Journal of Endodontics - Articles in Press

Effects of Four Instruments on Coronal Pre-enlargement by Using Cone Beam Computed Tomography - Corrected Proof

2010-03-08

Abstract: Introduction: This ex vivo study used cone beam computed tomography to evaluate the amount of dentin removal from the distal wall of the mesial canal of human mandibular first molars caused by 4 instruments used to flare the cervical third.Methods: Thirty-two mesial roots were divided into 4 groups prepared by using ProTaper, K3, Gates-Glidden, or LA Axxess. The dentin thickness of the distal cervical wall of mesial canals was measured before and after the preparation by using computed tomography and Adobe Photoshop software.Results: There was no statistically significant difference between the study groups (P > 05).Conclusions: All the instruments used for cervical preparation seemed to be safe and did not damage the dentin structure of the distal wall of mesial root canals of mandibular molars.

Environmental Scanning Electron Microscopy Connected With Energy Dispersive X-ray Analysis and Raman Techniques to Study ProRoot Mineral Trioxide Aggregate and Calcium Silicate Cements in Wet Conditions and in Real Time - Corrected Proof

2010-03-08

Abstract: Introduction: ProRoot mineral trioxide aggregate (MTA) and calcium silicate cements are able to set in a moist environment. The aim of the study was to examine the surface structure and composition of a cement paste under wet conditions and in real time during setting by environmental scanning electron microscopy connected with energy dispersive x-ray analysis (ESEM-EDX) and micro-Raman techniques.Methods: White ProRoot MTA and experimental white tetrasilicate cement (wTC) and wTC containing bismuth oxide (wTC-Bi) were studied. Cement disks were analyzed 10 minutes after powder-liquid mixing (freshly prepared samples) and after immersion in Dulbecco phosphate-buffered saline at 37°C for 24 hours (24-hour-aged samples).Results: Freshly prepared wet cements at ESEM-EDX exposed an irregular surface (displaying calcium, silicon, aluminum, chlorine reflexes, and bismuth traces in MTA and wTC-Bi) with needle-like and cubic-hexagonal shaped crystals. Aggregates of spheroidal Ca-P–rich crystals (spherulites) appeared on the surface of 24-hour-aged samples. The starting unhydrated powders displayed the typical Raman bands of Portland cement components: alite, belite, and calcium sulfate (only as anhydrite in MTA and as both anhydrite and gypsum in wTC and wTC-Bi). MTA powder showed higher amount of calcium carbonate and lower quantities of anhydrite and higher crystallinity of the silicate component, leading to a slower hydration reaction. Products/markers of hydration reactions were present on fresh samples; ettringite formed on the surface of all the cements; calcium hydroxide (portlandite) was detected only on the surface of wTC, but no conclusion can be drawn on wTC-Bi and MTA because of the interference of bismuth oxide. Calcium phosphate and calcite/aragonite bands were detected on all 24-hour-aged cements; portlandite was no longer detected on wTC.Conclusions: ESEM and micro-Raman are powerful and suitable techniques to investigate endodontic calcium silicate hydrated cements in real time and in their humid state without inducing artifacts by sample preparation. The formation of apatite spherulites on calcium silicate cements might have clinical relevance.

Impact of a Retained Instrument on Treatment Outcome: A Systematic Review and Meta-analysis - Corrected Proof

Piyanee Panitvisai, Pimnalin Parunnit, Chankhrit Sathorn, Harold H. Messer — 2010-03-08

Abstract: Introduction: Fracture of root canal instruments is one of the most troublesome incidents in endodontic therapy. This systematic review and meta-analysis aim to determine the outcome difference between retained fractured instrument cases and matched conventional treated cases.Methods: The MEDLINE database, EMBASE, Web of Science, and the Cochrane Database were searched. Reference lists were scanned. A forward search was undertaken on identified articles. Papers citing these articles were identified through Science Citation Index to identify potentially relevant subsequent primary research. A systematic data extraction sheet was constructed. Data in these studies were independently extracted. Risk differences of included studies were combined by using the generic inverse variance data and fixed effects method. A 2-stage analysis was conducted. The first was limited to case-control studies, and the second included case series in which data were available for teeth with and without periradicular lesions.Results: Two case-control studies were identified and included, covering 199 cases. Weighted mean healing for teeth with a retained instrument fragment was 91%. The 2 studies were homogeneous. Risk difference of the combined data was 0.01, indicating that a retained fragment did not significantly influence healing. Overall, 80.7% of lesions healed when a periapical lesion was present, compared with 92.4% remaining healthy when no lesion was present initially (P < .02).Conclusions: On the basis of the current best available evidence, the prognosis for endodontic treatment when a fractured instrument fragment is left within a root canal is not significantly reduced.

