Comparison of the accuracy of apex locator, digital radiography, and cone-beam computed tomography in root canal working length determination in teeth with external root resorption: An in vitro study.

Background: The aim of this study was to compare the accuracy of apex locator, digital periapical radiography, and cone-beam computed tomography (CBCT) for determining the root canal working length (WL) in teeth with external root resorption (ERR). Materials and Methods: In this in vitro study, the sample consisted of 54 extracted permanent single-rooted human teeth. ERRs were performed at the 3 mm apical root using 65% of nitric acid for 24 h. After determining the actual WL by K-file #10 (gold standard) with the visualization method, the teeth were mounted in alginate and the WL of each tooth was determined using the electronic apex locator (EAL) equipped with a K-file #15. The teeth were mounted with wax in the teeth sockets of a dry human mandible, and the images were obtained by digital phosphor plate receptors and CBCT scans. The mean registered WL of each method was statistically compared with the gold standard WL using one-way ANOVA with P < 0.001. Results: The mean ± standard deviation (SD) of actual WL was 16.00 ± 2.24. The mean ± SD of WLs determined by CBCT, EAL, and digital radiography were 15.38 ± 2.19, 15.52 ± 2.32, and 16.83 ± 2.20, respectively. This study showed that the mean measured WL with ERR in all methods was significantly different from the actual WL (P < 0.001). Conclusion: This study showed that there was a significant difference between the actual mean WL and the EAL, digital periapical radiography, and CBCT mean WL. Thus, the combination of EAL and CBCT could be a reliable method for determining WL in the presence of ERR.

Evaluation of apical transportation and centering ability of three single-file systems in severely curved canals using micro-computed tomography.

Background: This study aimed to compare the apical transportation and centering ability of One Curve, HyFlex EDM, and EdgeFile X1 in curved mesiobuccal and mesiolingual canals of mandibular first molars. Materials and Methods: In this in vitro experimental study, 60 mesiobuccal and mesiolingual canals of the mandibular first molars with a minimum length of 19 mm and 25°-40° curvature were randomly divided into three groups (n = 20) for root canal preparation with One Curve, HyFlex EDM, and EdgeFile X1. After access cavity preparation and confirming the glide path, the baseline micro-computed tomography (micro-CT) scans were obtained, and the root canals were instrumented with the respective systems according to the manufacturers' instructions. Apical transportation and centering ability were assessed at 1, 3, 5, and 7 mm from the apex by comparing pre- and postinstrumentation micro-CT scans. One-way ANOVA, independent t-test, and Duncan's post hoc test were used to statistically compare the groups, and data were analyzed by SPSS version 24 (alpha = 0.05). Results: The three groups were not significantly different regarding apical transportation at 5 and 7 mm from the apex (P > 0.05). At 1 mm level, One Curve caused significantly lower apical transportation; while, at 3 mm level, HyFlex EDM resulted in significantly higher apical transportation (P < 0.05). No significant difference was noted in the centering ability of the three groups at 1, 3, and 5 mm from the apex (P > 0.05). At 7 mm level, EdgeFile X1 showed significantly lower centering ability (P < 0.05). Conclusion: One Curve caused lower canal transportation in the apical third compared with EdgeFile and HyFlex EDM, but no significant difference was noted among the three in the coronal third of the roots.

Microleakage of five separated nickel-titanium rotary file systems in the apical portion of the root canal.

Background: The aim of this study was to evaluate the rate of apical microleakage following the fracture of five types of nickel-titanium rotary file systems (ProTaper Universal, Mtwo, RaCe, Revo-s, HeroShaper) in the apical one-third of the canal. Materials and Methods: In this laboratory experiment, 49 mandibular premolars were collected and randomly divided into seven groups. Root canal treatment was performed by five different rotary file systems with different cross-sections. All files, except in the control groups, were scratched at the 3-mm end by a handpiece. After separation of the apical end of the file in the root canal, the apical seal was measured, using the fluid infiltration technique. Data were analyzed in SPSS, using one-way ANOVA and Tamhane's T2 tests at P < 0.05. Results: The Hero Shaper and RaCe files showed the highest (3.14 µL/min) and the lowest (2.51 µL/min) rates of microleakage over time, respectively. There were significant differences between the Hero Shaper and RaCe files and between Hero Shaper and ProTaper files in terms of microleakage (Tamhane's T2 tests, P < 0.05). Conclusion: The presence of a separated file and its cross-section type affects the apical microleakage.

