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. In-home and clinical whitening have been proven to increase the likelihood of an individual experiencing dental abrasion. It is believed that dental abrasion due to the whitening process is caused by a combination of both mechanical and chemical irritants, for example, using whitening toothpaste and at home bleaching kits together. 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 Relative dentin abrasivity (RDA) is a standardised measurement of the abrasive effect that the components of a toothpaste. The RDA scale was developed by the American Dental Association (ADA), government bodies and other stakeholders to quantify the abrasivity of a toothpaste. It was not designed to rank safety of toothpastes, and all toothpastes with an RDA of 250 or less are considered to be equally safe for regular use in terms of abrasivity. The RDA scale compares toothpaste abrasivity to standard abrasive materials and measures the depth