Root Canal Area Increase Promoted by the EndoSequence and ProTaper Systems: Comparison by Computed Tomography - Corrected Proof

2010-03-08

Abstract: Introduction: The aim of this study was to compare the increase of the root canal area after instrumentation with EndoSequence or ProTaper rotary systems.Methods: Twenty-two mesial root canals from mandibular molars were instrumented. Teeth were mounted on a base, numbered, and divided into 2 groups; teeth from 1–11 (PT group) were instrumented by using the ProTaper system, and teeth from 12–22 (ES group) were instrumented by using the EndoSequence system. Cone beam computed tomography was performed on all teeth before and after instrumentation. Measurements at 3, 5, and 7 mm as well as differences in instrument performance were statistically compared by the Student t test at 5% significance level.Results: Both systems increased significantly the root canal area (P < .05) at all levels. Comparison between the rotary systems showed significantly greater increase (P < .05) for EndoSequence at 3 mm, with no statistically significant difference (P < .05) at the other levels.Conclusions: Both rotary systems increased significantly the root canal area.

Effect of Mineral Trioxide Aggregates and Portland Cements on Inflammatory Cells - Corrected Proof

2010-03-08

Abstract: Introduction: Recently, some studies have compared mineral trioxide aggregate (MTA) with Portland cements, concluding that the principal ingredients of Portland cements are similar to those of MTA. The purpose of the present study was to evaluate the effect of gray MTA, white MTA, and gray and white Portland cements on inflammatory cells in rats.Methods: Fresh mixtures mixed with distilled water were placed in polyethylene tubes, which were implanted in the dorsal subcutaneous connective tissue of 60 Sprague-Dawley rats along with empty tubes as controls. Tissue specimens were collected after the rats were sacrificed after 7, 15, 30, 60, and 90 days. The specimens were fixed, stained, processed, and histologically evaluated under a light microscope. Inflammatory reactions were classified as grade 0: without inflammatory cells, grade I: sporadic infiltration of inflammatory cells, grade II: moderate infiltration (<25 cells), grade III: dense and severe infiltration (25-125 cells), and grade IV: very dense and severe infiltration (>125 cells). Data were analyzed with the nonparametric (two factor) analysis of variance and Kruskal-Wallis H-test.Results: All the groups showed grade III inflammation after 7 and 15 days; there was a decrease in the inflammatory process after 30, 60, and 90 days. After 90 days, gray MTA, white MTA, and control groups had grade 0 inflammatory process, but gray Portland cement and white Portland cement groups showed grade 0 to grade I inflammatory processes.Conclusion: MTAs were more biocompatible; however, more studies are required.

Effectiveness of Chemomechanical Preparation With Alternating Use of Sodium Hypochlorite and EDTA in Eliminating Intracanal Enterococcus faecalis Biofilm - Corrected Proof

2010-03-08

Abstract: Introduction: The elimination of microorganisms from root canals is a critical step in endodontic treatment. We aimed to evaluate the antimicrobial effectiveness of an alternating irrigation regimen during chemomechanical preparation (CMP).Methods: During 21 days, root canals of extracted human teeth were infected with Enterococcus faecalis, and colonization was confirmed by scanning electron microscopy (SEM). Canals were irrigated with saline solution (control group), with 5.25% NaOCl followed by a final rinse with 17% EDTA (conventional irrigation group), or with the alternating use of NaOCl and EDTA (alternating irrigation [AI] group). Samples were taken before treatment (S1), after CMP (S2), and during the following 14 days. Two specimens/group were analyzed by SEM.Results: The AI group yielded negative agar and liquid cultures from immediately after CMP and from the 5th day on, respectively. SEM confirmed several bacterium-free sites in the AI group.Conclusion: The irrigation regimen based on the alternating use of NaOCl and EDTA seems to be a promising endodontic tool because it promoted the elimination of root canal E. faecalis biofilms throughout the experimental period.

Adhesion of Self-adhesive Root Canal Sealers on Gutta-Percha and Resilon - Corrected Proof

2010-03-08

Abstract: Introduction: The aim of this study was to evaluate the bond strength of different adhesive sealers on Resilon and gutta-percha.Methods: Pellets of gutta-percha and Resilon were embedded into test tubes. Small eyelets were attached to those surfaces with a 0.5-mm film of different root canal sealers. Real Seal, Real Seal SE, Hybrid Root Seal (also known as Meta Seal), and AH Plus were used. AH Plus as a nonadhesive sealer served as a control group. In all groups (n = 10) shear bond strength was measured.Results: Shear bond strength was relatively low (0.1–3 MPa) and significantly higher in the groups with a single component adhesive sealer. No substantial bond strength was found in the control group. Overall bond strength to Resilon was higher than to gutta-percha but not significant compared with the Hybrid Root Seal group.Conclusions: With single component self-adhesive sealers, an adhesive connection might be formed to gutta-percha as well as to Resilon.

