Cavities, tooth

The calcium chelate cements are limited to the use of a cavity liner. They may be placed directly over an exposed tooth pulp to protect the pulp and stimulate the growth of secondary dentin, or used as a therapeutic insulating base under permanent restorations. The high alkalinity and high solubihty of these materials prohibits use in close proximity to soft tissues or in contact with oral fluids. 

The chelated calcium cementing materials are suppHed as two-part paste products. In use, equal parts of the two pastes are thoroughly mixed together to give a fluid mass that can be appHed without pressure over an exposed tooth pulp or in a deep-seated cavity. Under the influence of the oral temperature and humidity, the fluid mass sets to a hard, strong, therapeutic protective seal. 

The phases and their proportions present ia hardened amalgam are controlled by many factors. The composition of the alloy the size, shape, and size distribution of the particles the thermal history of the cast ingot and the comminuted alloy and the surface treatment of the particles are some of the factors for which the manufacturer is responsible. The tooth cavity preparation and the mixing, compacting, and finishing techniques of the dentist can make the difference between satisfactory and unsatisfactory restorations, even with the best of alloys. A minimal amount of residual mercury and porosity are needed to obtain the most serviceable restorations (138). 

Amalgam restorations are prepared by mixing a powdered alloy with mercury to form a plastic moldable mass that is packed or condensed iato the prepared cavity. The cavity is designed to provide mechanical retention, maximum marginal mass, support to absorb the functional stresses transmitted through the restoration, and maximum protection to the remaining tooth stmcture. The restoration reestabUshes the normal tooth anatomical form and function. 

Next, the amalgam must be condensed properly ia the prepared, clean, and dry cavity. In general, the maximum effective load tolerated by the patient should be used on a condenser of optimum size, to remove as much mercury from the mass as possible. The amalgam must be carved to the contour of the lost tooth tissue it is replaciag. 

They are used by direct placement in tooth cavities or by custom fabricating using composites on a gypsum model of the cavity and then cementing the restoration into the tooth cavity. 

Stannous fluoride is used in toothpastes and dental rinses to protect tooth enamel from attack by bacteria—cavities (also known as dental caries). It was the first fluoride used for that purpose, in the toothpaste Crest. 

Dental amalgam, a solid solution of silver and tin in mercury, is used for filling tooth cavities. Two of the reduction half-reactions that the filling can undergo are... 

The addition of fluoride ions to domestic water supplies (in the form of NaF) is now widespread and has resulted in a dramatic decrease in dental cavities. Fluoridated toothpastes, containing either tin(II) fluoride or sodium monofluorophos-phate (MFP, Na2FP03), are also recommended to strengthen tooth enamel. 

The glass polyalkenoate cement was originally intended as a substitute for dental silicate cements for the aesthetic restoration of front (anterior) teeth (Wilson Kent, 1972 Knibbs, Plant Pearson, 1986a Osborne Berry, 1986 Wilson McLean, 1988). It is suitable for restoring anterior cavities in low-stress situations, that is when the restoration is completely supported by surrounding tooth material. These cavities occur on the adjacent surfaces of neighbouring teeth (class III cavities) and at the gum line (class V cavities). 

Tay et al. (1974, 1979) have studied the mechanism of erosion of the dental silicate cement in service, finding that grooving occurs at the margin between the restoration and the tooth. Erosion exposes the cavity and provides sites for the accumulation of food debris and bacteria which can cause inflammation of the gingiva (Larato, 1971). It also leads to staining of the restoration (Bock, 1971 Kent, Lewis Wilson, 1973). 

Under these acidic conditions, tooth enamel starts to break down, leading to dental caries (or cavities). When S. mutans,... 

The nematodes are themselves insect parasitoids that are not very particular about their hosts. Fly maggots, moth larvae and pupae, beetle larvae, and numerous other hosts are all acceptable to them. Some of these nematodes do have narrow preferences, but one widespread species invades more than two hundred different kinds of insects. Juvenile nematodes infected with their bacteria seek out a host to parasitize, typically gaining entry through one of its body orifices. Some species enter through a hole they scrape in the insect s cuticle using a "tooth" on their head. Once inside the insect, the worms force their way through soft tissues and into their host s central body cavity. 

Sugar is a common ingredient in prepared foods. When sugar remains on your teeth, bacteria in your mouth convert it into an acid. The principal constituent of tooth enamel is a mineral called hydroxyapatite, Caio(P04)6(OH)2. Hydroxyapatite reacts with acids to form solvated ions and water. (Solvated ions are ions surrounded by solvent particles.) Eventually, a cavity forms in the enamel. 

Food is taken into the buccal cavity, where it is masticated by the teeth and mixed with saliva from three pairs of salivary glands. It moistens the food and dissolves some molecules enabling them to interact with the taste receptors on the tongue. Saliva contains Na% Cl and HCOs ions and a protein, mucin, which is a component of mucus that lubricates the chewed food on its way down the oesophagus. The pH of saliva is about 7.8, which neutralises acid formed by bacteria in the mouth this protects tooth enamel... 

They are considered to be the trees and bushes growing in the saline Intertidal zones of sheltered coastlines. Their root systems are thus regularly inundated with saline water however, dilution by flooding may occur once or twice annually O). Four vascular plants associated with tidal mangrove swamps in Southeast Asia have been utilized by local inhabitants for their toxic properties. The natural sap or aqueous extract from the leaves and bark is used to stupefy fish, as poison for spear and arrow tips, and applied to tooth cavities and skin to deaden aches and pain. 

Once an agent is topically applied in the oral cavity, the free drug can act at the primary site (i.e., bacteria in the plaque), or it can be partitioned to compartments where the drug binds nonspecifically. These drug reservoirs include the enamel, dentin, and/or cementum of the tooth, the oral mucosa, the organic and inorganic components of plaque, and salivary proteins. 

Salivary flow is extremely important in the removal of many agents from the oral cavity. Human sahva has a diurnal flow that varies between 500 and 1,500 mL in the daytime to less than 10 mL of secretion at night. The rate of clearance of a drug from the oral cavity therefore is profoundly important in determining the amount of time a drug is in contact with the tooth surface. 

For many years, the process of caries was thought to be irreversible and to result in permanent loss of tooth material. This process eventually leads to the development of a cavity, and a considerable part of the dental professions time... 

It is now known that teeth undergo a continuous process of demineralisation and remineralisation (see Table 2), which is driven by changes in the plaque composition [29]. In the presence of fermentable carbohydrates plaque microorganisms generate characteristic organic acids, that is, lactic and acetic [17], and these diffuse through the pellicle to the tooth surface and cause demineralisation [30]. Ions are then liberated from the mineral phase into this low pH liquid [31], and they diffuse outwards and re-precipitate at the surface layer of the demineralised lesion [32,33]. If this process is sufficiently rapid, there is a net loss of tooth mineral and irreversible cavity formation. 

In contrast to skeletal bone and dentine, which accumulate fluoride throughout life and whose levels are proportional to the absorbed dose of fluoride, fluoride in enamel is not an appropriate biomarker, because most of its fluorine was taken up during tooth formation [2]. The post-eruptive fluoride uptake of enamel is expressed only in the outer layer and depends on the concentration of fluoride in the oral cavity [6]. 

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