Tooth wear, also called dental abrasion, is a normal physiological process that occurs throughout the whole life of a human. It is negligible and at an early age depends on the type of food consumed and the way of chewing. Solid food and prolonged chewing could result in increased abrasion, which is still within the normal range. In some cases, however, such as lower mineralisation of the teeth, dental fluorosis, presence of bruxism (involuntary habitual grinding of the teeth at night), and nervous tension, the normal abrasion turns into a pathological process which leads to the loss of a large amount of hard dental tissue (dental abrasion).
It is scientifically proven that the upper and lower teeth in the human mouth touch on specific points, called articulation points. Right after growth of permanent teeth, these points are very small and over time expand due to normal abrasion. 
In the process of abnormal abrasion, the contact points transform very rapidly from points to whole surface, which can have a diameter of 5 to 10 mm. Firstly, the enamel is affected at the contact points, which are located on the slopes and tops of the tooth cusps. Over time the entire enamel is abraded and the dentine is exposed, which also begins to wear away in faster speed than the enamel because of its reduced hardness. So after a while the cusps of molars and premolars are abraded and become flat.
The incisors are also affected – their crowns are shortened, which disturbs biting and have flawed appearance. Teeth abrasion as a physiological process occurs slowly with no obvious symptoms; as a pathological process, however, it develops rapidly and passes through several stages – from abrading individual cusps to completely erased dentine and reaching the nerve of the tooth and in very severe cases – complete abrasion of an entire tooth. As a result of abrasion the facial appearance of a person is also affected – there is a descent of the lower third of the face. There are changes in the mandibular joint, which are characterized by clicking sound and pain. In the process of dental erosion after overcoming the enamel, sensitivity to thermal (hot and cold) and chemical irritants occurs. A special feature is that the chewing surfaces of the abraded teeth do not develop caries, due to continuous deposition of secondary dentine and the disappearance of places where plaque can accumulate. Often dental crowns which have been erased form sharp edges that could injure the tongue and cheeks during chewing.
Besides abrasion of the chewing surfaces of the teeth, there can be abrasion on the side surfaces (from the cheek). This erosion is called a wedge-shaped defect and does not occur naturally, but is a result of external factors.
Role in the formation of wedge-shaped defects have the use of a hard toothbrush, incorrect horizontal movements and abrasive toothpaste (whitening toothpastes). Wedge-shaped defect is a dent on the border between the tooth and gums (gum line) which has a smooth and polished surface and normal hardness. In an advanced stage it becomes yellow. Most often the incisors, canines, and premolars are affected. In most cases the wedge-shaped defect occurs with slight pain on touching or sensitivity from hot and cold.
At an early stage of tooth abrasion, fluoride varnishes and gels can be applied that reduce sensitivity and strengthen enamel. Changing the technique of brushing by avoiding horizontal movements and replacing the toothbrush could also help. At an advanced stage of tooth abrasion, composite restorations, ceramic inlays or metal-ceramic crowns can be made depending on the degree of progress of the process.
