RELATIVE ABILITY OF LASER FLUORESCENCE TECHNIQUES TO QUANTITATE EARLYMINERAL LOSS IN-VITRO

This in vitro investigation was undertaken to explore two different no ndestructive methods to detect very early demineralization. These meth ods were based on the premise that the clinical detection of caries at a very early stage of formation might permit more efficient reversal of the caries process than may occur when lesions are detected at a mo re advanced stage, such as a so-called 'white spot'. The methods evalu ated in this study were quantitative laser fluorescence (QLF) and an e xperimental dye-enhanced laser fluorescence (DELF) technique. Prepared and polished bovine enamel specimens were demineralized in a conventi onal lactic acid-Carbopol solution for varying periods of time between 0 and 24 h with an area of sound enamel retained on each specimen. Th e coded and randomized specimens were then analyzed for the presence a nd severity of enamel demineralization using QLF after which they were exposed to a selected dye (Pyrromethene 556) and similarly examined u sing DELE The specimens were then sectioned and examined by convention al transverse microradiography and by confocal laser-scanning microsco py. Results were analyzed statistically with sensitivity and specifici ty determined using sound enamel as the reference, The results indicat ed that QLF could detect demineralization which occurred as a result o f 8 h exposure to the decalcification solution and was able to quantif y changes in lesion severity associated with longer demineralization. While DELF was capable of detecting enamel demineralization after only 2 h exposure to the decalcification solution, it was unable to quanti fy increasing amounts of demineralization associated with longer perio ds of exposure to the decalcification solution. In summary, while DELF was able to detect very early demineralization, only QLF was capable of detecting and quantifying changes in the extent of the decalcificat ion occurring with demineralization periods up to 24 h.