In-vivo studies are advantageous in assessing<unk>  directly from the patient's mouth. There are numerous signs of dental<unk> , including changes in appearance and sensitivity. Color One of the physical changes can be the color of teeth. Dental<unk>  can lead to two major tooth colour change - the first being a change of color that usually happens on the cutting edge of the central incisors. This causes the cutting edge of the tooth to become transparent. A second sign is a yellowish tint on the eroded tooth. This occurs because the white enamel has eroded away to reveal the yellowish dentin beneath. On top of clinical examination, the dentist may take intra-oral photographs to monitor the extent and progress of<unk> . Clinical photographs lead to comparable results to a visual examination, however both may result in an underestimation of the extent of tooth wear. Shape Dental study casts A change in shape of the teeth is also a sign of dental<unk> . Teeth will begin to appear with a broad rounded concavity, and the gaps between teeth will become larger. There can be evidence of wear on surfaces of teeth not expected to be in contact with one another. If dental<unk>  occurs in children, a loss of enamel surface characteristics can occur. Amalgam restorations in the mouth may be clean and non-tarnished. As tooth substance around restorations erodes away, fillings may also appear to be rising out of the tooth. The teeth may form divots on the chewing surfaces when dental<unk>  is occurring. This mainly happens on the first, second, and third molars. To monitor the change in shape over time, dentists can create and retain accurate, serial study casts. Dentists may also employ dental indices to guide their diagnosis and management of the condition. A scoring system referred to as Basic Erosive Wear Examination (BEWE) grades the appearance or severity of wear on the teeth by the extent of hard tissue loss. It is noted that indices are useful in monitoring the most severe clinical changes in tooth wear. However, they lack comprehensiveness as they cannot measure the rate of progression and cannot monitor all teeth affected by<unk> . There is also a lack of an index which is universally accepted and standardised. One of the most severe signs of dental<unk>  is cracking, where teeth begin to crack off and become coarse. Other signs include pain when eating hot, cold, or sweet foods. This pain is due to the enamel having been eroded away, exposing the sensitive dentin. Optical properties Based on the optical changes induced in eroded tissue by the lesions, in 2015 Koshoji et al. also demonstrated in a novel method that by using laser speckle images (LSI) it is possible to acquire information on the microstructure of the enamel and detect minimal changes, such as early non-carious lesions. No clinical data has been published to demonstrate the effectiveness of this technique in vivo.
Acid erosion
Demineralization 
Necrosis
Craterization
Calcification
Inflammaging
Glandular metaplasia
Dysbiosis