# Regular Physical Activity and Dental Erosion: A Systematic Review
## 1 Introduction  
Dental erosion is the irreversible pathological loss of enamel and dentine, which are chemically dissolved by acids with an exogenous or endogenous origin, not those produced by oral bacteria [1, 2]. Tooth erosion is a condition with a multifactorial aetiology that includes chemical, biological, and behavioural factors. The erosive potential of acidic beverages depends on their chemical properties, such as the pH, titratable acidity, mineral content, adherence to the tooth surface or calcium chelation. Examples of biological factors are the salivary flow rate, acquired pellicle, and tooth structure and relation to cheeks or tongue. Moreover, behavioural factors, such as dietary habits, regular physical activity resulting in dehydration and decreased salivary flow, excessive oral hygiene, or, on the other hand, chronic additions (e.g., alcoholism), may predispose individuals to dental erosion [3]. Sources of acid delivery to the oral cavity can be divided into two groups: intrinsic and extrinsic. Among intrinsic factors there are vomiting in anorexia or bulimia, gastroesophageal reflux, or other chronic gastrointestinal disorders. Extrinsic acids come from external means, such as diet (e.g., acidic beverages: fruit juices, isotonic or energy drinks, wine), chronic consumption of selected medication, or the occupational environment [4, 5]. It can be challenging to detect initial erosion lesions because they may be imperceptible. The erosive process is much faster than caries, as frequent exposure to acids leads to permanent hard tissue loss with accompanying hypersensitivity. During the oralexamination, erosion defects have a characteristic appearance--a smooth glazed enamel surface [6; 7]. The fundamental principle of treatment is the reduction of acid exposure and the enhancement of remineralisation [8]. The basic prevention is mainly based on limiting the frequency of consuming low pH products [9]. Patients should also take care of their oral hygiene by using low abrasive pastes and regular application of preparations containing fluoride or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) [10; 11; 12]. Moreover, tooth brushing immediately after the enamel's exposure to acidic drinks must be avoided in order to enable pH neutralisation of the oral environment and not cause more considerable losses through the mechanical action [13; 14]. Physically active consumers are generally not aware of the erosive potential of sports drinks. These beverages have a low pH value and contain citric acid as an ingredient, which is an organic acid provoking a drop in salivary pH [15]. Citric acid might also induce the process of chelation, which is the dissolution of calcium ions from the structure of enamel [16]. Both of these factors play a significant role in the process of erosion. Most sports drinks' pH values are contained within the range from 3.16 to 3.70 [17]. Although critical pH value for enamel, depending on ontogenetic tendencies, oscillate between 5.5 to 6.5 [18]. This leads to the conclusion that beverages with a pH value below 5.5 can have an adverse effect on enamel and dentine. Other aspects influenced by ontogenetic predispositions are the quantity and quality of saliva as well as the resilience of the enamel. Saliva has protective values against acids causing dental erosion [19]. Therefore, athletes with any deficits of quality or quantity of saliva may be at higher risk of dental erosion. The common consumption of sports drinks might cause a reduction in the microhardness of enamel and lead to irreversible erosive lesions [15]. The level of lesions depends on the frequency of consumption and the length of time the beverage is kept in the mouth [20]. Frequent intake of isotonic drinks might cause sensitivity, loss of dental structure, and dentine exposure. Studies showed that the temperature of consumed sports drinks influences their erosive potential.