Demineralization effect of EDTA, EGTA, CDTA and citric acid on root dentin: a comparative study

The purpose of this study was to biochemically compare the decalcifying effects of 1% EDTA (pH 7.4), 1% EGTA (pH 7.4), 1% CDTA (pH 7.4), 1% citric acid solutions (pH 1.0 and 7.4) and saline solution (control) on root dentin. Forty-eight single-rooted teeth were used in this study. The canals were instrumented by the step-back technique and the roots were randomly divided into six equal experimental groups (n = 8) according to the irrigating agent tested. A total of 30 microL of each solution was pipetted into the root canal and allowed to set undisturbed for 5 minutes. After this time, 15 microL of the solutions were removed from each canal using a Hamilton syringe and placed in a container with 5 mL of deionised water. The microg/mL concentration of calcium ion (Ca2+) extracted from the root canal samples was determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by means of the Kruskal-Wallis and Mood's median tests. Citric acid solution at pH 1.0 removed more calcium than at pH 7.4 and than the other chelating solutions tested (p < 0.05). No differences were observed between EDTA and EGTA. Both EDTA and EGTA removed significantly more calcium than CDTA and citric acid at pH 7.4 (p < 0.05). There were no differences between citric acid at pH 7.4 and saline solution, which had the least efficacy for Ca2+ extraction (p > 0.05). These results indicate that citric acid at pH 1.0 is a good alternative as an irrigating solution to remove the smear layer and facilitate the biomechanical procedures.     

Calcium hydroxide intracanal dressing removal with different rotary instruments and irrigating solutions: a scanning electron microscopy study

This study evaluated the efficacy of 2 types of rotary instruments employed in association with sodium hypochlorite (NaOCl) or EDTA in removing calcium hydroxide (CH) residues from root canals dentin walls. Forty-two mandibular human incisors were instrumented with the ProTaper System up to F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA and filled with a CH intracanal dressing. After 7 days, the CH dressing was removed using 4 techniques: NiTi rotary instrument size 25, 0.06 taper (K3 Endo) and irrigation with 17% EDTA (Group 1), NiTi rotary F1 instrument (ProTaper) and irrigation with 17% EDTA (Group 2), NiTi rotary instrument size 25, 0.06 taper and irrigation with 2.5% NaOCl (Group 3) and NiTi rotary F1 instrument and irrigation with 2.5% NaOCl (Group 4). Two roots without intracanal dressing were used as negative controls. Teeth were evaluated by scanning electron microscopy, in the cervical and apical canal thirds. None of the techniques removed the CH dressing completely. In the apical and cervical thirds, F1 instrument was better than instrument size 25, 0.06 taper in removing CH residues (p<0.05), regardless of the final irrigating solution. No difference was found between the irrigating solutions in the groups of F1 instrument and of instrument size 25, 0.06 taper (p>0.05). The negative controls had no CH residues on the dentin walls. In conclusion, the ProTaper F1 instrument was better than K3 Endo instrument size 25, 0.06 taper in the removal of CH intracanal medication, regardless of irrigating solution used.     

Adhesion of Epiphany and AH Plus sealers to human root dentin treated with different solutions

This study evaluated comparatively the adhesion of Epiphany and AH Plus endodontic sealers to human root dentin treated with 1% NaOCl and 1% NaOCl+17% EDTA, using the push-out test. Sixty root cylinders obtained from maxillary canines had the canals prepared and were randomly assigned to 3 groups (n=20), according to root dentin treatment: GI - distilled water (control), GII - 1% NaOCl and GIII - 1% NaOCl+17% EDTA. Each group was divided into 2 subgroups (n=10) filled with either Epiphany or AH Plus. Bond strength push-out test data (kN) were obtained and analyzed statistically by ANOVA and Tukey's post-hoc test. There was statistically significant difference between sealers (AH Plus: 0.78 +/- 0.13; Epiphany: 0.61 +/- 0.19; p<0.01) and among root dentin treatments (distilled water: 0.58 +/- 0.19; 1% NaOCl: 0.71 +/- 0.12; 1% NaOCl+17% EDTA: 0.80 +/- 0.17; p<0.05). In conclusion, AH Plus sealer presented greater adhesion to dentin than Epiphany, regardless of the treatment of root canal walls.     

