Biological Behavior of Human Dental Pulp Cells in Response to Carious Stimuli Analyzed by PCNA Immunostaining and AgNOR Staining

Abstract

The change in proliferative and metabolic activities of human dental pulp cells responding to carious stimuli was studied by means of immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and silver-binding nucleolar organizer region (AgNOR) staining. We classified the pulp tissues into five groups according to the progression of dental caries, ranging from grade 0 (the pulp of noncarious teeth) to grade 4 (the pulp of perforated carious teeth). PCNA-positive pulp cells were detected only in advanced dental caries (grades 3 and 4), and the difference in immuno-positive rate was significant between the two grades (p < 0.001). However, the mean number of AgNORs per nucleus increased even in the early phase of dental caries, significant differences being detected between grades 1 and 2 (p < 0.005), 2 and 3 (p < 0.005), and 3 and 4 (p < 0.001). Our data suggested that the metabolic activity of dental pulp cells was enhanced in the early phase of dental caries. However, proliferation of pulp cells occurred later in small degrees during fully developed caries such as grades 3 and 4. The slow and weak response in cellular proliferation might contribute to the usual fragility of the pulp to various assaults including caries or pulpitis.

A Quantitative Light Microscopic Study of the Odontoblast and Subodontoblastic Reactions to Active and Arrested Enamel Caries without Cavitation

“…Those findings are in accordance with clinical observations [Massler, 1967;Nyvad and Fejerskov, 1987;Schüpbach et al, 1990] and after lesion arrest of deep carious lesions following stepwise excavation [Bjørndal et al, in press]. The second methodological problem has been technical difficulties in obtaining thin undemineralized tooth sections [Yoshida and Massler, 1964;Brännström and Lind, 1965;Kuwabara and Massler, 1966;Langeland, 1987;Magloire et al, 1988;Kobayashi et al, 1996]. In this study we applied a method to produce undemineralized tissue sections for cellular examinations, which previous studies have proved to be appropriate for examination of teeth [Donath, 1987;.…”

“…Due to technical difficulties it has not been possible to examine pulp-dentinal reactions to caries in relation to the undemineralized features of the overlying hard tissue lesion [Yoshida and Massler, 1964;Brännström and Lind, 1965;Kuwabara and Massler, 1966;Langeland, 1987;Magloire et al, 1988;Kobayashi et al, 1996]. It is well known that human enamel is a microporous solid [Bergman, 1963;Dibdin, 1993] allowing transport of stimuli from the external environment to the dentine/pulp complex.…”

Expression of insulin‐like growth factor‐1 and proliferating cell nuclear antigen in human pulp cells of teeth with complete and incomplete root development

“…It plays crucial roles during DNA replication in cell growth. PCNA allows detecting cell proliferation because it is increased specially during S phase of cell cycle, which is why it has been used as a biological or endogenous immunohistochemical marker to verify cell proliferation (Kobayashi et al. 1996, Matsuzaka et al.…”

Plithotaxis, a collective cell migration, regulates the sliding of proliferating pulp cells located in the apical niche

“…In physiological conditions, no proliferating cells are found in the human coronal pulp and only a low proliferative activity is confined to the radicular pulp (1). Upon advanced dental caries, PCNA stained cells become detectable in the coronal pulp (2). After dental lesion and 5-bromo-2 0 -deoxyuridine (BrdU) labeling, the staining disappears from the pulp-dentin border, and a wide range of proliferative cells is seen within the dental pulp.…”