Journal of Endodontics - Articles in Press

A Prospective Randomized Trial of Different Supplementary Local Anesthetic Techniques after Failure of Inferior Alveolar Nerve Block in Patients with Irreversible Pulpitis in Mandibular Teeth - Corrected Proof

Mohammad D. Kanaa, John M. Whitworth, John Gerard Meechan — 2012-02-06

Abstract: Objective: The objective of this study was to compare the efficacy of supplementary repeat inferior alveolar nerve block with 2% lidocaine and epinephrine, buccal infiltration with 4% articaine with epinephrine, intraligamentary injection, or intraosseous injection (both with 2% lidocaine with epinephrine) after failed inferior alveolar nerve block (IANB) for securing pain-free treatment in patients experiencing irreversible pulpitis in mandibular permanent teeth.Methods: This randomized clinical trial included 182 patients diagnosed with irreversible pulpitis in mandibular teeth. Patients received 2.0 mL of 2% lidocaine with 1:80,000 epinephrine as an IANB injection. Patients who did not experience pain-free treatment received randomly 1 of 4 supplementary techniques, namely repeat lidocaine IANB (rIANB), articaine buccal infiltration (ABI), lidocaine intraligamentary injection (PDL), or lidocaine intraosseous injection (IO). Successful pulp anesthesia was considered to have occurred when no response was obtained to the maximum stimulation (80 reading) of the pulp tester, at which time treatment commenced. Treatment was regarded as being successfully completed when it was associated with no pain. Data were analyzed by χ2 and Fisher exact tests.Results: Of the 182 patients, 122 achieved successful pulpal anesthesia within 10 minutes after initial IANB injection; 82 experienced pain-free treatment. ABI and IO allowed more successful (pain-free) treatment (84% and 68%, respectively) than rIANB or PDL supplementary techniques (32% and 48%, respectively); this was statistically significant (P = .001).Conclusions: IANB injection alone does not always allow pain-free treatment for mandibular teeth with irreversible pulpitis. Supplementary buccal infiltration with 4% articaine with epinephrine and intraosseous injection with 2% lidocaine with epinephrine are more likely to allow pain-free treatment than intraligamentary and repeat IANB injections with 2% lidocaine with epinephrine for patients experiencing irreversible pulpitis in mandibular permanent teeth.

Treatment of Root Canal Biofilms of Enterococcus faecalis with Ozone Gas and Passive Ultrasound Activation - Corrected Proof

Peter D. Case, Philip S. Bird, William A. Kahler, Roy George, Laurence J. Walsh — 2012-02-06

Abstract: Introduction: Biofilms of resistant species such as Enterococcus faecalis pose a major challenge in the treatment of root canals with established periapical disease. This study examined the effects of gaseous ozone delivered into saline on biofilms of E. faecalis in root canals of extracted teeth with and without the use of passive ultrasonic agitation.Methods: Biofilms of E. faecalis were established over 14 days in 70 single roots that had undergone biomechanical preparation followed by gamma irradiation. The presence and purity of biofilms were confirmed using scanning electron microscopy and culture. Biofilms were treated with saline (negative control), 1% sodium hypochlorite for 120 seconds (positive control), ozone (140 ppm ozone in air at 2 L/min delivered into saline using a cannula for 120 seconds), saline with passive ultrasonic activation (70 kHz and 200 mW/cm2 applied to an ISO 15 file held passively within the canal, for 120 seconds), and ozone followed immediately by ultrasonic agitation. After treatment, samples were taken from the biofilm and serially diluted for plate counting.Results: Analysis revealed that 1% sodium hypochlorite was the most effective disinfecting agent followed by ozone combined with ultrasonic agitation, ozone alone, and finally ultrasonic alone.Conclusions: Although none of the treatment regimes were able to reliably render canals sterile under the conditions used, ozone gas delivered into irrigating fluids in the root canal may be useful as an adjunct for endodontic disinfection.

Are Endodontically Treated Incisors Reliable Abutments for Zirconia-based Fixed Partial Dentures in the Esthetic Zone? - Corrected Proof

2012-02-06

Introduction: This ex vivo pilot study tested the influence of defect extension and quartz-fiber post placement (QFP) on the ex vivo survival rate and fracture resistance of root-treated upper central incisors served as abutments for zirconia 2-unit cantilever fixed partial dentures (2U-FPDs) exposed to 10 years of simulated clinical function.Methods: Human maxillary central incisors were endodontically treated and divided into the following 5 groups (n = 8): (1) access cavity filled with core build-up composite, (2) biproximal class III cavities filled as in group 1, (3) specimens restored as in group 2 with QFP placed, (4) specimens decoronated and core buildup as in group 1, and (5) specimens restored as in group 4 but with QFP as in group 3. On all specimens, 2U-FPDs were placed with dual-curing resin cement. In order to simulate 10 years of clinical function, specimens were exposed to thermal cycling and mechanical loading with subsequent loading to failure. Kaplan-Meier curves were constructed, and log-rank tests were performed. Fracture force and patterns were compared by means of Kruskal-Wallis, Mann-Whitney U (post hoc), and Fisher exact tests, respectively (P = .05).Results: For specimens only with an access cavity, it was observed that 25% had catastrophic tooth fractures and the lowest load-to-fracture values. In all other groups, chipping combined with or without debonding occurred. Groups did not differ significantly regarding the survival rate (P = .603) and fracture patterns (P = .633), but they did for fracture load including technical failures (P = .017).Conclusion: After 10 years of simulated clinical function, both defect extension and placement of QFP had no significant influence on survival of root-treated upper central incisors as abutments restored with zirconia-based 2U-FPDs.

Effects of Various Mixing Techniques on Push-out Bond Strengths of White Mineral Trioxide Aggregate - Corrected Proof

2012-02-06

Abstract: Introduction: The aim of this study was to evaluate the effect of 3 different mixing methods on push-out bond strength of white tooth-colored mineral trioxide aggregate (MTA).Methods: Sixty 2-mm-thick root sections were prepared from 60 single-rooted human teeth and filled with MTA. The samples were randomly divided into 3 groups (n = 20) of MTA mixed by ultrasonic, trituration, or conventional methods and then allowed to set for 72 hours in a synthetic tissue fluid environment. Push-out bond strength values of the specimens were measured by a universal testing machine and examined under a stereomicroscope at ×4 to determine the nature of the bond failure.Results: The means of push-out bond strength values of white MTA in the ultrasonic, conventional, and trituration groups were 105.67 ± 12.79, 118.95 ± 12.76, and 99.60 ± 14.27 MPa, respectively. The differences between the 3 groups were not statistically significant.Conclusions: On the basis of the results of this study, it can be concluded that different mixing methods have no significant effect on push-out bond strength of white MTA.

Effect of Disinfection Solutions on the Adhesion Force of Root Canal Filling Materials - Corrected Proof

Danielle Ferreira de Assis, Maíra do Prado, Renata A. Simão — 2012-02-06

Abstract: Introduction: Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) are usually used to disinfect gutta-percha (GP) and Resilon (Res) cones. This study investigated the adhesion force (Fad) between root canal sealers and GP and Res cones following different disinfection protocols by using atomic force microscopy.Methods: Nine flat surfaces of each material were obtained with medium points of GP and Res. The samples were divided into 6 groups (n = 3): control group GP, immersion in distilled water (DW); NaOCl group GP, immersion in 5.25% NaOCl and then washing with DW; CHX group GP, immersion in 2% CHX and then washing with DW; control group Res, immersion in DW; NaOCl group Res, immersion in 5.25% NaOCl and then washing with DW; and CHX group Res, immersion in 2% CHX and then washing with DW. Atomic force microscopy tips containing AH Plus sealer were used to obtain force versus distance curves regarding GP surfaces. Fad was calculated from the force curves. The same procedure was performed with Real Seal SE and Res surfaces. Data were statistically analyzed.Results: A higher Fad between solid filling materials (GP and Res) and root canal sealers was found when CHX solution was used. Treatment with NaOCl solution did not show influence on the Fad values.Conclusions: The decontamination of GP and Res with 2% CHX resulted in higher Fad values. The use of CHX in the disinfection process of GP and Res cones might be a better option before root canal obturation.

Filling Ability of Gutta-Percha and Resilon to Fill Simulated Lateral Canals by Using the Obtura II System - Corrected Proof

2012-02-06

Abstract: Introduction: The aim of this study was to evaluate the ability of Resilon (Resilon Research, LLC, North Branford, CT) and 2 types of gutta-percha to fill simulated lateral canals when using the Obtura II system (Model 823-700; Obtura Spartan, Fenton, MO).Methods: Forty-five human single-rooted teeth were selected and subjected to root canal preparation. After that, simulated lateral canals were made at 2, 5, and 8 mm from the working length (WL). The specimens were divided into 3 groups (n = 15) according to the filling material used: Obtura Flow 150 gutta-percha (Obtura flow), Odous Endo Flow gutta-percha (Odous; Odous De Deus Ind e Com. Ltda Belo Horizonte, MG, Brazil), and Resilon pellets (Resilon). Root canals were filled using the Obtura II system with the tip inserted to 3 mm from the WL. No sealer was used for root canal obturation. Specimens were subjected to a tooth decalcification and clearing method, and filling of the lateral canals was analyzed by digital radiography and photographs. The measurement of lateral canal filling was done using Image Tool software (UTHSCSA Image Tool for Windows version 3.0, San Antonio, TX). Data were statistically analyzed with the Kruskal-Wallis test at 5% significance.Results: All materials showed an ability to penetrate into the simulated lateral canals, with a minimum percentage of 73% in all thirds of the root canal.Conclusions: It was concluded that gutta-percha and Resilon are solid core materials with a lateral canal filling ability when used with the Obtura II system.

