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The purpose of this study was to determine if QLF could detect, and quantify, early secondary demineralisation adjacent to two restorative materials, one a fluoride-containing compomer (Dyract), the second a non-fluoride-containing composite (Spectrum). 18 human premolar teeth were selected based upon lack of clinically visible caries or enamel defect. Each was gently pumiced and abraded with wetand- dry paper. A single bur hole was placed in the buccal and lingual surface of each tooth using a high-speed handpiece. These 'cavities' were then restored, following manufacturer's instructions with either Dyract or Spectrum, randomly allocated ensuring that 50% of buccal surfaces were restored with Dyract. Transparent nail varnish was applied to the teeth, ensuring that an exposed enamel window was present around the restorative material. Baseline QLF images were taken. Teeth were then placed into a gently agitated demineralising solution. Each was removed at 48, 96, 144 and 192 h, gently air-dried and QLF images taken. Analysis was conducted by an examiner blinded to the restorative material allocation using QLF Version 2.00. Data recorded were ¢Q at 5% threshold. Demineralisation occurred around both materials, ¢Q at 48 h being: Dyract 8.97, Spectrum 10.71; 96 h: Dyract 8.64, Spectrum 17.26, and at 192 h: Dyract 24.6, Spectrum 40.05. There was a numerical trend for enamel adjacent to Dyract to demineralise less than that next to Spectrum, although this was only statistically significant at 192 h (p ! 0.05). The analysis of the demineralisation was rapid, incorporating the material within the analysis patch rather than excluding it. In both instances, the restorative material had an increased fluorescence in relation to enamel, enabling the loss of fluorescence associated with demineralisation to be quantified longitudinally with ease. |