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AAE Home > JOE > Abstracts > November 2006, Volume 32, Number 11

November 2006, Volume 32, Number 11

Rotary NiTi Instrument Fracture and its Consequences
Peter Parashos, MDSc, PhD, Harold H. Messer, MDSc, PhD

The fracture of endodontic instruments is a procedural problem creating a major obstacle to normally routine therapy. With the advent of rotary nickel-titanium (NiTi) instruments this issue seems to have assumed such prominence as to be a considerable hindrance to the adoption of this major technical advancement. Considerable research has been undertaken to understand the mechanisms of failure of NiTi alloy to minimize its occurrence. This has led to changes in instrument design, instrumentation protocols, and manufacturing methods. In addition, factors related to clinician experience, technique, and competence have been shown to be influential. From an assessment of the literature presented, we derive clinical recommendations concerning prevention and management of this complication.

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Articaine for Supplemental Intraosseous Anesthesia in Patients With Irreversible Pulpitis
Jason Bigby, DDS, MS, Al Reader, DDS, MS, John Nusstein, DDS, MS, Mike Beck, DDS, MA, Joel Weaver, DDS, PhD

The purpose of this study was to determine the anesthetic efficacy and heart rate effect of 4% articaine with 1:100,000 epinephrine for supplemental intraosseous injection in mandibular posterior teeth diagnosed with irreversible pulpitis. Thirty-seven emergency patients, diagnosed with irreversible pulpitis of a mandibular posterior tooth, received an inferior alveolar nerve block and had moderate-to-severe pain upon endodontic access. The Stabident system was used to administer 1.8 ml of 4% articaine with 1:100,000 epinephrine. Success of the intraosseous injection was defined as none or mild pain upon endodontic access or initial instrumentation. The results demonstrated that anesthetic success was obtained in 86% (32 of 37) of the patients. Maximum mean heart rate was increased 32 beats/minute during the intraosseous injection. We can conclude that when the inferior alveolar nerve block fails to provide profound pulpal anesthesia, the intraosseous injection of 4% articaine with 1:100,000 epinephrine would be successful 86% of the time in achieving pulpal anesthesia in mandibular posterior teeth of patients presenting with irreversible pulpitis.

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A Retrospective Clinical Study of Incidence of Root Canal Instrument Separation in an Endodontics Graduate Program: A PennEndo Database Study
Mian K. Iqbal, BDS, DMD, MS, Meetu R. Kohli, DMD, Jessica S. Kim, DDS

This study investigated the incidence of hand and rotary instrument separation (IS) in the endodontics graduate program at the University of Pennsylvania between 2000 and 2004. In 4,865 endodontic resident cases the incidence of hand and rotary IS was 0.25% and 1.68%, respectively. The odds for rotary IS were seven times more than for hand IS. The probability of separating a file in apical third was 33, and 6 times more likely when compared to coronal and middle thirds of the canals. The highest percentage of IS occurred in mandibular (55.5%) and maxillary (33.3%) molars. Furthermore, the odds of separating a file in molars were 2.9 times greater than premolars. Among the ProFile series 29 rotary instruments, the .06 taper # 5 and # 6 files separated the most. There was no significant difference in IS between the use of torque controlled versus nontorque controlled handpieces, nor between first and second year residency.

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Antibacterial Effect of Two Mineral Trioxide Aggregate (MTA) Preparations Against Enterococcus faecalis and Streptococcus sanguis In Vitro
Khalid Al-Hezaimi, BDS, Thakib A. Al-Shalan, BDS, PhD, Jafar Naghshbandi, DDS, Samuel Oglesby, DDS, James H.S. Simon, DDS, Ilan Rotstein, DDS