Comparison of the Anesthetic Efficacy between Bupivacaine and Lidocaine in Patients with Irreversible Pulpitis of Mandibular Molar - Corrected Proof

2012-02-06

Abstract: Introduction: The purpose of this study was to compare the anesthetic efficacy of 0.5% bupivacaine with 1:200,000 epinephrine with that of 2% lidocaine with 1:100,000 epinephrine during pulpectomy in patients with irreversible pulpitis in mandibular posterior teeth.Materials and Methods: Seventy volunteers, patients with irreversible pulpitis admitted to the Emergency Center of the School of Dentistry at the University of São Paulo, randomly received a conventional inferior alveolar nerve block containing 3.6 mL of either 0.5% bupivacaine with 1:200,000 epinephrine or 2% lidocaine with 1:100,000 epinephrine. During the subsequent pulpectomy, we recorded the patients’ subjective assessments of lip anesthesia, the absence/presence of pulpal anesthesia through electric pulp stimulation, and the absence/presence of pain through a verbal analog scale.Results: All patients reported lip anesthesia after the application of either inferior alveolar nerve block. By measuring pulpal anesthesia success with the pulp tester, lidocaine had a higher success rate (42.9%) than bupivacaine (20%). For patients reporting none or mild pain during pulpectomy, the success rate of bupivacaine was 80% and lidocaine was 62.9%. There were only statistically significant differences to the success of pulpal anesthesia.Conclusions: Neither of the solutions resulted in an effective pain control during irreversible pulpitis treatments of mandibular molars.

Erratum - Corrected Proof

2012-02-06

In the Discussion section of the article “Antibiotic Resistance in Primary and Persistent Endodontic Infections” (J Endod 2011;37[10]:1337–44), references were made to work previously performed by Rossi-Fedele et al (references 23 and 24 in the article). The authors wish to correct the language used to refer to that work in the following manner. The statement, “TetM has been identified in tetracycline-resistance Enterococcus faecalis found in endodontic infections (23, 24)” should be “TetM has been identified in tetracycline-resistance bacteria found in endodontic infections (23, 24).” Also, the statement, “These studies found that 8 of 15 tetracycline-resistance bacteria isolated possessed the tetM gene and were resistant to tetracycline irrigation in an in vitro tooth model” should be “These studies found that tetracycline-resistance bacteria were resistant to tetracycline irrigation in an in vitro tooth model.” The authors regret any confusion in describing the work done in these studies.

Erratum - Corrected Proof

2012-02-06

The article “Effect of Canal Length and Curvature on Working Length Alteration with WaveOne Reciprocating Files” by Elio Berutti, Giorgio Chiandussi, Davide Salvatore Paolino, Nicola Scotti, Giuseppe Cantatore, Arnaldo Castellucci and Damiano Pasqualini (J Endod 37[12]:1687–90; 2011] should have included this statement in the author information section: “Giuseppe Cantatore, Arnaldo Castellucci, and Elio Berutti declare that they have financial involvement (patent licensing arrangements) with Dentsply Maillefer with direct financial interest in the materials discussed in this article.” In addition, Dentsply provided some of the instruments used in this study." The authors regret this omission.

Vascular Endothelial Growth Factors and Receptors Are Up-regulated during Development of Apical Periodontitis - Corrected Proof

Athanasia Bletsa, Anca Virtej, Ellen Berggreen — 2012-02-03

Abstract: Introduction: Apical periodontitis is a common inflammatory disease caused by persistent root canal infection and is characterized by bone resorption. Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) have been described in many pathologic and inflammatory conditions, but their involvement in the development of apical periodontitis has not been thoroughly investigated. The aim of this study was to quantify gene expression and localize VEGF-A, VEGF-C, and VEGF-D and VEGFR-2 and VEGFR-3 in a rat model of apical periodontitis.Methods: Molar pulps were unilaterally exposed to the oral cavity for 10 or 21 days. Jaw sections were used for localization of VEGFs and VEGFRs with immunohistochemistry and identification of cells with double immunofluorescence. Gene expression analysis for VEGF-A, VEGF-C, and VEGFR-3 of periapical tissues was performed with quantitative real-time polymerase chain reaction.Results: All investigated factors and receptors were expressed immunohistochemically in blood vessels at the periodontal ligament of control teeth and were up-regulated during lesion development. In apical lesions, macrophages and neutrophils expressed all studied factors and receptors, with macrophages being an important source of VEGF-C and VEGF-D. Osteoclasts expressed VEGFR-2 and VEGFR-3, and the latter was also identified in fibroblast-like cells in the lesions. VEGF-A and VEGFR-3 gene expression was up-regulated at days 10 and 21 (P < .05).Conclusions: The current findings indicate that the VEGF family and receptors are involved in vascular remodeling and immune functions during disease development. The presence of VEGFR-2 and VEGFR-3 on osteoclasts indicates that bone resorbing activity is influenced by VEGFs.

Antagonistic Interactions between Sodium Hypochlorite, Chlorhexidine, EDTA, and Citric Acid - Corrected Proof

2012-02-03

Abstract: Introduction: Root canal irrigants play a significant role in the elimination of microorganisms, tissue dissolution, and the removal of debris and smear layer. No single solution is able to fulfill these actions completely; therefore, their association is required. The aim of this investigation was to review the antagonistic interactions occurring when sodium hypochlorite (NaOCl), chlorhexidine (CHX), EDTA, and citric acid (CA) are used together during endodontic treatment.Methods: A search was performed in the electronic database Medline (articles published through 2011; English language; and the following search terms or combinations: “interaction AND root canal irrigant or endodontic irrigant or sodium hypochlorite or chlorhexidine,” “sodium hypochlorite AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent or chlorhexidine,” and “chlorhexidine AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent”) to identify publications that studied unwanted chemical interactions between NaOCl, CHX, and EDTA and CA.Results: The search identified 1,285 publications; 19 fulfilled the inclusion/exclusion criteria of the review. Their research methodology was classified as either in vitro or ex vivo.Conclusions: Antagonistic interactions included the loss of free available chlorine for NaOCl when in contact with chelators, which consequently reduced the tissue dissolution capability and to a lesser extent antimicrobial activities. When CHX and NaOCl are mixed, a precipitate forms that can present detrimental consequences for endodontic treatment, including a risk of discoloration and potential leaching of unidentified chemicals into the periradicular tissues. CHX and EDTA mixtures cause a precipitate, whereas CHX and CA do not exhibit interaction.

Lipopolysaccharide Enhances Decorin Expression through the Toll-like Receptor 4, Myeloid Differentiating Factor 88, Nuclear Factor-Kappa B, and Mitogen-activated Protein Kinase Pathways in Odontoblast Cells - Corrected Proof

2012-02-02

Abstract: Introduction: Lipopolysaccharide (LPS) has been shown to regulate the function of odontoblasts. However, the molecular mechanisms of the effect of LPS on odontoblasts are poorly understood. Decorin (DCN), one of the major matrix proteoglycans, is known to affect the mineralization of teeth. In this study, we investigated whether LPS can regulate the expression of DCN in odontoblasts and determined the intracellular signaling pathways triggered by LPS.Methods: The DCN messenger RNA and protein expression changes in mouse odontoblast-lineage cells (OLCs) were detected by real-time polymerase chain reaction (PCR) analysis and enzyme-linked immunosorbent assay (ELISA). Whether TLR4, myeloid differentiating factor 88 (MyD88), nuclear factor-kappa B (NF-κB), or mitogen-activated protein kinase (MAPK) pathways were involved in the LPS-induced DCN expression was determined by examined real-time PCR, ELISA, and luciferase activity assay. The activation of extracellular signal-regulated kinase (ERK), p38, and JNK in OLCs was measured by Western blot analysis.Results: We found that the mouse OLCs expressed DCN. DCN messenger RNA was rapidly induced by LPS in a time- and dose-dependent manner. Pretreatment with a MyD88 inhibitory peptide, a TLR4 antibody, or a specific inhibitor for NF-κB or I Kappa B alpha (IκBα) significantly inhibited LPS-induced DCN expression. Moreover, the LPS-mediated increase in κB-luciferase activity in OLCs was suppressed by the overexpression of dominant negative mutants of TLR4, MyD88, and IκBα but not by a dominant negative mutant of TLR2. In addition, LPS stimulation activated the ERK, p38, and JNK MAPK pathways. The pretreatment of OLCs with specific inhibitors of the ERK, p38, and JNK MAPK pathways markedly offset the LPS-induced up-regulation of DCN expression.Conclusions: Our results show that LPS stimulation can up-regulate the gene expression of DCN via the TLR4, MyD88, NF-κB, and MAPK pathways in odontoblast cells.

