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Effect of Enamel Matrix Derivative on Mouse Fibroblasts and Marrow Stromal Osteoblasts

There is increasing evidence that the cells of the epithelial root sheath synthesize enamel matrix proteins and that these proteins play a fundamental role in cementogenesis and periodontal tissue formation. Emdogain, enamel matrix derivative (EMD), is a porcine enamel matrix derived product used to enhance regeneration of the peridontium after inflammatory destruction. Today, little is known about EMDs potential regenerative properties on cell function. The purpose of this study was to investigate the effects of EMD on mouse fibroblasts (L 929 cells) and rat marrow stromal osteoblasts. For effects on cell proliferation, the L 929 cell lines were plated in 24-well culture plates at an initial density of 10,000 cell/mL and allowed to attach. Following a 24-h incubation within Dulbeccos modified eagle medium (DMEM) enriched with 10% fetal bovine serum, DMEM supplemented with 0 (Control), 50 μg/mL and 100 μg/mL of EMD was added and cultures maintained for 96 h. Cell proliferation was measured at 24, 48, 72 and 96 h as the total cell number per well and cell morphology was investigated. Osteoblasts were digested from mouse tibia marrow and were plated in similar manner as with L 929 cells, while the observation periods were 2, 6, 8 and 10 days in this group. Although both cell types were able to maintain their original cell morphology throughout the tests, in both cell groups the number of cells in the EMD groups at each observation period were not significantly different than that in the control group (ANOVA, p > 0.05). Moreover, EMD failed to show any impact on cell growth with higher concentration (ANOVA, p > 0.05). These results suggest that although EMD had no cytotoxic effect on mouse fibroblasts and stromal marrow osteoblasts, the same material failed to enhance the growth of both cell types.

Effects of Current and Potential Dental Etchants on Nerve Compound Action Potentials

In this study, a 35% phosphoric acid gel (3M Scotchbond etchant), a nonrinse etchant (NRC), and two EDTA-containing conditioners (RC-Prep and File-Eze) were tested in vitro for blocking nerve conductance evoked in the rat sciatic nerve after local application. The phosphoric acid gel and NRC completely and irreversibly inhibited conductance. On the other hand, RC-Prep reduced the compound action potentials (cAPs) by 50% in 120 min. With File-Eze, the reduction in cAPs was less than 50% after an application time of 160 min (61.8 +/- 1.8%). At 160 min the cAPs in the RC-Prep group had been inhibited by 62.4%. These results indicated strong neurotoxic effects of phosphoric acid and NRC when applied directly on exposed pulp in the total etch procedure.

Effect of a fifth-generation bonding agent on vascular responses in rats.

In the last years, several single-bottle dental adhesives have been developed. They are supposed to chemically adhere to dentin, and a liner to protect pulp is not thought to be necessary. In the case of direct pulp capping, hemorrhage control is an important step in success, but little is known about the effect of these new bonding agents on pulpal bleeding. The aim of this study was to evaluate the effect of a new one-step single-bottle adhesive on the smooth muscle contraction of rat uterine muscle and carotid arteries. Efficacy of the bonding agent was compared with that of epinephrine (control), and the contraction forces induced were recorded using a force displacement transducer. Statistical analysis of data revealed that the bonding material produced epinephrine-like concentration-dependent contractions of the smooth muscle, suggesting that one-step bonding agents may act as candidates for hemorrhage control without the use of an additional agent in direct pulp capping procedures.

Vascular Response of Current and Potential Dental Etchants

This study investigated the hemostatic properties of current and potential dentin conditioners by observing the contraction of blood vessels using the rat carotid artery model. Four different agents (3M Scotchbond etchant, NRC, RC-Prep, File-Eze) were used. Dose-dependent contractions/relaxations of the test materials were first compared with epinephrine, followed by administration of papaverine, which was used to reverse epinephrine-induced contractions. In all sequences, the contraction or relaxation forces produced by the test and control materials were recorded using a force displacement transducer. RC-Prep was the only agent to produce epinephrine-like contractions (vasoconstriction) in the rat carotid artery. No contraction could be achieved with 3M etchant. Dose-dependent relaxations were observed with 3M etchant, which eventually led to collapse of the vessel wall; afterward, no response could be achieved with administration of adrenalin. File-Eze and NRC also did not cause vasoconstriction. Both materials caused dose-dependent relaxations in the smooth muscle. However, subsequent administration of adrenalin and papaverine caused dose-dependent contractions and relaxations, respectively, showing that these etchant effects did not lead to collapse of the vessel wall, as did 3M etchant.

Neurotoxic Effects of Fifth-Generation Dentin Adhesives on Rat Sciatic Nerve

This study evaluated the effect of the fifth-generation dentin adhesives, Single Bond (SB), Excite (EX), Prime & Bond NT (PB), and Optibond Solo (OS) on nerve conduction. Isolated rat sciatic nerves were placed between two suction electrodes in a bath containing tyrode solution. The bonding agents were brought into contact with the nerves and the evoked compound action potentials (cAPs) were recorded before and after contact with the materials. SB, EX, and PB caused total inhibition of the cAPs, with PB being the fastest (73 +/- 5.8 min). All cAPs except one in the PB group were irreversibly inhibited in the SB, EX, and PB groups. As for OS the reduction in cAP was not 50% after an application time of 200 min. Recovery of the cAPs in this group was recorded in an average time of 35 min.

