Mucin5b and albumin mediate greater protection against dental erosion than statherin

Our previous data demonstrated that whole saliva (WS) provided better protection against erosion than parotid saliva (PS) after five erosion cycles. Using a profilometer, WS produced significantly less step height (4.16 ± 0.57 μm) than PS (6.41 ± 0.71 μm) (p < 0.0001). The responsible proteins for protection are unknown. This study aimed to measure four key proteins in an in-vitro erosion model comparing WS and PS. 30 human enamel samples were prepared and assigned to 2 groups: (WMS: n = 15) and (PS: n = 15); three subgroups each: control (n = 5), one cycle (n = 5), five cycle erosion (n = 5). Samples were immersed in the corresponding saliva for 24 h (control) followed by a further 30 min prior to exposure to a 10 min citric acid (pH 3.2) followed by 2 min water rinse (one cycle). This cycle was repeated five times. Enamel pellicle was eluted using filter papers for all groups. Proteins were immunoblotted for: mucin5b, albumin, carbonic anhydrase VI (CA VI) and statherin. Antibody binding was quantified using ImageLab software using purified protein standards of known concentration (n = 3) to assess quantity and reproducibility. Data were log transformed to attain normality and linear models and post hoc tests were used for the statistical analysis. We found albumin and mucin5b were more dominant in WMS pellicles than PS (p < 0.0001) whereas CA VI and statherin were dominant in PS pellicles (p < 0.0001). Mucin5b in WS pellicles, but absent in PS, at control [(57.5 ± 33.3 ng) significantly increased after five cycles (121.5 ± 19.9 ng) p < 0.0001]. Statherin in PS pellicles increased after one cycle (415.8 ng ± 43.6 ng) compared to control [210.4 ± 25.9 ng] (p < 0.0001) but returned to control levels after five cycles (180.6 ± 23.5 ng). In conclusion The greater resistance of WMS pellicles to enamel erosion compared to PS pellicles relates to protein composition. Thus Mucin5b and albumin-rich pellicles gave better protection than carbonic anhydrase and statherin-rich pellicles. Funded from Departmental funding.