Comparative Analysis of Accessory Mesial Canal Identification in Mandibular First Molars by Using Four Different Diagnostic Methods - Corrected Proof

2012-02-02

Abstract: Introduction: The objective of the present in vitro study was to compare 4 diagnostic methods to identify accessory mesial canals (AMCs) in lower first molars.Methods: Forty-four lower first molars were selected for assessment with cone-beam computed tomography (CBCT), digital radiography (DR), clinical inspection (CI), and dental operating microscope (DOM). Initially, axial images were obtained by using CBCT, and radiographs were taken in ortho, mesial, and distal angulations. The images were assessed by 2 independent groups of examiners, and all of the results obtained remained undisclosed until the end of the experiment. Subsequently, root canal access was prepared, and the mesial subpulpal groove was located by using sharp endodontic explorers. The roots were examined with DOM, and all identified canals were negotiated and instrumented by using a ProTaper Rotary System. The results were tabulated and statistically analyzed by nonparametric McNemar tests.Results: Twelve AMCs (27.0%) were identified by CBCT, and 58.0% were instrumented. No AMCs were visualized in any DR examined. Fifteen potential AMCs (34%) were identified by CI, but only 47.0% were confirmed after instrumentation. Thirteen AMCs (30.0%) were identified by DOM, and 84.0% could be negotiated and instrumented.Conclusions: There were statistically significant differences between the 4 types of assessments for AMC identification. There was good agreement between DOM and CBCT, whereas DR and CI were not as precise as either of the other 2 diagnostic methods.

Canal Shaping with WaveOne Primary Reciprocating Files and ProTaper System: A Comparative Study - Corrected Proof

2012-02-02

Abstract: Introduction: This study compared the canal curvature and axis modification after instrumentation with WaveOne Primary reciprocating files (Dentsply Maillefer, Ballaigues, Switzerland) and nickel-titanium (NiTi) rotary ProTaper (Dentsply Maillefer).Methods: Thirty ISO 15, 0.02 taper, Endo Training Blocks (Dentsply Maillefer) were used. In all specimens, the glide path was achieved with PathFile 1, 2, and 3 (Dentsply Maillefer) at the working length (WL). Specimens were then assigned to 1 of 2 groups for shaping: specimens in group 1 were shaped with ProTaper S1-S2-F1-F2 at the WL and specimens in group 2 were shaped with WaveOne Primary reciprocating files at the WL. Pre- and postinstrumentation digital images were superimposed and processed with Matlab r2010b (The MathWorks Inc, Natick, MA) software to analyze the curvature-radius ratio (CRr) and the relative axis error (rAe), representing canal curvature modification. Data were analyzed with one-way balanced analyses of variance at 2 levels (P < .05).Results: The instrument factor was extremely significant for both the CRr parameter (F1 = 9.59, P = .004) and the rAe parameter (F1 = 13.55, P = .001).Conclusion: Canal modifications are reduced when the new WaveOne NiTi single-file system is used.

Apical Periodontium Response to Enamel Matrix Derivative as an Intracanal Medication in Rat Immature Teeth with Pulp Necrosis: Radiographic and Histologic Findings - Corrected Proof

2012-02-02

Abstract: Introduction: The aim of this study was to evaluate the enamel matrix derivative (EMD) biomaterial in nonvital immature teeth.Methods: To arrest root development, pulpectomies were performed in the lower first molars of 36 4-week-old rats; the cavities were left exposed to the oral environment for 3 weeks. Then, chemical disinfection was performed, and triple antibiotic paste (TAP) or EMD was applied in the root canals. A control group did not receive any treatment. Radiographic and histological data were evaluated after 3 and 6 weeks.Results: At 3 weeks, TAP promoted a milder inflammatory response and increased root lengths compared with the control group. At 6 weeks, root development and reduced periapical lesions could be observed in both test groups, mainly because of the deposition of a cementum-like tissue. EMD promoted narrower canals compared with TAP (P < .05).Conclusions: EMD deserves attention as a potential tool in the treatment of nonvital immature teeth. The ingrowth of cementum-like tissues into canal spaces favored dental wall thickness and may contribute to tooth resistance and support.

Effects of Calcium Silicate–based Materials on Collagen Matrix Integrity of Mineralized Dentin - Corrected Proof

2012-02-02

Abstract: Introduction: Calcium silicate–based materials (CSMs) are used in various endodontic procedures. The present study examined whether prolonged contact of mineralized dentin with recently commercialized versions of these materials adversely affects dentin collagen matrix integrity.Methods: Dentin slabs prepared from extracted human third molars (7 × 3 × 0.3 mm) were divided into 3 groups on the basis of the material to which dentin was exposed (MTA Plus, Biodentine, untreated control dentin slabs) and the time period of exposure (24 hours, 1, 2, and 3 months; n = 6). Hydroxyproline assay was performed on each group’s supernatant to quantify the collagen extraction amounts of each group per time period. Data were analyzed with two-factor repeated-measures analysis of variance and Holm-Sidak pair-wise comparisons (α = 0.05) to determine the effects of material and aging time on collagen extraction. Dentin slabs from the 3 months of aging group were demineralized for transmission electron microscopy examination of collagen matrix ultrastructural changes.Results: Material (P = .002), aging time (P < .001), and their interactions (P = .007) significantly affected the amount of hydroxyproline (pg/mg of mineralized dentin) extracted from mineralized dentin and were significantly correlated by power regression models. Collagen degradation was identified from the surface of dentin slabs that were in direct contact with CSMs.Conclusion: Prolonged contact of mineralized dentin with CSMs has an adverse effect on the integrity of the dentin collagen matrix. However, the amount of collagen extracted was limited to the contact surface. Clinicians can continue to apply CSMs in endodontic procedures; however, caution is advised when these materials are applied to thin dentinal walls.

High-purity Hepatic Lineage Differentiated from Dental Pulp Stem Cells in Serum-free Medium - Corrected Proof

2012-01-30

Abstract: Introduction: We have previously differentiated hepatocyte like cells from deciduous tooth pulp stem and extracted third molar pulp stem cells with a protocol that used fetal bovine serum, but it showed high contaminations of nondifferentiated cells. Both the lower purity of hepatically differentiated cells and usage of serum are obstacles for application of cell therapy or regenerative medicine. Objective of this study was to investigate the capacity for and purity of hepatocyte-like differentiation of CD117-positive dental pulp stem cells without serum.Methods: Mesenchymal cells from human deciduous and extracted third molar pulp were isolated and expanded in vitro. We separated CD117-positive cells by using a magnetic-activated cell sorter. The cells were characterized immunofluorescently by using known stem cell markers. For hepatic differentiation, the media were supplemented with hepatic growth factor, insulin-transferrin-selenium-x, dexamethasone, and oncostatin M. Expression of hepatic markers alpha fetoprotein, albumin, hepatic nuclear factor-4 alpha, insulin-like growth factor-1, and carbamoyl phosphate synthetase was examined immunofluorescently after differentiation. The amount of differentiated cells was assessed by using flow cytometry. Glycogen storage and urea concentration in the medium were defined.Results: Both cell cultures demonstrated a number of cells positive for all tested hepatic markers after differentiation, ie, albumin-positive cells were almost 90% of differentiated deciduous pulp cells. The concentration of urea in the media increased significantly after differentiation. Significant amount of cytoplasmic glycogen storage was found in the cells.Conclusions: Without serum both cell types differentiated into high-purity hepatocyte-like cells. These cells offer a source for hepatocyte lineage differentiation for transplantation in the future.

Coculture of Dental Pulp Stem Cells with Endothelial Cells Enhances Osteo-/Odontogenic and Angiogenic Potential In Vitro - Corrected Proof

2012-01-30

Abstract: Introduction: Dental pulp stem cells (DPSCs) have received much attention as a promising population of stem cells in regenerative endodontics. Securing a good blood supply during regeneration is a challenging task because of the constricted apical canal opening, which allows only a limited blood supply. The aim of this study was to investigate any potential synergistic effects of dental pulp stem cells and endothelial cells (ECs) on osteo-/odontogenic and angiogenic differentiation in vitro.Methods: Different ratios of DPSCs and ECs were cultured in direct contact using optimized medium for coculture. The 70% confluent cocultures were incubated in the osteo-/odontogenic differentiation medium for up to 3 weeks. Alkaline phosphatase (ALP) activity, the expression levels of ALP, bone sialoprotein (BSP), dentin sialophosphoprotein (DSPP) genes, and alizarin red staining for mineralization at different time points were analyzed. The tubular network formation on Matrigel and the gene expression levels of CD117, VEGF, CD34, and Flk-1 were used as assays to analyze angiogenesis.Results: The quantification of ALP in DPSC:EC cocultures revealed a greater ALP activity compared with DPSC-alone cultures. At all the time points, 1:1 cultures showed a significantly greater ALP activity than that of DPSC-alone cultures. Alizarin red staining and quantification revealed a much greater amount of calcification in the 1:1 and 1:5 cocultures compared with other cultures (P < .01). The expression levels of ALP, BSP, and DSPP genes further confirmed the greater osteo-/odontogenic differentiation in cocultures compared with those of DPSC-alone cultures. Matrigel assay showed that the addition of DPSCs stabilized preexisting vessel-like structures formed by ECs and increased the longevity of them.Conclusions: Direct coculture of DPSCs and ECs enhances the in vitro differentiation toward osteo-/odontogenic and angiogenic phenotypes.

Effects of Simvastain and Enamel Matrix Derivative on Portland Cement with Bismuth Oxide-induced Growth and Odontoblastic Differentiation in Human Dental Pulp Cells - Corrected Proof

2012-01-30

Abstract: Introduction: We previously reported that bismuth oxide containing Portland cement (BPC) showed similar biocompatibility to Portland cement (PC) in periodontal ligament cells. However, the bioactivity of simvastatin and Emdogain (Biora AB, Malmö, Sweden) on BPC was not reported. The aim of this study was to evaluate the effects of simvastatin and Emdogain on BPC compared with mineral trioxide aggregate (MTA) in human dental pulp cells (HDPCs).Methods: Cell growth was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay. Differentiation was evaluated by alkaline phosphatase (ALP) activity, alizarin red staining, and reverse-transcriptase polymerase chain reaction.Results: The cell growth of HDPCs exposed to Emdogain and simvastatin plus BPC was superior to those administered BPC alone and similar to those that received MTA for 14 days. The simvastatin and Emdogain groups increased the odontogenic potential of the BPC group with respect to ALP activity, mineralization nodules, messenger RNA expression of ALP, osteopontin, osteocalcin, Runx2, and osterix.Conclusions: These results suggest that simvastatin and Emdogain improved cell growth and the differentiation of the BPC group in HDPCs and may be useful ingredients in BPC as pulp-capping material.

