The overall aim of this thesis is to examine the underlying physical basis of dentinal hypersensitivity and to assess methods of treating this cause using imaging techniques. The scanned probe microscopy (SPM) techniques are then extended to the study of carbon-based electrode surfaces, as described in the final chapter. The use of scanning electrochemical microscopy (SECM), combined with in situ pressure-time measurements, is described as a means to investigate the flow of fluid through human and bovine dentine, and the subsequent effect of occlusion treatments on this flow. Scanning Ion Conductance Microscopy (SICM) is also introduced as a technique for imaging dentine, with instrument design and development described, and also calibration of the technique. Laser scanning confocal microscopy (LSCM) coupled to a constant volume flowpressure measuring system is introduced as a new technique for the quantitative measurement of fluid flow across porous materials. The methodology described herein firstly allows a ready assessment of the general efficacy of treatments via hydraulic permeability measurements. Second, LSCM images allow the nature of the flow process and the mode of action of the treatments to be revealed at high spatial resolution. For the particular case of dentine, we demonstrate how the method allows candidate treatments to be compared and assessed. To complement the studies into dentinal hypersensitivity, microscopic dissolution of bovine enamel is investigated. This chapter describes a novel approach, based on SECM, to promote the localised dissolution of bovine enamel, effected by the application of a proton flux to the enamel surface from a UME positioned within 5 μm of the surface, in aqueous solution. The approach results in a well-defined “acid challenge” yielding well-defined etch pits that were characterised using light microscopy and white light interferometry. The effect of etching in the presence of lactate is considered, as is the effect of treating the enamel samples with sodium fluoride prior to etching. The approach described is amenable to mass transport modelling, allowing quantitative interpretation of etch features. The techniques developed throughout the thesis are applied to the investigation of two types of carbon electrodes: boron-doped diamond (BDD) and highly ordered pyrolytic graphite (HOPG). Heterogeneities in the electroactivity of these substrates are explored.A scanning micropipet contact method (SMCM) is described which promises wide-ranging application in imaging and quantifying electrode activity at high spatial resolution.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:502848 |
| Date | January 2008 |
| Creators | Williams, Cara Gail |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/55855/ |
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