Tooth wear

Selecting a bit with more teeth and with shorter crested teeth results in smoother running and reduced rate of tooth wear. 

Eight factors about a worn fixed cutter bit can be recorded. The first four spaces are used to describe the cutting structure. In the first two spaces, the amount of cutting structure wear is recorded using the linear scale 0 to 8, based on the initial useable cutter height. This is consistent with grading tooth wear... 

Recommended Tooth Wear Parameters (After Bourgoyne and Young [137])... 

Equations 4-278, 4-279 and 4-280 are valid only if the bit life is limited by tooth wear or economical drilling rate. 

Conclusion Bit life is limited by tooth wear or economical drilling rate. 

The increase in backlash that results from tooth wear does not adversely affect operation with non-reversing drives, or drives with continuous load in one direction. However, for reversing drives and drives where timing is critical, excessive backlash that results from wear usually cannot be tolerated. 

In addition to gear-tooth wear, variations in the center-to-center distance between shafts creates erratic spacing and... 

Ganss, C., Klimek, J., and Borkowski, N. (2002). Characteristics of tooth wear in relation to different nutritional patterns indudmg contemporary and medievil subjects. Eur. J. Oral. Sci. 110,54-60. 

Richards JR, Brofeldt BT. Patterns of tooth wear associated with methamphetamine use. J Periodontal 2000 71(8) 1371 1. 

An unusual adverse effect of MDMA, tooth wear, has been reported (104). 

A healthy 17-year-old boy, who complained of dental sensitivity that occurred only when he consumed fizzy drinks, presented with marked tooth wear. All the teeth were involved, especially the premolars and permanent molars. He ate a poorly balanced diet, with 500 ml carbonated drinks twice daily. He subsequently admitted to frequent MDMA abuse. 

Current health promotions advise that ecstasy users should frequently consume sports type or fruit drinks to counteract dehydration and avoid ion imbalances. These particular drinks may be erosive to the teeth. Bruxism and trismus associated with ecstasy use can also contribute to tooth wear. 

Murray MO, Wilson NH. Ecstasy related tooth wear. Br Dent J 1998 185(6) 264. 

As mentioned above, the manufacture of aluminum is another important source of atmospheric F pollution that led to injuries to vegetation and wildlife. A comparative study was done in early 1970s on a black-tailed deer killed on a road near an aluminum plant in northwestern Washington (F-contaminated) and on another black-tailed deer killed on a road in an area with no industrial facilities (non-F-contaminated). The F-contaminated deer manifested marked dental disfigurement and abnormal tooth wear pattern compared to the non-F-contaminated animal. The F concentrations in the bones of the F-contaminated deer were 18 to 38 times higher than those in the bones of the non-F-contaminated deer (Table 8.2) (Newman and Yu 1977). 

Moreover, it has been speculated that the pellicle layer protects the tooth surface against abrasive damage and excessive tooth wear [86, 87], However, systematic investigations on the effect and influence of the salivary pellicle on tooth wear are lacking. 

Sonju Clasen AB, Hannig M, Sanju T Variations in pellicle thickness - a factor in tooth wear in Addy M, Embery G, Edgar M, Orchardson R (eds) Tooth Wear and Sensitivity. London, Martin Dunitz Ltd, 2000, pp 189-194. 

The term tooth wear is commonly used to describe the loss of tooth hard tissue due to non-carious causes [1], This encompasses a variety of both chemical and mechanical causes of both intrinsic and extrinsic origin. The term tooth wear is preferred over some of the more precise definitions of individual hard tissue loss mechanisms, because it acknowledges the fact that wear is usually a multifactorial process one mechanism may dominate, but the overall wear is commonly due to the interaction between two or more wear mechanisms. In dentistry, the terms erosion, abrasion, attrition and abfraction are widely used to describe particular mechanisms of hard tissue loss. 

This chapter contains a short review of factors affecting tooth wear, followed by a discussion of methods to measure tooth wear, illustrated with some selected examples. The chapter will not attempt to review the literature on tooth wear in detail, although specific publications of interest will be discussed. For detailed reviews, the reader is referred to papers by Azzopardi et al. [2] and Milosevic [3] and the book edited by Addy et al. [4]. 

The mechanisms of tooth wear fall into two distinct types those of chemical origin (e.g. erosion) and those of physical origin (e.g. abrasion, attrition). In any individual, both chemical and physical insults to the tooth hard tissue will be present in some form or other, so tooth wear is the combined effect of these insults. Despite the clear definition of a number of distinct tooth wear mechanisms, it is uncommon to find a single wear mechanism present in the... 

In the complex environment of the mouth, many potential wear events occur everyday. The overall degree of tooth wear present is, therefore, related to the many wear events a tooth is subjected to over a lifetime. It is clear, as was mentioned previously, that tooth wear is a complex multifactorial process and, in the majority of individuals, wear will be due to the interaction of many different factors and mechanisms. 

Of particular note is the importance of erosion in accelerating tooth wear. The softening of enamel and dentine surfaces by erosive attacks from acid renders the surface extremely susceptible to mechanical attacks [9]. Abfraction is also an example of interaction between wear mechanisms, where abrasion and erosion may act in combination with cyclic loading and unloading to produce an overall wear effect. 

The surfaces of the mouth are coated with a layer of salivary proteins known as the acquired pellicle, which provides a protective effect from both chemical and mechanical attacks to the tooth surface. The pellicle layer both moderates diffusion of ions away from the tooth surface, thus inhibiting the dissolution of enamel by erosion, and provides a lubricating layer to protect from mechanical attacks [10, 11], It is known that dental prophylaxis and the use of regular oral hygiene procedures are able to reduce or remove the pellicle layer. However, recent evidence has shown that the pellicle is able to re-form very rapidly and thus, maintain a protective layer over the tooth surface [10]. For this reason, tooth wear studies performed in vivo or in situ, where the mediating effects of pellicle are present, will give a much more realistic assessment of tooth wear than in vitro studies. For a more detailed discussion on the effects of pellicle, see chapter 2. 

The multifactorial nature of tooth wear makes the study of this phenomenon difficult, and it is therefore not surprising that many of the reported studies focus on a single wear mechanism, often using laboratory models. 

In order to fully understand wear in the oral environment, in vivo clinical trials are required. These are necessarily complex studies, run over substantial periods of time to account for the fact that tooth wear is a rather slow process in all but the most extreme conditions. Additional confounding variables, such as diet, illness and environment, are difficult to avoid, which may reduce the power of any study to discriminate between test treatments. A further complication is the requirement to accurately measure minute changes in tooth surface profile on natural teeth. However, a number of studies have been reported and provide valuable information. 

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