A scanning electron microscopic study on the differences between newly erupted teeth and old teeth with reference to fissure enamel surfaces and contents.

Scanning electron microscopy of the fissure enamel surfaces of newly erupted permanent teeth and old sound teeth long-standing against caries demonstrated two distinct features; prismatic enamel and prismless enamel. Prismatic enamel was commonly found on the walls of fissures of newly erupted teeth and rarely found on both sides of fissures of old teeth. Prismless enamel was usually found on both sides of fissures of old teeth. Various types of calcified contents were almost confined on the prismless enamel surfaces of the occlusal orifice of fissures of old teeth, while organic materials and bacterial contents were found on the prismatic enamel surfaces of newly erupted teeth.