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The aim of this in vitro study was to detect and monitor the severity of erosive lesions by quantitative light-induced fluorescence (QLF) using different thresholds (T) for fluorescence loss. 10 extracted human teeth were selected on the basis of lesion free buccal (n = 5) and occlusal surfaces (n = 5). All teeth were fixed in standardised acrylic blocks to allow an accurate resetting in a laboratory jack. The teeth were varnished leaving a small window which was exposed to 200 ml 0.1% citric acid (pH 2.74) under gentle agitation. After taking baseline QLF images (T -1%: mean .Qoccl = -12.7; .Qbucc = -6.8) fluorescence measurements of the teeth were performed every 30 min for 3 h immediately after rinsing with distilled H2O and air-drying for 5 s. The fluorescence loss of all specimens was determined using QLF software at T -1%, -5%, -10% and -20%. Fluorescence decreased significantly after 30 min at T -1% on occlusal surfaces (mean .Qoccl = -92.8; p = 0.043) and after 60 min on buccal surfaces (mean .Qbucc = -49.6; p = 0.032), respectively. At T -10% significant differences were first found after 2 h. However, at T -20% no significant changes were observed. QLF revealed a continuous progression of erosive lesions by increasing .Q values at each threshold throughout the experiment. It can be concluded that at a threshold of -1% QLF can detect early erosive changes. The method has the potential for monitoring of lesion formation in vitro. |