Anatomy assessment of permanent mandibular premolar teeth in a selected Iranian population using cone-beam computed tomography.

BACKGROUND: Appropriate cleaning and shaping and three-dimensional obturation of the root canal system lead to a successful endodontic treatment. To achieve this, complete knowledge of the internal anatomy of root canals is necessary. Therefore, this study evaluated the number and shape of mandibular premolar roots and canals and classified their Vertucci classification using cone-beam computed tomography (CBCT) images of an Iranian sample population. MATERIALS AND METHODS: This in vivo study was performed on CBCT images of patients aged 20-70 years who had attended a dental radiology center in Isfahan. CBCT images were examined in coronal, sagittal, and especially axial dimensions. Descriptive statistics were calculated. Groups were compared using the Chi-square of the Statistical Package for the Social Sciences. The level of significance was predetermined as 0.05. RESULTS: In both first and second premolars, the most common classes were Type I followed by Type V. The Chi-square did not show significant differences between males and females in terms of Vertucci classes in the first (P = 0.305) or second premolar (P = 0.315). CONCLUSION: Since a thorough knowledge of root canal anatomy is necessary for successful root canal treatment and almost one out of ten mandibular premolars has additional canal in their root canal system, accurate evaluating of preoperative radiographs, taking CBCT images if necessary, and probing the root canal system with fine and precurved files should be done to negotiate the entire canal system.

Cone-beam Computed Tomographic Analysis of Canal Transportation and Centering Ability of Single-file Systems.

INTRODUCTION: The purpose of this study was to compare canal transportation and the centering ability of Reciproc (VDW, Munich, Germany), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), and EdgeFile (EdgeEndo, Albuquerque, NM) rotary systems using cone-beam computed tomographic imaging. METHODS: Ninety mesiobuccal mandibular first molar uncalcified canals with at least a 19-mm length, a canal curvature of 15°-30° (the Schneider method), and a mature apex were selected. Canals were randomly divided into 3 groups of 30 teeth, and canal preparation with the Reciproc, WaveOne, and EdgeFile systems was performed according to the manufacturers' instructions. Cone-beam computed tomographic images were taken before and after instrumentation in the same position. Apical transportation was calculated in the distances of 2, 3, and 4 mm from the apex. Kruskal-Wallis and Mann-Whitney U tests were used to statistically analyze the data. RESULTS: The mean canal transportation was significantly lower with EdgeFile (P < .001) followed by the WaveOne rotary system. Moreover, the centering ability of the EdgeFile system was higher than that of the WaveOne and Reciproc systems. CONCLUSIONS: The EdgeFile rotary system showed the lowest transportation in both the mesiodistal and buccolingual directions and the highest centering ability. The Reciproc system showed the highest transportation and the lowest centering ability.

Mechanical or cold lateral compaction: The incidence of dentinal defects.

BACKGROUND: The incidence of dentinal defects may influence the outcome of root canal treatment. The aims of this study were to evaluate and compare the incidence of dentinal defects following root canal obturation with two different techniques. MATERIALS AND METHODS: A total of 110 mesial roots of human mandibular first molars were selected. Twenty-seven roots were left unprepared as negative controls (NCs). The mesiobuccal canals of 83 roots were prepared using rotary instruments. Twenty-seven roots were left unobturated as positive controls (PCs). Twenty-eight roots were obturated with cold lateral compaction (CLC) technique and the others were obturated with mechanical lateral compaction (MLC) technique. In the CLC and MLC groups, spreader penetration depth was measured by an electromechanical testing machine in canals containing master Gutta-percha cones. After root canal obturation, all the roots were sectioned horizontally at four levels from the apex and evaluated under a stereomicroscope at a magnification of ×40. The presence of dentinal defects was noted. Data were analyzed using the Chi-square and t-tests. RESULTS: The number of defects was not significantly different between the CLC, MLC, and PC groups. The CLC, MLC, and PC groups had significantly more defects compared to the NC group. CONCLUSION: According to the results of this study, the MLC and CLC techniques were the same in producing dentinal defects.

