Scanning Microscopy


Age-related changes in the closing of dentinal tubules of Japanese permanent mandibular incisors were surveyed using a non-destructive replication technique suitable for SEM analysis at the magnifications of up to X3,000. The areas of openings of dentinal tubules on occlusal surfaces decreased significantly between a 20-39-year age group and a 40+ age group, but the number of the openings tended to decrease. Heavy toothwear on occlusal surfaces of these Japanese permanent incisors was evident even at 27 years of age. A subject or 30 years of age showed surprisingly small number of the opening of dentinal tubules on occlusal surface. The occlusal surfaces became smoother in 40-59-year age group as closure of dentinal tubule of openings increased. Early heavy toothwear and early closure of the openings of dentinal tubules may be related to Japanese ethnic diet such as dried hard sardines whole which contain hard bones. Japanese often crush shells of crabs and shrimps with their incisors and canines as they eat.

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