Effects of Current and Potential Dental Etchants on Nerve Compounds Action Potentials
Çehreli, Onur, Taşman, Gümrükçüoğlu, and Artuner
Immunohistochemical Evaluation of the Effects of Sodium Hypochlorite on Dentin Collagen and Glycosaminoglycans
Oyarzún, Cordero, and Whittle
Interleukin-1b Activity and Collagen Synthesis in Human Dental Pulp Fibroblasts
Barkhordar, Ghani, Russell, and Hussain
The Effects of Sodium Hypochloride Concentrations on the Accuracy of an Apex Locating Device
Tinaz, Sevimli, Görgül, and Türköz
The Effectiveness of Various Disinfectants Used as Endodontic Intracanal Medications: An In Vitro Study
Almyroudi, Mackenzie, McHough, and Saunders
Actinomyces Species, Streptococci, and Enterococcus faecalis in Primary Root Canal Infections
Siqueira, Rôças, Souto, Uzeda, and Colombo
Calcium Salts Deposition in Rat Connective Tissue After the Implantation of Calcium Hydroxide-Containing Sealers
Holland, Souza, Nery, Estrada Bernabé, Otoboni Fiho, Junior, and Murata
Interleukin-10 Inhibits Expression of Interleukin-6 and -8 mRNA in Human Dental Pulp Cell Cultures via Nuclear Factor-k B Deactivation
Tokuda, Nagaoka, and Torii
Efficacy of Instrumentation Techniques and Irrigation Regimens in Reducing the Bacterial Population within Root Canals
Siqueira, Rôças, Santos, Lima, Magalhães, and Uzeda
Effect of Er:YAG Laser on Adhesion of Root Canal Sealers
Sousa-Neto, Marchesan, Pécora, Junior, Silva-Sousa, and Saquy
Cytotoxicity of Low pH Dentin-Bonding Agents in a Dentin Barrier Test In Vitro
Schmalz, Schuster, Koch, and Schweikl
Mitogenic Effect of L-dopa on Human Periodontal Ligament Fibroblast Cells
Partovi, Sadeghein, Azizi, and Ostad
Differential Regulation of Interleukin-6 and Inducible Cyclooxygenase Gene Expression by Cytokines Through Prostaglandin-Dependant and –Independent Mechanisms in Human Dental Pulp Fibroblasts
Lin, Kuo, Wang, Lee, Wang, Huang, Shun, and Hong
T Lymphocytes Subpopulations and Interleukin-2, Interferon-γ, and Interleukin-4 in Rat Pulpitis Experimentally Induced by Specific Bacteria
Kim and Lim
Effects of Current and Potential Dental Etchants on Nerve Compound Action Potentials
Zafer C. Çehrelį, DDS, PhD, Mehmet Alį Onur, PhD, Fügen Taşman, DDS, PhD, Ayşe Gümrükçüoğlu, BSc, and Harun Artuner, PhD
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.
Immunohistochemical Evaluation of the Effects of Sodium Hypochlorite on Dentin Collagen and Glycosaminoglycans
Alejandro Oyarzún, DDS, Ana M. Cordero, DDS, and Marta Whittle, DDS
To test the hypothesis that a commercial solution of 5% NaOCl produces structural and molecular alterations in the collagen and glycosaminoglycans of mineralized and demineralized dentin, radicular segments from human teeth were treated with 5% NaOCl for 2 min at room temperature. As a control, distilled water replaced NaOCl. The experimental and control specimens were processed for indirect immunofluorescence by using antitype I collagen and antichondroitin sulfate antibodies. Tissue sections were morphometrically analyzed. A single exposure for 2 min to a 5% NaOCl solution produced a drastic loss of immunoreactivity in the dentin surface for both antibodies that were used in demineralized specimens. A narrow and irregular band of fluorescence loss was detected in mineralized-dentin segments when anticollagen antibodies were used. The results of this study suggest that 5% NaOCl induces alterations in dentin collagen and glycosaminoglycans and show the protective role of hydroxyapatite on organic matrix stability.
