The Effects of Illumination and Focal Distance on Light-Induced Fluorescence Images in vitro

When using quantitative light-induced fluorescence a number of factors can influence illumination level. The purpose of this study was to investigate, using a high-resolution camera and fibre-optic light source, the impact of illumination level and focal distance on common quantitative light-induced fluorescence outcomes. Twenty-four extracted teeth were examined using 6 illumination levels and 4 focal distances. Analysis was conducted using multiple linear regression models fitted to log ΔQ, log ΔF and log area with clustering of teeth and robust standard errors. Separate models were used for the different light and focal levels. The regression coefficients were significant for both ΔQ and ΔF but not area. Despite the significant regressions the actual effect was very small, and unlikely to confound clinical trial or practice results.