## 1 Introduction  
Dental erosion is considered a partial chemical dissolution of the hard tissues of the tooth surface. This phenomenon is caused mainly by repeated exposure to acids of both microbiological and non-microbiological origin. Simultaneous and/or subsequent exposure to mechanical forces might result in tooth surface loss [1]. Furthermore, the dissolution of enamel is closely associated with some precise chemical parameters, such as pH, saliva buffering capacity, and quantity, and external factors, such as acidity, viscosity, calcium, phosphate and fluoride ion concentration in drinks and food [2]. It is widely demonstrated that these parameters have a direct influence on tooth surface strength, and this is the reason why they are normally used to calculate the degree of saturation of various substances, so as to quantify the demineralizing force in hard tissues [3]. Substances with a low pH, high tittatable capacity and high buffering capacity have the greatest erosive force; conversely, substances with high concentrations of the Ca\({}^{2+}\) ion and phosphate cause the least dissolution of the tooth surface, and can enhance its chemical stability and integrity [4]. At the present time, dental erosion is a daily problem, accentuated by the consumption of acidic drinks, which have a high demineralizing potential. Unfortunately, a lot of chemicals, additives and sugar are hidden in most food and drinks of regular intake, such as carbonated, alcoholic, non-alcoholic and sports drinks and fruit juices. These substances have the capability to decrease the pH of the saliva, which enhances the ongoing process of dental erosion [5]. As far as the origin of the acid is concerned, extrinsic and intrinsic erosions can be distinguished. In fact, the extrinsic ones are generally caused by acids in food, and the severity of the erosion is associated with several factors, such as nutrition, saliva and mechanical and frictional stress [6]. An important factor is contributed by the digestive enzymes released by the salivary glands, and, in particular, by their response to hunger and various food nutrients. In fact, these enzymes were found to increase their activity in response to food, revealing the dependence of their production on food [7]. It is known that tooth enamel is made up mostly of inorganic material, which represents about 96%, while the remaining 4% is organic material and water [8]. The inorganic material consists of hydroxyapatite crystals, which comprise a mineral with the chemical composition Ca\({}_{10}\)(PO\({}_{4}\))\({}_{6}\)(OH)\({}_{2}\) with a hexagonal prismatic structure. Enamel, which is predominantly inorganic, is not composed of living cells with specific repair capabilities with regard to diseases such as caries, abrasions and/or fractures [9]. When this happens, erosive tooth wear might occur, especially in the cervical region, just above the gingival margin, on the incisal edge of anterior teeth or on the cusps of posterior teeth. It is in particular the mechanical forces imposed on anterior teeth that can ultimately lead to the eventual breakage of a tooth in the esthetic region. A similar situation could cause an impairment, not only from an esthetic point of view, but also in terms of the masticatory function, and speech and labial support might be highly compromised. In the case of a growing child, changes in the occlusal vertical dimension may lead to an incorrect development of bones, muscles and temporomandibular joints [10; 11]. To sum up, when an acidic environment is formed inside the oral cavity and the surfaces of the enamel are consequently exposed, a process of demineralization begins, which may vary from person to person. To slow down this process, the use of specific products, such as toothpastes and fluoride varnish, allows repair by remineralization [12]. Moreover, the remineralization process can be also induced by products such as glass ionomer cements, which have the ability to release fluorine ions and composite materials that can release CaPO\({}_{4}\) anions.