Comparison of Canal Transportation and Centering Ability of Twisted Files, Pathfile-ProTaper System, and Stainless Steel Hand K-Files by Using Computed Tomography - Corrected Proof

Richard Gergi, Joe Abou Rjeily, Joseph Sader, Alfred Naaman — 2010-03-08

Abstract: Introduction: The purpose of this study was to compare canal transportation and centering ability of 2 rotary nickel-titanium (NiTi) systems (Twisted Files [TF] and Pathfile-ProTaper [PP]) with conventional stainless steel K-files.Methods: Ninety root canals with severe curvature and short radius were selected. Canals were divided randomly into 3 groups of 30 each. After preparation with TF, PP, and stainless steel files, the amount of transportation that occurred was assessed by using computed tomography. Three sections from apical, mid-root, and coronal levels of the canal were recorded. Amount of transportation and centering ability were assessed. The 3 groups were statistically compared with analysis of variance and Tukey honestly significant difference test.Results: Less transportation and better centering ability occurred with TF rotary instruments (P < .0001). K-files showed the highest transportation followed by PP system. PP system showed significant transportation when compared with TF (P < .0001).Conclusions: The TF system was found to be the best for all variables measured in this study.

Temperature Changes Accompanying Near Infrared Diode Laser Endodontic Treatment of Wet Canals - Corrected Proof

Raghad Hmud, William A. Kahler, Laurence J. Walsh — 2010-03-08

Abstract: Introduction: Diode laser endodontic treatments such as disinfection or the generation of cavitations should not cause deleterious thermal changes in radicular dentin.Methods: This study assessed thermal changes in the root canal and on the root surface when using 940 and 980 nm lasers at settings of 4 W/10 Hz and 2.5 W/25 Hz, respectively, delivered into 2000-μm fibers to generate cavitations in water. The root surface temperature in the apical third was recorded, as was the water temperature in coronal, middle, and apical third regions, by using thermocouples placed inside the canal. Lasing was undertaken with either rest periods or rinsing between 5-second laser exposures.Results: Both diode lasers induced only modest temperature changes on the external root surface at the settings used. Even though the temperature of the water within the canal increased during lasing by as much as 30°C, the external root surface temperature increased by only a maximum of 4°C. Irrigation between laser exposures was highly effective in minimizing thermal changes within the root canal and on the root surface.Conclusions: Diode laser parameters that induce cavitation do not result in adverse thermal changes in radicular dentin.

Three-dimensional Numeric Simulation of Root Canal Irrigant Flow with Different Irrigation Needles - Corrected Proof

2010-03-02

Abstract: Introduction: The purpose of this study was to investigate, by using computational fluid dynamics (CFD), the effect of needle tip design on irrigant flow pattern.Methods: Parameters of an in vitro irrigation model were used to create CFD models. Experimental data obtained by recording the dynamic fluid distribution during irrigation with 27-gauge notched (Appli-Vac) and side-vented open-ended (Vista-Probe) needles, placed at 3 and 5 mm from the apex of a simulated straight root canal prepared in a plastic block, were used to validate the results of CFD analysis. Two “virtual” needle tip designs were also included in CFD analysis, one with a beveled tip (based on Appli-Vac) and one with side-vent based on Vista-Probe needle but with a closed-end tip. Apical pressure, flow velocity at wall, and flow velocity distribution within root canal were determined by CFD.Results: Flow patterns generated by CFD were in close agreement with the in vitro model. When placed 3 mm from the apex, the irrigant reached, or almost reached, the apex with all 4 needle designs. When placed 5 mm from the apex, the irrigant did not reach the apex with the side-vented needles. Irrigant velocities on canal walls were very low (0–0.7 m/s) compared with that within the needle lumen (∼7 m/s) and varied as a function of needle tip design. Apical pressure was highest with the beveled needle and lowest with the side-vented closed-end needle.Conclusions: Irrigation needle tip design influences flow pattern, flow velocity, and apical wall pressure, all important parameters for the effectiveness and safety of irrigation. Computational fluid dynamics can be a valuable tool in assessing the implications of needle tip design on these parameters.

Analyzing Endosonic Root Canal File Oscillations: An In Vitro Evaluation - Corrected Proof

Simon C. Lea, A. Damien Walmsley, Philip J. Lumley — 2010-03-02

Abstract: Introduction: Passive ultrasonic irrigation may be used to improve bacterial reduction within the root canal. The technique relies on a small file being driven to oscillate freely within the canal and activating an irrigant solution through biophysical forces such as microstreaming. There is limited information regarding a file's oscillation patterns when operated while surrounded by fluid as is the case within a canal root.Methods: Files of different sizes (#10 and #30, 27 mm and 31 mm) were connected to an ultrasound generator via a 120° file holder. Files were immersed in a water bath, and a laser vibrometer set up with measurement lines superimposed over the files. The laser vibrometer was scanned over the oscillating files. Measurements were repeated 10 times for each file/power setting used.Results: File mode shapes are comprised of a series of nodes/antinodes, with thinner, longer files producing more antinodes. The maximum vibration occurred at the free end of the file. Increasing generator power had no significant effect on this maximum amplitude (p > 0.20). Maximum displacement amplitudes were 17 to 22 μm (#10 file, 27 mm), 15 to 21 μm (#10 file, 31 mm), 6 to 9 μm (#30 file, 27 mm), and 5 to 7 μm (#30, 31 mm) for all power settings. Antinodes occurring along the remaining file length were significantly larger at generator power 1 than at powers 2 through 5 (p < 0.03).Conclusions: At higher generator powers, energy delivered to the file is dissipated in unwanted vibration resulting in reduced vibration displacement amplitudes. This may reduce the occurrence of the biophysical forces necessary to maximize the technique's effectiveness.

