Introduction. Polymerization of light-cure materials is accompanied by the loss of intensity of luminous flux of photopolymerization apparatus in hard teeth tissues and in the materials layer. The intensity of luminous flux, passed through the tissues or material, depends on their optical density, which is directly related to transparency. How-ever, the quantitative assessment of hard teeth tissues transparency is not developed yet, and its age-related dynam-ics is not studied. Therefore, there are no objectively reasonable recommendations in restorative dentistry concerning recreation of transparency in frontal teeth restorations from the point of view of aesthetics. The purpose of the researchis operational analysis of luminous flux intensityofLED photopolymerization apparatus while passing through samples of hard teeth tissues, extracted from individuals of different age, as well as the analysis of tissues transparency indices. Materials and methods. Samples of hard teeth tissues were divided into 4 groups: the first group included sam-ples of hard teeth tissues extracted from children, aged 10-12 years old, the second, third and fourth groups included samples of hard teeth tissues extracted from individuals, aged18-20, 40-45 years old years and over 60 years old, respectively. Samples of enamel and dentin of 2. 0 mm thick, as well as enamel samples with subjacent dentine with total thickness of 4. 0 mm have been studied in each group. 180 samples have been studied in all. Operational analysis of luminous flux intensity has been performed by technique, developed at Donetsk National Medical University, named after M. Gorky, utilizing the original laboratory facility. Transparency of the samples has been examined by computer digital image analysis using the developed software product “LEKA 1”. Results of the research and their discussion. Once a luminous flux passed through the enamel samples its highest intensity was detected in the third age group and constituted 85,19+0,32%. The index of transparency of the highest intensity was also detected in the same group and constituted 8,73+0,08 a. u. (arbitrary units). Minimal indices have been detected in the enamel samples of the first group, i. e., 71,43+0,51% and 7,38+0,16 a. u., respectively. In all dentin samples the intensity of penetrated luminous flux and transparency was statistically lower than in enamel samples. The highest results were detected in the first group of samples and constituted 51,23+0,50% and 5,54+0,13 a. u., and the lowest ones were registered in samples from the fourth group and constituted 39,18+0,45% and 4,27+0,12 a. u., respectively. The results of operational analysis of intensity of luminous flux and transparency in samples of enamel and dentin were the following: the highest indices were in the samples from the third group and constituted 23,06+0,51% and 3,61+0,06 a. u., and the lowest indices were detected in samples from the fourth group and constituted 14,32+0,32% and 2,78+0,05 a. u. Conclusions. Thus,under the high indicesof transparency of samples of hard teeth tissues the indices of intensity of luminous flux, passed through the samples, were also high. The most transparent enamel was in the samples of teeth, extracted from individuals, aged from 40 to 45 years old, and the least transparent enamel was in samples, made from hard teeth tissues, extracted from children, aged 10-12 years old. At the same time, at this age dentin is the most trans-parent, and the least transparent it is in individuals older than 60 years old.
