Tooth parts

They set rapidly in the tooth, partly as a result of the accelerating influence of moisture. 

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. 

Nitriding permits increased tooth loading. The amount of increased capacity is not exactly known, but a 20% increase in load at 10,000-12,000 rpm has proven reliable. A further advantage of the nitrided coupling is that the coefficient of friction is lower than that for through-hardened parts. The heat from friction in the coupling decreases. More important, the transmission of axial forces is decreased by the reduced friction. 

Within several of the species there is significant interindividual variation (Table 6.2). This is due, in large part, to a lack of control for tooth type. Several recent studies (Bryant et al. 1996 Fricke and O Neil 1996 Stuart-Williams and... 

C04-0008.Tooth enamel consists, in part, of CajfPOq)] (OH). Tin(II) fluoride (toothpaste labels call it... 

Residual current in polarography. In the pragmatic treatment of the theory of electrolysis (Section 3.1) we have explained the occurrence of a residual current on the basis of back-diffusion of the electrolysis product obtained. In conventional polarography the wave shows clearly the phenomenon of a residual current by a slow rise of the curve before the decomposition potential as well as beyond the potential where the limiting current has been reached. In order to establish the value one generally corrects the total current measured for the current of the blank solution in the manner illustrated in Fig. 3.16 (vertical distance between the two parallel lines CD and AB). However, this is an unreliable procedure especially in polarography because, apart from the troublesome saw-tooth character of the i versus E curve, the residual current exists not only with a faradaic part, which is caused by reduction (or oxidation)... 

The vitamin A needs of the body are by no means centered in any one organ or tissue. It is necessary for vision, for tooth and bone development, for maintenance of healthy epithelial tissue in the skin and in many organs, for reproduction, etc. It is to be expected that deficiency would be exhibited in many ways and that in different individuals the symptoms would not be the same. The benefits of vitamin A administration may thus appear very different in different individuals, and this helps to explain why many kinds of benefits (part of which are probably real) have been ascribed (by physicians as well as others) to vitamin A administration. A substance with such diverse functions is bound to show different effects in different individuals, and, of course, for some individuals who have low requirements and get plenty in their food, its administration will appear to be wholly without effect. Otto Bessey, in discussing the problem of nutrition, has used vitamin A as an illustration of how widely different levels are needed to maintain different functions in experi-... 

Probably the most common use of fluorine is its addition to municipal water supphes to help prevent tooth decay. Stannous (II) fluoride (SnFj) is added to the water in proportions of about one part per million (1 ppm). In addition, many brands of toothpaste add stannous fluoride or other fluoride compounds to their product to help prevent tooth decay. Tooth enamel degenerates overtime. Fluorine promotes remineralization, essentially making a form of new enamel called fluorapatite, which is resistant to decay. 

The corrosive effects of sulfuric acid on teeth with chronic exposure are well established." The damage, etching of dental enamel followed by erosion of enamel and dentine with loss of tooth substance, is limited to tbe parts of the teeth that are exposed to direct impingement of acid mist upon the surface. Although etching typically occurs after years of occupational exposure, in one case exposure to an average of 0.23mg/m for 4 months was sufficient to initiate erosion. ... 

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... 

Remineralisation occurs when partly dissolved crystals are induced to grow by precipitation of the mineral-forming ions Ca + and POl". This is a natural process that occurs as a result of the concentration of these ions in saliva [23] and it serves to oppose the demineralising effects of caries. The processes involved are complex [24] and involve dynamic activity at the interface between the tooth, the saliva, the pellicle and the plaque. Fluoride plays a role in enhancing these processes, and though this is not the only contribution that fluoride makes to protect the tooth from caries, it is nonetheless an important one. 

Mouthrinses containing fluoride consist of a concentrated solution that is prepared for use at daily or weekly intervals. As is the case for toothpastes, fluoride from mouthrinses is retained by the dental plaque and increases the concentration in saliva [172]. Mouthrinses have the advantage that their viscosity is low [173], which is aided by the use of ethanol as at least part of the carrier liquid. This enables mouthrinses to penetrate into interproximal regions, and hence carry the fluoride to parts of the tooth that are difficult to access by other means, for example, with toothpastes. 

Decoction. A preparation made by boiling a plant part in water a boiled extract. Dental enamel. A hard, thin, transcluent layer of calcified substance that envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. 

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