The antibacterial effects of gray-colored MTA (GMTA) and white-colored MTA (WMTA) against Enterococcus faecalis and Streptococcus sanguis were assessed in vitro using the tube dilution test. Broth tubes were prepared and divided into experimental and control groups. Aliquots of each of the tested microorganisms were taken from a stock culture and added to each experimental and positive control group. All groups were incubated at 37°C and evaluated for turbidity at 0, 1, 24, 48, and 72-hour time periods. A direct correlation was found between GMTA and WMTA concentrations and their antibacterial effect. Tubes containing GMTA in concentrations of 50, 25, and 12.5 mg/ml did not show E. faecalis growth at any of the time periods tested whereas tubes containing WMTA showed E. faecalis growth at all concentrations and time periods tested. Statistically significant differences were found between tubes containing GMTA in concentrations of 50, 25 and 12.5 mg/ml and tubes containing similar concentrations of WMTA (p < 0.001). Tubes containing GMTA in concentrations of 50, 25, 12.5, 6.25, and 3.12 mg/ml and tubes containing WMTA in concentrations of 50, 25, and 12.5 mg/ml did not show S. sanguis growth at any of the time periods tested. Statistically significant differences were found between tubes containing GMTA in concentrations 6.25 and 3.12 mg/ml and tubes containing similar concentrations of WMTA (p < 0.001). It appears that the susceptibility of E. faecalis and S. sanguis to MTA differed and that GMTA requires lower concentrations than WMTA to exert the same antibacterial effect against each of the microorganisms tested.

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Characterization of Dialister Species in Infected Root Canals
Isabela N. Rôças, DDS, MSc, PhD, José F. Siqueira Jr, DDS, MSc, PhD

Members of the Dialister genus are asaccharolytic obligately anaerobic gram-negative coccobacilli that are culture-difficult or remain uncultivated. Their participation in endodontic infections has been only consistently demonstrated after advent of molecular biology approaches. This study was undertaken to characterize Dialister species in samples from primary endodontic infections using a devised 16S rRNA gene-based group-specific heminested PCR assay followed by sequencing of PCR products. Genomic DNA was isolated directly from clinical samples and used as template for PCR. Amplicons from positive specimens were sequenced and phylogenetically analyzed to determine species identity. Ten of 21 clinical samples yielded sequences with the highest percent similarities to oral Dialister species/phylotypes. Seven sequences were from Dialister invisus, and the other three sequences belonged to Dialister pneumosintes, Dialister oral clone BS095 and Dialister sp. clone IS013B24. Findings demonstrated that different Dialister species can take part in the microbiota associated with apical periodontitis lesions.

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C-shaped Canal System in Mandibular Second Molars Part IV: 3-D Morphological Analysis and Transverse Measurement
Yuan Gao, DDS, PhD, Bing Fan, DDS, MDS, PhD, Gary S.P. Cheung, DDS, MDS, James L. Gutmann, DDS, FACD, FICD, Mingwen Fan, DDS

The purpose of this study was to investigate three-dimensional (3-D) morphology of C-shaped root canal system using micro-computed tomography (μCT) and 3-D reconstruction. There were 102 extracted mandibular second molars with fused roots collected from a native Chinese population. The teeth were scanned by μCT and reconstructed by 3-D software. The 98 teeth that possessed a C-shaped canal system were further analyzed. The 3-D reconstructed images of canals were classified into three categories: merging type (type I), symmetrical type (type II), and asymmetrical type (type III). The cross-sectional images of each tooth were submitted to computer analysis, and the minimum canal wall thickness was measured. In these 98 molars, 32 (32.65%) teeth showed a merging type appearance, 38 (38.78%) a symmetrical type and 28 (28.57%) an asymmetrical type. The minimum canal wall thickness in type I was thicker than that in type II or type III in the apical and middle portion (p < 0.05). Being fully aware of the configuration of C-shaped root canal system and the location of minimum wall thickness will ensure more efficient root canal treatment.

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Formation of Odontoblast-Like Cells from Cultured Human Dental Pulp Cells on Dentin In Vitro
George T.-J. Huang, DDS, MSD, DSc, Kristina Shagramanova, DDS, Selina W. Chan, DDS

Recent characterization of human dental pulp stem cells has shed new light on the understanding of the odontoblastic lineage. The purpose of the study was to characterize human adult dental pulp cells isolated and cultured in vitro and to examine the cell differentiation potential grown on dentin. We observed that some pulp cells isolated with an enzyme-digestion approach proliferated at a similar rate as the immortal cell line NIH 3T3. Population doubling time (PDt) for pulp cells at passage 3 was 22.6 ± 0.5 hours and for NIH 3T3 was 23.1 ± 2.3 hours. The pulp cells formed mineral nodules stimulated with dexamethasone or dexamethasone plus 1,25-dihydroxyvitamin D3. Pulp cells, after being seeded onto mechanically and chemically treated dentin surface, appeared to establish an odontoblast-like morphology with a cytoplasmic process extending into a dentinal tubule revealed by scanning electron microscopy analysis. Our data demonstrated the formation of cells with odontoblastic morphologies on existing dentin, suggesting that isolated human pulp stem cells may differentiate into odontoblasts on dentin in vitro.