The effects of calcium hydroxide removal methods on bond strength of Epiphany SE with two irrigation protocols

Abstract

Objective: The purpose of this study was to compare the effects of five calcium hydroxide removal methods on the bond strength of Epiphany SE sealer after canal irrigation with NaOCl+EDTA or NaOCl+MTAD. Materials and methods: The 120 roots were instrumented by using the ProTaper rotary system under irrigation with 2.5% sodium hypochlorite and randomly divided into two major groups according to the final irrigation: 1.3% NaOCl + MTAD and 5% NaOCl + 17% EDTA. For controls, 10 roots from each of the final irrigations with NaOCl + MTAD and NaOCl + EDTA (20 roots) were not filled with Ca(OH)₂. The intra-canal paste, Ca(OH)₂ was applied to each of the 100 remaining roots and stored at 37°C for 7 days. Each group was sub-divided into five sub-groups (n = 10) according to the removal technique for the intra-canal dressing: Group-1: recapitulation with size 30 K file + 3 ml of saline solution, Group-2: recapitulation with size 30 K file + 3 ml of 5% NaOCl, Group-3: using 5% NaOCl + 17% EDTA, Group-4: using 5%NaOCl + 15% citric acid, and Group-5: using 1.3% NaOCl + 5 ml MTAD. The root canals were filled with Resilon and Epiphany SE sealer. The bond strength was measured. Results: The mean bond strength of Epiphany SE to root dentine irrigated with NaOCl + MTAD was lower than that of NaOCl + EDTA. The highest bond strengths were 3.31 ± 0.057 and 2.60 ± 0.054 in the NaOCl + citric acid group when Ca(OH)₂ was applied to roots treated with NaOCl + EDTA and NaOCl + MTAD, respectively (p < 0.05). Conclusion: For root canals treated with NaOCl + EDTA or NaOCl + MTAD, the use of NaOCl + chelating agent for Ca(OH)₂ removal does not adversely affect the bond strength of Epiphany SE to dentin.     

Application of biologically-oriented dentin bonding principles to the use of endodontic irrigants

PURPOSE: To compare the removal of smear layer and the structure of the hybrid layer formed after the use of EDTA or MTAD solutions when used as a final flush. METHODS: Single-rooted extracted premolars (n=18) were collected and treated for root canal therapy using NaOCl irrigation followed by a final rinse of 17% EDTA, Biopure MTAD, or saline (negative control). The roots were obturated with gutta-percha and a hydrophilic HEMA-containing root canal sealer. The TEM specimens were impregnated with 50% silver nitrate to visualize sealing imperfections and nanoleakage. The structure of the coronal, middle and apical parts of root canal walls was examined using transmission electron microscopy. RESULTS: After NaOCl irrigation, a final rinse with BioPure MTAD or 17% EDTA completely removed the 2 microm-thick smear layer on mechanically instrumented root canal walls. The BioPure MTAD hybrid layer was thicker than the 17% EDTA hybrid layer. Both the BioPure MTAD and EDTA caused a collapse of the dentin matrix structure which impeded sealer infiltration and the formation of high quality hybrid layer bonding. The hybrid layers created in smear layer-covered dentin exhibited less potential for nanoleakage than the MTAD or EDTA hybrid layers.     

Effects of endodontic irrigation solutions on mineral content of root canal dentin using ICP-AES technique

The aim of this in vitro study was to evaluate mineral content of root canal dentin after treatment with several endodontic irrigation solutions. Sixty mandibular anterior teeth extracted for periodontal reasons used. The crowns of the teeth were removed at the cemento-enamel junction. Pulp tissues were removed and the teeth were randomly divided into six groups including 10 teeth each. Root canals were enlarged with gates-glidden burs (# 1, 2, and 3). The groups were treated as follows: group 1, 0.2% chlorhexidine gluconate for 15 min; group 2, 3% H2O2 for 15 min; group 3, 17% EDTA for 15 min; group 4, 5.25% NaOCl for 15 min; group 5, 2.5% NaOCl for 15 min; and group 6, distilled water (control). Dentin chips were obtained using gates-glidden burs (# 4, 5, and 6). The levels of five elements calcium, phosphorus, magnesium, potassium, and sulfur in each specimens were analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry) technique. Changes in the levels of the chemical elements were recorded. The results were then statistically analyzed by one-way ANOVA and Tukey tests. There was a significant decrease in the calcium and phosphorus levels after treatment with all irrigation solutions except for 5.25% NaOCl when compared with the control group (p < 0.05). The K, Mg, and S level changes were not statistically significant (p > 0.05). It has been concluded that endodontic irrigation solutions have an effect on mineral contents of root dentin.     