Interleukin-1b Activity and Collagen Synthesis in Human Dental Pulp Fibroblasts
Rahmat A. Barkhordar, DMD, Q. Perveen Ghani, PhD, Thomas R. Russell, DDS, and M. Zamirul Hussain, PhD
Immunopathologic reactions play a significant role in inflammatory diseases of dental pulp. Interleukin-1b (IL-1b ) is recognized as a key player in mediating cellular immune response. In this study, we measured the content of IL-1b and its effect on collagen synthesis in cultures of fibroblasts derived from healthy and diseased dental pulps. We found that diseased pulp fibroblasts contain 2.5-fold greater amounts of IL-1b and synthesized 80% greater amounts of collagen compared with healthy pulp fibroblasts. However, exogenous IL-1b failed to stimulate collagen synthesis by diseased fibroblasts, whereas collagen synthesis by healthy pulp fibroblasts was stimulated by more than 2-fold. These observations imply that pulp disease induces abnormalities associated with fibroblast response toward IL-1b.
The Effects of Sodium Hypochloride Concentrations on the Accuracy of an Apex Locating Device
A. Cemal Tinaz, PhD, L. Sibel Sevimli, DDS, Güliz Görgül, PhD, and Emin G. Türköz, PhD
This study aimed to evaluate Root ZX accuracy with different NaOCl concentrations and to observe effects of the alginate model when NaOCl was used in the canal during electronic measurements. Fifty extracted single-rooted, single-canal human teeth were used in five experimental groups. NaOCl concentrations of 5.25%, 2.65%, 1.00%, and 0.50%, respectively, were injected into the root canals of teeth in four groups and distilled water in control group 5. After measuring root lengths with Root ZX, the files were locked in place. There were no statistically significant differences among all the groups (p > 0.95) when evaluating the distance of the file tips and apical constriction or for the distance from file tip to apical foramen. Root ZX could be used in root canal length measurements with various NaOCl concentrations. Designation of apical constriction needs more care. The alginate model could be used for in vitro electronic measurements with various NaOCl concentrations.
The Effectiveness of Various Disinfectants Used as Endodontic Intracanal Medications: An In Vitro Study
Alexandra Almyroudi, DDS, MSc (Med Sci), D. Mackenzie, Siobhan McHugh, BSc, and W. P. Saunders, BDS, PhD, FDS RCS Edin, FDS, RCPS Glas, MRD
The purpose of this study was to compare in vitro the suitability of four disinfectants as intracanal medications: calcium hydroxide, chlorhexidine gel, chlorhexidine in the form of a controlled-release delivery system (PerioChipÒ ), and the combination of chlorhexidine gel with calcium hydroxide. Saline was used as the control. The disinfectants were tested at three different time periods (3, 8, and 14 days) by using human tooth specimens that had been previously contaminated with Enterococcus faecalis. Calcium hydroxide worked very efficiently in killing E. faecalis in the 3-day group and 8-day group. It was not as effective in the 14-day group. The different chlorhexidine formulations were also found to be effective for all time periods. More specifically, the combination of chlorhexidine gel with calcium hydroxide and the chlorhexidine gel worked slightly better than the PerioChipÒ , but there was no significant difference among the medications.
Actinomyces Species, Streptococci, and Enterococcus faecalis in Primary Root Canal Infections
José F. Siqueira, Jr. DDS, MSc, PhD, Isabela N. Rôças, DDS, Renata Souto, Bmic, Milton de Uzeda, DDS, MSc, PhD, and Ana Paula Colombo, DDS, MSc, PhD
The purpose of this study was to evaluate the prevalence of Actinomyces species, streptococci, and Enterococcus faecalis in primary root canal infections by using a molecular genetic method. Samples were obtained from 53 infected teeth, of which 27 cases were diagnosed as acute periradicular abscesses. DNA was extracted to evaluate the occurrence of 13 bacterial species by using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Polymerase chain reaction using an ubiquitous bacterial primer was undertaken to check the presence of bacterial primer was undertaken to check the presence of bacterial DNA in clinical samples. All root canal samples contained bacteria as demonstrated by polymerase chain reaction. The checkerboard DNA-DNA hybridization assay allowed the detection of streptococci in 22.6% of the samples, Actinomyces species in 9.4%, and E. faecalis in 7.5%. The most prevalent species were members of the Streptococcus anginosus group. With regard to the asymptomatic lesions, the most prevalent species were S. intermedius (11.5% of the cases), E. faecalis (11.5%), and S. anginosus (7.7%). S. constellatus was the most prevalent species in pus samples (25.9% of the cases). The other most prevalent species in abscessed teeth were A. gerencseriae (14.8%), S. gordonii (11.1%), S. inter-medius (11.1%), A. israelii (7.4%), S. anginosus (7.4%), and S. sanguis (7.4%), S. constellatus was the only species positively associated with acute periradicular abscess (p < 0.01).