A Systematic Evaluation of the Quality of Meta-analyses in Endodontics - Corrected Proof

Siriwan Suebnukarn, Sureeporn Ngamboonsirisingh, Angwara Rattanabanlang — 2010-02-22

Abstract: Introduction: Meta-analyses have been suggested to be the highest form of evidence available to clinicians to guide clinical practice in dental care. High methodologic quality is a prerequisite for valid interpretation and application of review findings. However, meta-analyses are complex exercises, and assessing quality can be a daunting task. Clinicians and policymakers require guidance, which is not provided adequately by the available literature on the quality of meta-analyses. The purpose of this study was to systematically evaluate the quality of meta-analyses that address topics pertinent to endodontics.Methods: To identify potentially eligible meta-analyses for inclusion, systematic searches performed in MEDLINE and the Cochrane Database of Systematic Reviews were enriched by hand searches, citation mining, and expert recommendation. Comprehensive search strategies were constructed for electronic searches. Predetermined inclusion criteria were applied to each identified meta-analysis independently by two reviewers. To assess report quality, the included meta-analyses were assessed by using A Measurement Tool to Assess Systematic Reviews (AMSTAR).Results: A total of 16 reports of meta-analyses were included (kappa = 0.96). The overall quality of reports of meta-analyses was found to be high, with an estimated mean overall AMSTAR score of 8.33 out of 11 (95% confidence interval, 7.62-8.88). The weakest areas within the included meta-analyses were failure to report the likelihood of publication bias.Conclusions: The overall quality of the reports of meta-analyses available in endodontics is high according to AMSTAR.

In Vitro Sustained Release of Calcium Ions and pH Maintenance From Different Vehicles Containing Calcium Hydroxide - Corrected Proof

2010-02-22

Abstract: Introduction: Calcium hydroxide is widely used as an intracanal medicament in endodontics. Its therapeutic effects depend on the dissociation of calcium hydroxide into calcium and hydroxyl ions, which, in turn, depends on the vehicle used. The purpose of this in vitro study was to evaluate the sustained release of calcium ions and the pH change of calcium hydroxide over a period of 30 days when formulated with propylene glycol, polyethylene glycol 6000, chitosan, and guar gum.Methods: Various formulations were prepared and placed inside the root canals of human teeth and were suspended in glass vials containing distilled water. At specific time intervals, the calcium ion concentration was analyzed using an ultraviolet spectrophotometer. pH changes of the medium were measured at various time intervals up to 30 days.Results: Results revealed that chitosan formulation showed the maximum sustained release of calcium ions compared with the other three formulations. All the formulations exhibited high alkaline pH upto 30 days.Conclusion: From the results of this in vitro study, it can be concluded that chitosan can be used as a promising vehicle for for the sustained release of calcium ions from the calcium hydroxide in the root canal system.

Efficacy of Cone-Beam Computed Tomography as a Modality to Accurately Identify the Presence of Second Mesiobuccal Canals in Maxillary First and Second Molars: A Pilot Study - Corrected Proof

2010-02-22

Abstract: Introduction: The achievement of successful nonsurgical endodontic therapy relies on the location, disinfection, and obturation of all canals in the root canal system. This study evaluated the ability of the i-CAT cone-beam computed tomography (CBCT) unit (Imaging Sciences International, Hatfield, PA) to accurately identify the presence or absence of the second mesiobuccal canal (MB2) in maxillary first and maxillary second human molars.Methods: Twenty completely intact maxillary first and second molars were used as test subjects. The existence of the MB2 canal was evaluated by the following three methods: (1) periapical radiograph evaluation, (2) CBCT evaluation, and (3) clinical sectioning evaluation. The evaluation methods were used to compare the accuracy of CBCT scanning and clinical sectioning (gold standard) in the identification of the MB2 canal.Results: The i-CAT CBCT unit accurately identified the presence or absence of the MB2 canal in 78.95% of samples. Statistical analysis showed that there was no significant difference in the ability of CBCT scanning to detect the MB2 canal when compared with the gold standard of clinical sectioning (p > 0.5).Conclusion: The results of this in vitro investigation may be interpreted to show that CBCT scanning is a reliable method to detect the MB2 canal when compared with the gold standard of physical sectioning of the specimen.

