Odontoblast processes in dentin revealed by fluorescent Di-I.

Abstract

There has been controversy about the length and structure of the odontoblast process within dentin since the earliest histologic studies of teeth. Our objective was to use the fluorescent carbocyanine dye Di-I combined with a new gelatin embedment procedure and confocal microscopy to determine the structure and extent of odontoblast processes in developing and mature rat teeth, injured rat molars, reparative dentin, and adult monkey teeth. We found that odontoblast processes do not extend into outer dentin or to the dentin-enamel junction except during early stages of development. Those in innervated regions of crown are long and straight, whereas those in roots are extensively branched and shorter. Cavity injury to crown dentin caused odontoblast fragments to be aspirated into outer dentin. In reparative dentin the odontoblast pmceses were branched and similar to those in roots. We used photoconversion and electron microscopy to show that Di-I f i i the entire odontoblast after gelatin embedment, including the cytoplasm. This is a different type of carbocganine staining from any previously reported, and it also stains other cells in adjacent hard tissues such as bone and cementum. The Di-I-gelatin method is a new way to use carbocyanine dyes. It has enabled us to solve a long-standing controvezsy about the histology of teeth, and it should be useful for many other studies of cell structure. ( J Hisrochem Cyrochem 43159-168, 1995)

Glial Network Responses to Polymicrobial Invasion of Dentin

“…These observations are consistent with previous studies where an increased density, and a notable development of afferent peptidergic innervations, was recorded in early stages of pulp response [Byers and Sugaya, 1995;Rodd and Boissonade, 2002]. Further, numerous studies on dental pulp innervation have shown that sensory nerve fibres are dynamic elements which react to injury and inflammation by sprouting and altered cytochemical phenotype [Byers and Närhi, 1999].…”

Confocal microscopy of dentinal tubules in human tooth stained with alizarin red

“…Interglobular dentine is present only in the crown and not in the root, whereas the granular layer of Tomes is present only in root dentine (Avery 1991;Piesco 1994). The branching pattern of the dentinal tubules is different in the crown and the root (Byers and Sugaya 1995). These characteristics of coronal and radicular dentine are confirmed in the present study.…”

“…The structure of dentinal tubules has been investigated using various methods such as light microscopy including the use of microradiographs, scanning and transmission electron microscopy, and atomic force microscopy. Confocal microscopy has been also applied for the observation of dentine (Watson 1989(Watson ,1990Byers and Sugaya 1995;Kabasawa et al 1995), however, the effective staining method for the dentinal tubules is limited. For the staining of mineralized tissues, fluorescent dyes such as alizarin red, calcein, and tetracycline have been used for vital staining.…”

Dental neuroplasticity, neuro‐pulpal interactions, and nerve regeneration

“…2), with much fewer nerve endings in peripheral pulp or dentin of the roots. The gradients are present from the earliest periods in development of the dental sensory innervation of crown, and they correspond to gradients in pulpal secretion of growth factors such as nerve growth factor (Byers et al, , 1992a or glial-derived neurotrophic factor (de Vincente, 2002) and to odontoblast morphologic phenotypes (Byers and Sugaya, 1995;Ohshima et al, 2001). During maturation and aging, the neural patterns are maintained where primary dentin and odontoblasts survive, with a continued focus on the pulp/ dentin complex beneath enamel Byers, 1996).…”

“…2). The pulp cells are varied by region within the tooth, and very different cytochemistry and cell structure have been noted for coronal odontoblasts compared to radicular odontoblasts, subodontoblastic fibroblasts, undifferentiated mesenchymal cells, resident immunocompetent cells, vascular endothelium, vascular pericytes, and the supportive cells for the nerve fibers Byers and Sugaya, 1995;Fouad, 2002;Maeda et al, 1994;Ohshima et al, 2001;Okiji, 2002;Suda and Ikeda, 2002). Thus, the possible cellular interactions between the varieties of dental nerve fiber and the local cells are vast in normal teeth, and are amplified after injury by invading inflammatory and immune cells, and by infection (Inoue and Shimono, 1992).…”