The Effect of Chlorhexidine Gluconate as an Endodontic Irrigant on the Apical Seal: Long-term Results
Ferguson, Marley and Hartwell
In Vitro Evaluation of the Cytotocicity of Two Root Canal Sealers on Macrophage Activity
Mendes, Sobrinho, Côrtes and Vieira
Antibacterial Effect of a Hydraulic Calcium Phosphate Cement for Dental Applications
Kouassi, Michaïlesco, Lacoste-Armynot and Boudeville
The Effect of Extracellular Calcium Ion on Gene Expression of Bone-related Proteins in Human Pulp Cells
Rashid, Shiba, Mizuno, Mouri, Fujita, Shinohara, Ogawa, Kawaguchi and Kurihara
Immunohistochemical Localization of µ-Opioid Receptors in Human Dental Pulp
Jaber, Swaim and Dionne
Peptostreptococcus micros in Primary Endodontic Infections as Detected by 16S rDNA-based Polymerase Chain Reaction
Siqueira, Rôças, Andrade and Uzeda
Induction of Tissue Plasminogen Activator Gene Expression by Proinflammatory Cytokines in Human Pulp and Gingival Fibroblasts
Chang, Yang, Huang, Tai and Hsieh
Antibacterial Effects of Resinous Retrograde Root Filling Materials
Lai, Huang, Chan, Yang, Huang, Chou and Chang
A Comparison of One Versus Two Appointment Endodontic Therapy in Dogs’ Teeth with Apical Periodontitis
Holland, Filho, Souza, Nery, Bernabé and Dezan,
Effect of Fatigue Testing on Core Integrity and Post Microleakage of Teeth Restored with Different Post Systems
Reid, Kazemi and Meiers
Fabrication of Hard Coatings on NiTi Instruments
Tripi, Bonaccorso and Condorelli
Changes in TrkB-like Immunoreactivity in Rat Trigeminal Ganglion After Tooth Injury
Behnia, Zhang, Charles and Gold
Generation of Free Randicals and/or Active Oxygen by Light or Laser Irradiation of Hydrogen Peroxide or Sodium Hypochlorite
Kashima-Tanaka, Tsujimoto, Kawamoto, Senda, Ito and Yamazaki
The Effect of Chlorhexidine Gluconate as an Endodontic Irrigant on the Apical Seal: Long-term Results
David B. Ferguson, DDS, John T. Marley, DDS, and Gary R. Hartwell, DDS, MS
The purpose of theis study was to determine whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution, would affect the apical seal of three root canal cements. One hundred, extracted, human, single-canal teeth were divided into 9 experimental groups of 10 teeth each, in addition to a positive and negative control group of 5 teeth each. The teeth were decoronated at the level of the CEJ, accessed, instrumented to a Master apical file #50, irrigated with either sterile saline, 5.25% NaOCI, or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and one of three endodontic sealers: Roth’s 811, AH 26, or Sealapex. Postobturation apical leakage was measured at 270- and 360-day observation periods using the fluid filtration method. Using the mixed-model repeated-measures ANOVA test with Turkey’s honest significance difference multiple comparison procedure, the results showed the saline-Sealapex combination had significantly more leakage (p<0.05) than either the Peridex-Sealapex or saline-Roth’s combinations at 270 days. No other significant differences were noted between any sealer-irrigant combination at 270 days. The saline-Sealapex combination had significantly more leakage than the saline-Roth’s combination at 360 days. No other significant differences were noted at 360 days. No other significant differences were noted at 360 days. Under the conditions of this study, chlorhexidine gluconate irrigant did not adversely affect the apical seal of three root canal cements at 270 and 360 days.