Effects of different irrigation solutions on root dentine microhardness,smear layer removal and erosion

This study aimed to compare the effects of different irrigants on root dentine microhardness, erosion and smear layer removal. A total of 72 root dentine slices were divided into six groups, according to the final irrigants used: Group 1: 17% ethylenediamine tetra‐acetic acid (EDTA) + 2.5% NaOCl, Group 2: 7% maleic acid (MA) + 2.5% sodium hypochloride (NaOCl), Group 3: 1.3% NaOCl + mixture of tetracycline, acid and detergent (MTAD), Group 4: Smear Clear + 2.5% NaOCl, Group 5: 5% NaOCl, Group 6: saline. Vickers microhardness values were measured before and after treatment. In total, 42 root‐halves were prepared for scanning electron microscope to evaluate the amount of smear and erosion in the coronal, middle and apical thirds. Data were analysed using two‐way anova , Duncan and two‐proportion z‐tests. Maleic acid showed the greatest reduction in dentine microhardness (P < 0.05), followed by EDTA and MTAD. EDTA, maleic acid, MTAD and Smear Clear removed smear layer efficiently in the coronal and middle thirds of root canal. However, in the apical region, maleic acid showed more efficient removal of the smear layer than the other irrigants (P < 0.05).     

Effect of EDTA,Sodium Hypochlorite,and Chlorhexidine Gluconate with or without Surface Modifiers on Dentin Microhardness

Introduction

This study aimed to evaluate the effects of root canal irrigants on the microhardness of root canal dentin in the presence and absence of surface-modifying agents.

Methods

Forty-eight root halves were prepared by longitudinal splitting of the distal roots of 24 freshly extracted mandibular human third molars and embedded in autopolymerizing acrylic resin, leaving the dentin surface exposed. After polishing, the microhardness values of the untreated dentin surfaces were recorded by using Vickers tester at the mid-root level. The root halves were randomly assigned to 6 groups composed of 8 samples each and treated for 5 minutes with one of the following irrigants: 17% EDTA, REDTA, 2% chlorhexidine gluconate (CHX), 2% CHX with surface modifiers (CHX-Plus), 6% NaOCl, or 6% NaOCl with surface modifiers (Chlor-XTRA). After surface treatment, dentin microhardness values were recorded at close proximity to the initial indentation areas. Experimental data were statistically analyzed by using the t test and one-way analysis of variance, followed by Tukey honestly significant difference test at α = 0.05.

Results

EDTA, REDTA, NaOCl, and Chlor-XTRA significantly decreased the microhardness of root dentin compared with intact controls (P < .05).

Conclusions

The addition of surface modifiers to the irrigants did not affect the microhardness of the samples.     

Comparison of the Efficacy of Maleic Acid and Ethylenediaminetetraacetic Acid in Smear Layer Removal from Instrumented Human Root Canal: A Scanning Electron Microscopic Study

IntroductionThe aim of this study was to assess, by scanning electron microscopic (SEM) analysis, the ability of 17% EDTA and 7% maleic acid in the removal of the smear layer from the human root canal system.MethodsEighty single-rooted human anterior teeth were subjected to standardized root canal instrumentation (step-back technique) and were irrigated with 2.5% NaOCl after each instrument. Based on the final irrigating solution used, samples were divided randomly into three groups: (1) the EDTA group: 17% EDTA+ 2.5% NaOCl (n = 30), (2) the maleic acid group: 7% maleic acid + 2.5% NaOCl (n = 30), and (3) the control group: 0.9% saline (n = 20). After final irrigation, teeth were prepared for SEM analysis to evaluate the cleaning of the coronal, middle, and apical thirds of radicular dentin by determining the presence or absence of smear layer. The data was statistically analyzed using the Kruskall-Wallis test.ResultsAt the coronal and middle thirds, there was no significant difference between EDTA and maleic acid. Both were equally efficient in the removal of smear layer. In the apical third, maleic acid showed significantly better smear layer removing ability than EDTA.ConclusionFinal irrigation with 7% maleic acid is more efficient than 17%EDTA in the removal of smear layer from the apical third of the root canal system, which is a crucial area for disinfection.     

