Oral microbiota species in acute apical endodontic abscesses.

BACKGROUND AND OBJECTIVES: Acute apical abscesses are serious endodontic diseases resulting from pulpal infection with opportunistic oral microorganisms. The objective of this study was to identify and compare the oral microbiota in patients (N=18) exhibiting acute apical abscesses, originating from the demographic region in Portland, Oregon. The study hypothesis is that abscesses obtained from this demographic region may contain unique microorganisms not identified in specimens from other regions. DESIGN: Endodontic abscesses were sampled from patients at the Oregon Health & Science University (OHSU) School of Dentistry. DNA from abscess specimens was subjected to polymerase chain reaction amplification using 16S rRNA gene-specific primers and Cy3-dCTP labeling. Labeled DNA was then applied to microbial microarrays (280 species) generated by the Human Oral Microbial Identification Microarray Laboratory (Forsyth Institute, Cambridge, MA). RESULTS: The most prevalent microorganisms, found across multiple abscess specimens, include Fusobacterium nucleatum, Parvimonas micra, Megasphaera species clone CS025, Prevotella multisaccharivorax, Atopobium rimae, and Porphyromonas endodontalis. The most abundant microorganisms, found in highest numbers within individual abscesses, include F. nucleatum, P. micra, Streptococcus Cluster III, Solobacterium moorei, Streptococcus constellatus, and Porphyromonas endodontalis. Strong bacterial associations were identified between Prevotella multisaccharivorax, Acidaminococcaceae species clone DM071, Megasphaera species clone CS025, Actinomyces species clone EP053, and Streptococcus cristatus (all with Spearman coefficients >0.9). CONCLUSIONS: Cultivable and uncultivable bacterial species have been identified in endodontic abscesses obtained from the Portland, Oregon demographic region, and taxa identifications correlated well with other published studies, with the exception of Treponema and Streptococcus cristae, which were not commonly identified in endodontic abscesses between the demographic region in Portland, Oregon and other regions.

Apical extrusion of sodium hypochlorite using different root canal irrigation systems.

INTRODUCTION: Root canal irrigation carries a risk of extrusion of irrigant into the periapical tissues. The objective of this study was to compare different irrigation systems in matched pairs of teeth prepared to an apical size of 35.06 and 50.06 by measuring the frequency and extent of apical extrusion of sodium hypochlorite (NaOCl) into a simulated periapical environment. The null hypothesis was tested that there is no difference between systems. METHODS: Bilaterally matched pairs (n = 10) of single-canal extracted human anterior teeth were instrumented to an apical size of either 35.06 or 50.06. Teeth were embedded in a gel containing the pH-sensitive dye M-cresol purple that changes from yellow at pH 7.4 to purple at pH 9. Root canals were irrigated with 6% NaOCl (pH 11) by using EndoActivator (EA), EndoVac (EV), Rispi-Sonic/MicroMega 1500 (MM), passive ultrasonic irrigation (PUI), and syringe irrigation with a slot-tipped needle (SN), so that each tooth underwent all irrigation procedures in a randomized crossover design. Apical extrusion was evaluated by image analyses. RESULTS: The frequency of extrusion was less in teeth with apical preparation size 35.06 (36%) compared with 50.06 (60%) (P = .014) and was dependent on the irrigation system in 35.06 (P = .039) but not 50.06 groups. In the 35.06 group the frequency of extrusion was less for EV than for MM and SN (both P = .029). The extent of extrusion was less for MM compared with PUI (P = .024) and SN (P = .046) in the 35.06 group and greater for SN compared with all other systems in the 50.06 group (P < .05). The null hypothesis was rejected. CONCLUSIONS: The frequency of apical extrusion of NaOCl was dependent on the type of root canal irrigation system and apical preparation size. The extent of extrusion depended on the irrigation system, with syringe and slotted-needle irrigation resulting in the greatest extent of extrusion.

Comparison of the debridement efficacy of the EndoVac irrigation system and conventional needle root canal irrigation in vivo.

