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Objective: The objective was to determine the effect of imaging geometry on evaluating natural white-spot lesions with Quantitative Light-induced Fluorescence (QLF). Methods: A total of thirty-four extracted human permanent premolars and molars that had white-spot lesions on the interproximal surface were selected based on visual inspection. The specimens were each adjusted to a final thickness of 3.0 mm. Images were acquired with the QLF system at 5° intervals from the white-spots ranging from 60° to 120°. The specimens were rotated transverse to the long axis of the tooth (pitch angle) and around the long axis of the tooth (roll angle). Fluorescence loss (DF [%]) and lesion size [mm2] were determined with QLF. DQ, fluorescence loss integrated over the lesion size [% x mm2], was also calculated. The effects of the pitch angle and roll angle were examined using ANOVA. Results: Statistically significant differences were found among different angles. Pitch angle appeared to have a linear effect on DF, with a lower DF for angles less than 90° and a higher DF for angles greater than 90°. Roll angle did not appear to affect DF. Pitch and roll angles affected lesion size, with the largest size observed at 90° and sizes diminishing in both directions from 90°. The effect of pitch angle on size was more pronounced than was roll angle. DQ was affected by pitch and roll angles with the largest value at 90° and values decreasing in both directions from 90°. Conclusion: This study suggests that angle is an important factor to control when performing in vitro and in vivo QLF studies. |