Proteomic profile of the dentine pellicle modified with plant polyphenols and fluoride.

OBJECTIVES: Despite its protective role, the dentine pellicle has rarely been studied, therefore we aimed to map out the proteomic profile of in vitro dentine pellicles before and after modification. MATERIALS AND METHODS: A total of 135 human dentine specimens were prepared. After initial pellicle formation with 150 µl pooled human saliva (37 °C, 30 min), the dentine specimens were immersed in one of 9 pellicle modification solutions (2 ml/specimen): deionized water (non-modified pellicle), SnCl2/NaF/AmF (commercial solution containing 800 ppm Sn2+ and 500 ppm F-), NaF solution (500 ppm F- ), and six polyphenol solutions (2 mg / ml) with or without 500 ppm F-: blueberry extract (BBE and BBE + F-), green tea extract (GTE and GTE + F-) and grape seed extract (GSE and GSE + F-). After another aliquot of saliva (150 µl, 37 °C, 60 min), the pellicles were harvested with sodium dodecyl sulphate by rubbing with cotton balls, and taken to proteomic analyses by Liquid Chromatography-Tandem Mass Spectrometry after tryptic digestion. RESULTS: A total of 382 proteins were identified in all the proteomic analyses for all groups. Pellicle modification with fluoride, either NaF or SnCl2/NaF/AmF, led to the presence of 12 or 14 exclusive proteins, respectively, whereas modification with the solutions containing polyphenols presented less exclusive proteins (4-6 proteins). The number of exclusive proteins was even lower for when polyphenols and fluoride (GTE + F- and GSE + F-) were used, with lower abundance of proteases. CONCLUSIONS: We conclude that NaF and SnCl2/NaF/AmF significantly modify the proteome of the dentine pellicle. The combination of fluoride with polyphenols further lowers the abundance of proteins and proteases, which explains the positive effect of these solutions on the dentine pellicles. CLINICAL RELEVANCE: Plant extract solutions with fluoride can significantly modify the proteomic structure of the dentine pellicle, which clarifies the mechanism of action of polyphenols on the protection of dentine demineralization.