INTRODUCTION: The purpose of this study was to compare the debridement efficacy of EndoVac irrigation versus conventional needle irrigation in vivo. METHODS: Seven adult patients with a total of 22 matched pairs of single-canaled vital teeth with fully formed apices were recruited. Canals were instrumented to a master apical file size #40/.04 taper. One tooth from each matched pair was irrigated by using the EndoVac system. The other tooth was irrigated by conventional needle irrigation. Five additional teeth were used as positive controls. A #10 K-file was inserted into the control canals to determine working length (WL), with no other instrumentation or irrigation performed to confirm the presence of debris. The teeth were extracted, fixed, and decalcified. Six histologic slides each 6 µm thick were made from sections at 1 and 3 mm from WL and stained. The slide with the most debris was photographed at each level for each tooth. A Wilcoxon signed rank test was used to compare the percentage of debris remaining in the canals between the 2 irrigation techniques. RESULTS: The median amount of debris remaining at 1 mm was 0.05% for the EndoVac group and 0.12% for the conventional irrigation group (P < .05). The median amount of debris remaining at 3 mm was 0.09% for the EndoVac group and 0.07% for the conventional needle irrigation group (P > .05). CONCLUSIONS: EndoVac irrigation resulted in significantly less debris at 1 mm from WL compared with conventional needle irrigation. There was no significant difference at the 3-mm level.

Comparison of the antimicrobial efficacy of irrigation using the EndoVac to endodontic needle delivery.

INTRODUCTION: The purpose of this investigation was to compare the antimicrobial efficacy of root canal irrigation with the EndoVac (Discus Dental, Culver City, CA) to endodontic needle irrigation in the apical 5 mm of root canals infected with Enterococcus faecalis. METHODS: Bilaterally matched, extracted human teeth were sterilized and inoculated with E. faecalis. Specimens in the EndoVac group were irrigated using the EndoVac system, whereas those in the needle group were irrigated with a 30-G side-vented needle. After chemomechanical preparation, the apical 5 mm of the roots were removed, frozen in liquid nitrogen, and pulverized to expose E. faecalis in dentinal tubules or other morphologic irregularities. The number of colony forming units (cfus) of E. faecalis per mg dentin was determined. RESULTS: The EndoVac Group had a mean of 31.6 cfu/mg, whereas the needle group had a mean of 157 cfu/mg. This represents a bacterial reduction of 99.7% in group A and 98.8% in group B when compared with positive controls. CONCLUSION: Although there were fewer cfu/mg when using the EndoVac, there was not a statistically significant difference between the EndoVac and needle groups.

Comparison of push-out bond strengths of Resilon with three different sealers.

INTRODUCTION: The purpose of this study was to evaluate the push-out bond strengths of different obturating materials. METHODS: Forty single-rooted human extracted teeth were used in this study. The teeth were instrumented and irrigated by using 5.25% NaOCl, 15% ethylenediaminetetraacetic acid, and sterile water. The teeth were then filled with Resilon/RealSeal, Resilon/RealSeal SE, Resilon/MetaSeal , or gutta-percha/Kerr EWT sealer. The roots were then sectioned into 1-mm-thick slices and subjected to vertical loading to displace the obturating material toward the coronal side of the slice. The bond strength was then calculated and subjected to statistical analysis. Slices were examined by using a stereomicroscope at 30x to determine the mode of failure. RESULTS: The mean push-out bond strengths were as follows: Resilon/RealSeal, 1.45 +/- 0.99 MPa; RealSeal SE, 0.88 +/- 0.49 MPa; Resilon/MetaSeal, 2.41 +/- 1.7 MPa; and gutta-percha/Kerr EWT sealer, 2.32 +/- 0.74 MPa. CONCLUSIONS: The push-out bond strengths of Resilon/MetaSeal and gutta-percha/Kerr EWT were significantly (P < .05) higher than either Resilon/RealSeal or Resilon/RealSeal SE. Resilon/MetaSeal and gutta-percha/Kerr EWT did not differ significantly.

Comparison of apical extrusion of NaOCl using the EndoVac or needle irrigation of root canals.

INTRODUCTION: The purpose of this study is to compare extrusion of irrigants delivered with a 27-G needle or the EndoVac system (Discus Dental, Culver City, CA) during instrumentation and final irrigation of teeth. METHODS: Matched paired single canal teeth were divided into four sample groups and controls. The experimental groups were needle irrigation International Standards Organization (ISO) size #40 (N40) and #60 (N60) and EndoVac ISO size #40 (E40) and #60 (E60). Teeth were secured and embedded in 0.2% agarose gel (ph = 7.3-7.4) containing 1 mL 0.1% m-cresol purple, which changes color at a pH of 9.0. Teeth received NaOCl and EDTA irrigation with the 27-G slot needle or the EndoVac system. The amount of irrigation was controlled for each sample. Standardized digital photographs were taken 20 minutes after the first irrigant was used. Photographs were analyzed by using Adobe Photoshop 7 (Adobe, San Jose, CA) to determine the amount of extrusion expressed as percent of total pixels. RESULTS: Data from sample groups show the following: N40 with 50% extrusion (6/12), E40 with 8.33% extrusion (1/12), N60 with 58.33% (7/12), and E60 with 8.33% (1/12). The overall extrusion frequency, regardless of apical preparation size, was 54.17% (13/24) for needle and 8.33% (2/24) for EndoVac. Analysis of N40 and E40 revealed p < 0.03. Analysis of N60 and E60 revealed p < 0.01. Comparison of needle irrigation versus EndoVac showed a significant p value of 0.0007. CONCLUSIONS: This study showed significantly less extrusion risk using the EndoVac system compared with needle irrigation.