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Bacterial Microleakage of Barrier Materials in Obturated Root Canals
Esra Uzer Çelik, DDS, Ayşe Gözde Duransoy Yapar, DDS, Mustafa Ateş, DDS, PhD†, Bilge Hakan Şen, DDS, PhD

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p = 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p < 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p < 0.05).

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The Influence of Canal Curvature on the Mechanical Efficacy of Root Canal Irrigation In Vitro Using Real-Time Imaging of Bioluminescent Bacteria
Donald Nguy, DDS, Christine Sedgley, PhD

There are no quantitative data on the mechanical efficacy of irrigation in the removal of bacteria from curved canals. This study quantitatively analyzed the effects of root canal curvature and preparation size on the mechanical efficacy of irrigation using 33 mandibular single-rooted bicuspids allocated to groups according to root canal curvatures, group 1 (straight) 4 to 8 degrees, group 2 (intermediate curvature) 15 to 19 degrees, and group 3 (greatest curvature) 24 to 28 degrees. Teeth were sequentially instrumented to sizes 27/.04, 36/.04, and 46/.04 using a crown-down technique. Suspensions of the bioluminescent reporter strain Pseudomonas fluorescens 5RL (1.5 × 106 cells) were inoculated into canals of sterilized teeth after each sequential instrumentation. Canals were irrigated with 6 ml of irrigant delivered 1 mm from working length using a 30-gauge needle. Remaining bacteria were quantified using real-time bioluminescent imaging. Irrigation was significantly less effective in 24 to 28 degrees curvature canals prepared to size 27/.04 compared to 46/.04 (p < 0.007, repeated-measures ANOVA).

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Variability of the Diameter and Taper of Size #30, 0.04 Gutta-Percha Cones
Kevin P. Cunningham, DDS, Mary P. Walker, DDS, PhD, James C. Kulild, DDS, MS, John T. Lask, DDS

The purpose of this investigation was to examine variability of gutta-percha (GP) cone tip diameter (D0) and taper among five different brands of #30, 0.04 GP cones (n = 15/brand). Mean percent D0 difference from the manufacturer’s reported (nominal) diameter of Maillefer (−15.42 ± 7.16%) and Lexicon (−12.76 ± 4.98%) were significantly different (p ≤ 0.05) from Maxima (3.18 ± 7.06%), Diadent (3.62 ± 11.37%), and K3 (7.27 ± 7.84%), which were not significantly different from each other but exhibited diameters larger than the nominal diameter as indicated by positive values. Mean taper percent difference of Maxima (−3.00 ± 3.80%) was significantly different (p ≤ 0.05) from Lexicon (3.67 ± 3.64%) and Maillefer (6.67 ± 3.49%), with comparisons to Diadent (−0.17 ± 6.37%) and K3 (1.50 ± 6.93%) not significantly different (p > 0.05) from each other or any other brand. Based on the evidence, there is significant variability between GP cone brands for both diameter and taper, with Maxima and Diadent, respectively, exhibiting the smallest mean difference from manufacturer’s nominal tip diameter and taper. However, the high standard deviation values associated with most of the diameter and taper differences from nominal values also suggest high variability within individual brands.

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The Effect of Ultrasonic Post Instrumentation on Root Surface Temperature
Andrew S. Huttula, DDS, MS, Patricia A. Tordik, DMD, Glen Imamura, DDS, MS, Frederick C. Eichmiller, DDS, Scott B. McClanahan, DDS, MS

This study measured root surface temperature changes when ultrasonic vibration, with and without irrigation, was applied to cemented endodontic posts. Twenty-six, extracted, single-rooted premolars were randomly divided into two groups. Root lengths were standardized, canals instrumented, obturated, and posts cemented into prepared spaces. Thermocouples were positioned at two locations on the proximal root surfaces. Samples were embedded in plaster and brought to 37°C in a water bath. Posts were ultrasonically vibrated for 4 minutes while continuously measuring temperature. Two-way ANOVA compared effects of water coolant and thermocouple location on temperature change. Root surface temperatures were significantly higher (p < 0.001) when posts were instrumented dry. A trend for higher temperatures was observed at coronal thermocouples of nonirrigated teeth and at apical thermocouples of irrigated teeth (p = 0.057). Irrigation during post removal with ultrasonics had a significant impact on the temperature measured at the external root surface.