Calcium Salts Deposition in Rat Connective Tissue after the Implantation of Calcium Hydroxide-Containing Sealers
Roberto Holland, PhD, Valdir de Souza, PhD, Mauro Juvenal Nery, PhD, Pedro Felicio Estrada Bernabé, PhD, José Arlindo Otoboni Fiho, PhD, Eloi Dezan Junior, MS, and Sueli Satomi Murata, DDS
This study was conducted to observe the rat subcutaneous connective tissue reaction to implanted dentin tubes the were filled with mineral trioxide aggregate, Sealapex, Calciobiotic Root Canal Sealer (CRCS), Sealer 26, and the experimental material, Sealer Plus. The animals were sacrificed after 7 and 30 days, and the specimens were prepared for histological analysis after serial sections with a hard-tissue microtome. The undecalcified sections were examined with polarized light after staining according to the Von Kossa technique for calcium. At the tube openings, there were Von Kossa-positive granules that were birefringent to polarized light. Next to these granulations, there was irregular tissue, like a bridge, that was Von Kossa-positive. The dentin walls of the tubes exhibited a structure highly birefringent to polarized light, usually like a layer, in the tubules. These results were observed with all the studied materials, except the CRCS, which didn’t exhibit any kind of mineralize structure. The results suggest that among the materials studied, the CRCS could have the least possibility of encouraging hard tissue deposition.
Interleukin-10 Inhibits Expression of Interleukin-6 and -8 mRNA in Human Dental Pulp Cell Cultures via Nuclear Factor-k Deactivation
Masayuki Tokuda, DDS, PhD, Shigetaka Nagaoka, DDS, PhD, and Mitsuo Torii, DDS, PhD
The effects of interleukin (IL)-10 on the expression of IL-6 and IL-8 mRNA in human dental pulp cell cultures were investigated by using the Northern blot analysis. On stimulation with Prevotella intermedia lipopolysaccharides (PiLPS), IL-10 was produced in peripheral blood but was not detected in human dental pulp cell culture supernatants. IL-10 inhibited IL-8 mRNA expression, which is normally stimulated by PiLPS, IL-1a , and tumor necrosis factor-a and inhibited IL-6 mRNA expression, which is normally stimulated by IL-1a . In addition, IL-10 inhibited the activation of nuclear factor-k B, which is normally induced by PiLPS. We conclude that IL-10 inhibits expression of IL-6 and IL-8 mRNA in dental pulp cell cultures by inhibiting the activation of nuclear factor-k B.
Efficacy of Instrumentation Techniques and Irrigation Regimens in Reducing the Bacterial Population within Root Canals
José F. Siqueira, Jr., DDS, MSc, PhD, Isabela N. Rôças, DDS, Sandra R. L. D. Santos, DDS, Kenio C. Lima, DDS, MSc, Fernando A. C. Magalhães, and Milton de Uzeda, DDS, MSc, PhD
The purpose of this study was to compare the in vitro intracanal bacterial reduction produced by using two instrumentation techniques and different irrigation methods. Root canals inoculated with Enterococcus faecalis were prepared by using the following techniques and irrigants: alternated rotary motions (ARM) technique, hand nickel-titanium files and 2.5% sodium hypochlorite (NaOCl) as irrigant; ARM technique and combined irrigation with 2.5% NaOCl and citric acid; ARM technique and combined irrigation with 2.5% NaOCl and 2% chlorhexidine gluconate; and Greater Taper rotary files, using 2.5% NaOCl as irrigant. Controls were instrumented by using the ARM technique and irrigated with sterile saline. Canals were sampled before and after preparation. After serial dilution, samples were plated onto Mitis-Salivarius agar, and the colony forming units that were grown were counted. All test techniques and solutions significantly reduced the number of bacterial cells within root canal (p < 0.05). There was no significant difference between the experimental groups (p > 0.05). Nonetheless, all of them were significantly more effective than the control group (p < 0.05). These findings support the importance of using antimicrobial irrigants during the chemomechanical preparation, regardless of the solutions or instrumentation techniques used.
