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Bis-GMA
Bis-GMA (bisphenol A-glycidyl methacrylate) is a resin commonly used in dental composite, dental sealants. and dental cement. It is the diester derived from methacrylic acid and the bisphenol A diglycidyl ether. Bearing two polymerizable groups, it is prone to form a crosslinked polymer that is used in dental restorations. For dental work, highly viscous bis-GMA is mixed with aluminosilicate particles, crushed quartz and other related acrylates; changes to component ratios lead to different physical properties in the end product. Bis-GMA was incorporated into composite dental resins in 1962 by Rafael Bowen. Until matrix development work in the early 2000s, bis-GMA and related methacrylate monomers were the only options for organic matrix composition. Safety Concerns have been raised about the potential for bis-GMA to break down into or be contaminated with the related compound bisphenol A. However, no negative health effects of bis-GMA use in dental resins have been found. C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bis-HPPP
Bis-HPPP (2,2-bis (2,3-hydroxypropoxy)phenylropane) is an organic compound that is formed when the dental composite material bis-GMA is degraded by salivary esterases. It is also called BADGE·2H2O in reference to it being the hydrolyzed form of BADGE, which is used in the formation of epoxy resins. Structurally, it is a di-ether of bisphenol A. Formation Together with methacrylic acid, bis-HPPP is released following the CE-catalyzed hydrolysis of 2,2- (2-hydroxy 3-methacryloxypropoxy)-phenylropane (bis-GMA). This reaction is very common in hydrolytic degradation of the dental resin since salivary esterases are able to cleave the ester bonds in acrylic polymers of dental composites. Analysis by mass spectrometry demonstrated that hydrolytic reactions would cleave the ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Composite
Dental composite resins (better referred to as "resin-based composites" or simply "filled resins") are dental cements made of synthetic resins. Synthetic resins evolved as restorative materials since they were insoluble, of good tooth-like appearance, insensitive to dehydration, easy to manipulate and inexpensive. Composite resins are most commonly composed of Bis-GMA and other dimethacrylate monomers (TEGMA, UDMA, HDDMA), a filler material such as silica and in most applications, a photoinitiator. Dimethylglyoxime is also commonly added to achieve certain physical properties such as flow-ability. Further tailoring of physical properties is achieved by formulating unique concentrations of each constituent. Many studies have compared the lesser longevity of resin-based composite restorations to the longevity of silver-Mercury (element), mercury Amalgam (dentistry), amalgam restorations. Depending on the skill of the dentist, patient characteristics and the type and location of dam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Sealant
Dental sealants (also termed pit and fissure sealants, or simply fissure sealants) are a dental treatment intended to prevent tooth decay. Teeth have recesses on their biting surfaces; the back teeth have fissures (grooves) and some front teeth have cingulum pits. It is these pits and fissures that are most vulnerable to tooth decay because food and bacteria stick in them and because they are hard-to-clean areas. Dental sealants are materials placed in these pits and fissures to fill them in, creating a smooth surface which is easy to clean. Dental sealants are mainly used in children who are at higher risk of tooth decay, and are usually placed as soon as the adult molar teeth come through. Background Dental caries is an upset of the balance between loss and gain of minerals from a tooth surface. The loss of minerals from the teeth occurs from the bacteria within the mouth, fermenting foods and producing acids, whereas the tooth gains minerals from our saliva and fluoride th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bisphenol A
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on an industrial scale by the condensation reaction of phenol and acetone. Global production in 2022 was estimated to be in the region of 10 million tonnes. BPA's largest single application is as a co-monomer in the production of polycarbonates, which accounts for 65–70% of all BPA production. The manufacturing of epoxy resins and vinyl ester resins account for 25–30% of BPA use. The remaining 5% is used as a major component of several high-performance plastics, and as a minor additive in polyvinyl chloride (PVC), polyurethane, thermal paper, and several other materials. It is not a plasticizer, although it is often wrongly labelled as such. The health effects of BPA have been the subject of prolonged public and scientific debate. BPA is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resin
A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Common resins include amber, hashish, frankincense, myrrh and the animal-derived resin, shellac. Resins are used in varnishes, adhesives, food additives, incenses and perfumes. Resins protect plants from insects and pathogens, and are secreted in response to injury. Resins repel herbivores, insects, and pathogens, while the volatile natural phenol, phenolic compounds may attract benefactors such as predators of insects that attack the plant. Composition Most plant resins are composed of terpenes. Specific components are alpha-Pinene, alpha-pinene, pinene, beta-pinene, carene, delta-3 carene, and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene, and cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Cement
