Changes in the Proteomic Profile of Acquired Enamel Pellicles as a Function of Their Time of Formation and Hydrochloric Acid Exposure

Abstract

Objective: Changes in the protein profile of acquired enamel pellicles (AEP) formed in vivo over different time periods were evaluated after the application of hydrochloric acid (HCl). Methods: Nine subjects were submitted to dental prophylaxis with pumice. After 3 or 120 min, the teeth were isolated with cotton rolls and 50 μL of 0.1 M HCl (pH 1.0), 0.01 M HCl (pH 2.0), or deionized water were applied on the buccal surface of the teeth for 10 s. The AEP was then collected using an electrode filter paper presoaked in 3% citric acid. After protein extraction, the samples were submitted to reverse-phase liquid chromatography coupled to mass spectrometry (nano LC-ESI-MS/MS). Label-free quantification was performed (Protein Lynx Global Service software). Results: A total of 180 proteins were successfully identified in the AEP samples. The number of identified proteins increased with the time of pellicle formation. Only 4 proteins were present in all the groups (isoforms of IgA, serum albumin, and statherin). The greatest number of proteins identified uniquely in one of the groups was obtained for the groups treated with HCl after 2 h of pellicle formation (approx. 50 proteins). Conclusion: Proteins resistant to removal by HCl, such as serum albumin and statherin, were identified even in the short-term AEP. In addition, 120-min pellicles present many proteins that are resistant to removal by HCl. This suggests an increase in protection against intrinsic acids with the time of pellicle formation, which should be evaluated in future studies.

Deep Proteomic Insights into the Individual Short‐Term Pellicle Formation on Enamel—An In Situ Pilot Study

“…Most published methods for in vivo‐biofilm analyses include mechanical elution by rubbing the dental surface with filter papers. [ 14,19,20,22,25–28,52 ] These protocols imply weak points like relatively poor elution yields and the need to recover the rubbed proteins from the used filter papers. Consequently the eluted protein amounts are comparatively low and necessitate the use of pooled samples from several subjects, preventing insights in individual proteomic profiles.…”

“…[ 23 ] In some studies, the identified proteins were classified according to their biological function, origin, and molecular interaction. [ 14,25,28,29 ] However, due to the deficiency of individual proteomic profiles and the analysis of the corresponding saliva, no trends of favored protein adsorptions based on these classifications were revealed. Two recent in situ‐studies focused on the characterization of the individual 3‐min pellicle proteome formed on ceramics specimens.…”

Differences in the Natural Enamel Surface and Acquired Enamel Pellicle following Exposure to Citric or Hydrochloric Acid

“…Furthermore, statherin is reduced in the AEP in eroded teeth compared to healthy teeth in the same individual . Interestingly, statherin is resistant to removal from the AEP by HCl although only to short, 10 s exposures [Taira et al, 2018]. However, the reduced protein in the AEP measured in this study has not been attributed to reduction in specific protein/s.…”

“…Laboratory studies have shown that saliva can play a greater protective role against citric acid than HCl [Wiegand et al, 2008]. TPCs have been observed to remain high after acid exposure suggesting that the HCl penetrates through the pellicle [Taira et al, 2018]. Interestingly, statherin has been observed to remain stable after HCl exposure which is different to the in vivo studies testing dietary acids [Taira et al, 2018].…”

“…TPCs have been observed to remain high after acid exposure suggesting that the HCl penetrates through the pellicle [Taira et al, 2018]. Interestingly, statherin has been observed to remain stable after HCl exposure which is different to the in vivo studies testing dietary acids [Taira et al, 2018]. This has important implications when researching preventive mechanisms, as it is unknown if salivary pellicle composition influences erosive tooth wear or eroded tooth surfaces influence the salivary pellicle composition.…”