Enamel and dentin microhardness of deciduous and permanent teeth formed in fluoride-iodine deficiency

Abstract

Aim. To study the microhardness of enamel and dentin of deciduous and permanent teeth formed in fluoride-iodine deficiency.
 Methods. Enamel and dentin microhardness was examined on sections of 47 deciduous and 43 permanent teeth. Six topographic zones were examined on each tooth section, 24 imprints were performed. Enamel and dentin microhardness was determined on PMT-3M device and by Vicker’s Hardness Test with a load of 50 g for 5 seconds.
 Results. Enamel and dentin microhardness of permanent teeth is higher than that of deciduous ones. In the surface layer of enamel the microhardness of permanent teeth is 2.33-2.09 times higher compared to deciduous teeth (in incisors - by 2.24 times, canines - by 2.09 times, molars - by 2.33 times); 2.25-1.94 times higher in the middle layer (in incisors - by 2.17 times, canines - by 1.94 times, molars - by 2.25 times); 2.15-1.89 times higher in the enamel layer at the enamel-dentine junction (in incisors - by 2.15 times, canines - by 1.89 times, molars - by 2.03 times). In the dentin layer at the enamel-dentin junction, dentin microhardness of permanent teeth is 1.90-1.71 times higher than of deciduous ones (in incisors - by 1.78 times, canines - by 1.71 times, molars - by 1.90 times); 2.14-2.0 times higher in the middle dentin layer (in incisors - by 2.08 times, canines - by 2.0 times, in molars - by 2.14 times); 2.05-1.71 times higher in the near-pulp layer (in incisors - by 2.05 times, canines - by 1.71 times, molars - by 1.87 times).
 Conclusion. Enamel and dentin microhardness of deciduous and permanent teeth formed in fluoride-iodine deficiency varies considerably; microhardness of hard tissues of permanent teeth is approximately 2 times higher than that of deciduous teeth.