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The purpose of this study was to determine if QLF could be used to longitudinally monitor lesion progression following application of a fluorescein dye. Cementum was removed from the root surface of 12 human premolars and the exposed dentine gently abraded. Each root was covered in transparent nail varnish, save for a small exposed window (5E3 mm). Two teeth were selected as controls, one positive (demineralisation, no fluorescein) and the other negative (fluorescein, no demineralisation). The teeth were mounted in black plastic caps. 5 ml of sodium fluorescein (0.1 g in 500 ml) was added for 10 min and baseline QLF images were taken (mean .Q -9.7). The teeth were then exposed to a demineralising solution at 37°C with gentle agitation. At 12, 48, 72 and 120 h, the teeth were removed from the solution, gently dried and the fluorescein applied. QLF images were taken, before returning the teeth to the demineralising solution for the required time. Each tooth was sectioned with one half retained for TMR analysis. The other half was exposed to fluorescein and a baseline QLF image taken (mean .Q -216.13). The roots were then placed into a remineralising solution for 7 and 28 days. Each QLF image was imported into an image analysis package (Paint Shop Pro v.5), inverted, grey-scaled and analysed by one examiner using QLF v.2.00. Mean .Q for the demineralising stages was -131.62 (12 h), -252.65 (48 h), -303.1 (72 h) and -363.78 (120 h). For remineralisation mean .Q for 7 days was -95.59 and 120 days -75.85. TMR data confirmed the presence of demineralisation/remineralisation. This study has shown that the application of fluorescein to dentinal lesions permits longitudinal analysis with QLF. This may have an application in in situ and in vivo studies. |