erosion; infants using feeding bottles containing fruit juices (especially when used as a comforter) are therefore at greater risk of acid erosion. Saliva acts as a buffer, regulating the pH when acidic drinks are ingested. Drinks vary in their resistance to the buffering effect of saliva. Studies show that fruit juices are the most resistant to saliva's buffering effect, followed by, in order: fruit-based carbonated drinks and flavoured mineral waters, non-fruit-based carbonated drinks, sparkling mineral waters; mineral water being the least resistant. Because of this, fruit juices in particular, may prolong the drop in pH levels. A number of medications such as chewable vitamin C, aspirin and some iron preparations are acidic and may contribute towards acid erosion. Certain drugs can cause hyposalivation (low quantity or quality of saliva) which is considered a risk factor for acid erosion. Intrinsic acidic sources Intrinsic dental erosion, also known as perimolysis, is the process whereby gastric acid from the stomach comes into contact with the teeth. This is often secondary to conditions such as anorexia nervosa, bulimia nervosa, gastroesophageal reflux disease (GERD) and rumination syndrome. Dental erosion can also occur by non-extrinsic factors. There is evidence linking eating disorders with a range of oral health problems including dental erosion, caries and xerostomia. Reduced salivary flow rate, a common symptom of bulimia, predisposes an individual to dental erosion due to increased vulnerability to the effects of acidic food and drinks. Self-induced vomiting increases the risk of dental erosion by a factor of 5.5 compared to healthy controls. Lesions are most commonly found on the palatal surfaces of the teeth, followed by the occlusal and then the buccal surfaces. The main cause of GERD is increased acid production by the stomach. This is not exclusive to adults, as GERD and other gastrointestinal disorders may cause dental erosions in children. Behaviour Acid erosion often coexists with abrasion and attrition. Abrasion is most often caused by brushing teeth too hard. Any frothing or swishing acidic drinks around the mouth before swallowing increases the risk of widespread acid erosion. Sucking citrus fruits can also contribute to acid erosion. Diagnosis In-vivo studies are advantageous in assessing erosion directly from the patient's mouth. There are numerous signs of dental erosion, including changes in appearance and sensitivity. Colour One of the physical changes can be the colour of teeth. Dental erosion can lead to two major tooth colour change – the