Abstract: A reciprocal sliding friction and wear tester was performed to investigate and compare the friction and wear behaviors of enamel and dentin with primary and permanent teeth sliding against Si₃N₄ ball under the lubrication of artificial saliva. The worn surface morphologies and microstructures of the tested teeth were observed by scanning electron microscopy. The wearing capacity was measured by 3D phase shift laser interferometer. It was found that the friction and wear behaviors of the natural teeth were strongly dependent on the microstructures. The permanent teeth enamel had the best wear resistance among the different test samples, there were slight abrasion and scuffing on the surfaces. The primary teeth enamel showed that the flaw and slight scuffing on the appearance of sample. Corrosive-abrasive characteristics appeared on the enamel of permanent and primary teeth. The primary teeth dentin showed similar friction and wear behaviors as the permanent dentin. Contrary to the above, they had relatively weak and fragile microstructures, so there was more severe scuffing and abrasion signs on the worn surface.