Механический износ зубов: причины, проявления и профилактика.

Abrasion is the non carious, mechanical wear of tooth from interaction with objects other than tooth tooth contact. It most commonly affects the premolars and canines, usually along the cervical margins. Based on clinical surveys, studies have shown that abrasion is the most common but not the sole aetiological factor for development of non carious cervical lesions (NCCL) and is most frequently caused by incorrect toothbrushing technique. Abrasion frequently presents at the cemento enamel junction and can be caused by many contributing factors, all with the ability to affect the tooth surface in varying degrees. The appearance may vary depending on the cause of abrasion, however most commonly presents in a V shaped caused by excessive lateral pressure whilst tooth brushing. The surface is shiny rather than carious, and sometimes the ridge is deep enough to see the pulp chamber within the tooth itself. Non carious cervical loss due to abrasion may lead to consequences and symptoms such as increased tooth sensitivity to hot and cold, increased plaque trapping which will result in caries and periodontal disease, and difficulty of dental appliances such as retainers or dentures engaging the tooth. It may also be aesthetically unpleasant to some people. and having occupation such as joiner, are subjected to higher risks of abrasion. The aetiology of dental abrasion can be due to a single stimulus or, as in most cases, multi factorial. The most common cause of dental abrasion is the combination of mechanical and chemical wear. Tooth brushing is the most common cause of dental abrasion, which is found to develop along the gingival margin, due to vigorous brushing in this area. The type of toothbrush, the technique used and the force applied when brushing can influence the occurrence and severity of resulting abrasion. Further, brushing for extended periods of time (exceeding 2 3 min) in some cases, when combined with medium/hard bristled toothbrushes can cause abrasive lesions. Abrasion may also be exacerbated by overzealous use of certain types of dentifrice; some have more abrasive qualities to remove stains such as whitening toothpastes. The bristles combined with forceful brushing techniques applied can roughen the tooth surface and cause abrasion as well as aggravating the gums. Repetitive irritation to the gingival margin can eventually cause recession of the gums. When the gums recede, the root surface is exposed which is more susceptible to abrasion. Comparatively, electric toothbrushes have less abrasive tendencies. When combined with incorrect brushing technique, toothpastes can also damage enamel and dentine due to the abrasive properties. Specific ingredients are used in toothpaste to target removal of the bio film and extrinsic staining however in some cases can contribute to the pastes being abrasive. However, if an individual is regimented in their after whitening care then they can avoid loss of tooth structure and in turn abrasion can be avoided. Another factor that can contribute to abrasive loss of tooth structure is the alteration of pH levels at the tooth surface. This can associated with the consumption of acidic foods and liquids or regurgitation of stomach acid, a process known as dental erosion. An increase in acidity at the tooth surface can induce demineralization and softening, therefore leaving the tooth structure susceptible to abrasive factors such as tooth brushing. When the surface of the tooth structure is softened by acid, mechanical forces such as brushing can cause irreparable damage on tooth surface. Remineralization of the softened surface can help prevent this damage from occurring.

Relative dentin abrasivity (RDA) is a standardised measurement of the abrasive effect that the components of a toothpaste. It was not designed to rank safety of toothpastes, The RDA scale compares toothpaste abrasivity to standard abrasive materials and measures the depth of cut at an average of 1 millimetre per 100,000 brush strokes onto dentine. Currently, the claim on products such as toothpaste are not regulated by law, however a dentifrice is required to have a level lower than 250 to be considered safe and before being given the ADA seal of approval. The vast majority of toothpastes commercially available have RDA values of 250 or less and are unlikely to have a significant impact on abrasion of tooth structure over a lifetime of use. On average, data suggests less than 400 μm of tooth wear occurs over a lifetime using toothpastes of RDA 250 or less. The RDA score of a toothpaste is not the primary factor to consider when managing and preventing dental abrasion. Other factors such as the amount of pressure used whilst brushing, the type, thickness and dispersion of bristle in the toothbrush and the time spent brushing are significant factors that contribute to the risk of dental abrasion.

If the cause of abrasion is due to habitual behaviours, the discontinuation and change of habit is critical in the prevention of further tooth loss. The correct brushing technique is pivotal and involves a gentle scrub technique with small horizontal movements with an extra soft/soft bristle brush. A toothpaste containing increased fluoride will also help combat the increased sensitivity and risk to dental decay. Toothpastes containing stannous fluoride have been shown to inhibit acid erosion of tooth structure, thereby reducing its susceptibility to abrasive wear. Fluoride varnish can also be used as a preventive measure for patients at high risk of dental erosion, as the fluoride varnish increases resistance to erosion and subsequent tooth wear. However, in the case of dental decay, aesthetic concerns or defects close to the pulp a restoration may be completed. Further restorative work may be required when the lesion compromises the overall strength of the tooth or when the defect contributes to a periodontal problem the lesion may be restored. Once abrasive lesions have been diagnosed and treated they should be closely monitored to identify further progression or potential relief of symptoms.