to improve dentistry, and polymeric materials might not be reliable compared to metals and ceramics. It was hypothesized that the bonding of restoration materials to the tooth structure is required in order to inhibit the detachment of prostheses. However, bonding of artificial materials to natural tissues is difficult. It has been found that a polymer network interpenetrated with dental hard tissues resolves this problem, that formal bonding is not required and that protection of prepared dentin against lactic acid demineralization with an impermeable barrier is a requisite for prevention of caries. Copyright © 2007 Society of Chemical Industry [source] Proliferative activity of cells from remaining dental pulp in response to treatment with dental materialsAUSTRALIAN DENTAL JOURNAL, Issue 1 2010AN Lutfi Abstract Background:, The biological examination of pulp injury, repair events and response of dental pulp stem cells to dental restorative materials is important to accomplish restorative treatment, especially to commonly used dental materials in paediatric dentistry, such as glass ionomer cement (GIC) and calcium hydroxide (Ca(OH)2) lining cement. Methods:, Healthy patients aged between 9 to 11 years with carious primary molars without pulp exposure were selected and divided into two groups: Group 1 (teeth restored with GIC) and Group 2 (teeth lined using Ca(OH)2 and restored with GIC). The proliferative activity of stem cells of teeth between these two groups was compared using colourimetric cell proliferation reagent, alamarBlue. Immunocytochemistry and flow cytometry confirmation were performed using mesenchymal stem cell markers, CD105 and CD166. Results:, The proliferative activity using alamarBlueÔ assay showed that cells derived from the remaining dental pulp of exfoliated deciduous teeth were positive for CD105 and CD166 and exhibited no difference between the two groups. Conclusions:, It can be concluded that the use of Ca(OH)2 or GIC as a lining material in indirect pulp capping procedures has the same effect on cells derived from the remaining dental pulp of exfoliated deciduous teeth which have responded favourably to the restorative treatments. [source] Dental Erosion: In Vitro Model of Wine Assessor's ErosionAUSTRALIAN DENTAL JOURNAL, Issue 4 2001Tong Bee Mok Background: Wine makers and assessors frequently experience severe dental erosion. The objectives of this study were to develop an in vitro model of dental erosion caused by frequent wine contact with teeth, and to use this model to assess the effectiveness of a variety of methods which might protect against this form of erosion. Methods: An initial pilot study found that riesling style wine was more erosive than champagne style, and both more than claret. Wine tasting was simulated by subjecting exposed windows of enamel and root surfaces on 50 intact, extracted human teeth to 1400 one minute exposures to white wine (pH 3.2). A variety of dental materials were applied to the exposed windows on groups of teeth prior to erosive challenge, to assess their protective ability. Results: Protective resin coatings and fluoride varnishes protected both enamel and roots against wine induced erosion. A high degree of protection was provided by APF gel, with less by NaF gel. Conclusions: It was concluded that dentists may be able to help minimise erosion resulting from frequent wine-tasting in their patients by the clinical application of one or a combination of these agents at times prior to prolonged assessment periods. [source] Do adverse effects of dental materials exist?CLINICAL ORAL IMPLANTS RESEARCH, Issue 2007What are the consequences, how can they be diagnosed, treated? Abstract Objectives: All dental biomaterials release substances into the oral environment to a varying degree. Various preclinical biocompatibility test systems have been introduced, aiming at an evaluation of the potential risks of dental materials. Potential pathogenic effects of released substances from dental materials have been demonstrated. For the biocompatibility of a biomaterial, it is not only important that minimal diffusable substances are released when it is in body contact , the material must also fulfill the function for which it has been designed. This is also very much dependent on the material properties and its handling properties. The aim of this review was to generate an overview of the present status concerning adverse reactions among patients and personnel. Materials and methods: A systematic review was performed using a defined search strategy in order to evaluate all MEDLINE-literature published between 1996 and 2006. Results: The compilation of the literature available has revealed that the majority of studies have been carried out on patients compared with personnel. Adverse reactions towards dental materials do occur, but the prevalence and incidence are difficult to obtain. The results were essentially based on cohort studies. Clinical trials, especially randomized-controlled trials, are in the minority of all studies investigated, with the exception of composite and bonding studies, where clinical trials, but not randomized-controlled trials, represent the majority of studies. Patients and personnel were treated separately in the manuscript. Amalgam studies show the lowest degree of verified material-related diagnosis. Even if objective symptoms related to adverse reactions with polymer resin-based materials have been reported, postoperative sensitivity dominates reports concerning composites/bondings. Verified occupational effects among dental personnel show a low frequency of allergy/toxic reactions. Irritative hand eczema seemed to be more common than in the general population. Conclusions: Patient- and personnel-related studies are of variable quality and can be improved. There is a need for a better description of the content of materials. A registry for adverse effects of dental materials would be useful to detect the occurrence of low-incidence events. [source] | |||||||||||||