Quantitative analysis of the effect of irrigant solution sequences on dentin erosion

Objective

The purpose of the study was to examine the level of erosion on root canal wall dentin caused by immersion in different irrigant solutions in alternative sequences.

Methods

Dentin specimens from teeth with one root canal were instrumented and randomly divided into five groups. Each group was subjected to 17% EDTA, 17% ethyleneglycoltetraacetic acid (EGTA), or 10% citric acid (CA) and 5.25% sodium hypochlorite (NaOCl) varying the time of irrigant exposure and the order of the irrigants. The specimens were examined by scanning electron microscopy (SEM), and randomized digital images of the dentin surface were taken. The area of tubule openings was measured by a semiautomatic method.

Results

No erosion was detected when demineralizing agents were used as a final rinse after NaOCl. However, the erosion of peritubular and intertubular dentin was detected when EDTA, EGTA, or CA were used first followed by 5.25% NaOCl (P < .05), and an increase over 100% in the area of dentin tubule openings was measured (P < .01).

Conclusions

NaOCl used as a final irrigant solution after demineralization agents causes marked erosion of root canal dentin.     

A novel model for testing the efficiency of removal of calcium hydroxide from complex root canal anatomies

The purpose of this study was to evaluate the efficacy of several irrigation protocols in the removal of calcium hydroxide [Ca(OH)₂] from simulated internal root resorption cavities in a complex root canal anatomy model. The 20° to 35° curved mesiobuccal roots of 94 maxillary molars were sectioned longitudinally; internal resorption cavities were prepared in the apical third of the canal walls. Calcium hydroxide was placed into the cavities and the root halves reassembled. Four teeth were used as controls, and 90 teeth were randomly divided into six experimental groups (n = 15), according to the irrigation protocols used: syringe irrigation; H₂O₂ (HP); Navitip FX; Vibringe‐syringe; Vibringe‐NaviTip FX; ultrasonically activated irrigation (UAI) using an ultrasonic K‐file. In the HP group, 2.5% NaOCl and 3% H₂O₂ were used, while 2.5% NaOCl and 17% EDTA were used in the remaining groups. Stereomicroscope images and radiographs were used to measure the remaining Ca(OH)₂. The model proved to be suitable for simulating complex anatomy. Positive correlation was found between stereomicroscope and radiographic analyses (P < 0.05). UAI removed significantly more Ca(OH)₂ than the other experimental groups (P < 0.05). The HP group was the least efficient protocol (P < 0.05). It would appear that a reliable model has been developed that simulates complex root canal anatomy. Irrigant activation protocols enhanced Ca(OH)₂ removal.     

Dentinal tubule penetration of root canal sealers after root canal dressing with calcium hydroxide.

The purpose of this study was to evaluate the dentinal tubule penetration of root canal sealers after root canal dressing with calcium hydroxide (Ca(OH)2). Forty-two single-rooted teeth were instrumented to size 60. Six teeth served as the control group, and the remaining teeth were assigned to two groups. Root canals of the first group were filled with the Ca(OH)2 paste; the second group was filled with TempCanal, and all were incubated for 7 days. The samples were either irrigated with only NaOCl or with EDTA, followed by NaOCl to remove Ca(OH)2. All of the teeth were obturated with CRCS, AH26, and Ketac Endo by a lateral condensation technique. The specimens were then kept at the same conditions for another 7 days, and then all of the roots were prepared for scanning electron microscopic evaluation. Scanning electron microscopic examination revealed that Ca(OH)2 was not completely removed from the root canal surfaces, and root canal sealers did not penetrate into the dentinal tubules when only NaOCl was used. EDTA followed by NaOCl irrigation resulted in complete removal of Ca(OH)2 and root canal sealers penetrated into the dentinal tubules.     

