Scanning electron microscopy of the walls of tubules in human coronal dentine

Abstract

Twenty-one fully-formed healthy human premolars were fixed, resin-impregnated and freeze-fractured. Specimens were critical-point dried. The wall of the dentinal tubules was lined with a two-layered structure which extended from the pulp-predentine border to the dentine-enamel junction; there was a fibrous outer layer and an amorphous, membrane-like inner layer. The lining sheath was separated from the odontoblast process by a space which widened toward the outer surface of the dentine, although occasionally in the mid and outer dentine the lumen was constricted by transverse septa of the sheath which were in close proximity with the odontoblast process. Some tubules were divided into a system of chambers by transverse extensions of the membrane-like inner layer of the sheath.