Effect of Er:YAG Laser on Adhesion of Root Canal Sealers
Manoel D. Sousa-Neto, DDS, PhD, Melissa A. Marchesan, DDS, Jesus D. Pécora, DDS, PhD, Aldo Brugnera Junior, DDS, MSc, Yara T.C. Silva-Sousa, DDS, PhD, and Paulo C. Saquy, DDS, PhD
This in vitro study evaluated the effect of Er:YAG laser on adhesion to human dentin of Grossman, Endomethasone, N-Rickert, and Sealer 26 root canal sealers. The crowns of 40 human molars were cut on the occlusal side until a flat dentine surface was obtained. The teeth were divided into two groups: group 1, no laser application; and group 2, irradiation with Er:YAG laser (KaVo Key Laser 2; 11 mm focal distance, perpendicular to the dentin surface, 4 Hz frequency, 200 mJ energy, 62 J total energy and 313 pulses, 1-min application time, and 2.25 W power). Five samples were tested for each sealer and each group. An Instron universal testing machine was used for the adhesion test. Sealer 26 showed the best adhesion both with and without laser application (p < 0.01). Grossman and N-Rickert sealers had intermediate values, and Endomethasone had the worst adhesion. Application of Er:YAG laser did not alter the adhesion of Grossman, N-Rickert, or Endomethasone sealers. However, Laser application increased the adhesion of Sealer 26. The epoxy resin-based root canal sealer (Sealer 26) adhered better to dentin prepared with and without Er:YAG laser than the zinc oxide/eugenol-based sealers (Endomethasone, N-Rickert, and Grossman).
Cytotoxicity of Low pH Dentin-Bonding Agents in a Dentin Barrier Test in Vitro
Gottfried Schmalz, DMD, PhD, DDS, Uta Schuster, PhD, Angela Koch, DMD, DDS, and Helmut Schweikl, PhD
The reaction of three-dimensional cultures of pulp-derived cells in a dentin barrier tests was recorded after exposure to All-Bond 2, Prime & Bond NT, Syntac SC, Syntac Classic, and Prompt L-Pop. The materials were applied on bovine dentin disks in a perfusion chamber, and the experiments were performed with (0.3 ml/h, 2 ml/h) and without perfusion of the pulpal part of the chamber. The cell reaction was recorded (MTT assay) and related to noncytotoxic controls. Bonding agents with low pH did not show any cytotoxicity. Syntac Classic decreased the cell activities from 38% to 72%, depending on different experimental conditions, and was more Cytotoxic than Syntac SC. Perfusion (2 ml/h) reduced the cytotoxicity for Syntac Classic and increased cell activities from 52% to 72%. Because low pH bonding agents did not show toxic reactions in the dentin barrier test, pulp damage caused by the tested substance is unlikely if a dentin layer protects the pulp.
Mitogenic Effect of L-dopa on Human Periodontal Ligament Fibroblast Cells
Mandana Parovi, DDS, MS, Ahmad Sadeghein, DDS, MS, FICD, Ebrahim Azizi, Pharm D, PhD, and S. Nasser Ostad, Pharm D, PhD
In cases of tooth avulsion, immediate replantation is the treatment of choice. In the event of any problem, the tooth should be stored in a medium that supports the periodontal ligament cell viability. Theoretically, mitotic promoting agents may be of use to preserve cell viability. It has previously been reported that levodopa (L-dopa) accelerates healing by increasing the growth hormone level. In this study, the direct effect of L-dopa was investigated on human periodontal ligament fibroblast (HPLF) cells. Cell culture methods were used to assess the potential mitogenic effect of L-dopa. Results show that in low concentrations of L-dopa (1μg/μl in this study), the number of HPLF cells were remarkably higher than the control group, and the number of viable cells were not affected by increasing the L-dopa concentration in the range of the study. These results suggest that L-dopa can also have a direct local effect on the growth of HPLF cells. Theses results may be of use clinically to increase the viability of HPLF cells in cases of an avulsed tooth preserved in storing medium.