Identify and define all diagnostic terms for periapical/periradicular health and disease states.

INTRODUCTION: The purpose of this in-depth investigation was to identify, clarify, and substantiate clinical terminology relative to apical/periapical/periradicular diagnostic states, which is used routinely in the provision of endodontic care. Furthermore, the information gleaned from this investigation was used to link diagnostic categories to symptoms, pathogenesis, treatment, and prognosis wherever possible, along with establishing the basis for the metrics used in this diagnostic process. MATERIALS AND METHODS: Diagnostic terminologies and their relevance to clinical situations were procured from extensive historic and electronic searches and correlated with contemporary concepts in disease processes, clinical assessments, histologic findings (if appropriate), and standardized definitions that have been promulgated and promoted for use in the last 25 years in educational programs and test constructions and for third-party concerns. RESULTS: In general, clinical terminology that is used routinely in the practice of endodontics is not based on the findings of scientific investigations. The diagnostic terms are based on assumptions by correlating certain signs, symptoms, and radiographic findings with what is presumed (not proven) to be the underlying disease process of a given clinical state. There were no studies that specifically tried to assess the accuracy of the metrics used contemporarily for the classification of clinical disease states. CONCLUSION: A succinct diagnostic scheme that could be described thoroughly, agreed on unanimously, coded succinctly for easy electronic input, and ultimately used for follow-up analysis would not only drive treatment modalities more accurately, but would also allow for future outcomes assessment and validation.

An in vivo comparison of the Root ZX II, the Apex NRG XFR, and Mini Apex Locator by using rotary nickel-titanium files.

INTRODUCTION: The purpose of this study was to compare the accuracy of working length (WL) measurements by using the Root ZX II, Apex NRG XFR, and Mini Apex Locator with rotary nickel-titanium (NiTi) instruments. METHODS: Twenty-eight teeth had their WLs determined with each electronic apex locator (EAL) by using 0.04 taper ProFiles sizes 40-20 in a crown-down technique until WL was reached. Four control teeth had their WL determined by using stainless steel hand files. The files were cemented at WL, and the teeth were extracted. The apical 4 mm of each root was shaved to the apical constriction, exposing the file. Photographs were taken under 15x and 30x magnification and projected at 360x and 720x for evaluation. RESULTS: The accuracy of the Root ZX II, Apex NRG XFR, and Mini Apex Locator in locating the minor diameter within +/-0.5 mm was 50%, 46.43%, and 39.29%, respectively. There was no statistically significant difference between the EALs in locating the minor diameter. The determination of WL by using hand files in the control teeth was more accurate. CONCLUSIONS: The Root ZX II, Apex NRG XFR, and Mini Apex Locator used with rotary NiTi files were able to locate the apical constriction within +/-0.5 mm only 50% or less of the time.

Herpesviruses in abscesses and cellulitis of endodontic origin.

Acute apical abscesses and cellulitis are severe endodontic diseases caused by opportunistic bacteria with possible coinfection with latent herpesviruses. The objectives of this study are to identify herpesviruses, including human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), herpes simplex virus-1 (HSV-1), and Varicella zoster virus (VZV) in patients (n = 31) presenting with acute apical abscesses and cellulitis of endodontic origin. Primary and nested polymerase chain reaction (PCR) was conducted using virus-specific primers and DNA isolated from cell-free abscess fluid. From patients exhibiting concurrent spontaneous pain (n = 28), nine abscesses contained HCMV, two abscesses contained EBV, one abscess contained HSV-1, and no abscesses contained VZV. Control PCR using genomic or recombinant templates showed detection limits to a single genomic copy of HCMV, 100 genomic copies for EBV, and 1 to 10 copies for HSV-1 with no cross-amplification between herpesviral DNA targets. Nested PCR was required for detection of herpesviral DNA in the abscess specimens, indicating that these viruses were present in low copy number. Filtration of abscess specimens and virus transfer experiments using human fibroblastic MRC-5 cells confirmed the presence of HCMV particles in several abscess specimens. We conclude that herpesviruses are present but not required for the development of acute apical abscesses and cellulitis of endodontic origin.