Time-dependent Decalcifying Effects of Endodontic Irrigants with Antibacterial Properties

The aim of this study was to investigate the extent of calcium ion (Ca²⁺) removal on root dentin after treatment with 1.25% NaOCl, 2.5% NaOCl, 5.25% NaOCl, 2% chlorhexidine (CHX), 2% iodine potassium iodide (IKI), and MTAD in 3 immersion time periods. Extracted human mandibular premolars were bisected longitudinally, and the root halves (n = 70) were isolated with nail varnish, leaving the root canal exposed. The specimens were immersed in the test solutions, during which the amount of Ca²⁺ release into the solutions was determined at 5, 10, and 15 minutes by flame photometry. The decalcifying effect of 5%, 2.5%, and 1.25% NaOCl and 2% IKI significantly increased within time (P < .05), with 5% NaOCl extracting the greatest amount of Ca²⁺ at all treatment times. For 2% CHX and distilled water, a significant increase in the amount of Ca²⁺ extraction from root dentin was only evident at 10 minutes (P < .05) and did not change at 15-minute readings. Between the 5- to 10-minute and 10- to 15-minute intervals, the greatest amount of increase in the rate of Ca²⁺ extraction from root dentin was observed in the 2.5% NaOCl group. At 15 minutes, 2% CHX and distilled water showed the least amount of change. Among the test solutions, MTAD extracted the least amount of Ca²⁺ at 5 minutes.     

Impact of irrigant sequence on mechanical properties of human root dentin

To get the root canal system free of organic debris and the smear layer, it has been recommended to irrigate with a NaOCl solution during instrumentation, followed by a rinse with a chelating agent such as ethylenediaminetetraacetic acid (EDTA) and a final irrigation with NaOCl. However, both hypochlorite and EDTA weaken dentin through dissolution of its organic and inorganic components, respectively. EDTA exposes the organic dentin matrix, which could then be attacked more easily by hypochlorite. It was the aim of this study to assess the impact of different irrigation sequences of NaOCl (2.5% w/v; total exposure time, 24 minutes) and EDTA (17%; 3 minutes) on the elastic modulus and flexure strength of standardized human root dentin bars (n = 11 per group). Exposures to solely EDTA (3 minutes), NaOCl (24 minutes), and water were used as control treatments. Specimens were subjected to 3-point bending tests; modulus of elasticity and flexure strength values were compared between groups with one-way analysis of variance followed by Fisher probable least-squares difference test. The alpha-type error was set at .05. The 24-minute exposure to the hypochlorite solution caused a significant drop in flexure strength compared with water- or EDTA-treated controls (P < .05), whereas the elastic modulus remained unaffected. In contrast, the short exposure to EDTA as is clinically recommended did not affect the mechanical dentin parameters under investigation, regardless of the irrigant sequence that was used.     

17％EDTA与1％NaOCl组合用于根管超声冲洗抗菌效果的临床研究

目的研究17％EDTA＋1％NaOCl与超声波联合应用杀灭感染根管内厌氧菌的效果。方法将100例慢性根尖周炎患者共100颗患牙随机分为A组（2．5％NaOCl）、B组（1％NaOCl）、C组（17％EDTA＋1％NaOCl）、D组（17％EDTA）、E组（生理盐水）5组,每组各20颗患牙,采用手持器械预备根管后,分别采用2．5％NaOCl、1％NaOCl、17％EDTA＋1％NaOCl、17％EDTA、生理盐水超声法冲洗根管,根管预备前后分别取样进行厌氧培养。结果根管预备前后,五组根管内厌氧菌减少程度之间有显著性差异（P〈0．01）,其中C组（17％EDTA＋1％NaOCl组）厌氧茵的减少程度明显大于B组（1％NaOCl组）（P〈0．05）,显著大于D组（17％EDTA组）和E组（生理盐水组）（P〈0．01）,与A组（2．5％NaOCl组）之间无显著性差异（P〉0．05）。结论17％EDTA＋1％NaOCl与超声波联合应用可有效杀灭根管内的厌氧菌,其抗菌效果优于单独使用的1％NaOCl,与单独使用的2．5％NaOCl效果相近,是一种有效的根管冲洗液组合。     

