Efficacy of Two Toothpaste in Preventing Tooth Errosive Lesions Associated with Gastroesophageal Reflux Disease  
[PERSON]  
1 Department of Neurosciences--Dentistry Section, Padova University, 35128 Padova, Italy;  
[EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (A.G.S.); [EMAIL_ADDRESS] (S.M.)  
[PERSON]  
1 Department of Neurosciences--Dentistry Section, Padova University, 35128 Padova, Italy;  
[EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (A.G.S.); [EMAIL_ADDRESS] (S.M.)  
[PERSON]  
1 Department of Neurosciences--Dentistry Section, Padova University, 35128 Padova, Italy;  
[EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.S.); [PERSON](S.M.)  
[PERSON]  
1 Department of Neurosciences--Dentistry Section, Padova University, 35128 Padova, Italy;  
[EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.S.); [EMAIL_ADDRESS] (S.M.)  
[PERSON]  
2 Department of Industrial Engineering, Padova University, 35131 Padova, Italy; [EMAIL_ADDRESS] (L.P.); [EMAIL_ADDRESS] (R.B.)  
[PERSON]  
2 Department of Industrial Engineering, Padova University, 35131 Padova, Italy; [EMAIL_ADDRESS] (L.P.); [EMAIL_ADDRESS] (R.B.)  
[PERSON]  
1 Department of Neurosciences--Dentistry Section, Padova University, 35128 Padova, Italy;  
[EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.); [EMAIL_ADDRESS] (M.C.S.); margiula.ssignoriello@student.  
is returned to the oral cavity can cause erosion of dental enamel [7]. Dental enamel is composed of 96% inorganic material and the remaining 4% organic material and water [8]. The inorganic part is mainly composed of hydroxyapatite, which is a crystalline structure made up of calcium (Ca) and phosphate (P). Enamel does not have the intrinsic ability to repair itself when it is affected by specific dental pathologies, such as caries, abrasions or fractures, because it contains no living cells [9]. Therefore, when enamel is exposed to the acidic environment of oral cavity, the only possibility of repairing it is through the application of alloplastic materials, such as toothpastes. They are valuable vehicles through which enamel can be protected and potentially improved in its ability to resist an acid reflux. In the context of dental erosion, fluoride toothpastes have been shown to offer some amount of protection, but erosive lesions develop despite their widespread use: Presence of fluoride in solution during dissolution of hydroxyapatite during an acid attack will make the solution highly supersaturated with fluorhydroxyapatite. Fluoride will adsorb to the surface of the partially demineralized crystals and attract calcium ions. Since carbonate-free or low-carbonate apatite is less soluble, these phases will form preferentially instead of the original mineral, under the action of the dissolved minerals. This coating will be less soluble due to the exclusion of carbonate and incorporation of fluoride, rendering the enamel more resistant to future acidic challenges [10]. Therefore, research is focusing on different chemical compounds to make dental hard tissues more resistant to erosive demineralization. At present, polyvalent metal cations, phosphates or biopolymer additives have shown encouraging results [11].  
The aim of this study is to investigate the effectiveness of two different toothpastes, containing fluoride and non-fluoride, in preventing erosion due to gastroesophageal reflux disease. The first null hypothesis is that no difference in term of teeth remineralization is present between the two toothpaste. The second null hypothesis is that no difference in terms of teeth protection against an acid attack is present between the two studied toothpastes.