The Physico-chemical Characterisation of Bioactive Glass Air-abrasion on Human Enamel

Student thesis: Doctoral ThesisDoctor of Philosophy


Objectives: This research aimed to characterise the physico-chemical interaction of bioactive glass 45S5 (BAG) air-abrasion with human enamel including the controlled and selective removal of substrates and the remineralisation of enamel white spot lesions (WSLs). Materials and methods: The effect of six operating parameters on air-abrasion dynamic cutting efficiency / patterns was assessed using an enamel analogue material (MacorTM) and white light profilometry. Standardised resin composite restorations created within MacorTM blocks, were removed in simulated clinical conditions and scanned using triangulation laser profilometry to investigate the effect of operating parameters on the selective resin composite removal using BAG air-abrasion. The remineralisation of artificial enamel WSLs treated using BAG mixtures were evaluated using Raman micro-spectroscopy, microhardness and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). The physical and optical changes in WSLs pre-conditioned using air-abrasion with BAG-polyacrylic acid (PAA-BAG) powder were detected using non-contact profilometry and optical coherence tomography (OCT). All comparisons were considered statistically significant if p<0.05. Results: Significant differences in air-abrasion cutting efficiency / pattern were observed according to the tested parameters. BAG air-abrasion removed resin composite more selectively than conventional alumina air-abrasion and the effect of altering the unit’s operating parameters was significant. Enamel WSLs treated with BAG mixtures exhibited a significantly higher Knoop microhardness compared to the negative control. Raman micro-spectroscopy detected significantly higher phosphate content and the SEM images revealed mineral depositions on the surface of treated lesions. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion increased WSL surface area. This pre-treatment increased Knoop microhardness and the mineral content of remineralised WSLs. Conclusions: The ultraconservative clinical applications of BAG air-abrasion can be improved by altering the operating parameters. BAG and PAA-BAG can remineralise enamel WSLs. Pre-conditioning the lesion surface with PAA-BAG air-abrasion modifies the lesion surface physically and consequently enhances remineralisation using BAG 45S5 therapy.
Date of Award2014
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAvijit Banerjee (Supervisor) & Ian Thompson (Supervisor)

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