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 and FL 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.

Influence of a self-etching primer on compound nerve action potentials.

The aim of this study was to evaluate the effect of self-etching primers on nerve conductance. A self-etching primer (One Up Bond F) which combines etching and bonding in one step, and a fifth-generation bonding agent (Prime&Bond NT ) were tested. Isolated rat sciatic nerves were placed between two platinum electrodes in a bath containing Tyrode solution. The bonding agents were brought into contact with the nerves and the evoked compound action potentials (CAP) were recorded before and after contact with the materials. One Up Bond F caused total inhibition of the CAP within an average time of 7 min. All CAPs in this group were blocked irreversibly. As with Prime&Bond NT, the reduction in CAP was 45.9% after an application time of 15 min, after which readings were terminated. Recovery of the CAP in this group were maintained after rinsing with fresh tyrode solution. One Up Bond F elicited faster blocking of nerve conductance under the conditions of this model. In the context of dentin desensitization with bonding agents, the self-etching primer may be more effective, clinically.

Immunohistochemical study of cyclosporin-induced gingival overgrowth in renal transplant recipients.

BACKGROUND: Cyclosporin A (CsA) is an immunosuppressant widely used to treat transplant patients and various systemic diseases with immunological components. Gingival overgrowth (GO) is a common side effect of CsA administration; however, the pathogenesis of drug-induced GO is poorly understood. The aim of this study was to evaluate the expression of Ki-67, activation molecules (CD71, CD98), leukocytes activation antigens (CD45, CD45RA, CD50, CD11a, CD162, CD227, CD231), neurothelin (CD147), and novel endothelial cell antigens (B-F45, SCF87, B-D46, B-C44, VJ1/6) in gingival tissue in renal transplant recipients treated with CsA. METHODS: Tissues from 15 renal transplant patients with significant GO and 10 systemically healthy control subjects with gingivitis were studied. Frozen-section biopsies were stained with monoclonal antibodies specific for the above-mentioned antigens using an indirect immunoperoxidase technique. RESULTS: Comparison of the CsA-treated and control groups revealed no significant differences with respect to expression of Ki-67; CD50; activation molecules; neurothelin; or novel endothelial cell antigens B-D46, B-C44, and VJ1/6. However, expression patterns of CD45, CD45RA, CD11a, CD162, CD227, CD231, B-F45, and SCF87 were significantly different in CsA and control groups. CONCLUSION: Leukocyte activation antigens play an important role in CsA-induced gingival overgrowth.

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 EMD's 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 L929 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 Dulbecco's modified eagle medium (DMEM) enriched with 10% fetal bovine serum, DMEM supplemented with 0 (Control), 50 microg/mL and 100 microg/mL of EMD was added and cultures maintained for 96h. 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.

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.