Antibacterial and Neutralizing Effect of Human β-Defensins on Enterococcus faecalis and E. faecalis Lipoteichoic Acid - Corrected Proof

Sung-Hoon Lee, Dong-Heon Baek — 2012-01-30

Abstract: Introduction: Enterococcus faecalis is frequently found in the root canal of teeth, is a major microorganism of endodontic therapy failure, and is associated with chronic apical periodontitis. Human β-defensins (HBDs) are known to play critical roles in defending the host against infectious microbes and producing dental pulp in healthy and patients. The purpose of the present study was to investigate the bactericidal and neutralizing effects of HBDs on E. faecalis and E. faecalis lipoteichoic acid (Ef LTA) as a major virulence factor of E. faecalis.Methods: HBD-1, -2, -3, and -4 were synthesized and investigated the susceptibility against E. faecalis. Also, the neutralizing effects of HBDs on cytokine and intercellular adhesion molecule 1 (ICAM-1) expression by activity of E. faecalis and Ef LTA were analyzed using enzyme-linked immunosorbent assay and flow cytometry.Results: HBD-1 and -2 were weakly susceptible, and HBD-3 and HBD-4 were strongly susceptible to E. faecalis. All of the HBDs exhibited neutralizing effects on the activity of Ef LTA, and HBD-3 strongly neutralized the activity of E. faecalis in tumor necrosis factor-α, interleukin-8, and ICAM-1 expression. The neutralizing effects of HBDs were to inhibit E. faecalis or Ef LTA binding to the host cells.Conclusions: These results suggest that the induction of HBDs might have great potential as endodontic therapeutic agents.

Proliferation and Multilineage Potential of CXCR4-positive Human Dental Pulp Cells In Vitro - Corrected Proof

Long Jiang, Wei-Wei Peng, Li-Fen Li, Ya Yang, Ya-Qin Zhu — 2012-01-30

Abstract: Introduction: Although the results of our previous studies showed that the stromal cell-derived factor (SDF)-1α–CXC chemokine receptor 4 (CXCR4) axis may play a role in the recruitment of CXCR4-positive dental pulp cells (CXCR4+ DPCs) toward the damaged sites, the specific function of CXCR4+ DPCs in the injured dental pulp was still unknown. The purpose of this study was to verify whether CXCR4+ DPCs possessed stem cells properties so that we can understand their role in area of injury.Methods: CXCR4+ DPCs were isolated from normal DPCs with magnetic-activated cell sorting. The characteristics of the cells from the 3 groups of cells (ie, CXCR4+ DPCs, CXCR4− DPCs, or nonsorted DPCs) were analyzed in colony formation, proliferation, and multilineage differentiation including odontogenic and adipogenic lineages.Results: The results showed that CXCR4+ DPCs were the most dominant population in colony formation, proliferation, alkaline phosphatase activity, calcium content, and adipogenic differentiation among the 3 groups.Conclusions: CXCR4+ DPCs may contain more stem cells than nonsorted DPCs.

Surgical Management of Vertical Root Fractures for Posterior Teeth: Report of Four Cases - Corrected Proof

Spyros G. Floratos, Samuel I. Kratchman — 2012-01-30

Abstract: Introduction: The objective of this article was to present a surgical treatment option for teeth with incomplete vertical root fracture in maxillary and mandibular posterior teeth.Methods: Four cases are presented in which 1 endodontically treated maxillary or mandibular molar had an incomplete vertical root fracture involving 1 of the roots. The tooth underwent a flap elevation procedure to visualize the pattern of bone loss and assess the extent of root fracture. The fracture line was eliminated by resecting the root in a beveled manner, after which root-end preparation and root-end filling were performed by using mineral trioxide aggregate. The osteotomy was covered with an absorbable collagen membrane. Cases were followed up for 8–24 months after surgery.Results: The procedure was shown to be predictable and successful in this series. Root length was preserved, and tooth extraction was avoided.Conclusion: The microsurgical treatment option for multirooted teeth with incomplete vertical root fracture resulted in long-term clinical success.

Physical Effects of Sodium Hypochlorite on Bone: An Ex Vivo Study - Corrected Proof

Frank M. Kerbl, Patricia DeVilliers, Mark Litaker, Paul D. Eleazer — 2012-01-30

Abstract: Introduction: Sodium hypochlorite (NaOCl) accidents during endodontic therapy require accurate and prompt action. Understanding the physical properties of bone and evaluating the resultant cell damage from NaOCl exposure could improve management of these accidents. This study assessed the physical and histologic properties of dog femurs exposed to NaOCl for a period of 30 minutes.Methods: Four dog femurs were dissected and frozen. Twelve 40-mm-long sections were obtained and cut into 20-mm paired sections. Adjacent surfaces were randomly selected for shallow injection of either NaOCl or saline. Sections were visually assessed for gross physiologic effects. The structural integrity of the cancellous bone was measured by micro-indentation testing, and statistical analysis of needle penetration was conducted. Histologic evaluation of specimens was also conducted.Results: Grossly, NaOCl caused remarkable changes in cancellous structure, leaving craters of apparent demineralization. There was a significant difference in mean depth of needle penetration and demineralization between the treatments (P = .0397), with NaOCl showing greater mean depth than saline. The NaOCl group showed degradation of the organic matrix collagen.Conclusions: These results indicate that NaOCl compromises the integrity of cancellous bone. Calcified elements, especially cortical bone, appeared less affected.

In Vitro Comparison of Passive and Continuous Ultrasonic Irrigation in Simulated Lateral Canals of Extracted Teeth - Corrected Proof

2012-01-30

Abstract: Introduction: Complete endodontic system disinfection requires the removal of vital and necrotic pulp tissue, microorganisms, and toxins. The purpose of this study was to compare the effects of 2 ultrasonic irrigation techniques on the penetration of sodium hypochlorite into the main canal and simulated lateral canals of extracted teeth.Methods: Two simulated lateral canals each were created 2, 4, and 6 mm from the working length in 60 single-rooted teeth (6 canals/tooth, n = 360). To resemble the clinical situation, a closed system was created in each tooth. The teeth were randomly assigned to 3 experimental irrigation groups: group 1 (n = 20), positive pressure irrigation (PPI); group 2 (n = 20), passive ultrasonic irrigation (PUI); and group 3 (n = 20), continuous ultrasonic irrigation (CUI). Samples were evaluated by direct observation of still images recorded under a dental operating microscope. To examine irrigating solution penetration, 20% Chinese ink (Sanford Rotring GmbH, Hamburg, Germany) was added to a 5% sodium hypochlorite solution and delivered into the root canals.Results: The results showed a significantly higher (P < .05) penetration of irrigant into the lateral canals in the CUI group. PUI and CUI did not differ significantly in solution penetration into the apical thirds of the main canals. The PPI group showed a significantly lower penetration of sodium hypochlorite into the main and lateral canals compared with the CUI and PUI groups.Conclusion: CUI as a final rinse significantly increased the penetration of irrigating solution into simulated lateral canals.

An In Vitro Cyclic Fatigue Analysis of Different Endodontic Nickel-Titanium Rotary Instruments - Corrected Proof

Nilav Bhagabati, Seema Yadav, Sangeeta Talwar — 2012-01-30

Abstract: Introduction: The study compared Twisted File (TF) with 3 traditionally manufactured systems to determine whether changes in the manufacturing process improved the cyclic fatigue resistance.Methods: Four rotary file systems, (1) ProFile (PF), (2) Mtwo, (3) K3, and (4) TF, were tested in artificial canals with 45° and 90° angles of curvature. Ten instruments each of the 4 file systems were tested in both angles of curvature (n = 10). All instruments had identical size and taper (.06/0.25 tip diameter).Results: A statistically significant difference (P < .05) was noted between TF and other nickel-titanium instruments in both 45° and 90° angles of curvature. TF showed the greatest mean number of cycles to failure. There was no statistical difference between PF and K3 (P > .05) in both canal curvatures; however, statistically significant difference (P < .05) was observed between Mtwo and the other 2 traditionally manufactured instruments. Mtwo showed the lowest mean number of cycles to failure.Conclusions: Under the conditions of this study, size .06/0.25 TF was significantly more resistant to fatigue than the other 3 instrument systems produced with the traditional grinding process.

Evaluation of Push-out Bond Strength of Two Endodontic Post Systems - Corrected Proof

2012-01-30

Abstract: Introduction: The aim of this study was to evaluate the push-out bond strengths of a new polyfiber post system and a fiber post that were adhesively luted with a dual-cure resin cement.Methods: Forty single-rooted human maxillary teeth were sectioned below the cementoenamel junction, and the roots were endodontically treated. The roots were randomly divided into 2 groups of 20 specimens each according to the post type used: SpiraPost (group A; DMG, Englewood, NJ) and DT Light-Post Illusion X-RO (group B; Bisco Inc, Schaumburg, IL). All posts were cemented with dual-cure resin cement. Bonded specimens were cut into 1-mm-thick sections, and push-out tests were performed using a universal testing machine. All specimens were loaded until fracture, and the failure modes were evaluated with a stereomicroscope at 50× magnification. Representative specimens were analyzed by scanning electron microscopy.Results: Push-out bond strength was significantly affected by the type of post (P < .05). In all root sections, the SpiraPost push-out bond strength values were significantly higher than that those of DT Light-Post Illusion X-RO (P < .05). Cohesive failure within the post was the most frequent type of failure for the SpiraPost system.Conclusions: In all root segments, the SpiraPost system provided significantly increased post retention compared with the fiber post.

