Keratin protein mediated bio-remineralisation of early enamel erosion. A pilot study

To investigate the potential of keratin protein to mediate remineralisation of early enamel erosion by acting as a scaffold.

Polished human enamel samples (n = 44) were eroded in 0.3 % citric acid (pH 2.7, 20 min) and baseline step height (SH) and Knoop microhardness (KHN) were recorded. Samples (n = 11) were randomly assigned to artificial saliva (C, control), 1450 ppm sodium fluoride (NaF), 10 % keratin (K), or 10 % keratin cross-linked with 7.48 µL TEGDMA (KT). A single application of NaF, K, or KT was applied onto enamel surface, while C was untreated. This was followed by 7 days of incubation in unstirred artificial saliva at 37 °C. SH and KHN were remeasured, after which samples were re-challenged with citric acid and measured again. Randomly, selected specimens were examined with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

Mean baseline SH and KHN for all groups after erosion were - 5.66 µm (SD 0.16) and 249.08kgf/mm (3.95). After the first erosion and remineralisation cycle, there were no significant differences in, SH and KHN between groups (p > 0.05). After re-challenge, there was significant differences in SH between C and NaF (p < 0.05). For KHN, significant differences were observed between control and NaF with both K and KT (p < 0.05). Profilometric images, SEM and EDS confirmed a retained precipitate layer on K, KT and NaF after acid re-challenge.

The deposition of keratin onto human enamel produced significantly less step height and microhardness change than the control but showed comparable efficacy to NaF. Keratin offered no added benefit when cross-linked with TEGDMA.

These results suggest keratin can facilitate enamel remineralisation, forming a protective layer resistant to chemical challenge.