Effect of Nd: YAG laser on the apical seal after root-end resection and MTA retrofill: a bacterial leakage study.

Laser irradiation has been investigated in terms of preventing leakage in retrofilled root canals. The aim of the present study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the bacterial leakage of mineral trioxide aggregate (MTA)-retrofilled roots. In this ex vivo experimental study, 90 single-rooted incisor teeth were filled with gutta-percha and AH26 sealer. The apical 3 mm of all the roots were resected and 3-mm retrocavities were prepared by an ultrasonic device. The specimens were randomly divided into two experimental (n = 25), one positive control (n = 10), and two negative control (n = 10) groups. In the laser + MTA group, the cavity walls were irradiated by Nd: YAG laser prior to MTA placement. In the MTA group, MTA was placed without laser irradiation. The root surfaces were covered with two layers of nail varnish except for the apical 2 mm. The specimens were then embedded in a bacterial leakage test system and examined daily for 90 days. Contamination periods were recorded. Data were analyzed by Kaplan-Meier and Mann-Whitney U tests (α = 0.05). Five teeth with and five teeth without laser irradiation underwent scanning electron microscopic evaluation. The specimens in the laser + MTA group were contaminated earlier than those in the MTA group (p < 0.05). Comparison of survival times between the two groups showed significant differences (p < 0.05). Nd: YAG laser irradiation can decrease the sealing capacity of MTA in comparison to the apical seal achieved by MTA without laser irradiation. Further studies are recommended to provide a better seal for the MTA-retrofilled teeth after laser irradiation.

Antibacterial effect of triantibiotic mixture versus calcium hydroxide in combination with active agents against Enterococcus faecalis biofilm.

The aim of the present study was to compare the antibacterial effect of calcium hydroxide (CH), triantibiotic mixture (TAM), and CH in combination with chlorhexidine (CHX), sodium hypochlorite (NaOCl) or colchicine (COL) against Enterococcus faecalis (E. faecalis) in surface and deep dentinal tubules. Seventy five fresh single-rooted human teeth were infected and divided into five experimental groups (n=15). The experimental groups were treated with CH+distilled water, CH+CHX, CH+NaOCl, CH+COL+distilled water and TAM+distilled water. Dentin chips obtained from surface and deep dentin of these root canals were prepared and analyzed by counting the number of colony forming units. There was significant difference between groups in the surface dentin (p<0.05). TAM showed higher antibacterial activity compared to CH-containing groups. There was no significant difference between TAM and CH-containing groups in the deep dentin (p>0.05). CH-containing medications and TAM can be used as effective disinfectants in treatment of infected root canals.

Antibacterial effect of triantibiotic mixture, chlorhexidine gel, and two natural materials Propolis and Aloe vera against Enterococcus faecalis: An ex vivo study.

BACKGROUND: The aim of this ex vivo study was to compare the antimicrobial effect of triantibiotic paste, 0.2% chlorhexidine gel, Propolis and Aloe vera on Enterococcus faecalis in deep dentin. MATERIALS AND METHODS: Ninety fresh extracted single-rooted teeth were used in a dentin block model. Seventy-five teeth were infected with E. faecalis and divided into four experimental groups (n = 15). Experimental groups were treated with triantibiotic mixture with distilled water, 0.2% chlorhexidine gel, 70% ethanol + Propolis and Aloe vera. Fifteen teeth treated with distilled water as the positive control and 15 samples, free of bacterial contamination, were considered as the negative control. Gates-Glidden drill #4 was used for removal of surface dentin and Gates-Glidden drill #5 was used to collect samples of deep dentin. The samples were prepared and colony-forming units were counted. Data were analyzed by one-way ANOVA and post hoc Tukey tests. Statistical significance was defined at P < 0.05. RESULTS: Triantibiotic mixture group exhibited the least bacterial growth. However, the rate of bacterial growth showed no significant differences between chlorhexidine and Propolis groups (P > 0.05). Aloe vera had antibacterial effects on E. faecalis, but in comparison with other medicaments, it was less effective (P < 0.05). CONCLUSION: This experimental study showed that triantibiotic mixture, 0.2% chlorhexidine gel, Propolis and Aleo vera were relatively effective against E. faecalis. All the intracanal medicements had similar effects on E. faecalis in deep dentin except for Aloe vera.