Herpesviruses in endodontic pathoses: association of Epstein-Barr virus with irreversible pulpitis and apical periodontitis.

Irreversible pulpitis and apical periodontitis are inflammatory diseases caused by opportunistic bacteria with possible co-infection with latent herpesviruses. The objectives of this study are to identify herpesviruses, including human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV-1), and Varicella zoster virus (VZV) in patients with irreversible pulpitis (n = 29) or apical periodontitis, either primary (n = 30) or previously treated (n = 23). Using primary and nested polymerase chain reaction (PCR) and reverse transcription-PCR, EBV DNA and RNA were present in endodontic pathoses in significantly higher percentages (43.9% and 25.6%, respectively) compared with healthy pulp controls (0% and 0%, respectively). HCMV DNA and RNA were found in measurable numbers in both endodontic patients (15.9% and 29.3%, respectively) and in healthy pulp controls (42.1% and 10.5%, respectively). HSV-1 DNA was found in low percentages in endodontic patients (13.4%), and only one patient showed the presence of VZV. In conclusion, EBV may be associated with irreversible pulpitis and apical periodontitis.

An evaluation of Guttaflow and gutta-percha in the filling of lateral grooves and depressions.

The purpose of this study was to compare the flow of GuttaFlow (Coltène/Whaledent Inc, Cuyahoga Falls, OH) and gutta-percha into lateral grooves and depressions in the apical 7 mm of the root canal system. A maxillary canine was used to fabricate a split-tooth model with depressions and lateral grooves placed in the canal walls at 1 mm, 3 mm, 5 mm, and 7 mm from the working length. The model was obturated with GuttaFlow or gutta-percha and Roth's 801 sealer (Roth International, Chicago, IL). Obturations with gutta-percha were performed by using warm vertical compaction with the System B plugger (Analytic Endodontics, Orange, CA) advanced to 5 mm, 4 mm, or 3 mm from the working length. All obturations with GuttaFlow showed extrusion of material beyond the apex. GuttaFlow completely obturated the grooves and depressions at all levels from the working length, and, at the 1-mm level, GuttaFlow flowed significantly better into grooves. GuttaFlow flowed better than gutta-percha into depressions at the 1-mm level when the System B plugger was inserted to 5 mm and 4 mm from the working length, but no significant differences were seen when the System B plugger was inserted to 3 mm from the working length. Gutta-percha flowed significantly better into grooves and depressions at the 1-mm level when the System B plugger was inserted 3 mm from the working length compared with 5 mm and 4 mm from working length.

Evaluation of the interaction between sodium hypochlorite and chlorhexidine gluconate and its effect on root dentin.

The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) forms a precipitate. The aim of this study was to evaluate the effect of irrigating root canals with a combination of NaOCl and CHX on root dentin and dentinal tubules by using the environmental scanning electron microscope (ESEM) and a computer program (Photoshop CS2). Forty-four extracted single-rooted human teeth were instrumented and irrigated with both NaOCl and CHX to produce a precipitate. Root canal surfaces were analyzed with the ESEM. The amount of remaining debris and number of patent tubules were determined. There were no significant differences in remaining debris between the negative control group and the experimental groups. There were significantly fewer patent tubules in the experimental groups when compared with the negative control group. The NaOCl/CHX precipitate tends to occlude the dentinal tubules. Until this precipitate is studied further, caution should be exercised when irrigating with NaOCl and CHX.

Effect of electropolishing ProFile nickel-titanium rotary instruments on cyclic fatigue resistance, torsional resistance, and cutting efficiency.

This study investigated the effect of electropolishing ProFile nickel titanium rotary instruments on torque resistance, fatigue resistance, and cutting efficiency. Size 25/.04 ProFile files (Dentsply Maillefer, Switzerland) that were nonpolished for the control group (n = 15) and electropolished for the experimental group (n = 15) were used for each experiment. Cyclical fatigue was determined by counting rotations until breakage with an applied 30 degrees , 45 degrees , and 60 degrees curve with a 5-mm radius. Torque and angle at failure were measured by rotating clamped files at 2 rpm until breakage. Cutting efficiency was determined by measuring the velocity of file advancement into plastic blocks with 100-g constant force for 5 seconds. Data were analyzed by either an unpaired t test or analysis of variance followed by a Fisher probable least-square difference test. Electropolishing significantly reduced resistance to cyclic fatigue but did not affect torsional resistance. However, electropolishing reduced the angle at failure and amount of unwinding. Electropolishing did not significantly affect cutting efficiency.

