Inductive effect of native dentin on the dentinogenic potential of adult dog teeth.

Autogenous dentinal matrix was exposed to the pulp cells of adult dogs in order to determine whether the mature pulp cells possess the ability to differentiate into odontoblast-like cells as a direct response to known inductive influences. The pulps of molars, premolars, and canines of three dogs (2 to 4 yr old) were mechanically exposed through buccal class V cavities. Pieces of demineralized or native dentin and predentin were implanted in the pulp sites for periods of 2 to 6 wk. The reactions were analyzed by light microscopy. Induction of dentin formation was observed only after native dentin implantation; either as early response to exposure of predentinal surfaces or around mineralized dentin after 3 postoperative wk. Encapsulation by fibrous connective tissue or matrix degradation was seen around demineralized dentin implants. A characteristic enhancement of circumferential pulpal dentin deposition around the implantation site was demonstrated after native dentin exposure to light and scanning electron microscopic examination. These data indicate that specific inductive influences given by the native but not the acid-conditioned dentin, when it is exposed to the pulp environment of adult teeth, are able to direct differentiation of odontoblast-like cells and to enhance the biosynthetic activity of primary odontoblasts.