In vitro evaluation of two methods of ultrasonic irrigation on marginal adaptation of MTA plugs in open apex teeth: a SEM analysis.

CONTEXT: Different factors can affect the marginal adaptation of MTA. AIMS: The present study was designed to investigate the effect of two ultrasonic irrigation methods on the marginal adaptation of MTA plug in open apex teeth by scanning electron microscope. SETTINGS AND DESIGN: Thirty single mature teeth were included in this in vitro experimental prospective study. MATERIALS AND METHODS: A total of 5 mm thickness of MTA plug was inserted at the end of the canals and after 24 h an ultrasonic file was used to irrigate the canals and remove the MTA remnants. Teeth were randomly divided into three groups: In the first and second groups, the canals were irrigated for 1 min by 2.5% sodium hypochlorite as #25 ultrasonic file was in direct contact and 1 mm away from MTA plug, respectively. The third group was not irrigated and left as control. A total of 1 mm transverse sections were prepared through the coronal and the apical parts of MTA plug and specimens were prepared for SEM analysis. The extent of gap was measured linearly under SEM device. STATISTICAL ANALYSIS USED: Statistical analysis of the results was performed using the kruskal-Wallis test by SPSS software ver.18(a = 0.05). RESULTS: There was no significant difference between groups regarding the marginal gap size in apical (P: 0.17) and coronal sections (P: 0.33). However, the mean marginal gap size was higher in apical section compared to coronal section. CONCLUSIONS: It can be concluded that ultrasonic irrigation dose not adversely affect the marginal adaptation of MTA plugs.

Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study.

INTRODUCTION: The aim of this in vivo study was to evaluate the influence of apical periodontitis (AP) on the accuracy of Dentaport ZX (J Morita, Kyoto, Japan), Raypex 5 (VDW, Munich, Germany), and i-Root (S-Denti, Seoul, Korea) electronic root canal length measurement devices (ERCLMDs). METHODS: Thirty-two single-rooted teeth scheduled for extraction, consisting of 16 teeth with AP and 16 teeth with normal periapex (NP), were selected. The access cavity was prepared, and the coronal portion of the canal was flared. The electronic working length (EWL) was determined by each ERCLMD according to each manufacturer's instructions. Each tooth was extracted, and the actual working length (AWL) was determined by inserting a size 15 K-file until the tip could be seen at a position tangential to the major foramen and then 0.5 mm was subtracted from the measurement. The distance from the file tip (EWL) to the point 0.5 mm coronal to the major foramen (AWL) was calculated. Data were analyzed using the nonparametric Fisher exact test and the chi-square test. Statistical significance was set at P < .05. RESULTS: The accuracies of Dentaport ZX, Raypex 5, and i-Root within ± 0.5 mm in the AP group were 93.8%, 81.3%, and 75.0%; they were 93.3%, 86.7%, and 73.3% in the NP group, respectively. There were no significant differences between the accuracy of each device in the 2 groups (P > .05). Considering the 2 groups of AP and NP, there were no statistically significant differences in the accuracy of the ERCLMDs (P > .05). CONCLUSIONS: The presence of AP did not influence the accuracy of ERCLMDs.

Effect of Patency File on Transportation and Curve Straightening in Canal Preparation with ProTaper System.