In Vitro Evaluation of the Cytotocicity of Two Root Canal Sealers on Macrophage Activity
Sônia Teresa de Oliveira Mendes, MSc, Antônio Paulino Ribeiro Sobrinho, MSc, André Teixeira de Carvalho, Maria llma de Souza Côrtes, PhD, and Leda Quercia Vieira, DSc
Although some studies have been concerned with they cytotoxicity of endodontic sealers and their components, few have approached the effects of endodontic sealers on macrophage viability and activity. In this study the effect of two zinc oxide-eugenol-based sealers, freshly prepared or after setting for 24 h, was determined on macrophage activity in vitro. Sealers were placed inside a glass capillary tube and added to mouse-elicited macrophage cultures. Sealers did not affect macrophage viability; however, adherence to glass and phagocytosis were impaired. Moreover, nitric oxide production in response to activation with interferon-γ was dimished, but interleukin-12 production in response to Listeria monocytogenes was not altered. Interestingly, freshly mixed and solid test samples had similar inhibitory activities. In conclusion, the tested sealers did not affect a pro-inflamatory response (interleukin-12 production) but had an inhibitory effect on the effector responses measured (phagocytosis and nitric oxide production).
Antibacterial Effect of a Hydraulic Calcium Phosphate Cement for Dental Applications
Michael Kouassi, DDS, Pierre Michaïlesco, DDS, PhD, Anne Lacoste-Armynot, PhD, and Philippe Boudeville, PhD
Calcium hydroxide is currently used in dentistry for endodontic treatment where its main advantage consists of its antibacterial and anti-inflammatory potency. However, it also has some drawbacks such as pulp necrosis, slight solubility, slow and low hardening, and retraction on drying. Since the studies conducted by Brown and Chow (IADR 1983, abst. 207), calcium phosphate-based cements (CPC) have attracted considerable interest in bone reconstruction because of their good osteoconductivity. By mixing calcium bis-dihydrogenphosphate monohydrate (MCPM) and calcium oxide with sodium phosphate buffer in the form of liquid phase, we obtained a CPC with better mechanical properties than calcium hydroxide. The setting reaction produced a mixture of calcium-deficient hydroxyapatite and calcium hydroxide, making this cement more suitable for dental applications than orthopedic ones. The presence of calcium hydroxide a priori confers antibacterial properties to this cement, which were investigated in agar plates (diffusion method) against Streptococcus mutans, Lactobacillus acidophilus, Candida albicans (clinical isolates) and a preparation of polymicrobial flora isolated from dental plaque. The cement samples tested were prepared at calcium-to-phosphate molar ratios (Ca/P) ranging from 1.67 to 2.75. A pure calcium hydroxide paste was used as reference material. Clear and reproducible bacterial growth inhibition was observed for cement samples with Ca/P ≥ 2 against all the microorganisms tested. MCPM-CaO-based cement is therefore a potential candidate for pulp capping and cavity lining.
The Effect of Extracellular Calcium Ion on Gene Expression of Bone-related Proteins in Human Pulp Cells
Fashmida Rashid, BDS, Hideki Shiba, DDS, PhD, Noriyoshi Mizuno, DDS, PhD, Yoshihiro Mouri, DDS, Tsuyoshi Fujita, DDS, PhD, Hiroaki Shinohara, DDS, PhD, Tetsuji Ogawa, DDS, PhD, PhD, Hiroyuki Kawaguchi, DDS, PhD, and Hidemi Kurihara, DDS, PhD
Calcium hydroxide is often used for induction of reparative dentin formation in endodontic treatment. However, little is known about the mechanism by which calcium hydroxide works. The calcium ion (Ca2+) is an important regulator of cell functions. In this study, we examine the effect of extracellular Ca2+ on gene expression of bone-related proteins inhuman cultured pulp cells in serum-free conditions. A Ca2+ level elevated by 0.7 mM induced an increase in mRNA expression of osteopontin and bone morphogenetic protein (BMP)-2. However, mRNA levels of BMP-4 and alkaline phosphatase decreased under the elevated decreased under the elevated Ca2+ culture condition. The same concentration of additional magnesium ions had little effect on expressions of the examined bone-related protein mRNAs. These findings suggest that Ca2+ in Ca(OH)2 specifically modulates osteopontin and BMP-2 levels during calcification in pulp.