Effect of Acidic Environment on the Push-Out Bond Strength of Mineral Trioxide Aggregate - Corrected Proof

2010-02-22

Abstract: Introduction: Reduced surface microhardness and decreased sealing ability have been shown after the placement of mineral trioxide aggregate (MTA) in an acidic environment. In this study, the effect of an acidic environment on the push-out strength of MTA was evaluated.Methods: Eighty root dentin slices from freshly extracted single-rooted human teeth were sectioned and their lumen instrumented to achieve a diameter of 1.3 mm. One gram of tooth-colored ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN) was mixed with 0.33 g of distilled water and introduced into the canals of the root-dentin slices and treated with ultrasonic energy. The specimens were then randomly divided into four groups (n = 20) and wrapped in pieces of gauze soaked in phosphate buffer saline solution (pH = 7.4) and butyric acid buffered at pH values of 4.4, 5.4, or 6.4, respectively. They were then incubated for 4 days at 37°C. The push-out bond strengths were then measured using a universal testing machine. The slices were examined under a light microscope at ×40 magnification to determine the nature of the bond failure. The data were analyzed using one-way analysis of variance and the Tamhane post hoc test.Results: The greatest mean push-out bond strength (7.28 ± 2.28 MPa) was observed after exposure to a pH value of 7.4. The values decreased to 2.47 ± 0.61 MPa after exposure to a pH value of 4.4. There were significant differences between the groups (p < 0.001). Inspection of the samples revealed the bond failure to be predominantly adhesive.Conclusion: The force needed for displacement of MTA was significantly lower in samples stored at lower pH values.

Evaluation of Irrigant Flow in the Root Canal Using Different Needle Types by an Unsteady Computational Fluid Dynamics Model - Corrected Proof

2010-02-22

Abstract: Introduction: The aim of this study was to evaluate the effect of needle tip design on the irrigant flow inside a prepared root canal during final irrigation with a syringe using a validated Computational Fluid Dynamics (CFD) model.Methods: A CFD model was created to simulate the irrigant flow inside a prepared root canal. Six different types of 30-G needles, three open-ended needles and three closed-ended needles, were tested. Using this CFD model, the irrigant flow in the apical root canal was calculated and visualized. As a result, the streaming velocity, the apical pressure, and the shear stress on the root canal wall were evaluated.Results: The open-ended needles created a jet toward the apex and maximum irrigant replacement. Within this group, the notched needle appeared less efficient in terms of irrigant replacement than the other two types. Within the closed-ended group, the side-vented and double side-vented needle created a series of vortices and a less efficient irrigant replacement; the side-vented needle was slightly more efficient. The multi-vented needle created almost no flow apically to its tip, and wall shear stress was concentrated on a limited area, but the apical pressure was significantly lower than the other types.Conclusions: The flow pattern of the open-ended needles was different from the closed-ended needles, resulting in more irrigant replacement in front of the open-ended needles but also higher apical pressure.

Biofilm Formation Capability of Enterococcus faecalis Cells in Starvation Phase and Its Susceptibility to Sodium Hypochlorite - Corrected Proof

Hongyan Liu, Xi Wei, Junqi Ling, Weilu Wang, Xiangya Huang — 2010-02-08

Abstract: Introduction: Enterococcus faecalis is commonly associated with persistent periapical infections. The physiologic state of the cells in the canal is probably closest to the starvation state. However, the biofilm formation capability of starved E. faecalis cells on human dentin and the susceptibility of the biofilm to 5.25% sodium hypochlorite remain poorly understood.Methods: E. faecalis American Type Culture Collection (ATCC) 29212 in different growth phases were incubated on human dentin and polystyrene blocks. Scanning electron microscopy and biofilm assay were used to investigate the biofilm formation capability of these cells. The susceptibility of the biofilm to 5.25% NaClO was also determined by the plate count method.Results: Scanning electron microscopy and biofilm assay showed that starved cells were able to form biofilm on dentin with reduced efficiency as compared with the cells in the exponential phase and stationary phase (p < 0.05). Biofilm grown on dentin harbored more cells than polystyrene (p < 0.05). Biofilms of starved cells were more resistant to 5.25% NaClO than those of stationary cells (p < 0.05), and the impact of 5.25%NaClO on them decreased as the biofilm matured.Conclusion: E. faecalis cells in the starvation phase could develop biofilm on human dentin, which is responsive to 5.25% NaClO. It may contribute to the predominant role of E. faecalis involved in persistent periapical infections.

Comparison of Bacterial Reduction in Straight and Curved Canals Using Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet Laser Treatment versus a Traditional Irrigation Technique With Sodium Hypochlorite - Corrected Proof

2010-02-08

Abstract: Introduction: This study compared the reduction of Enterococcus faecalis in straight and curved canals using an erbium, chromium:yttrium-scandium-gallium-garnet laser and irrigation with 6.15% sodium hypochlorite (NaOCl).Methods: Fifty-five single-rooted extracted teeth were divided into straight and curved canal groups. The root lengths were standardized (14.0mm) and NiTi instruments were used to prepare the canals to a size #40/0.06 taper. Irrigation was performed with 6.15% NaOCl and RCPrep (Premier Dental Products Co, Plymouth Meeting, PA) as lubricant. The smear layer was removed with 17% EDTA. The samples were sterilized, inoculated with E. faecalis, and incubated for 48hours at 37° in a CO2 chamber. They were then divided into 7 groups: NaOCl in straight canals (NS); NaOCl in curved canals (NC); laser in straight canals (LS); laser in curved canals (LC); positive control straight canals (PCS); positive control curved canals (PCC); and negative control (NegC). Bacterial reduction was measured by counting the colony-forming units (CFUs) and determining the optical density.Results: Groups NS, NC, and LS exhibited bacterial growth in 1 out of 10 samples (10%). In group LC, three out of 10 samples (30%) showed bacterial growth. Kruskal-Wallis showed a statistically significant difference between all treatment groups and the positive controls (p<0.001). Analysis of variance showed a statistical significant difference in optic density between experimental and positive controls.Conclusions: Traditional irrigation techniques using 6.15% NaOCl effectively eliminated all bacteria in straight and curved canals. Er,Cr:YSGG laser also effectively removed all bacteria from straight canals. However, in three curved canals, even though there were significant bacterial reductions, they failed to render canals completely free of bacteria.