The aim of this ex vivo study was to evaluate the effect of using a patency file on apical transportation and curve straightening during canal instrumentation with the ProTaper rotary system. Seventy permanent mandibular first molars with mesiobuccal canals, measuring 18-23 mm in length and with a 25-40° curvature (according to the Schneider method), were selected. The working lengths were determined and the teeth were mounted and divided into two experimental groups: (A) prepared by the ProTaper system without using a patency file (n = 35) and (B) prepared by the ProTaper system using a patency file (n = 35). Radiographs taken before and after the preparation were imported into Photoshop software and the apical transportation, and curve straightening were measured. Data were analyzed using independent t-test. Partial correlation analysis was performed to evaluate the relationship between the initial curvature, transportation, and curve straightening (α = 0.05). Using a patency file during canal preparation significantly decreased both apical transportation and curve straightening (P < 0.001). There were significant relationships between the angle of curvature, transportation and curve straightening in pairs (P < 0.001). Apical patency is recommended during root canal preparation with the ProTaper rotary system.

Comparing the sealing properties of mineral trioxide aggregate and an experimental ceramic based root end filling material in different environments.

BACKGROUND: An apical seal is an important factor in achieving success in surgical endodontics. AIM: The purpose of this study was to compare the sealing properties of mineral trioxide aggregate (MTA) with a new ceramic based root end filling material (Cold Ceramic) in different environments. MATERIALS AND METHODS: One hundred teeth were selected. The root canals were instrumented and obturated. Except for the apical 2 mm, the root surfaces were sealed. After root resection, 3 mm depth root-end cavities were prepared. For each material, roots were divided into 3 equal subgroups and the root-end filling was done in different environments (dry, saliva contaminated, blood contaminated). Five roots served as positive and 5 roots as negative controls. Samples were immersed in 2% methylene blue dye. Roots were sectioned longitudinally and examined under stereomicroscope to record the extension of dye penetration. RESULTS: All experimental groups demonstrated dye penetration. The lowest linear leakage was seen in Cold Ceramic blood contaminated group while the highest leakage was observed in MTA blood contaminated group. The linear dye penetration of both MTA and Cold Ceramic (CC) groups did not show any significant differences among different environments. Also, the difference between MTA and CC was not significant in dry and saliva contaminated subgroups. Only the difference between dye penetration of MTA and CC in blood contaminated subgroups showed significant difference ( P = 0.008). CONCLUSION: The sealing property of this ceramic based root end filling material (Cold Ceramic) is better than MTA in blood contaminated condition and at least similar to MTA in other conditions.

The effect of calcium hydroxide placement on pH and calcium concentration in periapical environment: an in vitro study.

AIMS: Comparing the calcium concentration and pH levels of Ca(OH) 2 medicament placing in pulp chamber and root canal. MATERIALS AND METHODS: Ninety-nine extracted human mandibular second premolars were instrumented to size #40 k file. Nine teeth served as the control group and the remaining teeth were assigned into two groups. Group 1-Ca(OH) 2 was placed in the dried pulp chamber, while root canals remained wet with normal saline; group 2-Ca(OH) 2 was placed in dried root canals. In control group, canals remained wet without medication. Each group was divided into 3 sub-groups of 15 teeth in which pH and calcium concentration were measured in three intervals of 2 days, 1 week, and 2 weeks by pH meter and atomic absorption spectrometer system, respectively. Findings were assessed using Kruskal-Wallis and t-test. RESULTS: At 1 and 2 weeks, the calcium concentration had increased without being significantly different from Ca(OH) 2 placed either in the root canal or in the pulp chamber. Ca(OH) 2 placed in the pulp chamber or root canal provided similar pH values (P=0.362). CONCLUSIONS: Placing Ca(OH) 2 in pulp chamber is as effective as placing it in the root canal.

A Comparative Study of the Removal of Smear Layer by Two Endodontic Irrigants and Nd:YAG Laser: A Scanning Electron Microscopic Study.