Immunohistochemical Localization of µ-Opioid Receptors in Human Dental Pulp
L. Jaber, DDS, W.D. Swaim, PhD, and R.A. Dionne, DDS, PhD
Studies in both animal and clinical models suggest that opioids exert their analgesic effects not only through activation of receptors in the CNS bus also through interaction with peripheral opioid receptors. This study evaluated the presence and distribution of µ-opioid receptors in human dental pulp. Human third molars indicated for extraction were removed, fixed in 4% paraformaldehyde and 0.2% picric acid, and decalcified in 10% EDTA and 7.5% polyvinylpyrrolidone. The teeth were cut using a cryostat, and the avidin-biotin peroxidase immunohistochemistry technique was used. Immunostaining for µ-opioid receptors was detected along the nerve bundle of the radicular as well as coronal dental pulp. Positive immunostaining was also observed in the individual nerve fibers in the coronal region, This demonstration of opiate receptors on pulpal nerve fibers suggests a peripheral site in the dental pulp where endogenous or extogenous opioids can interact with µ-opioid receptors.
Peptostreptococcus micros in Primary Endodontic Infections as Detected by 16S rDNA-based Polymerase Chain Reaction
José F. Siqueira, Jr., DDS, MSc, PhD, Isabela N. Rôças, DDS, Arnaldo F.B. Andrade, MD, PhD, and Milton de Uzeda, DDS, MSc, PhD
A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect Peptostreptococcus micros in primary root canal infections. Samples were collected from 50 teeth having carious lesions, necrotic pulps, and different forms of periradicular diseases. NDA extracted from the samples was amplified using the PCR assay, which yielded a specific fragment of P. micros 16S rDNA. P. micros was detected in 6 of 22 root canals associated with asymptomatic chronic periradicular lesions (27.3%), 2 of 8 teeth with acute apical periodontitis (25%), and 6 of 20 cases of acute periradicular abscess (30%). In general, P. micros was found in 14 of 50 cases (28%). There was no correlation between the presence of P. micros and the occurrence of symptoms. Findings suggested that P. micros can be involved in the pathogenesis of different forms of periradicular lesions.
Induction of Tissue Plasminogen Activator Gene Expression by Proinflammatory Cytokines in Human Pulp and Gingival Fibroblasts
Yu-Chao Chang, DDS, MMS, Shun-Fa Yang, MS, Fu-Mei Huang, DDS, MMS, Kuo-Wei Tai, DDS, MSD, and Yih-Shou Hsieh, PhD
Plasminogen activator converts plasminogen to plasmin, and plasmin activates the latent matrix met-alloproteinases. Tissue plasminogen activator (t-PA) is one of the important proteolysis factors present in human inflamed tissues. However, few studies reported on tht emechanisms of tissue destruction via a t-PA proteolysis pathway in pulpal and periapical diseases. The subsequent reactions leading to pulpal and periapical injury after the induction of proinflamatory cytokines remains to be elucidated, The aim of this study was to investigate the effects of intereleukin-1χ and tumor necrosis factor- χ on the expression of t-PA mRNA gene in cultures human pulp and gingival fibroblasts. The mRNAs for t-PA were measured by reverse transcription-polymerase chain reaction at 2, 6, and 24 h. The results show that both cytokines induced significantly high levels of t-PA mRNA gene expression in human pulp fibroblasts. The peak of t-PA mRNA levels induced by both proinflammatory cytokines was at the 6-h incubation period. Interleukin-1χ was found to be more effective in induction of t-PA gene expression that tumor necrosis factor-χ. In addition, a similar induction pattern was also found in human gingival fibroblasts. These results indicate that proinflammatory cytokines can induce t-PA gene expression and such an effect may partially contribute to the destruction of pulpal and periapical tissues through dysregulated pericellular proteolysis. An understanding of the mechanism could not only further define the role of immune events in pulpal and periapical diseases but also have important implication for pharmacological intervention.