Antimicrobial Photodynamic Therapy for the Treatment of Teeth with Apical Periodontitis: A Histopathological Evaluation - Corrected Proof

2012-01-27

Abstract: Introduction: This study evaluated the in vivo response of apical and periapical tissues of dogs’ teeth with apical periodontitis after one-session endodontic treatment with and without antimicrobial photodynamic therapy (aPDT).Methods: Sixty root canals with experimentally induced apical periodontitis were instrumented and assigned to 4 groups receiving aPDT and root canal filling (RCF) or not: group aPDT+/RCF+ (n = 20): aPDT (photosensitizer phenothiazine chloride at 10 mg/mL for 3 minutes and diode laser [λ = 660 nm, 60 mW/cm2] for 1 minute) and RCF in the same session; group aPDT+/RCF− (n = 10); group aPDT−/RCF+ (n = 20), and group aPDT−/RCF− (n = 10). Teeth were restored, and the animals were killed after 90 days. Sections from the maxillas and mandibles were stained with hematoxylin-eosin and Mallory trichrome and examined under light microscopy. Descriptive (ie, newly formed apical mineralized tissue, periapical inflammatory infiltrate, apical periodontal ligament thickness, and mineralized tissue resorption) and quantitative (ie, periapical lesion size and number of inflammatory cells) microscopic analysis was performed. Quantitative data were analyzed by the Kruskal-Wallis and Dunn tests (α = .05).Results: In the aPDT-treated groups, the periapical region was moderately/severely enlarged with no inflammatory cells, moderate neoangiogenesis and fibrogenesis, and the smallest periapical lesions.Conclusions: Although apical closure by mineralized tissue deposition was not achieved, the absence of inflammatory cells, moderate neoangiogenesis, and fibrogenesis in the periapical region in the groups treated with aPDT indicate that this can be a promising adjunct therapy to cleaning and shaping procedures in teeth with apical periodontitis undergoing one-session endodontic treatment.

Bacteria-reactive Immune Response May Induce RANKL-expressing T Cells in the Mouse Periapical Bone Loss Lesion - Corrected Proof

2012-01-27

Abstract: Introduction: The present study investigated whether bacteria infecting the root canal can activate any infiltrating T cells to produce receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL).Methods: Using a mouse model of periapical lesion induced by artificial dental pulp exposure, the presence of RANKL-positive T cells and osteoclasts in the periapical lesion was examined by an immunohistochemical approach. The bacteria colonizing the exposed root canal were identified by 16S ribosomal RNA (rRNA) sequence analysis. The isolated endodontic bacteria were further immunized to normal mice, and soluble activator of NF-κB ligand (sRANKL) production by the T cells isolated from the immunized mice was evaluated by ex vivo culture system.Results: RANKL-positive T cells along with TRAP+ osteoclasts were identified in periapical bone resorption lesions. The gram-negative bacterium Pasteurella pnumotropica, which was most frequently detected from the root canal of exposed pulp, showed remarkably elevated serum immunoglobulin G (IgG)-antibody response in pulp-exposed mice compared with control nontreated mice. Immunization of mice with P. pneumotropica induced not only serum IgG-antibody but also primed bacteria-reactive T cells that produced sRANKL in response to ex vivo exposure to P. pneumotropica.Conclusions: T cells infiltrating the periapical region express RANKL, and the endodontic bacteria colonizing the root canal appear to induce RANKL expression from bacteria-reactive T cells, suggesting the possible pathogenic engagement of the immune response to endodontic bacteria in the context of developing bone resorptive periapical lesions.

Resistance to Flexural Fatigue of Reciproc R25 Files under Continuous Rotation and Reciprocating Movement - Corrected Proof

2012-01-27

Abstract: Introduction: The aim of the present work was to evaluate the resistance to flexural fatigue of Reciproc R25 nickel-titanium files, 25 mm, used in continuous rotation motion or reciprocation motion, in dynamic assays device.Methods: Thirty-six Reciproc R25 files were divided into 2 groups (n = 18) according to kinematics applied, continuous rotary (group CR) and reciprocation motion (group RM). The files were submitted to dynamic assays device moved by an electric engine with 300 rpm of speed that permitted the reproduction of pecking motion. The files run on a ring’s groove of temperate steel, simulating instrumentation of a curved root canal with 40° and 5 mm of curvature radius. The fracture of file was detected by sensor of device, and the time was marked. The data were analyzed statistically by Student's t test, with level of significance of 95%.Results: The instruments moved by reciprocating movement reached significantly higher numbers of cycles before fracture (mean, 1787.78 cycles) when compared with instruments moved by continuous rotary (mean, 816.39 cycles).Conclusions: The results showed that the reciprocation motion improves flexural fatigue resistance in nickel-titanium instrument Reciproc R25 when compared with continuous rotation movement.

Effects of Calcium Silicate–based Materials on the Flexural Properties of Dentin - Corrected Proof

2012-01-27

Abstract: Introduction: Prolonged exposure of root dentin to calcium hydroxide alters the fracture resistance of dentin. Calcium silicate–based materials (CSMs) used in endodontics release calcium hydroxide on setting. This study examined whether prolonged contact of dentin with CSMs adversely affects its mechanical properties.Methods: Dentin beams prepared from extracted human molars (7 × 3 × 0.3 mm) were divided into 3 groups on the basis of the material to which dentin was exposed (Biodentine, MTA Plus, and untreated control beams). Three-point flexure to failure was performed for each beam at designated exposure times (24 hours, 1, 2, and 3 months; n = 10). Data were analyzed with 2-factor repeated-measures analyses of variance to determine the effects of material and aging time on flexural modulus, flexural strength, and modulus of toughness (α = 0.05).Results: For flexural modulus, there was no significant difference for material (P = .947) or aging time (P = .064) when compared with baseline control. For flexural strength, significant differences were associated with aging time (P < .001) but not with material (P = .349). Flexural strength of dentin exposed to Biodentine decreased significantly after 2 and 3 months, whereas that exposed to MTA Plus decreased significantly after 3 months of aging (P < .05). For modulus of toughness, significant declines were observed for both material (P < .004) and aging time (P < .001).Conclusions: Both CSMs alter material toughness more than the strength and stiffness of dentin after aging in 100% relative humidity. Because dentin toughness is attributed to its collagen matrix, the amount of collagen extracted from mineralized dentin and changes in collagen ultrastructure should be further examined after exposure of dentin to CSMs.

Residual Filling Material in Dentinal Tubules after Gutta-percha Removal Observed with Scanning Electron Microscopy - Corrected Proof

Li-li Xu, Lan Zhang, Xue-dong Zhou, Rui Wang, Yan-han Deng, Ding-ming Huang — 2012-01-24

Abstract: Introduction: In cases of failed root canal treatment, endodontic retreatment of the root canal system is necessary. The present study aimed to assess variation in the incidence and depth of residual filling material in dentinal tubules after gutta-percha removal with H-files, the ProTaper Universal System (Dentsply Maillefer, Ballaigues, Switzerland), and the SybronEndo K3 System (SybronEndo Corporation, Orange, CA).Methods: Forty human mandibular premolars with single straight root canals were prepared with K-files (up to size 40) using the step-back technique and filled by cold lateral condensation with gutta-percha and AH Plus sealers (Dentsply DeTrey, Konstanz, Germany). After 1 year, the 40 teeth were divided into one control group and 3 retreatment groups (n = 10 each). Gutta-percha was removed using H-files, the ProTaper Universal System, or the SybronEndo K3 System. The teeth were sectioned, and the incidence and depth of residual filling material in the dentinal tubules were measured under scanning electron microscopy.Results: The depth of filling material in the dentinal tubules did not differ significantly among groups (P > .05). Residual filling material was present in significantly more dentinal tubules in the ProTaper (P = .043) and K3 groups (P = .001) than in the H-file and control groups.Conclusions: The ProTaper Universal System and the SybronEndo K3 System left filling material in a greater proportion of dentinal tubules than did H-files.

T-Lymphocyte and Cytokine Expression in Human Inflammatory Periapical Lesions - Corrected Proof

2012-01-24

Abstract: Introduction: Lymphocytes, among many cells, express different sets of cytokines, chemokines, and receptors, which are considered important mediators of periapical immune response to infection.Methods: The aim of this study was to evaluate the mRNA expression of CD4+CD28+ and CD8+ T genes and the gene expression of interferon-γ, tumor necrosis factor-α, interleukin (IL)-1β, IL-17A, IL-10, CCL2/MCP-1, CCL4, CCL5, CXCR4, CCR5, and receptor activator for nuclear factor kappa B ligand (RANKL) in periapical interstitial fluid from human root canal infections. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions.Results: Real-time polymerase chain reaction demonstrated significantly higher levels of CD4+CD28+ and CD8+ T-cell markers in the former root canal condition and an increase of IL-10 and CXCR4, followed by a decrease of proinflammatory cytokines such as RANKL, interferon-γ, IL-1β, and CCL5.Conclusions: Analyses of T-lymphocyte and cytokine expression in periapical area were able to show that distinct root canal conditions might play regulatory roles in controlling local immune/inflammatory processes.

