On the use of collagen type-I in the growth of hydroxyapatite on micro-fabricated biomimetic dentin

Abstract

Dentin hypersensitivity is a condition that affects 4 – 14% of western populations like the U.K. It is characterised by a short sharp pain in the gums, usually experienced when an individual consumes cold food or drink. Typical treatments that are primarily delivered by sensitive toothpastes initially relied upon disruption of neuronal activity with potassium ions. However, more recently the most advanced over the counter treatments now act to occlude the tubules present in dentin that are involved in the hydrodynamic cause of dentinal pain. Pre-clinically, the efficacy of these occlusive treatments are assessed in a hydraulic conductance apparatus. This apparatus forces a simulated saliva through a thin section of dentin known as a Pashley dentin disc to determine a volumetric flow rate before and after treatment with the active of interest. Due to the innate variability of dentin a high degree of variability makes the assessment of novel actives difficult and unreliable. This body of work covers the attempt to fabricate a synthetic dentin disc that replicates the microstructure of the dentin and its tubules and in addition, the surface chemistry of the collagen and hydroxyapatite composite observed in dentin in vivo. The focus of this thesis is largely on the exploration of using collagen immobilised at the surface of this silicon mimetic dentin disc to template the growth of hydroxyapatite via a biomineralisation-like processes. An automated perfusion apparatus is used in attempt to mineralise a collagen coated mimetic dentin disc under conditions of continuous flow. A study of this flow mineralisation process over time was undertaken largely by Scanning Electron Microscopy. Whilst deposition of material was achieved at the mimetic dentin surface the full composition and morphology remained inconclusive however this work made significant headway into highlighting suitable routes forward in terms of fabrication and characterisation.