Effect of the Combination of Sodium Hypochlorite and Chlorhexidine on Dentinal Permeability and Scanning Electron Microscopy Precipitate Observation - Corrected Proof

2010-02-08

Abstract: Introduction: This study compared the combined use of sodium hypochlorite (NaOCl) and chlorhexidine (CXH) with citric acid and CXH on dentinal permeability and precipitate formation.Methods: Thirty-four upper anterior teeth were prepared by rotary instrumentation and NaOCl. The root canal surfaces were conditioned for smear layer removal using 15% citric acid solution under ultrasonic activation and a final wash with distilled water. All teeth were dried, and 30 specimens were randomly divided into three equal groups as follows: positive control group (PC), no irrigation; 15% citric acid + 2% CHX group (CA + CHX); and 1% NaOCl + 2% CHX group (NaOCl + CHX). All roots were immersed in a 0.2% Rhodamine B solution for 24 hours. One-millimeter-thick slices from the cementum-enamel junction were scanned at 400 dpi and analyzed using the software ImageLab (LIDO-USP, Sao Paulo, Brazil) for the assessment of leakage in percentage. For scanning electron microscopy analysis, four teeth, irrigated for NaOCl + CHX samples, were split in half, and each third was evaluated at 1,000× and 5,000× (at the precipitate).Results: Using the analysis of variance test followed by the Bonferroni comparison method, no statistical differences between groups were found when analyzed at the cervical and medium thirds. At the apical third, differences between the PC and NaOCl + CHX (p < 0.05) and CA + CHX and NaOCl + CHX could be seen (p < 0.05).Conclusion: The combination of 1% NaOCl and 2% CHX solutions results in the formation of a flocculate precipitate that acts as a chemical smear layer reducing the dentinal permeability in the apical third.

Effect of Vapor Lock on Root Canal Debridement by Using a Side-vented Needle for Positive-pressure Irrigant Delivery - Corrected Proof

2010-02-08

Abstract: Introduction: This study examined the effect of vapor lock on canal debridement efficacy by testing the null hypothesis that there is no difference between a “closed” and an “open” system design in smear layer and debris removal by using a side-vented needle for irrigant delivery.Methods: Roots in the closed system were sealed with hot glue and embedded in polyvinylsiloxane to restrict fluid flow through the apical foramen during cleaning and shaping. For the open system, the apical foramen was enlarged and connected to the external environment via a channel within the polyvinylsiloxane to permit unrestricted fluid flow. Smear and debris scores were evaluated by using scanning electron microscopy and analyzed by using Cochran-Mantel-Haenszel statistic.Results: No difference in smear scores was detected between the 2 systems at all canal levels. Significant differences in debris scores between the 2 systems were found at each canal level: coronal (P < .001), middle (P < .001), and apical (P < .001).Conclusions: The null hypothesis was rejected; presence of an apical vapor lock effect adversely affects debridement efficacy. Thus, studies with unspecified or questionable mechanisms to restrict fluid flow through the apical foramen have to be interpreted with caution.

Dissolution of Nickel-Titanium Endodontic Files via an Electrochemical Process: A New Concept for Future Retrieval of Fractured Files in Root Canals - Corrected Proof

2010-02-08

Abstract: Introduction: The retrieval of fractured instruments from root canals has been largely reported in the literature. However, a less complex retrieval method that causes minimum damage to the dental structures is needed. The aim of this article is to introduce a new concept of retrieval of fractured instruments from root canals based on an electrochemical process.Methods: Current register tests were used to evaluate the dissolution process of 25.04 nickel-titanium (NiTi) K3 rotary files. A constant anodic potential was applied to the NiTi files, whereas the Potentiostat registered the anodic current. After the tests, all files were observed by using an optical microscope.Results: The current attained initial values of approximately 55 mA that declined during the entire test. A good reproducibility of results was observed. The optical microscopy analysis evidenced a progressive consumption of the files with increasing polarization time.Conclusions: The results presented here show that the concept of fractured file retrieval by an electrochemical process is feasible. This concept resulted in a consistent basis for the development of a method to remove fractured instruments from root canals.