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Effect of Chemical Irrigants on the Bond Strength of a Self-Etching Adhesive to Pulp Chamber Dentin
Juliana Nascimento Santos, MSc, Marcela Rocha de Oliveira Carrilho, PhD, Mario Fernando De Goes, PhD, Alexandre Augusto Zaia, PhD, Brenda Paula Figueiredo de Almeida Gomes, PhD, Francisco José de Souza-Filho, PhD, Caio Cezar Randi Ferraz, PhD

The aim of this study was to evaluate the influence of endodontic irrigants on adhesion to pulp chamber dentin. Seventy crowns of bovine incisors were cut to expose the pulp chamber. Specimens were divided into seven groups, according to the irrigant solution used: G1, 0.9% sodium chlorite (control); G2, 5.25% NaOCl; G3, 5.25% NaOCl + 17% EDTA; G4, 2% chlorhexidine solution; G5, 2% CHX solution + 17% EDTA; G6, 2% chlorhexidine in a gel base; and G7, 2% CHX gel + 17% EDTA. After irrigation, Clearfil SE Bond was applied to pulp chamber dentin, followed by Filtek Z250 composite. Six rectangular sticks were obtained from each specimen and dentin/resin interface was tested in tension. Bond strength means were analyzed by ANOVA and Tukey test. There was a significant decrease in bond strength associated to NaOCl, whereas chlorhexidine irrigation showed no effects on adhesion. It was concluded that endodontic irrigants affected differently bond strength to pulp chamber dentin.

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Surface Tension Comparison of Four Common Root Canal Irrigants and Two New Irrigants Containing Antibiotic
Luciano Giardino, MD, DDS, Emanuele Ambu, MD, DDS, Carlo Becce, MD, DDS, Lia Rimondini, MD, DDS, Marco Morra

The aim of this study is to compare the surface tension of four common endodontic irrigants: Moltendo EDTA 17%, Cetrexidin, Smear Clear, Sodium hypochlorite 5.25%, with the surface tension of MTAD and Tetraclean. Freshly produced MilliQ water was used as a reference. All measurements were performed following the Wilhelmy plate technique, using a Cahn DCA-322 Dynamic Contact Angle Analyzer at the temperature of 22°C. MilliQ water, sodium hypochlorite 5.25%, and EDTA 17% had the highest surface tension, whereas those of Cetrexedin and Tetraclean has shown the lowest surface tension value. Both new irrigants, MTAD and Tetraclean, are capable of removing the smear layer. Thanks to their low surface tension, increasing the intimate contact of irrigant solutions with the dentinal walls, they may permit deeper penetration.

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Reactions of Connective Tissue to Amalgam, Intermediate Restorative Material, Mineral Trioxide Aggregate, and Mineral Trioxide Aggregate Mixed With Chlorhexidine
Mahmut Sumer, DDS, PhD, Mehtap Muglali, DDS, PhD, Emre Bodrumlu, DDS, PhD, Tolga Guvenc, PhD

The aim of this study was to histopathologically examine the biocompatibility of the high-copper amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), and MTA mixed with chlorhexidine (CHX). This study was conducted to observe the rat subcutaneous connective tissue reaction to the implanted tubes filled with amalgam, IRM, MTA, and MTA mixed with CHX. The animals were sacrificed 15, 30, and 60 days after the implantation procedure. The implant sites were excised and prepared for histological evaluation. Sections of 5 to 6 μm thickness were cut by a microtome and stained with hemotoxylin eosin and examined under a light microscope. The inflammatory reactions were categorized as weak (none or few inflammatory cells ≤25 cells), moderate (>25 cells), and severe (a lot of inflammatory cells not to be counted, giant cells, and granulation tissue). Thickness of fibrous capsules measured five different areas by the digital imaging and the mean values were scored. Amalgam, IRM, and MTA mixed with CHX caused a weak inflammatory response on days 15, 30, and 60. MTA provoked an initial severe inflammatory response that subsided at the 30 and 60 day study period. A clear fibrous capsule was observed beginning from the 15 days in all of the groups. Within the limits of this study, amalgam, IRM, MTA, and MTA mixed with CHX materials were surrounded by fibrous connective tissue indicated that they were well tolerated by the tissues, therefore, MTA/CHX seemed to be biocompatible.