Antibacterial Effects of Resinous Retrograde Root Filling Materials
Chung-Chih Lai, DDS, Fu-Mei Huang, DDS, MMS, You Chan, DDs, PhD, Hui-Wen Yang, DDS, MMS, Min-Sheng Huang, DDS, PhD, Ming-Yung Chou, DDS, PhD, and Yu-Chao Chang, DDS, MMS
The effect of three resinous retrograde root filling materials on the growth of four obligate anaerobic bacteria associated with endodontic infections was determined by using the agar diffusion inhibitory test. Samples of the following resinous materials (resin-modified, glass-ionomer cement, Fuji II LC; compomer, Dyract; and composite resin, Spectrum) were incubated for 1 week with the following anaerobic bacteria: Fusobacterium nucleatum, Porphyromonas gingivalis, P. endodontalis, and Prevotella intermedia. The freshly mixed and set resinous materials were placed into the prepared wells of agar plates inoculated with the test microorganisms for 1 week. After the end of the incubation period, the zone of growth inhibition was observed and measured. Analysis of variance of the mean diameter of the zone of inhinition indicated no statistically significant overall differences in the response of the black-pigmented Bacteroides species (p > 0.05). For F. nucleatum, Spectrum had more antibacterial effect against this bacteria than Dyract (p < 0.05). Additionally, Fuji II LC was ineffective against F. nucleatum (p < 0.05). However, positive control plates showed bacterial growth in all cases. Our data suggest that the antibacterial potency of polymerized materials varied considerably, depending on the type and the product tested.
A Comparison of One Versus Two Appointment Endodontic Therapy in Dogs’ Teeth with Apical Periodontitis
Roberto Holland, PhD, José Arlindo Otoboni Filho, PhD, Valdir de Souza, PhD, Mauro Juvenal Nery, PhD, Pedro Felício Estrada Bernabé, PhD, and Eloi Dezan, Jr., MS
This study was conducted to observe the healing process in dogs’ teeth with apical periodontitis after root canal treatment in one or tow appointments. Premolars and anterior dogs’ teeth had their root canals opened to the oral environment for 6 months before being treated. After root canal negotiation they were filled by the lateral condensation technique with gutta-percha points and Sealapex in one appointment or after a dressing with calcium hydroxide for 7 and 15 days. Six months after the treatment the animals were killed and the tissue prepared for histomorphological analysis. Scores attributed to the different histomorphological events were submitted to statistical analysis, which resulted in ranking the experimental groups from the best to the worst in the following way: (a) calcium hydroxide 14 days; (b) calcium hydroxide 7 days; and (c) one appointment. It was concluded that the use of a calcium hydroxide dressing helps to achieve better results (p < 0.01) than the treatment in one appointment.
Effect of Fatigue Testing on Core Integrity and Post Microleakage of Teeth Restored with Different Post Systems
Lester C. Reid, DMD, MS, Reza B. Kazemi, DMS, and Jonathan C. Meiers, DMD, MS
The purpose of this study was to evaluate a new nondestructive test system, which could test con-currently fatigue and microleakage. Fifty, single-rooted teeth were restored with one of the following posts systems and a composite core: titanium ParaPost cemented with zinc phosphate cement; CosmoPost; C-Post; Esthetic C-Post; and FibreKor post, all cemented with resin cement. Samples were embedded and placed in a positioning jig. They were impacted at 45 degrees to the long axis of the tooth with a force of 55 N at a frequency of 3 Hz for a total of 100,000 impacts. After 60,000 impacts, samples were thermocycled. Core integrity and post microleakage were evaluated periodically throughout the 100,000 impacts. Samples showed no detectable displacement of any of the cores, but the metallic group showed a statistically significant increase in microleakage (p < 0.05) at the conclusion of the study compared with the nonmetallic groups.