Effect of calcium hydroxide intracanal dressing on the bond strength of a resin-based endodontic sealer

The aim of this in vitro study was to evaluate the bond strength of Epiphany resin-based sealer to dentin walls after placement of calcium hydroxide [Ca(OH)2] dressings. Fifteen extracted single-rooted human teeth were instrumented using 2.5% NaOCl + EDTA as irrigants. The teeth were randomly assigned to 3 groups (n=5), according to the intracanal dressing: G1= Ca(OH)2 + saline; G2= Ca(OH)2 + 2% chlorhexidine gluconate (CHX) gel; and G3= saline (control). After 10 days of storage in 100% humidity at 37 degrees C, the dressings were removed and the root canals were filled with Epiphany sealer. After additional 48 h of storage, the specimens were sectioned transversally into 2-mm-thick discs. Push-out tests were performed (1 mm/min, Instron 4411) and the maximum loads at failure were recorded in MPa. One-way ANOVA and Newman-Keuls tests showed a statistically significant decrease in bond strength when a Ca(OH)2 dressing was used before root canal filling with Epiphany (G1= 10.18 +/- 1.99 and G2= 9.98 +/- 2.97) compared to the control group (13.82 +/- 3.9) (p< 0.05). It may be concluded that the use of Ca(OH)2 as an intracanal dressing material affected the adhesion of Epiphany to the root canal walls, but even though the values were within the acceptable range found in the literature.     

Effect of medications for root canal treatment on bonding to root canal dentin

Use of resin-based restorative materials recently has become widely accepted for treatment of endodontically treated teeth. However, some solutions routinely used during endodontic treatment procedures may have an effect on bond strengths of adhesive materials to root canal dentin. The purpose of this in vitro study was to evaluate the effect of various medications on microtensile bond strength to root canal dentin. Fourteen extracted human single-rooted teeth were used. The crowns and the pulp tissues were removed. The root canals were then instrumented and widened to the same size. The teeth were randomly divided into seven groups of two teeth each. The root canal dentin walls of the roots were treated with 5% sodium hypochloride (NaOCI), 3% hydrogen peroxide (H2O2), the combination of H2O2 and NaOCl, or 0.2% chlorhexidine gluconate for 60 s; or calcium hydroxide or formocresol for 24 h. The teeth in control group were irrigated with water. The root canals were obturated using C&B Metabond. After 24 h of storage in distilled water, serial 1-mm-thick cross-sections were cut, and approximately 12 samples were obtained from each group. Microtensile bond strengths to root canal dentin were then measured by using an Instron machine. The data were recorded and expressed as MPa. The results indicated that NaOCI, H2O2, or a combination of NaOCl and H2O2 treatment decreased bond strength to root canal dentin significantly (p < 0.05). The teeth treated with chlorhexidine solution showed the highest bond strength values (p < 0.05). In conclusion, chlorhexidine is an appropriate irrigant solution for root canal treatment before adhesive post core applications.     

Effect of Different Final Irrigation Methods on the Removal of Calcium Hydroxide from an Artificial Standardized Groove in the Apical Third of Root Canals

Introduction

The aim of this study was to compare the efficacy of conventional syringe, ultrasonic, EndoVac (Discus Dental, Culver City, CA), and Self-Adjusting File (SAF) (Re-Dent-Nova, Ra'nana, Israel) irrigation systems in removing calcium hydroxide (Ca[OH]₂) from simulated root canal irregularities.

Methods

The root canals of 88 extracted single-rooted teeth were prepared using ProTaper rotary instruments (Dentsply Maillefer, Ballagiues, Switzerland) up to size F4. The roots were split longitudinally, and a standardized groove was prepared in the apical part of 1 segment. The root halves were reassembled, and Ca(OH)₂ medicament was placed into the root canals using a Lentulo spiral. The roots were randomly divided into 4 experimental groups and 2 control groups according to the different irrigation systems used: conventional syringe irrigation, continuous passive ultrasonic irrigation (PUI), EndoVac irrigation, and SAF irrigation. Each group was then divided into 2 subgroups (n = 10) according to the irrigation protocol: subgroup 1: 10 mL 2.5% NaOCl and subgroup 2: 10 mL 17% EDTA + 10 mL 2.5% NaOCl. The amount of remaining medicament was evaluated under a stereomicroscope at 30× magnification using a 4-grade scoring system. The influences of the different Ca(OH)₂ medicament removal methods and irrigation protocols were statistically evaluated using 2-way analysis of variance and Tukey post hoc tests.

