Inductive Influences of Demineralized Dentin and Bone Matrix on Pulp Cells: an Approach of Secondary Dentinogenesis

Abstract

The effects of demineralized dentin and bone matrix on dental ectomesenchymal cells were evaluated after observation periods of two or three weeks. Autogenous dentin and bone matrix, obtained from the crowns of primary molars or maxillary cortical bone, respectively, were demineralized with 3% acetic acid and implanted into pulpal or papilla sites of erupting dog teeth: first molars, fourth premolars, and canines. Dentin histogenesis associated with odontoblastic arrangement was demonstrated in relation to all dentin implants in pulpal sites. Deposition of osteodentin, followed in some areas by tubular predentin formation, was observed in contact with bone implants in pulpal sites. In papilla sites, the dentin implantation exhibited bone-like matrix formation, while bone implants were encapsulated by connective tissue. The interactions of pulp cells with demineralized dentin matrix constitute a model for experimental induction of secondary dentinogenesis and odontoblast-like cell differentiation.

Autoradiographic analysis of odontoblast replacement following pulp exposure in primate teeth

“…Also, the fibroblast-like cell population most likely contains multiple types including undifferentiated and differentiated lines (Baume, 1980;Yamamura et al, 1980). Based on our findings and those of others (Fitzgerald, 1979;Yamamura et al, 1980;Ruth, 1984;Tziafas and Kolokuris, 1990), the following hypothesis for the odontoblast cell replacement mechanism would seem reasonable. Odontoblast replacement under our experimental conditions involves multiple DNA replications and.…”

“…Indeed, fibroblast-like cells are able to differentiate into either osteoblasts or chondroblasts depending on the nature of the surrounding matrix and the amounts of vascular-derived oxygen (Indue et al, 1981). Given the proper environment, they may also be able to differentiate into replacement odontoblasts, as suggested by Fitzgerald (1979), Yamamura et al (1980, Yamamura (1985) and Tziafas and Kolokuris (1990). The shift in numbers of fibroblast-like and odontoblast-like cells in zone 1 between Days 8 and 10, was not seen between Days 10 and 12 in zone 1.…”

“…(1980) and Yamamura (1985). Tziafas and Kolokuris (1990) demonstrated that cells in the deep pulp can differentiate into odontoblasts when exposed to demineralized dentine surgically implanted in the pulp. Yamamura et al (1980) concluded that injury caused by partial pulpotomy capped with pure calcium hydroxide leads either to dedifferentiation of mesenchymal cells in the deep pulp into undifferentiated mesenchymal cells, which then migrate toward the wound, undergo all phases of division and subsequently redifferentiate into new odontoblasts, or to direct induction and differentiation of existing undifferentiated mesenchyma1 cells.…”

“…Studies with [3H]-thymidine in wounded, non-exposed pulps (Sveen and Hawes, 1968) as well as in pulps wounded by exposure (Feit, Metelova and Sindelka, 1970;Yamamura et al, 1980;Yamamura, 1985) have demonstrated that DNA replication can occur during the replacement of odontoblasts lost due to trauma. The replacement cell population in this type of pulp healing could be located anywhere within the coronal pulp, as suggested by Fitzgerald (1979) Yamamura et al (1980) Yamamura (1985 and Tziafas and Kolokuris (1990). The cell types involved could be from fibroblastic (Fitzgerald, 1979;Yamamura et al, 1980), vascularrelated (Yamamura et al, 1980), and undifferentiated mesenchymal (Yamamura et al, 1980) lines.…”

“…Others have proposed that replacement odontoblasts are derived from either undifferentiated mesenchymal cells in the pulp proper that are induced to differentiate into odontoblasts or from differentiated pulpal cells that are induced to dedifferentiate into undifferentiated cells and then redifferentiate into odontoblasts (Fitzgerald, 1979;Yamamura et al, 1980;Yamamura, 1985;Tziafas and Kolokuris, 1990). This process would require recruitment and induction of a cell population(s) within the pulp proper after pulpal trauma, one or more DNA replication cycles and finally differentiation into functioning odontoblasts.…”