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Removal Efficiency of Calcium Hydroxide Intracanal Medicament With Two Calcium Chelators: Volumetric Analysis Using Spiral CT, An In Vitro Study
Suresh Nandini, BDS, Natanasabapathy Velmurugan, MDS, Deivanayagam Kandaswamy, MDS

The vehicles used to carry calcium hydroxide intracanal medicament are many and may affect the retrieval. Access cavities were prepared in 40 single rooted anterior teeth, cleaning and shaping was done and filled with either Metapex or pure calcium hydroxide powder in distilled water. After 7 days the calcium hydroxide was retrieved using either 17% EDTA or 10% citric acid in combination with ultrasonic agitation. Volume analysis was done using spiral computed tomography. The percentage difference was calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney U test. 10% citric acid showed better removal efficiency than 17% EDTA for Metapex (p = 0.003). The 17% EDTA showed excellent removal efficiency of powder form of calcium hydroxide in distilled water than Metapex (p < 0.001). Ten percent citric acid removed powder form of calcium hydroxide in distilled water better than Metapex (p = 0.05).

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Cleaning Efficacy and Dentin Micro-Hardness After Root Canal Irrigation With a Strong Acid Electrolytic Water
Yu Qing, DDS, PhD, Yasumitsu Akita, DDS, PhD, Satoshi Kawano, DDS, PhD, Sukeyuki Kawazu, DDS, Takakazu Yoshida, DDS, PhD, Ichiro Sekine, DDS, PhD

The purpose of this study was to evaluate the cleaning effect of root canal walls using strong acid electrolytic water (SAEW) as a root canal irrigant, and to investigate the influence of SAEW on the root canal dentin by micro-hardness test. Forty-three single-rooted, single-canaled teeth were instrumented using standard step-back technique with K-files. Irrigation was performed using distilled water, 5.25% NaOCl and 3% H2O2, SAEW, or 15% EDTA solution in five groups. Samples were prepared to be examined under a scanning electron microscope (SEM) and micro Vickers hardness (HV) test machine. Our results showed that the root cleaning effects of the combined use of SAEW and NaOCl solution as root canal irrigants were equivalent to those in the group with NaOCl and 15% EDTA. When SAEW was used for 1 min under ultrasonic vibration, no decreases in the hardness of dentin inside the root canal were detected.

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Submandibular Tuberculous Lymphadenitis after Endodontic Treatment of the Mandibular First Premolar Tooth: Report of a Case
Umit Ertas, Sinan Tozoglu, M. Hamidullah Uyanik

Cervical tuberculous lymphadenitis (scrofula) is an infectious granulomatous disease that requires a precise diagnosis. The differential diagnosis involves mainly the pathologic conditions involving the regional lymph nodes and the submandibulary salivary glands. Although tuberculous lesions generally develop secondary to pulmonary disease, clinical manifestations are occasionally seen with no evidence of involvement of the lungs. In this report, a case of tuberculous submandibular lymphadenitis developing after endodontic treatment of the mandibular first premolar tooth is described.

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Case Series of Four Different Headache Types Presenting as Tooth Pain
Aurelio A. Alonso, DDS, Donald R. Nixdorf, DDS, MS

Case reports in the literature discuss various headache disorders that present as pain in the face. The current understanding of neuroanatomy and headache mechanisms suggests that headache pain originates within intracranial structures and is then referred to the face, jaws, and teeth. This case series describes four patients, one each with migraine headache, cluster headache, paroxysmal hemicrania, and hemicrania continua, all of which who presented to dentists with the chief complaint of tooth pain. This is the first report of hemicrania continua presenting as tooth pain. It is important that dentists be cognizant of headache disorders so that they may be able to identify headache pains masquerading as toothache.

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