Apexogenesis Treatment with a New Endodontic Cement: A Case Report - Corrected Proof

Ali Nosrat, Saeed Asgary — 2010-02-08

Abstract: Introduction: This article describes an apexogenesis report of an 8-year old boy referred to our clinic 4 weeks after an impact trauma to the maxillary left central incisor that caused a complicated crown fracture and pulpal exposure.Methods: In the radiographic examination, the tooth was observed to be immature. After access cavity preparation, cervical pulpotomy was performed, and the remaining pulp was capped with calcium enriched mixture (CEM) cement. The crown was restored by using the fractured incisal segment on the next day.Results: The radiographic and clinical examinations on the 6-month and 12-month follow-ups showed that the tooth remained functional, root development was completed, and the apex was formed. A calcified bridge was produced underneath the capping material. No further endodontic intervention was necessary.Conclusions: Considering the healing potential of traumatized immature vital pulp, the use of CEM cement for apexogenesis might be an applicable choice; however, further clinical studies with longer follow-up periods are recommended.

Effect of Unintentionally Extruded Mineral Trioxide Aggregate in Treatment of Tooth with Periradicular Lesion: A Case Report - Corrected Proof

Erhan Tahan, Davut Çelik, Kürşat Er, Tamer Taşdemir — 2010-02-08

Abstract: Introduction: This case report describes the effect of unintentionally extruded mineral trioxide aggregate (MTA) into periradicular lesions and tissues on the prognosis of periradicular healing in maxillary left central incisor with periradicular lesion.Methods: A 17-year-old girl with a large periradicular lesion from the apices of her maxillary left central to lateral incisors was referred. Tooth #9 had an open apex, but tooth #10 was normal. Conservative root canal treatment was performed to tooth #10. The apical third of the canal of tooth #9 was filled with MTA as an apical plug because of open apex. During this procedure, a radiograph was taken, and it showed an excessive extrusion of MTA into the periradicular lesion. The remaining canal space was filled with gutta-percha and AH Plus sealer by using a lateral condensation technique.Results: At follow-up examinations, the tooth was asymptomatic and radiographically showed repair of the lesion. Healing was achieved without any need for further endodontic surgical intervention.Conclusions: The results of this case showed that complete periapical healing is possible despite the extrusion of the MTA. This might be due to biologic properties of the MTA. Even so, extrusion of the filling material is not advocated.

Effect of Apical Preparation Size and Preparation Taper on Irrigant Volume Delivered by Using Negative Pressure Irrigation System - Corrected Proof

Matthew Brunson, Carlos Heilborn, D. James Johnson, Nestor Cohenca — 2010-02-08

Abstract: Introduction: The purpose of this investigation was to determine the effect that apical preparation size and preparation taper had on the volume of irrigant delivered to the working length of a root canal preparation in a clinically relevant amount of time.Methods: Forty intact human single-rooted teeth were randomly distributed into 2 separate phases. The first phase aimed to determine the smaller apical size that will allow more volume of irrigant at working length. All samples had the same taper and were sequentially instrumented to sizes of 30.06, 35.06, 40.06, and 45.06. The second phase aimed to determine the taper that will allow more volume of irrigant at working length. Teeth were sequentially instrumented to 40.02, 40.04, 40.06, and 40.08. All samples were irrigated by using the micro-cannula, and the volume of sodium hypochlorite suctioned at working length under negative pressure was measured during a period of 30 seconds by using a custom recovery device.Results: An increase in size from ISO #35 to ISO #40 resulted in a percentage gain of approximately 44% in mean irrigant volume, whereas an increase in size from ISO #40 to ISO #45 resulted in a percentage gain of approximately 4%. An increase in taper from 0.02 through 0.08 resulted in percentage gains of approximately 74%, 5.4%, and 2.4% increase, respectively.Conclusions: The data demonstrated that an increase in apical preparation size and taper resulted in a statistically significant increase in the volume of irrigant. In addition, an apical enlargement to ISO #40 with a 0.04 taper will allow for tooth structure preservation and maximum volume of irrigation at the apical third when using the apical negative pressure irrigation system.

Distortion and Breakage of Liberator, EndoSequence, and ProFile Systems in Severely Curved Roots of Molars - Corrected Proof

Jeffrey T. Stewart, Shawn Lafkowitz, Keith Appelbaum, Gary Hartwell — 2010-02-08

Abstract: Introduction: The aim of this study was to investigate the incidence of endodontic file distortion and breakage when the Liberator (Miltex Inc, York, PA), EndoSequence (Brasseler USA, Savannah, GA), and ProFile (Tulsa Dental Products, Tulsa, OK) systems were used to instrument severely curved root canals of extracted human molars.Methods: Eighty-four roots of extracted human molars with curvatures measuring 40° to 80° were used. The roots were randomly assigned into four groups based on the rotary instrumentation system: group 1, ProFile (.04 taper); group 2, EndoSequence (.04 taper); group 3, Liberator (.04 taper); and group 4, Liberator (.02 taper).Results: File distortion was 19.4%, 10%, 44.4%, and 59.1% for the ProFile, EndoSequence, and Liberator .04 and Liberator .02 groups, respectively. There were statistically significant differences between the ProFile and Liberator .04 groups (p < 0.05), the ProFile and Liberator .02 groups (p < 0.01), the EndoSequence and Liberator .04 groups (p < 0.01), and the EndoSequence and Liberator .02 groups (p < 0.01). Broken files occurred in 2.8% of the ProFile group and 7.4% of the Liberator .04 group. There were no broken files in the EndoSequence or Liberator .02 groups. No statistically significant differences were found among the four groups (p = 0.28) with regard to file breakage.Conclusion: It can be concluded that more file distortions occurred in both Liberator groups than with either the ProFile or the EndoSequence groups to a statistically significant degree.