Effect from Cyclic Fatigue of Nickel-Titanium Rotary Files on Torsional Resistance - Corrected Proof

2012-01-24

Abstract: Introduction: The aim of this study was to evaluate the effect of cyclic fatigue on the torsional resistance of nickel-titanium (NiTi) rotary instruments.Methods: ProFile (#25/0.06; Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper (F1, Dentsply Maillefer), both of which have the same external diameter at D5, were tested using a fatigue testing machine for the mean number of cycles of failure (mNCF). Then, new files were cyclic precycled to 4 conditions (ie, 0%, 25%, 50%, and 75% of the mNCF) before the torsional resistance test was performed on these cyclic preloaded files. A uniform clockwise rotation was applied to the file in a straight state in a torsion tester. The torsional load and distortion angle were recorded during rotation until the file succumbed to the torque. The toughness was computed. The results were analyzed statistically using one-way analysis of variance and the Duncan post hoc comparison to find any differences between groups at a significance level of 95%.Results: In both ProFile and ProTaper groups, the 75% preloading groups had significantly lower torsional strength than other preloaded files. In the ProFile group, the 50% and 75% preloading groups had a smaller distortion angle until fracture than the 25% and no preloading groups. The 75% preloading group showed a lower toughness value than the 25% and no preloading groups. In the ProTaper group, all preloading groups had less distortion and toughness than the no preloading group. Fractographic examinations revealed the 75% preloaded files showed less amount of reverse-wound flute than other preloading groups.Conclusions: Within the limitations of the methodology, it could be concluded that approximate 75% cyclic fatigue may reduce the torsional resistance of NiTi rotary instruments significantly.

Reduction of Hard-tissue Debris Accumulation during Rotary Root Canal Instrumentation by Etidronic Acid in a Sodium Hypochlorite Irrigant - Corrected Proof

Frank Paqué, Dan-Krister Rechenberg, Matthias Zehnder — 2012-01-24

Abstract: Introduction: Hard-tissue debris is accumulated during rotary instrumentation. This study investigated to what extent a calcium-complexing agent that has good short-term compatibility with sodium hypochlorite (NaOCl) could reduce debris accumulation when applied in an all-in-one irrigant during root canal instrumentation.Methods: Sixty extracted mandibular molars with isthmuses in the mesial root canal system were selected based on prescans using a micro–computed tomography system. Thirty teeth each were randomly assigned to be instrumented with a rotary system and irrigated with either 2.5% NaOCl or 2.5% NaOCl containing 9% (wt/vol) etidronic acid (HEBP). Using a side-vented irrigating tip, 2 mL of irrigant was applied by one blinded investigator to the mesial canals after each instrument. Five milliliters of irrigant was applied per canal as the final rinse. Mesial root canal systems were scanned at high resolution before and after treatment, and accumulated hard-tissue debris was calculated as vol% of the original canal anatomy. Values between groups were compared using the Student's t test (α < .05).Results: Irrigation with 2.5% NaOCl resulted in 5.5 ± 3.6 vol% accumulated hard-tissue debris compared with 3.8 ± 1.8 vol% when HEBP was contained in the irrigant (P < .05).Conclusions: A hypochlorite-compatible chelator can reduce but not completely prevent hard-tissue debris accumulation during rotary root canal instrumentation.

Postorthodontic External Root Resorption in Root-filled Teeth Is Influenced by Interleukin-1β Polymorphism - Corrected Proof

2012-01-24

Abstract: Introduction: External apical root resorption (EARR) is a frequent iatrogenic effect of orthodontic treatment. The way root-filled teeth respond to orthodontic forces with respect to EARR has been reported as varying widely between individuals. Genetic variants in the interleukin-1 gene have been associated with an increased risk of experiencing postorthodontic EARR on vital teeth. The objective of this study is to determine whether variants in the interleukin-1 gene have a positive or negative influence on EARR on teeth that have been endodontically treated.Methods: Ninety-three orthodontic patients underwent genetic screening for 2 single nucleotide polymorphisms (rs1800587, rs1143634) in the IL1 gene cluster. Subjects were divided into 2 groups depending on the presence (affected group) or absence (control group) of more than 2 mm of EARR on root-filled teeth after orthodontic treatment as shown by radiography. Logistic regression analysis was used to obtain adjusted estimates of EARR and IL1 polymorphisms. Allele frequencies, genotype distributions, and adjusted odds ratios were also calculated (95% confidence interval).Results: No positive or negative statistical association was found between postorthodontic treatment EARR in root-filled teeth and genetic variations in IL1A (P > .05). A direct relationship was found for the IL1B gene in the comparative analysis of homozygous subjects (2/2[TT]) and (1/1[CC]), which led to an increased risk of experiencing postorthodontic treatment EARR in root-filled teeth (odds ratio = 11.59; P = .006; confidence interval, 95%) and (odds ratio = 2.54; P = .035; confidence interval, 95%), respectively.Conclusions: The development of EARR in subjects with root-filled teeth who undergo orthodontic treatment might be attributable to genetic variations in the interleukin-1β gene (rs1143634).

Cone-Beam Computed Tomography Study of Incidence of Distolingual Root and Distance from Distolingual Canal to Buccal Cortical Bone of Mandibular First Molars in a Korean Population - Corrected Proof

Sin-Young Kim, Sung-Eun Yang — 2012-01-16

Abstract: Introduction: The purpose of this study was to investigate the incidence of separate distolingual (DL) root and separate DL canal in 1 distal root and to measure the distance from distobuccal (DB) and DL canal to buccal cortical bone of mandibular first molars in a Korean population by using cone-beam computed tomography images.Methods: Screening identified 1400 subjects with bilateral permanent mandibular first molars for inclusion in this investigation. The incidences of separate DL root (distal 2 roots with 1 canal for each root, 2 roots 2 canals [2R2C]) and separate DL canal in 1 distal root (distal 1 root with 2 separate canals, 1 root 2 canals [1R2C]) were investigated. The distances from DL canal to buccal cortical bone and from DB canal to buccal cortical bone were measured.Results: The incidence of 2R2C was 26.6% (373 of 1400) on the right side and 19.0% (266 of 1400) on the left side, with a statistically significant difference (P < .001). The incidence of 1R2C was 3.5% (49 of 1400) on the right side and 4.5% (63 of 1400) on the left side. Mean distance from DB canal to buccal cortical bone was 3.37 mm in 2R2C (n = 639) and 4.17 mm in 1R2C (n = 112). Mean distance from DL canal to buccal cortical bone was 8.63 mm in 2R2C and 7.19 mm in 1R2C. Statistical difference was detected between 2R2C and 1R2C for both DB and DL canals (P < .001 and P < .001, respectively).Conclusions: Separate DL root is common in the mandibular first molar in a Korean population. Knowledge of the occurrence of DL root and buccal bone thickness can improve the success rate of endodontic microsurgery.

Vesicular Glutamate Transporters in Axons That Innervate the Human Dental Pulp - Corrected Proof

2012-01-13

Abstract: Introduction: Vesicular glutamate transporters (VGLUTs) are involved in the transport of transmitter glutamate into synaptic vesicles and are used as markers for glutamatergic neurons.Methods: To assess which types of VGLUTs are involved in the glutamate signaling in pulpal axons and to investigate their distribution, we performed light microscopic immunohistochemistry by using antibodies against VGLUT1, VGLUT2, calcitonin gene-related peptide, and Western blot analysis in human dental pulp.Results: VGLUT1 was expressed in a large number of pulpal axons, especially in the peripheral pulp where the axons branch extensively. The VGLUT1 immunopositive axons showed bead-like appearance, and the majority of these also expressed calcitonin gene-related peptide. VGLUT2 was expressed in few axons throughout the pulp.Conclusions: Our findings suggest that VGLUT1 is involved mainly in the glutamate-mediated signaling of pain, primarily at the level of the peripheral pulp.

Erratum - Corrected Proof

2012-01-13

Oliver Pontius and Jeffrey W. Hutter, authors of the article “Survival Rate and Fracture Strength of Incisors Restored with Different Post and Core Systems and Endodontically Treated Incisors without Coronoradicular Reinforcement” (J Endod 2002;28[10]:710–5), would like to add 3 coauthors to their article. The author order now reads: Pontius O, Nathanson D, Giordano R, Schilder H, Hutter JW. They would also like to add the following citation to their article: Strub JO, Pontius O, Koutayas S. Survival rate and fracture strength of incisiors restored with different post and core systems after exposure in the artificial mouth. J Oral Rehabil 2001;28(2):120–4.

Revitalization Procedures in Two Traumatized Incisors with Different Biological Outcomes - Corrected Proof

Renato Lenzi, Martin Trope — 2012-01-12

Abstract: Introduction: The revitalization of a previously necrotic pulp space has been shown to be possible and even considered predictable. However, exact criteria for success are still lacking, and, in fact, some cases do not respond as predicted.Methods: In this case, the same operator treated 2 teeth similarly according to the principles laid out by Banch and Trope. The tooth that according to our expectations was more likely to be revitalized successfully failed to do so, whereas the second tooth that, in our estimation, was less likely to succeed was successful. In the tooth that failed to revitalize, auto-apexification occurred.Conclusions: Complete understanding for the criteria for predictable revitalization and apexification is still lacking.