Differential Regulation of Interleukin-6 and Inducible Cyclooxygenase Gene Expression by Cytokines Through Prostaglandin-Dependant and –Independent Mechanisms in Human Dental Pulp Fibroblasts
Sze-Kwan Lin, DDS, MS, PhD, Mark Yen-Ping Kuo, DDS, PhD, Juo-Song Wang, DDS, MS, Jih-Jong Lee, DVM, MS, Chih-Chiang Wang, MS, Shen Huang, DVM, MS, Chia-Tung Shun, MD, MS, and Chi-Yuan Hong, DDS, DMSc
Increased levels of interleukin-1 (IL)-1, tumor necrosis factor-a (TNF-a ), IL-6, and prostaglandin E2 (PGE2) have been detected in inflamed pulp tissue. To gain further insight into the molecular pathogenesis of pulpitis, we investigated the effects of IL-1a or TNF-a and PGE2, either alone or in combination on IL-6 and cyclooxygenase (COX)-2 messenger RNA (mRNA) production in cultured human dental pulp (HDP) fibroblasts. Exposure of HDP fibroblasts to IL-1a or TNF-a resulted in elevated levels of IL-6 (~3.4 to ~10.4-fold) and COX-2 (~5 to ~6.2-fold) mRNA. Simultaneous addition of IL-1a and PGE2 or TNF-a and PGE2 to the cultured significantly reduced the cytokine-induced IL-6 mRNA synthesis ranging from 45% to 65%. However, indomethacin enhanced the cytokine-stimulated IL-6 mRNA synthesis by ~1.7 to ~3.4-fold. This action could be reversed by exogenous PGE2. In contrast, PGE2 or indomethacin failed to modify the stimulatory effect of IL-1a or TNF-a on COX-2 gene expression. Because excessive levels of IL-6 and prostaglandins have been connected with the pathogenesis of several inflammatory diseases, our results suggest the involvement of HDP fibroblasts in the development of pulpitis via producing IL-6 and COX-2. Furthermore, expression of IL-6 and COX-2 genes in this cell seems to be differentially regulated by cytokines through prostaglandin-dependent and –independent pathways.
T Lymphocytes Subpopulations and Interleukin-2, Interferon-γ, and Interleukin-4 in Rat Pulpitis Experimentally Induced by Specific Bacteria
Seon-Ah Kim, DDS, MS, and Sung-Sam Lim, DDS, PhD
The objective of this study was to investigate the expression of surface markers on T lymphocytes and the Th1/Th2 immune response in pulpal inflammation associated with specific bacteria. Pulpal inflammation was experimentally induced in rat mandibular incisors by drilling, without coolant, to open pulp chambers. Streptococcus mutans (S. mutans group), Porphyromonas endodontalis (P. endodontalis group), and a sterile cotton pellet only (control group) were inoculated in the canal. The expression of CD25 and CD54 on CD4+, and CD8+ lymphocytes in pulp tissues was determined by using a flow cytometer. The levels of interleukin (IL)-2, interferon (INF)-γ, and IL-4 were measured by ELISA. Flow-cytometric analysis showed that the mean ratio of CD4+:CD8+ was 0.96 in the control group, 0.99 in the S. mutans group, and 0.52 in the P. endodontalis group. An increase in CD25 and CD54 expression on CD4+ T lymphocytes was related to the bacterial infection (p < 0.05) and accompanied an increase in IL-2 concentration. The higher the concentration of IFN-γ than IL-4 in the P. endodontalis group suggested a Th1 reaction in the early stage of pulpal inflammation induced by P. endodontalis.