An X-ray Microtomography Study of the Effect of an Experimental Statherin-like Peptide on Demineralisation and Remineralisation of Enamel

Abstract

The salivary protein, statherin, plays an important role in enamel homeostasis. It forms a bioactive complex with calcium and phosphate releasing these ions when pH decreases. Statherin also forms part of the enamel pellicle forming a protective barrier against bacterial and dietary acids. The purpose of this thesis was two-fold: firstly, to study the effect of a 21 amino acid peptide identical to the N terminus of Statherin (StN21) on enamel de - and remineralisation in vitro and secondly, to undertake biocompatibility assays of this peptide to demonstrate its safety for use in a clinical trial. X-ray microtomography (XMT) is a quantitative, non-destructive method of measuring mineral change. Using XMT to quantify mineral changes, StN21 demonstrated a statistically significant decrease in demineralisation rate when compared to control lesions exposed to phosphate buffered saline (PBS). Whole Statherin protein and sodium fluoride solutions were used as positive controls and were found to have demineralisation rates equivalent to those seen with StN21. Remineralisation was neither enhanced and nor inhibited by StN21. Biocompatibility assays were undertaken using a well-established buccal mucosal model. Viability assays measured enzyme activity within the mitochondria of the cell; after 48 hours in growth medium, the cell cultures remained viable with no difference between PBS and StN21 exposed cells. Enzyme linked immunosorbant assays measuring IL-1α and IL-8 production by mucosal cells exposed to StN21 showed no difference when compared with PBS and whole protein Statherin exposed samples. StN21 does not irritate or sensitise the mucosa and cells indicating a lack of toxicity. In conclusion, StN21 significantly decreases the rate of enamel demineralisation in vitro and is non-toxic to the oral mucosa. StN21 has potential as a therapeutic agent for prevention of dental caries and erosion. Further clinical research is required.