Objective: To investigate the microstructures and mechanical characteristics of enamel and dentin of primary and permanent teeth by AFM, analyze their relationships and provide information for bionics and designs of dental materials. Methods: After embedding, cutting and grinding, 10 primary teeth and 10 permanent teeth were randomly divided into four groups. The morphology of samples was obtained by AFM and the roughness and Young’s modulus were calculated by JPK DP Data processing version 4.0 software. Results: In permanent teeth groups, the enamel rods arrange more tightly than those in primary teeth groups. The roughness of primary enamel （1203±39.5nm）was higher than permanent teeth（954.6±30.5nm）.The Young′s modulus of enamel in primary teeth（80.4±7.7GPa）was lower than permanent teeth（90.8±2.2GPa）. The roughness of dentin in primary teeth （1695±67.6nm）is higher than permanent teeth （1210±45.3nm）and the Young′s modulus of dentin in primary teeth（19.8±1.9 GPa）was lower than the permanent teeth （23.1±1.0 GPa）. Conclusions: The mechanical characteristics of primary and permanent teeth are closely related to their microstructures.

Objective: To test and contrastive analysis the crystal structure and mechanical characteristics of enamel and dentin of primary and permanent teeth by XRD and contact angle meter, provide information and experimental data for bionics and designs of dental materials. Methods: Teeth were randomly divided into four groups, including permanent teeth enamel group, permanent teeth dentin group, primary teeth enamel group, and primary teeth primary teeth. The crystal structure and mechanical characteristics of teeth were tested by XRD and contact angle meter. The results were analyzed with one-way ANOVA. Results: The crystalline and grain size of enamel were significantly larger than dentin’s. The crystalline and grain size of enamel and dentin of permanent teeth were also larger than primary teeth. Conclusions: The XRD and contact angle of primary and permanent teeth are closely related to their structures, Dental filling material to give full consideration to their different property.