Exposure to Acids Changes the Proteomic of Acquired Dentine Pellicle

Objectives: For the first time, this study characterized the proteome of the acquired pellicle formed on human dentine. The changes in this proteome after exposure to lactic or citric acid were also evaluated.

Methods: Volunteers (n=9) wore a mandibular device containing 6 specimens of human root dentine. After the device remained in the volunteers' oral cavities for 10min or 2h to allow the formation of the acquired pellicle in situ, the specimens were immersed in citric acid (1%, pH 2.5) or lactic acid (0.1M, pH 4.8) or deionized water for 20s. In sequence, the pellicle was collected with an electrode filter paper soaked in 3% citric acid. This procedure was repeated for two additional days following a crossover protocol. After harvest, proteins were subjected to reverse phase liquid chromatography coupled to mass spectrometry (nLC-ESI-MS/MS). MS/MS data were processed and submitted to Proteome Discoverer software. Searches were done using SWISS-PROT and TrEMBL databases for human proteins.

Results: In total, 223 distinct proteins were identified in the dentine acquired pellicle in each of the different conditions. Exposure to citric acid dramatically reduced the number of identified proteins. This did not occur for lactic acid. Acid-resistant proteins, such as mucins, were identified after pellicle was exposed to lactic or citric acid.

Conclusions: These proteins could be related to protective effect of tooth homeostasis. Moreover, in the future, they could be candidates to the development of a supplemental therapy for the prevention and treatment of dental caries and dental erosion.

Clinical Significance: This study indicates some acid-resistant proteins that could be used in dental products to prevent dental caries and erosion.