Results

In the NaOCl-irrigated groups, PUI removed significantly more Ca(OH)₂ medicament than the other techniques (P < .05). There was no significant difference among the other groups (P > .05). In the EDTA/NaOCl-irrigated groups, the SAF and PUI removed significantly more Ca(OH)₂ than the other techniques (P < .05).

Conclusions

The use of the SAF system with the combination of EDTA and NaOCl enhanced Ca(OH)₂ removal when compared with the use of only NaOCl irrigation with the SAF. Continuous PUI and SAF were more effective than EndoVac, and conventional syringe irrigation in the removal of the Ca(OH)₂ medicament from an artificial standardized groove in the apical part of the root canal.     

Evaluation of the effect of endodontic irrigation solutions on the microhardness and the roughness of root canal dentin

The purpose of this study was to evaluate the effect of 0.2% chlorhexidine gluconate on the microhardness and roughness of root canal dentin compared with widely used irrigation solutions. Ninety, mandibular, anterior teeth extracted for periodontal reasons were used. The crowns of the teeth were removed at the CEJ. The roots were separated longitudinally into two segments, embedded in acrylic resin, and polished. A total of 180 specimens were divided into 6 groups of 30 teeth at random according to the irrigation solution used: group 1: 5.25% NaOCl for 15 min; group 2: 2.5% NaOCl for 15 min; group 3: 3% H2O2 for 15 min; group 4: 17% EDTA for 15 min; group 5: 0.2% chlorhexidine gluconate for 15 min; and group 6: distilled water (control). Each group was then divided into 2 subgroups of 15 specimens: groups 1a, 2a, 3a, 4a, 5a, and 6a were submitted to Vickers microhardness indentation tests; groups 1b, 2b, 3b, 4b, 5b, and 6b were used for determination of the roughness of root dentin. The data were recorded as Vickers numbers and Ra, microm for roughness test. The results were analyzed statistically by using one-way ANOVA and Tukey tests. The results indicated that all the irrigation solutions except chlorhexidine significantly decreased microhardness of root canal dentin (p < 0.05); 3% H2O2 and 0.2% chlorhexidine gluconate had no effect on roughness of the root canal dentin (p > 0.05). Although there are many other factors for irrigation solution preference, according to the results of this study, 0.2% chlorhexidine gluconate seems to be an appropriate endodontic irrigation solutions because of its harmless effect on the microhardness and roughness of root canal dentin.     

Adhesion of a glass-ionomer root canal sealer to the root canal wall

Glass-ionomer root canal sealer is commonly used because of its chemical bonding and favorable physical characteristics when bonding to dentin. This study was designed to determine the tensile bond strength of a glass-ionomer sealer (Ketac Endo, Espe, Seefeld, Germany) on root canal walls after pretreatment with different conditioners. Flat inner surfaces of root canal specimens were prepared. The specimens were divided into five groups of 10 teeth, and the groups were conditioned with one of the following smear layer removal solutions: 15% EDTA/NaOCl, 10% polyacrylic acid, 35% phosphoric acid, 6% citric acid, and 5.25% NaOCl as a control. Then the exposed root canal areas were coated with Ketac-Endo. Tensile bonding was measured using a universal testing machine until ultimate failure was obtained. The groups that were treated with phosphoric acid and citric acid showed significantly higher bond strengths than the groups that were treated with 15% EDTA and polyacrylic acid (p < 0.05). Bonding to dentin without smear layer removal (NaOCl group) was too low to be measured in the testing apparatus. Scanning electron microscopy confirmed that phosphoric and citric acids were more effective in removing smear layer than EDTA or polyacrylic acid. The result supported the view that pretreatment with phosphoric acid or citric acid should be used in association with glass-ionomer root canal sealer to achieve the most effective removal of the smear layer and to provide better adhesion.