Endothelial Cell and Stromal Antigens in Human Periapical Granulation Tissue

Periapical granulation tissue consists of vasculature of varying sizes and types, infiltrating cells, and other stromal elements. We examined the differential expression of endothelial and stroma antigens in this tissue to determine their tissue distribution in order to obtain hints on their functions. Some of the antigens examined were present only in the endothelial lining of vasculature, including high endothelial venules (e.g. CD31 and CD105), whereas others were more widely expressed by both vascular and stromal elements (e.g. CD29, CD63, CD44, and CD151). Immunohistochemical analysis using monoclonal antibodies specific to certain tissue compartments revealed the tissue architecture more precisely and the expression of certain antigens in the tissue suggested special roles for these antigens. Tissue distribution of CD63, CD143, CD147, and CD151 in periapical granulation tissue is first reported in the present study.

Endothelial cell adhesion molecules in human dental pulp: a comparative immunohistochemical study on chronic periodontitis.

Migration of leukocytes to inflammation sites through vascular endothelium is controlled by the interactions of adhesion molecules expressed on both endothelial cells and leukocytes, most of which are already covered by cluster of differentiation (CD) codes. We examined the expression of a variety of endothelial cell adhesion molecules in human dental pulp vasculature to obtain further evidence on the tissue distribution and function of these molecules by using an indirect immunoperoxidase technique. We obtained the pulp tissue samples from teeth extracted due to orthodontic reasons as controls and compared with those extracted due to chronic periodontitis. In all samples, both CD31 and CD146 were expressed by arterial, venous, and capillary endothelia. There was no significant difference between the staining intensity of normal and inflamed pulp tissues. CD102 expression on the endothelium was significantly stronger in chronic periodontitis pulp samples. CD106, CD62-E, CD62-P, CD105, and CD54 were variably expressed in control and chronic periodontitis groups. Our results indicate that CD102 represents the major endothelial cell adhesion molecule probably involved in the inflammatory reactions in chronic periodontitis.

CD45/Isotypes Expression in the Immune Cells of Human Periapical Lesions

Expression of some leukocyte antigens (including CD45) and its isoforms (CD2, CD4, CD5, CD6, CD7, and CD8) was examined in the human periapical granulation tissue samples in the present study. The majority of the infiltrating cells expressed heavy molecular-weight isoforms of the CD45 antigen. Expression of CD2, CD5, CD6, and CD7 antigens was also detected, implying significant roles for these antigens in the immune reaction taking place in periapical lesions. This suggests that the immune response taking place at the periapical region is predominantly cellular and the humoral responses to antigenic challenge are conducted mainly by regional lymph nodes.

Cytotoxicity of Two-step Self- etching Primer/Adhesives on L929 Cells

The cytotoxicity of four self-etching primer/adhesive systems (Clearfil® SE Bond, Clearfil® Protect Bond, Mac Bond® II and FL® Bond) was tested against L929 fibroblasts. The primer or adhesive component of each adhesive system was diluted serially with the culture medium at a ratio of 1:1,000 and 1:4,000 (v/v). Cytotoxicity was identified by adding L929 cells in 24-well culture plates at an initial density of 35,000 cells mL 1. The cells were maintained for 5 days; every 24h, the medium was changed with fresh medium containing specific dilutions of the primer or adhesive components of the test materials. Cytotoxicity was assessed quantitatively at 24, 48, 72, 96 and 120h. Physiological and pathological cellular changes as well as reactions and growth of the cell cultures were examined under an inverted microscope. All self-etching systems were found to be cytotoxic to varying degrees; more pronounced toxic effects were observed at lower dilution (1:1,000 [v/v]). The adhesive components of Mac Bond® II and FL® Bond showed the highest cytotoxicity at 1:1,000 (v/v). The primer and adhesive of Clearfil® SE Bond, the primer of Mac Bond® II and the antibacterial monomer (MDPB)-containing Clearfil® Protect Bond (at 1:4,000 [v/v]) were relatively less cytotoxic.

Inhibition of compound action potentials following administration of dental self-etching primer/adhesives

Self-etching dentin adhesive systems, a new generation of dental-bonding agents, were investigated for their ability to block nerve conductance in the rat sciatic nerve model. Clearfil SE Bond, Mac Bond and FL Bond were used as test materials. Isolated rat sciatic nerves obtained from female albino rats were placed between two electrodes in a bath containing Tyrode solution. The bonding agents were brought into contact with the nerves and the evoked compound action potentials were recorded versus time before and after contact with the materials. Statistical analysis was performed using the Friedman and Wilcoxon Signed-Ranks tests (P = 0.01) to compare the mean percentage of inhibition between test materials versus time. All test materials were able to block nerve transmission rapidly (3.3 ± 0.5, 5.1 ± 2.3 and 8.0 ± 1.9 min for SE Bond, Mac Bond andFL Bond, respectively). Significant differences were found between FL Bond and SE and Mac Bond (P < 0.01). These results indicated that the bonded systems tested, intended primarily as dentinal tubule occluders, may also exert some direct desensitizing effect on intratubular or pulpal nerve terminals in extremely deep cavities or pulpal microexposures, contributing to decreased postoperative pain.