Dental cements have a wide range of dental and orthodontic applications. Common uses include temporary restoration of teeth, cavity linings to provide pulpal protection, sedation or insulation and cementing fixed prosthodontic appliances. Recent uses of dental cement also include two-photon calcium imaging of neuronal activity in brains of animal models in basic experimental neuroscience. Traditionally cements have separate powder and liquid components which are manually mixed. Thus working time, amount and consistency can be individually adapted to the task at hand. Some cements, such as glass ionomer cement (GIC), can come in capsules and are mechanically mixed using rotating or oscillating mixing machines. Resin cements are not cements in a narrow sense, but rather polymer based composite materials. ISO 4049: 2019 classifies these polymer-based luting materials according to curing mode as class 1 (self-cured), class 2 (light-cured), or class 3 (dual-cured). Most of the commerc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid, sulfuri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methacrylic Acid
Methacrylic acid, abbreviated MAA, is an organic compound with the formula CH2=C(CH3)CO2H. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA), and to poly(methyl methacrylate) (PMMA). Production In the most common route, methacrylic acid is prepared from acetone cyanohydrin, which is converted to methacrylamide sulfate using sulfuric acid. This derivative in turn is hydrolyzed to methacrylic acid, or esterified to methyl methacrylate in one step. Another route to methacrylic acid starts with isobutylene, which obtainable by dehydration of ''tert''-butanol. Isobutylene is oxidized sequentially to methacrolein and then methacrylic acid. Methacrolein for this purpose can also be obtained from formaldehyde and ethylene. Yet a third route involves the dehy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bisphenol A Diglycidyl Ether
Bisphenol A diglycidyl ether (commonly abbreviated BADGE or DGEBA) is an organic compound and is a liquid epoxy resin. The compound is a colorless viscous liquid (commercial samples can appear pale straw-coloured). It is a key component of many epoxy resin formulations. Addition of further Bisphenol A and a catalyst and heat can produce Bisphenol A glycidyl ether epoxy resins of higher molecular weight that are solid. Preparation and reactions It is prepared by O-alkylation of bisphenol A with epichlorohydrin. This reaction mainly affords bisphenol A diglycidyl ether, as well as some oligomer. The degree of polymerization may be as low as 0.1. The epoxide content of such epoxy resins is of interest. This parameter is commonly expressed as the epoxide number, which is the number of epoxide equivalents in 1 kg of resin (Eq./kg), or as the equivalent weight, which is the weight in grams of resin containing 1 mole equivalent of epoxide (g/mol). Since unsymmetrical epoxides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Dental Research
The ''Journal of Dental Research'' is a peer-reviewed medical journal that covers all aspects of dentistry. The editor-in-chief is Nicholas Jakubovics (Newcastle University, UK). It was established in 1919 and is published by SAGE Publications on behalf of the International and American Association for Dental Research. Abstracting and indexing The journal is abstracted and indexed in Scopus and the Science Citation Index. According to the ''Journal Citation Reports'', the journal has an impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 8.924 for the year 2021. References External links * {{Official website, https://journals.sagepub.com/home/jdr International & American Associations for Dental Research SAGE Publishing academic journals English-language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saliva
Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be extracted), enzymes (such as lingual lipase and amylase), and antimicrobial agents (such as secretory IgA, and lysozymes). The enzymes found in saliva are essential in beginning the process of digestion of dietary starches and fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices, thus protecting teeth from bacterial decay. Saliva also performs a lubricating function, wetting food and permitting the initiation of swallowing, and protecting the oral mucosa from drying out. Saliva has specialized purposes for a variety of animal species beyond predigestion. Certain swifts construct nests with their sticky saliva. The foundation of bird's nest soup is an aerodramus nest. Venom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterase
In biochemistry, an esterase is a class of enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis (and as such, it is a type of hydrolase). A wide range of different esterases exist that differ in their substrate specificity, their protein structure, and their biological function. EC classification/list of enzymes * ''EC 3.1.1'': Carboxylic ester hydrolases ** Acetylesterase (EC 3.1.1.6), splits off acetyl groups *** Cholinesterase **** Acetylcholinesterase, inactivates the neurotransmitter acetylcholine **** Pseudocholinesterase, broad substrate specificity, found in the blood plasma and in the liver ** Pectinesterase (EC 3.1.1.11), clarifies fruit juices * ''EC 3.1.2'': Thiolester hydrolases ** Thioesterase *** Ubiquitin carboxy-terminal hydrolase L1 * ''EC 3.1.3'': Phosphoric monoester hydrolases ** Phosphatase (EC 3.1.3.x), hydrolyses phosphoric acid monoesters into a phosphate ion and an alcohol *** Alkaline phosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