A comparison of gutta-percha and Resilon in the obturation of lateral grooves and depressions.

The purpose of this study was to compare the flow of gutta-percha and Resilon (RealSeal; SybronEndo, Orange, CA) into lateral grooves and depressions in the apical 7 mm of a root canal by using warm vertical compaction. A split-tooth model was constructed with lateral grooves and depressions prepared at 1, 3, 5, and 7 mm from working length (WL). Groups A, B, and C were obturated with gutta-percha with a System B plugger placed 5 mm, 4 mm, and 3 mm from WL. Groups D, E, and F were obturated with Resilon with a System B plugger placed 5 mm, 4 mm, or 3 mm from WL. Gutta-percha and Resilon showed similar movement into lateral grooves and dentin depressions, with a significant difference found only with increased flow of gutta-percha into depressions at the 1-mm level when the System B plugger was placed 3 mm or 4 mm from WL (p

Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation.

The purpose of this study was to compare the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation. Twenty-six bilaterally matched pairs of human teeth were collected. The teeth were incubated with Enterococcus faecalis for 4 weeks. The teeth were divided into two experimental groups and one positive control group. The canals were instrumented and irrigated with either 5.25% NaOCl/15% EDTA or 1.3% NaOCl/BioPure MTAD. Bacterial samples were collected after instrumentation/irrigation and after additional canal enlargement. Statistical analysis of the data using the Wilcoxon Signed Rank test showed significant differences between the experimental groups. The first bacterial samples revealed growth in 0 of 20 samples with 5.25% NaOCl/15% EDTA irrigation and in 8 of 20 samples with 1.3% NaOCl/BioPure MTAD irrigation. Samples taken after additional canal enlargement revealed growth in 0 of 20 samples in 5.25% NaOCl/15% EDTA and in 10 of 20 samples in 1.3% NaOCl/BioPure MTAD group. This investigation showed consistent disinfection of infected root canals with 5.25% NaOCl/15% EDTA. The combination of 1.3% NaOCl/BioPure MTAD left nearly 50% of the canals contaminated with E. faecalis.

Prevalence of selected bacterial named species and uncultivated phylotypes in endodontic abscesses from two geographic locations.

Evidence is mounting that the prevalence of some putative endodontic pathogens can significantly vary according to the geographic location in which samples were taken. This study aimed to provide additional knowledge on this subject by comparing the frequencies of 10 selected candidate endodontic pathogens in samples of acute apical abscesses obtained from two distinct geographic locations; Portland, OR, and Rio de Janeiro, Brazil. DNA was extracted from aspirates and used as template in nested PCR assays using 16S rRNA gene taxon-specific oligonucleotide primers. Of the target species/phylotypes, Treponema denticola (73% of the cases), Porphyromonas endodontalis (70%), and Tannerella forsythia (57%) were the most prevalent taxa found in Brazilian samples. Dialister invisus (70% of the cases), P. endodontalis (63%) and Dialister pneumosintes (55%) were the most frequent taxa in the Portland, OR samples. Data analysis revealed that T. denticola and T. forsythia were significantly more detected in Brazilian samples than in the Portland, OR samples. Although D. invisus, Filifactor alocis, and Synergistes oral clone W090 were detected in many more samples from the Portland, OR patients, differences were not found to be statistically significant. These findings confirmed that some bacterial taxa can markedly differ in the frequencies they occur in samples from different locations. It remains to be clarified whether this observation translates into relevant therapeutic implications.

The antimicrobial effect of chloroform on Enterococcus faecalis after gutta-percha removal.

The purpose of this in vitro study was to evaluate the antimicrobial effectiveness of chloroform on Enterococcus faecalis when used as a gutta-percha solvent during endodontic retreatment. Bilaterally matched human teeth were instrumented, infected with E. faecalis, and obturated. The gutta-percha was then removed using either chloroform or saline. Bacterial samples were collected after gutta-percha removal and following additional apical enlargement. A significant difference was seen (p<0.05) between the number of colony forming units (CFU) of E. faecalis for teeth retreated using chloroform (mean 21+56 CFU/ml) versus saline (mean 280+480 CFU/ml). Negative cultures were obtained in 11 of 17 chloroform samples and none of the saline samples. Samples taken after apical enlargement two sizes larger than the original master apical file showed a significant difference (p<0.05) between teeth retreated using chloroform versus saline. Negative cultures were seen in 9 of 17 chloroform samples and 1 of 17 saline samples. This study demonstrated that the use of chloroform during endodontic retreatment significantly reduced intracanal levels of cultivatable E. faecalis.

