Assessment of the Effects of Enamel Remineralization After Treatment with Hydroxplapatite Active Substance: SEM Study  
[PERSON]  
1 Department of Medicine and Technological Innovation, University of Insubria, 21100 Varese, Italy;  
1 [EMAIL_ADDRESS] (M.R.J. deor973@outlookit (D.L.P); [EMAIL_ADDRESS] (E.I.S. );  
[EMAIL_ADDRESS] (M.C.) [PERSON]  
2 Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy;  
2 [EMAIL_ADDRESS] (M.C.) [PERSON]  
1 Department of Medicine and Technological Innovation, University of Insubria, 22100 Varese, Italy;  
1 [EMAIL_ADDRESS] (M.R.J. deor973@outlookit (D.L.P); [EMAIL_ADDRESS] (E.I.S. );  
[EMAIL_ADDRESS] (M.C.) [PERSON]  
1 Department of Medicine and Technological Innovation, University of Insubria, 21100 Varese, Italy;  
[EMAIL_ADDRESS] (M.C.) [PERSON]  
1 Department of Medicine and Technological Innovation, University of Insubria, 221100 Varese, Italy;  
[EMAIL_ADDRESS] (M.C.) [PERSON] 1  
2 Department of Medicine and Technological Innovation, University of Insubria, 221100 Varese, Italy;  
[EMAIL_ADDRESS] (M.C.) [PERSON]  
3 Department of Human Sciences, Innovation and Territory, University of Insubria, 22100 Como, Italy;  
[EMAIL_ADDRESS] (Correspondence: [EMAIL_ADDRESS] (Correspondence: pieroantonio. Demineralization is a slow process that weakens tooth structure and causes erosion by dissolving calcium and phosphate ions from the HA crystals in the enamel with acids from food or bacterial metabolism [13]. Under the acidic circumstances caused by bacterial metabolism or food, H+ ions attach to the carbonate and phosphate groups in the hydroxyapatite, releasing the previously bonded anions and dissolving the mineral structure. Because hydroxyapatite contains many carbonates, which react with a small amount of H+ ions, it is especially vulnerable to acid attack. The integrity of the enamel is weakened over time by this acid-driven process, which produces an acidic chemical reaction [11; 14; 15]. Although demineralization is often challenging to diagnose in its early stages, it becomes visible as a change in enamel translucency and color as the structural changes affect optical properties. Demineralized dental tissues are weak regions that open the door to possible cavity formation and are more prone to fracture [15; 16; 17; 18; 19]. In 2010, caries was the most common disease in adults and the 10 th most frequent in children: around 2.4 billion people had untreated caries in permanent teeth, while 621 million children had the same problem in their primary teeth [20; 21; 22]. [PERSON]'s chemical-parasitic theory postulates that oral bacteria convert sugars derived from carbohydrate consumption into acids. This pH lowering demineralizes teeth and results in caries [23]. There are factors affecting the two crucial processes of demineralization and remineralization. The main factors contributing to enamel demineralization are cariogenic bacteria, fermentable carbohydrates, and alterations in salivary composition, which facilitate the dissolution of the apatite crystal lattice and calcium and phosphate ions. However, minerals such as fluoride, an adequate level of saliva, antimicrobials, and specific local ions in the oral environment promote enamel remineralization. Although both of these interconnected processes create a dynamic balance within the oral cavity [19; 24; 25; 26], the natural remineralization process or redeposition of minerals within the enamel is essential to the maintenance of dental health by preventing caries. Fluoride is a substance particularly known for its remineralizing properties. The presence of fluoride promotes the deposition of calcium (Ca\({}^{2+}\)) and phosphate (PO\({}_{4}\)\({}^{3-}\)) ions on the enamel surface and creates a compound, fluorapatite, that is more resistant to acidic conditions than hydroxyapatite [24; 27; 28]. However, one must always consider the amount of fluoride present, because too much can lead to fluorosis, a pathological condition that causes enamel hypomineralization and aesthetic problems.