The posteruptive enamel maturation of the primary dentition requires a longer period as can be suspect from quick progress of embryogenesis. It is characterized by alterations of the surface area of teeth. After eruption the deciduous teeth not yet satisfy to requirements of function. There are needy a lot of physico-chemical adaptations. By means of scanning micoscopy from 51 children during 2 years (six times each after 4 months) were 306 labial surface replicas of the first maxillar incisor examined. At replication the children were aged between 26 and 70 months. Every labial areal was subdivided to 9 sectors and quantfied the number of usures, scratches etc. (2754 sectors) to frequency distributions according quantities between 0 - 3. The frequeny curve had a increasing linearity from 26. up to 54. month of life. After that till 66. month of life they were steady, and after this age the frequency of scratches decreases. In 30 % of the children the relief become shallow. We can conclude, that after the age of 60 month of life the maturity is almost completed. This phase occurs in the late functional time. The maturation process needs more than 60 % of the functional period of the tooth in the mouth. The polarizing microscopy at 32 ground slides from Dentes lactales gave a favorable support to the maturation results.