Fabrication of Hard Coatings on NiTi Instruments
Teresa Roberta Tripi, DHD, Antonio Bonaccorso, DHD, and Guglielmo Guido Condorelli, DHD
The present study was designed to compare the nature of modified surface layers obtained by tow different procedures on endodontic files made of NiTi alloy: the procedures were arc evaporation physical vapor deposition and thermal metal organic chemical vapor deposition (MOCVD). Experimental samples were GT Rotary Instruments. The first method was based on the physical deposition of elemental titanium in the presence of nitrogen. The second technique is a typical MOCVD procedure which adopts Ti(Et2N)4 as a titanium and nitrogen precursor. Control samples were not exposed to any process. The chemical composition of the surface and in-depth layers of each sample were examined by X-ray photoelectron spectroscopy and X-ray diffraction measurements. The instruments showed surface chemical compositions that were different from those seen in the control group; samples treated with the first method show a surface Nitrogen/Titanium ratio of 1; MOCVD instruments show a surface Nitrogen/Titanium ratio of 1.7; control samples show a Nitrogen/Titanium ratio of 1.7; control samples show a Nitrogen/Titanium ratio of 0.2. Both techniques can produce a high nitrogen concentration on the surface. However, data showed that the morphologies, the in-depth nitrogen distribution, and the chemical nature of the coatings obtained with the two procedures were different. The paper also reports the effects of the two deposition procedures on the nickel/titanium ratio of the surface.
Changes in TrkB-like Immunoreactivity in Rat Trigeminal Ganglion After Tooth Injury
Ali Behnia, DMD, Lei Zhang, MD, Makepeace Charles, BS, and Michael S. Gold, PhD
The purpose of this study was to characterize the impact of tooth injury on the distribution of tyrosine receptor kinase B (TrkB) among trigeminal ganglion neurons and assess the time course for tooth injury-induced TrkB distribution changes. In addition, we sought to further characterize the subpopulation of the afferents expression TrkB receptors. Fifteen adult male Sprague-Dawley rats were studied. Pulpal inflammation was induced and ganglia were subsequently harvested and processed at different time points. Standard immunohistochemical fluorescence techniques were used to visualize TrkB-like immunoreactivity and isolectin B4 binding. Results indicate that full-length TrkB receptors are present in 36.6% of trigeminal ganglion neurons. This percentage decreases for the first 48 h and then increases to 41% by 7 days after tooth injury. Finally, TrkB appears to be present in a large percentage (54%) of isolectin B4 + neurons, suggesting that it is present in nociceptive afferents. These data highlight the fact that even mild injury results in sustained changes in nociceptive circuitry and raise the possibility that the brain-derived neurotrophic factor/TrkB system may contribute to persistent pain after tooth repair.
Generation of Free Randicals and/or Active Oxygen by Light or Laser Irradiation of Hydrogen Peroxide or Sodium Hypochlorite
Midori Kashima-Tanaka, DDS, PhD, Yashuhisa Tsujimoto, DDS, PhD, Kohji Kawamoto, DDS, Naoki Senda, DDS, PhD, Koichi Ito, DDS, MSD, PhD, and Muneyoshi Yamazaki, DDS, PhD
Generation of free radical and/or active oxygen by light or laser irradiation of hydrogen peroxide (H2O2) or sodium hypochlorite (NaCIO), which have been used for tooth whitening or root canal irrigation, was investigated using electron spin resonance spectroscopy combined with a spin-trapping technique. When H2O2 was exposed to light or laser radiation, the amount of hydroxyl radical generated changed according to the concentration of H2O2 and irradiation time. The amount of 5,5-dimethyl-1-pyrrolidone-(2)-oxyl-(1) (DMPO-X) also changed in accordance with irradiation time. The amounts of hydroxyl radical generated from H2O2 after irradiation were in the order: plasma lamp > halogen lamp > He-Ne laser > Yellow He-Ne laser. On the other hand, the amounts of DMPO-X generated from NaCIO after irradiation were in the order: plasma lamp > Yellow He-Ne laser > halogen lamp > He-Ne laser.