The aim of this study was to compare the effect of 17% EDTA, 5% maleic acid, and Nd:YAG laser on smear layer removal by SEM. Eighty single-rooted teeth were divided into three groups of 25 according to the final procedure for smear layer removal: irrigation by 17% EDTA or 5% maleic acid or Nd:YAG laser irradiation. The other five teeth was used as control. Roots were sectioned into buccal and lingual parts, and smear layer presence was recorded in the coronal, middle, and apical thirds under SEM. Data were analyzed by Kruskal-Wallis, Mann-Whitney, Friedman, and Wilcoxon tests. There was no significant difference between smear layer removal of 17% EDTA and 5% maleic acid. Nd:YAG laser showed the least effect significantly. The coronal part of samples was significantly cleaner than the middle, and the middle was cleaner than the apical section. 17% EDTA and 5% maleic acid were more effective in smear layer removal compared to Nd:YAG laser.

A comparative study of three treatment methods of direct pulp capping in canine teeth of cats: a histologic evaluation.

Direct pulp capping (DPC) is coverage of exposed pulp by a biocompatible material after traumatic or carious exposure. The purpose of this procedure is to seal this spot against bacterial leakage, stimulate dentinal barrier formation, and maintain the vitality of the pulp. Several factors contribute to the consequence of this treatment, such as the kind of material used and the procedural technique. The aim of this study was to evaluate histologically the outcome of DPC using three methods. Thirty-six canine teeth of nine cats were selected for this experiment. After the cats had been anesthetized, the teeth were exposed under sterile condition. The teeth were randomly divided into three groups. In group I, the exposed pulp was covered with mineral trioxide aggregate (MTA) alone. In group II, the pulp, after being treated with erbium:yttrium-aluminum-garnet (Er:YAG) laser (energy = 200 mJ, pulse duration = 700 micros, repetition rate = 3 Hz, exposure time = 15 s, no air, no water, beam diameter = 0.6 mm), was covered with MTA. In group III, the pulp was treated with laser and covered with calcium hydroxide [Ca(OH)(2)]. All cavities were filled with amalgam after DPC. After 4 months, the animals were sacrificed and block sections were prepared. The specimens were histologically evaluated. The data were analyzed by Mann-Whitney and chi-square tests. Dentinal barrier had formed in all groups. The laser + MTA group showed little superiority to the other groups in dentinal barrier formation, type and intensity of inflammatory responses, and soft tissue changes, especially necrosis, but these differences were not statistically significant (P > 0.05). We concluded that laser + MTA produced better healing. According to the conditions in this study, Er:YAG laser could be used in direct pulp capping treatment in combination with both common materials.

Histologic Evaluation of Three Treatment Methods for Direct Pulp Capping of Cat's Canine.

INTRODUCTION: Direct pulp capping (DPC) is coverage of exposed pulp by a biocompatible material after traumatic or carious exposure. The purpose of this procedure is to seal against bacterial leakage, stimulate dentinal barrier formation, and maintain the vitality of pulp. Several factors contribute to the consequence of this treatment such as material and the procedural technique. The aim of this study was to histological evaluation of three treatment methods (Laser+MTA, Laser+Ca(OH)2 and MTA alone) in direct pulp capping of cat's canines. MATERIALS AND METHODS: Thirty six canine teeth of 9 cats were selected for this experimental study. After anesthesia, the teeth were exposed under isolated condition. The teeth were randomly divided into three treatment groups. In group I, the pulp exposures were covered by Mineral Trioxide Aggregate (MTA) alone. In group II, the pulps after treating with Er: YAG laser, were covered by MTA. In group III, treating with laser and covering with Ca(OH)2 was performed. All cavities were filled by Amalgam after DPC. After 4 months, the animals were sacrificed and block sections were prepared. Then, the specimens were histologically evaluated according to the scores that designed by a pathologist. The data was analyzed by Mann-Whitney and Chi-square tests with significant level of 95%. RESULTS: Dentinal barrier was formed in all groups. Laser+MTA group showed nearly similar results to other groups in dentinal barrier formation, type and intensity of inflammatory responses and soft tissue changes (P>0.05). CONCLUSION: Although Laser+MTA had slightly better effects, but this difference was not statistically significant. Based on this study, it seems that laser treatment has no effect on outcome of DPC.