Study on the Influence of Refreshment/Activation Cycles and Irrigants on Mechanical Cleaning Efficiency During Ultrasonic Activation of the Irrigant - Corrected Proof

2010-02-08

Abstract: Introduction: The aims of this study were to evaluate dentin debris removal from the root canal during ultrasonic activation of sodium hypochlorite (2% and 10%), carbonated water, and distilled water and to determine the influence of 3 ultrasonic refreshment/activation cycles of the irrigant by using the intermittent flush technique.Methods: Root canals with a standardized groove in 1 canal wall, which was filled with dentin debris, were irrigated ultrasonically. The irrigant was refreshed and ultrasonically activated 3 times for 20 seconds. The quantity of dentin debris after irrigation was determined after each refreshment/activation cycle.Results and Conclusions: Ultrasonic activation of the irrigant combined with the intermittent flush method produces a cumulative effect over 3 refreshment/activation cycles. Sodium hypochlorite as an irrigant is significantly more effective than carbonated water, which is significantly more effective than distilled water, in removing dentin debris from the root canal during ultrasonic activation.

Effect of Final Irrigation Regimen on Sealer Penetration in Curved Root Canals - Corrected Proof

2010-02-08

Abstract: Introduction: The purpose of this study was to evaluate the effect of different final irrigation regimens on the sealer penetration into dentinal tubules of curved root canals.Methods: The mesiobuccal canals from 45 extracted maxillary and mandibular molars were instrumented with sodium hypochlorite (NaOCl) irrigation. The samples were divided into 3 groups according to the final irrigation used: group N (control), 3.5% NaOCl; group E, 17% ethylenediaminetetraacetic acid (EDTA); and group EN, 17% EDTA followed by 3.5% NaOCl. All teeth were obturated with gutta-percha and AH Plus sealer labeled with fluorescent dye. Transverse sections at 2 mm (apical) and 5 mm (coronal) from root apex were examined by using confocal laser scanning microscopy. Then, total percentage and maximum depth of sealer penetration were measured.Results: The apical sections in each group showed significantly lower percentage and maximum depth of sealer penetration than the coronal sections (P < .05). In apical levels, group E and EN resulted in a higher percentage of sealer penetration than the control group (P < .05), but there was no significant difference of maximum depth between group E and the control group (P > .05).Conclusions: In curved canal, final rinse with NaOCl after the use of EDTA had no additional effect on sealer penetration. Complete debridement with a 1-minute application of EDTA remains a challenge in the apical area of curved canals.

Flexural Fatigue and Torsional Resistance of ProFile GT and ProFile GT Series X Instruments - Corrected Proof

2010-02-08

Abstract: Introduction: The purpose of this study was to compare the flexural fatigue and torsional resistance of ProFile GT and GT Series X instruments, taking into account their structural and dimensional characteristics.Methods: Instrument diameter at each millimeter from the tip and pitch length were the dimensional parameters measured. Chemical composition was determined by energy-dispersive x-ray spectroscopy and phase constitution by x-ray diffraction. Vickers microhardness measurements were performed to assess instrument strength. One group of 20/.06 GT and GTX instruments (n = 10 each) was tested until failure in a flexural fatigue test device, whereas another group of 20/.04 files (n = 10 each) was tested in torsion based on ISO 3630-1.Results: GT and GTX instruments showed approximately the same chemical composition, namely 51at%Ni-49at%Ti (56wt%Ni-44wt%Ti) and contained mainly the β-phase. GTX instruments showed higher intensity x-ray diffraction peaks and a statistically higher Vickers microhardness. There was a significant decrease in the diameter of GTX in relation to GT instruments from D6 to D9 for 20/.04 instruments and from D4 to D7 for 20/.06 instruments. Pitch length increased along the active part of both instruments, with a steeper increase in GTX. In general, GT Series X instruments were significantly more resistant to flexural fatigue than were similar GT instruments (p < 0.001) but exhibited lower torsional strength (p < 0.001).Conclusions: Different structural and dimensional characteristics were found in GTX instruments in comparison with GT instruments; this is probably the cause for their higher flexural fatigue resistance and lower torsional strength.

Clinical Evaluation of Restoration Quality in Studies Assessing the Influence of the Coronal Seal on Periapical Health - Corrected Proof

Jean Camps — 2010-01-25

I read with pleasure the article entitled “Prevalence of Apical Periodontitis in Root Canal–Treated Teeth From an Urban French Population: Influence of Quality of Root Canal Fillings and Coronal Restoration” . The article is interesting, and the study was performed on a large scale. This article is in line with the famous paper published by Ray and Trope , which has been cited 235 times (Scopus data); the article disclosed the influence of coronal seal on periapical health and launched a series of interesting studies on this topic.