In Vivo Efficacy of Three Different Endodontic Irrigation Systems for Irrigant Delivery to Working Length of Mesial Canals of Mandibular Molars - Corrected Proof

Hugo Roberto Munoz, Karla Camacho-Cuadra — 2012-01-12

Abstract: Introduction: Many in vitro studies have debated over the ability of different irrigant delivery and/or agitation systems to reach the apical third of curved root canals; however, little is known about irrigant penetration in vivo. Therefore, the purpose of this study was to compare the efficacy of the conventional endodontic irrigation needle, passive ultrasonic irrigation (PUI), and a negative pressure system for irrigant delivery to working length (WL) of mesial canals of mandibular molars.Methods: Thirty mesial canals of 30 vital mandibular first or second molars were randomly assigned into 3 groups (n = 10): (1) Monoject syringe with 27-gauge needle; (2) PUI with IrriSafe tip; and (3) EndoVac system. All canals were treated following the same preparation protocol to size 35/0.04 by using 5.25% NaOCl as irrigant during preparation procedure. Before obturation, canals were irrigated with 1 mL of a radiopaque solution by using the assigned irrigation system, and a digital radiograph was taken by using a parallel technique. With the aid of image editing software the distance between WL and maximum irrigant penetration was measured.Results: Mean distances for Monoject, PUI, and EndoVac groups were 1.51 mm, 0.21 mm, and 0.42 mm, respectively. Analysis of variance test showed statistically significant differences between groups (P < .001). Tukey honestly significant difference test showed statistically significant differences between the Monoject group and the other 2 groups (P < .001) but no significant differences between PUI and EndoVac groups (P = .06).Conclusions: PUI and EndoVac are more effective than the conventional endodontic needle in delivering irrigant to WL of root canals.

Development of a Multispecies Biofilm Community by Four Root Canal Bacteria - Corrected Proof

Luis E. Chávez de Paz — 2012-01-09

Abstract: Introduction: The development of multispecies biofilm models are needed to explain the interactions that take place in root canal biofilms during apical periodontitis. The aim of this study was to investigate the ability of 4 root canal bacteria to establish a multispecies biofilm community and to characterize the main structural, compositional, and physiological features of this community.Methods: Four clinical isolates isolated from infected root canals, Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus gordonii, and Enterococcus faecalis, were grown together in a miniflow cell system. Simultaneous detection of the 4 species in the biofilm communities was achieved by fluorescence in situ hybridization in combination with confocal microscopy at different time points. The LIVE/DEAD BacLight technique (Molecular Probes, Carlsbad, CA) was used to assess cell viability and to calculate 3-dimensional architectural parameters such as biovolume (μm3). Redox fluorescence dye 5-cyano-2,3-ditolyl tetrazolium chloride was used to assess the metabolic activity of biofilm bacteria.Results: The 4 species tested were able to form stable and reproducible biofilm communities. The biofilms formed in rich medium generally showed continuous growth over time, however, in the absence of glucose biofilms showed significantly smaller biovolumes. A high proportion of viable cells (>90%) were generally observed, and biofilm growth was correlated with high metabolic activity of cells. The community structure of biofilms formed in rich medium did not change considerably over the 120-hour period, during which E. faecalis, L. salivarius, and S. gordonii were most abundant.Conclusions: The ability of 4 root canal bacteria to form multispecies biofilm communities shown in this study give insights into assessing the community lifestyle of these microorganisms in vivo. This multispecies model could be useful for further research simulating stresses representative of in vivo conditions.

Computed Micro-tomographic Evaluation of Glide Path with Nickel-Titanium Rotary PathFile in Maxillary First Molars Curved Canals - Corrected Proof

2012-01-09

Abstract: Introduction: X-ray computed micro-tomography scanning allows high-resolution 3-dimensional imaging of small objects. In this study, micro-CT scanning was used to compare the ability of manual and mechanical glide path to maintain the original root canal anatomy.Methods: Eight extracted upper first permanent molars were scanned at the TOMOLAB station at ELETTRA Synchrotron Light Laboratory in Trieste, Italy, with a microfocus cone-beam geometry system. A total of 2,400 projections on 360° have been acquired at 100 kV and 80 μA, with a focal spot size of 8 μm. Buccal root canals of each specimen (n = 16) were randomly assigned to PathFile (P) or stainless-steel K-file (K) to perform glide path at the full working length. Specimens were then microscanned at the apical level (A) and at the point of the maximum curvature level (C) for post-treatment analyses. Curvatures of root canals were classified as moderate (≤35°) or severe (≥40°). The ratio of diameter ratios (RDRs) and the ratio of cross-sectional areas (RAs) were assessed. For each level of analysis (A and C), 2 balanced 2-way factorial analyses of variance (P < .05) were performed to evaluate the significance of the instrument factor and of canal curvature factor as well as the interactions of the factors both with RDRs and RAs.Results: Specimens in the K group had a mean curvature of 35.4° ± 11.5°; those in the P group had a curvature of 38° ± 9.9°. The instrument factor (P and K) was extremely significant (P < .001) for both the RDR and RA parameters, regardless of the point of analysis.Conclusions: Micro-CT scanning confirmed that NiTi rotary PathFile instruments preserve the original canal anatomy and cause less canal aberrations.

In Vitro Evaluation of MTAD and Nisin in Combination Against Common Pathogens Associated with Root Canal Infection - Corrected Proof

Zhongchun Tong, Lin Zhou, Rong Kuang, Haipeng Lv, Tiejun Qu, Longxing Ni — 2012-01-09

Abstract: Introduction: Many pathogenic microorganisms were found in an infected root canal. The object of this study was to evaluate the effect of MTAD in combination with nisin on the pathogens associated with root canal infection.Methods: The survival rates of 9 pathogenic bacteria were determined after 1-, 5-, and 10-minute treatment with MTAD, MTAN (substitution of doxycycline with nisin), and MTADN (nisin in combination with doxycycline). The survival rates of Enterococcus faecalis in the starvation phase and pretreatment alkalization as well as in the normal physiological state under MTAD, MTAN, and MTADN challenge for 1, 5, and 10 minutes were evaluated and compared. Furthermore, scanning electron microscopy was used to observe the morphologic modification of Actinomyces naeslundii, Lactobacillus paracasei, and Porphyromonas gingivalis after MTAD and MTADN treatment.Results: L. fermenti, L. paracasei, A. viscosus, A. naeslundii, Streptococcus gordonii, and Peptostreptococcus were more sensitive to MTADN and MTAN than to MTAD. MTAD, MTAN, and MTADN showed a rapid antibacterial effect on P. gingivalis, Prevotella intermedia, and Fusobacterium nucleatum. Enterococcus faecalis in the stress state was as sensitive to MTAD, MTAN, and MTADN as the control E. faecalis. Furthermore, in the observation of scanning electron microscopy, the membranes in A. naeslundii and L. paracasei presented significant rupture, and P. gingivalis did not exhibit significant damage after MTADN treatment.Conclusion: MTAD in combination with nisin improved antibacterial efficacy against pathogens, especially for some gram-positive bacteria associated with persistent intracanal infection. Therefore, the combination had the potential to be used as an effective intracanal irrigation.

Analysis of Factors Associated with Cracked Teeth - Corrected Proof

Deog-Gyu Seo, Young-Ah Yi, Su-Jung Shin, Jeong-Won Park — 2012-01-09

Abstract: Introduction: The purpose of this study was to analyze the characteristics, distribution, and associated factors of longitudinal fractured teeth according to the well-defined criteria of the American Association of Endodontists (AAE).Methods: One hundred seven teeth with longitudinal fracture from 103 patients were diagnosed and analyzed. The patients’ signs, symptoms, age, and sex were noted as well as the tooth number, dental arch, filling materials, size/classification of restoration, crack direction, pulp vitality, whether the patient had undergone endodontic treatment, bite test results, percussion test results, wear facet, and periodontal pocket depth.Results: Eighty-seven teeth were diagnosed with a cracked tooth (81.3%), 14 were diagnosed with vertical root fracture (VRF, 13.1%), 4 had a split tooth (3.7%), and 2 had a fractured cusp (1.9%); 82.2% showed a sensitive reaction on the bite test. Longitudinal tooth fractures were observed most frequently in patient in their 40s. The upper first molar (28.0%) was most frequently cracked, followed by the lower first molar (25.2%), the lower second molar (20.6%), and the upper second molar (16.8%). Most longitudinal tooth fractures (72.0%) occurred mainly in restored teeth, whereas only 28.0% were found in intact teeth. Compared with resin (4.7%) or porcelain (0.9%), the use of nonbonded inlay restoration materials such as gold (20.5%) or amalgam (18.7%) increased the occurrence of longitudinal tooth fractures. Out of 107 of longitudinal fractured teeth, 33 (30.8%) were treated endodontically and 74 (69.2%) were not. VRF was associated with endodontic treatment.Conclusions: The bite test is most reliable for reproducing symptoms. The combined use of various examination methods is recommended for detecting cracks and minutely inspecting all directions of a tooth.