A comparison of the efficacy of Er,Cr:YSGG laser and rotary instrumention in root canal debridement.

BACKGROUND: The authors evaluated the efficacy of an erbium,chromium: yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser-powered hydrokinetic system (HKS) versus that of rotary instrumentation for root canal débridement. METHODS: The authors studied four uninstrumented controls and two test groups of 18 matched pairs of teeth. Teeth from each pair underwent different instrumentation but received identical irrigation solutions. The instrumentation protocol involved either rotary instrumentation or the Er,Cr:YSGG laser. The irrigation groups received 0.5 milliliter of distilled water or 5.25 percent sodium hypochlorite (NaOCl) between instruments. The authors measured the amount of debris remaining at 2 and 4 mm from the apex as a percentage of total lumen area. RESULTS: Lased canals had significantly more debris than did canals that received rotary instrumentation (Wilcoxon signed rank test, P < .001). With distilled water irrigation, the debris remaining in lased canals at both the 2-and 4-mm levels was not statistically different from that remaining in uninstrumented controls. Rotary instrumentation yielded significantly less remaining debris than did laser instrumentation (Wilcoxon signed rank test, P < .001). With 5.25 percent NaOCl irrigation, there was no difference in remaining debris between the two groups (Wilcoxon signed rank test , P < .001). The lased group received significantly more irrigant than did the rotary group (Wilcoxon rank sum test, P < .001). CONCLUSIONS: This study indicates that the débridement efficacy of the HKS with distilled water irrigation is unacceptable; with 5.25 percent NaOCl irrigation, it is similar to that of rotary instrumentation. CLINICAL IMPLICATIONS: If the HKS is to be used for débridement, then NaOCl irrigation must be used for predictable tissue removal.

Safety of electronic apex locators and pulp testers in patients with implanted cardiac pacemakers or cardioverter/defibrillators.

The purpose of this study was to determine if electronic apex locators (EAL) or electric pulp testers (EPT) interfere with the function of implanted cardiac pacemakers (ICP) or cardioverter/defibrillators (ICD). Twenty-seven patients with ICPs or ICDs had continuous electrocardiogram monitoring and device interrogation to detect interferences during the use of two types of EALs and one EPT. No interferences were detected by any ICP or ICD. In six patients, with intermittent pacing, a significant increase in pacing was observed during EAL/EPT stimulation (p < 0.05). Examination of RR intervals (a measure of intrinsic heart rate) demonstrated significantly longer RR intervals (slower intrinsic heart rate) during EAL/EPT stimulation (p < 0.05). Evaluation of the electrocardiograms for each patient failed to show any abnormalities in pacing during testing. These findings led us to conclude that the increased pacing frequency observed was related to a slower intrinsic heart rate and not electrical interference with the cardiac devices. In conclusion, the two EALs and one EPT used in this study did not interfere with the functioning of any of the cardiac devices tested.

A comparison of the antimicrobial efficacy of NaOCl/Biopure MTAD versus NaOCl/EDTA against Enterococcus faecalis.

The purpose of this investigation was to compare the antimicrobial efficacy of irrigating with 1.3% NaOCl/Biopure MTAD versus irrigation with 5.25% NaOCl/15% EDTA in the apical 5 mm of roots infected with Enterococcus faecalis. Bilaterally matched human teeth were sterilized and inoculated with E. faecalis. After chemomechanical root canal preparation, the root-ends were resected and pulverized in liquid nitrogen to expose E. faecalis in dentinal tubules or other recesses away from the main root canal system. The number of colony forming units (CFU) of E. faecalis per mg was determined from the pulverized root-ends. No significant differences were seen (t = 0.70, p = 0.495) between the number of colony forming units of E. faecalis for teeth irrigated with 5.25% NaOCl/15% EDTA (mean 131 +/- 291 CFU/mg) versus those teeth irrigated with 1.3% NaOCl/Biopure MTAD (mean 187 +/- 237 CFU/mg). This study demonstrated that there is no difference in antimicrobial efficacy for irrigation with 5.25% NaOCl/15% EDTA versus irrigation with 1.3% NaOCl/Biopure MTAD in the apical 5 mm of roots infected with E. faecalis.