Identification of acid resistant proteins in the acquired enamel pellicle in vivo after exposure to citric acid and hydrochloric acid as a function of variation of formation time: proteomic study

Abstract

Dental erosion is a chronic lesion, characterized by the loss of hard tissue due to exposure to acids of non-bacterial origin. It can be classified taking into account its etiology, extrinsic or intrinsic, determined by acids from the diet or from the condition of gastroesophageal reflux episodes, respectively. The acquired pellicle (PA) is an integument formed in vivo as a result of the selective adsorption of salivary proteins on the surface of the tooth, which also contains glycoproteins and lipids. The presence of proteins in PA forms a protective interface on the surface of the tooth, participating in all the interfacial events that occur in the oral cavity. It is an organic film, free of bacteria, that covers the dental tissues. Studies have focused on the characterization and protective impact of the acquired pellicle formed on the enamel surface. However, the studies present in the literature in relation to the analysis of the alterations of PA composition after exposure to acids, studied these acids separately, that is, in different experiments. Based on this, the objective of this study will be to evaluate the protein profile of the pellicle obtained after exposure to citric acid (1%, pH 2.5) and hydrochloric acid (0.01 M, pH 2.0) at two different times of (3 minutes and 2 hours), in order to identify possible acid-resistant proteins according to the type of acid used. Participants will be 9 volunteers, over 18 years of age, non-smokers, with good general and oral health. The acquired pellicle will be formed in the morning, for 3 minutes and 120 minutes, after prophylaxis with pumice stone. Pellicles formed will be collected after application of citric acid (1%, pH 2.5) and hydrochloric acid (0.01 M, pH 2.0) and collected at two different formation times as mentioned above using filter paper soaked in citric acid 3%. Samples will be processed for nLC-ESI-MS/MS analysis. The MS/MS spectra obtained will be compared with human protein databases (SWISS-PROT). The free quantification of markers will be performed using the PLGS software.