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The objective of this study was to determine if changes in fluorescence intensity during dehydration could be used to assess white-spot status with quantitative light-induced fluorescence (QLF). 120 human sound polished enamel specimens, 4E4E2.5 mm, were used. Sound, The in vivo repositioning with an intra-oral camera of dental images with or without the use of rigid frames is tedious and time consuming. Anew way to enable video assisted repositioning (VID-REP) of QLF images is presented. To compare two digital images each image was divided into an array of blocks. Per block, the average grey level of the pixels was calculated and plotted in a regression graph. The relative tooth position in the images was represented by the angle and correlation of the regression line. VID-REP was developed further to perform these calculations on a live image compared with a reference image. At a correlation higher than a user-defined value, the live images were stored automatically. The buccal surface of an extracted molar, which contained a very large and difficult to analyse white spot area extending over several surfaces was used. 29 QLF images were made without and with the video repositioning software. To simulate in vivo conditions, both the tooth and the camera were handheld. The average correlation between baseline and follow-up images was 0.93 (SD 0.04) for repositioning by eye and 0.995 (SD 0.002) using VID-REP. .Q was -272 (SD24, SD% 9) mm2·% for repositioning by eye and -247 (SD 9, SD% 4) mm2·% using VID-REP. In conclusion, the use of video repositioning allows to follow changes in teeth more reliably than with repositioning only by eye. Its application for in vivo use seems promising. |