Effect of Environment on Fatigue Failure of Controlled Memory Wire Nickel-Titanium Rotary Instruments - Corrected Proof

Ya Shen, Wei Qian, Houman Abtin, Yuan Gao, Markus Haapasalo — 2012-01-09

Abstract: Introduction: This study examined the fatigue behavior of 2 types of nickel-titanium (NiTi) instruments made from a novel controlled memory NiTi wire (CM wire) under various environment conditions.Methods: Three conventional superelastic NiTi instruments of ProFile (Dentsply Maillefer, Ballaigues, Switzerland), Typhoon (Clinician’s Choice Dental Products, New Milford, CT), and DS-SS0250425NEYY (Clinician’s Choice Dental Products) and 2 new CM wire instruments of Typhoon CM and DS-SS0250425NEYY CM were subjected to rotational bending at the curvature of 35° in air, deionized water, 17% EDTA, or deionized water after immersion in 6% sodium hypochlorite for 25 minutes, and the number of revolutions of fracture (Nf) was recorded. The fracture surface of all fragments was examined by a scanning electron microscope. The crack-initiation sites and the percentage of dimple area to the whole fracture cross-section were noted.Results: Two new CM Wire instruments yielded an improvement of >4 to 9 times in Nf than conventional NiTi files with the same design under various environments (P < .05). The fatigue life of 3 conventional superelastic NiTi instruments was similar under various environments, whereas the Nf of 2 new CM Wire instruments was significantly longer in liquid media than in air (P < .05). The vast majority of CM instruments showed multiple crack origins, whereas most instruments made from conventional NiTi wire had one crack origin. The values of the area fraction occupied by the dimple region were significantly smaller on CM NiTi instruments than in conventional NiTi instruments under various environments (P < .05).Conclusions: Within the limitations of this study, the type of NiTi metal alloy (CM files vs conventional superelastic NiTi files) influences the cyclic fatigue resistance under various environments. The fatigue life of CM instruments is longer in liquid media than in air.

A Comparison of the Cytotoxicity and Proinflammatory Cytokine Production of EndoSequence Root Repair Material and ProRoot Mineral Trioxide Aggregate in Human Osteoblast Cell Culture Using Reverse-Transcriptase Polymerase Chain Reaction - Corrected Proof

Maria Ciasca, Anita Aminoshariae, Ge Jin, Thomas Montagnese, Andre Mickel — 2012-01-09

Abstract: Introduction: The purpose of this study was to compare the cytotoxicity and cytokine expression profiles of EndoSequence Root Repair Material (ERRM; Brasseler, Savannah, GA) putty, ERRM flowable, and ProRoot mineral trioxide aggregate (MTA; Dentsply Tulsa Dental, Johnson City, TN) using osteoblast cells (MG-63).Methods: Four millimeters in diameter of each material was placed in the center of a 6-well culture plate, and a 2-mL suspension (105 cells/mL) of human osteoblasts was seeded in each well. Photomicrograph images were used to evaluate cytotoxicity as evidenced by the lack of osteoblast cell growth in relation to the materials with AH-26 (Dentsply Tulsa Dental) as the positive control. In addition, reverse-transcriptase polymerase chain reaction (RT-PCR) was used to evaluate the expression of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α). Cytokine expression of MG-63 cells upon lipopolysaccharide treatment was used as controls. RT-PCR results were normalized by the expression of the housekeeping gene β-actin and were used to measure cytokine expression. Statistical analysis was performed using analysis of variance.Results: Results showed that ERRM putty and MTA exhibited minimal levels of cytotoxicity; however, ERRM was slightly more cytotoxic although not statistically significant. The expression of IL-1β, IL-6, and IL-8 was detected in all samples with minimal TNF-α expression.Conclusions: We concluded that ERRM and MTA showed similar cytotoxicity and cytokine expressions.

Failure of Setting of Mineral Trioxide Aggregate in the Presence of Fetal Bovine Serum and Its Prevention - Corrected Proof

Yuran Kim, Sinyoung Kim, Yoo Seok Shin, Il-Young Jung, Seung Jong Lee — 2012-01-09

Abstract: Introduction: The purpose of this study was to examine the effect of fetal bovine serum (FBS) on the setting of 2 white mineral trioxide aggregates (MTAs) and to determine if calcium chloride (CaCl2) alters the setting behavior of both MTAs under this condition.Methods: Two types of MTA cements (ProRoot MTA [Dentsply Tulsa Dental, Tulsa, OK] and MTA-Angelus [Angelus Dental Solutions, Londrina, Brazil]) were mixed with either distilled water (DW) or 10% CaCl2 solution. Mixed MTA was placed in a polyethylene mold, and each mold was then placed in saline or FBS-soaked Oasis. After storing for 4 days, the MTA samples were removed from the molds, and the microhardness was independently measured at 3 different levels: 0.5 mm, 2 mm, and 4 mm away from the bottom in contact with the immersion solution.Results: None of the samples mixed with DW and exposed to FBS for 4 days had set at the 0.5-mm and 2-mm levels. CaCl2 was effective in reducing (the 0.5-mm level) or eliminating (the 2- and 4-mm levels) the adverse effect of FBS. The groups with short-term exposure to FBS had the same surface microhardness as the groups stored in saline-soaked Oasis.Conclusions: MTA did not set when the mixed MTA was exposed to FBS for 4 days. In these cases, 10% CaCl2 helped the setting of MTA, and the effect was more pronounced in ProRoot MTA than in MTA-Angelus. In contrast, short-term exposure to FBS had minimal or no detrimental effects on the setting behaviors of both MTAs.

Effect of Laser-Activated Irrigation of 1320-Nanometer Nd:YAG Laser on Sealer Penetration in Curved Root Canals - Corrected Proof

2012-01-09

Abstract: Introduction: The purpose of this study was to investigate the efficacy of laser-activated irrigation (LAI) of 1320-nm neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser on sealer penetration into dentinal tubules in the presence of 5.25% sodium hypochlorite (NaOCl) or 17% ethylenediaminetetraacetic acid (EDTA).Methods: The curved root canals (>20°) from 63 extracted human molars (negative control, n = 3) were prepared to size #30.06 with NaOCl irrigation. Teeth were divided into 4 groups (n = 15) as follows: group N, NaOCl irrigation without LAI; group E, EDTA irrigation without LAI; group NL, LAI with NaOCl; group EL, LAI with EDTA. In all groups, the laser fiber was inserted and withdrawn 4 times for 5 seconds each. Teeth were obturated with gutta-percha and fluorescent-labeled sealer. Transverse sections at 2 and 5 mm from root apex were examined with confocal laser scanning microscopy, and the percentage of sealer penetration into dentinal tubules was measured.Results: Groups E, NL, and EL showed higher percentage of sealer penetration than group N (P < .05). With NaOCl as irrigant, LAI (group NL) resulted in significantly higher amount of sealer penetration than nonactivated group (group N) in both levels (P < .05). However, with EDTA, no significant differences in sealer penetration were observed between the laser-activated group (group EL) and its nonactivated counterpart (group E) in both levels (P > .05).Conclusions: The 1320-nm Nd:YAG laser activation with either NaOCl or EDTA was much better than NaOCl irrigation alone and as effective as EDTA final flush for sealer penetration into dentinal tubules. Additional use of laser with EDTA did not improve the quality of obturation in the curved canals.

Success Rates for Removing or Bypassing Fractured Instruments: A Prospective Clinical Study - Corrected Proof

2012-01-09

Abstract: Introduction: The objective of this study was to evaluate the success rates of standardized techniques for removing or bypassing fractured instruments from root canals and determine whether visualization of the fractured instrument with the aid of an operating microscope has any impact on the success rates.Methods: In this prospective study, attempts were made to visualize 112 fractured instruments under a dental operating microscope after creating a straight-line access to the fragment. By using ultrasonic tips alone or associated with bypassing, the Ruddle technique was attempted to remove the 68 visible instruments. Bypassing was performed for the 44 nonvisible fragments. The χ2 test was performed to assess whether any significant difference occurred between the success rates observed for the visible and nonvisible fractured instrument groups.Results: The overall success rate (removal and bypassing) was 70.5% (n = 79). In the visible fragment group, the success rate was 85.3% (n = 58), and in the nonvisible fragment group it was 47.7% (n = 21). Success rates were significantly higher when the fragment was visible (P = .0009).Conclusions: The standardized techniques used in this study for removing or bypassing fractured instruments were effective, and approximately 2 times greater success rate was obtained when the fragment was visible inside the root canal compared with when it was nonvisible.

Physicochemical and Pulp Tissue Dissolution Properties of Some Household Bleach Brands Compared with a Dental Sodium Hypochlorite Solution - Corrected Proof

Holger Jungbluth, Christine Peters, Ove Peters, Beatrice Sener, Matthias Zehnder — 2012-01-09

Abstract: Introduction: Many clinicians use household bleach to irrigate root canals. Sodium hypochlorite solutions are also available from dental suppliers. We compared physicochemical features of these products and investigated their impact on pulp tissue dissolution.Methods: Six different brands of household bleach were bought from drugstores. These were compared with Chlor-XTRA and technical NaOCl solutions of controlled concentration and alkalinity regarding their chlorine content (wt% NaOCl), pH, alkaline capacity, osmolarity, surface tension (Wilhelmy plate method), and price. Bovine pulp tissue (n = 10 specimens per group) dissolution at 37°C by test and control solutions adjusted to 1.0% NaOCl was assessed. Reduction in tissue weight was compared between groups by one-way analysis of variance, followed by Bonferroni correction (P < .05).Results: The pH of undiluted solutions ranged between 11.1 and 12.7. Batches of the same product differed in NaOCl content. No product contained more than an equivalent of 0.1 mol/L NaOH. One household bleach brand (Safeway Bleach Summit Fresh) was slightly alkalized; the other solutions under investigation were not. Osmolarity was similar between products. The surface tension of Chlor-XTRA and Safeway Bleach Summit Fresh was about half that of the other solutions. Tissue dissolution was statistically similar (P > .05) among all solutions. Price was about 100-fold higher per liter of Chlor-XTRA compared with household bleach.Conclusions: Other than its price, the Chlor-XTRA solution had no unique features. In contrast to an earlier report, reduced surface tension did not result in greater soft tissue dissolution by NaOCl.