Methods: 50 previously extracted teeth of all types were selected to ensure a wide range of ages (mean 52.5 years (±14.7), 56% female). The enamel and dentine of each sample was imaged using QLF; enamel (buccal and palatal), dentine (mesial and distal). Following imaging each tooth was sectioned into two halves and then the cut surfaces imaged using QLF. An assessment of dentine translucency was then undertaken. From each QLF image the red/green values were obtained and these were then correlated against age. The dentine translucency estimated age was also correlated against known age to act as a positive control.
Results: QLF values correlated poorly using any of the surfaces imaged, with the most favourable being the composite red green value, r=0.06. The results showed that translucent dentine, when imaging intact teeth, had no significant effect on the auto-fluorescence of enamel or dentine (á=0.05). When teeth were sectioned, the correlation improved dramatically to r=0.59 but fell below the r=0.82 achieved using the translucency measurement.
Conclusions: Age of dental sample has no effect on the translucency of either enamel or dentine imaged under QLF conditions despite the presence of histological changes in dentine. This is an important finding for those researchers employing teeth from unknown sources in vitro or those undertaking long term clinical trials over a number of years in vivo. These findings tend to support the theory that the stable enamel-dentinal junction is responsible for the auto-fluorescence observed under QLF conditions.