Evaluation of the interaction between endodontic sealers and dentin treated with different irrigant solutions

Introduction

Dentin surface treatment with different substances might cause alterations in chemical and structural compositions of the human dentin. The aim of this study was to investigate the wettability of endodontic sealers in contact with dentin treated with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) in the presence or absence of smear layer.

Methods

Thirty-six dentin slices were used. They were irrigated with NaOCl and washed with distilled water (DW) to simulate irrigation during chemomechanical preparation. After this procedure, the samples were divided into 6 groups: group 1, DW (control); group 2, NaOCl + DW; group 3, CHX + DW; group 4, ethylenediaminetetraacetic acid (EDTA) + DW; group 5, EDTA + DW + NaOCl + DW; group 6, EDTA + DW + CHX + DW. The Ramé-Hart goniometer was used to measure the contact angle between the dentin surfaces and the AH Plus and Real Seal SE sealers. Data were statistically analyzed.

Results

With regard to the contact angle between AH Plus and treated surfaces, the values of contact angle were lower when CHX was used, regardless of the presence or absence of smear layer. When Real Seal SE was evaluated, in the absence of smear layer, CHX presented lower values of contact angle. In the presence of smear layer, the use of NaOCl and CHX did not favor the spread of the sealer.

Conclusions

The present study has revealed that smear layer removal and final flush with CHX favor the wettability of AH Plus and Real Seal SE sealers.     

EVALUATION OF APICAL MICROLEAKAGE OF TEETH SEALED WITH FOUR DIFFERENT ROOT CANAL SEALERS

Objectives:

to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.

Results:

AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).

Conclusions:

the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.     

Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials

Objective

The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus) combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany).

Material and Methods

Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC) and immersed in a 50-wt% aqueous silver nitrate solution at 37ºC (24 h). After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM). The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS). The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (α=0.05).

Results

Epiphany presented more regions containing gaps between dentin and sealer (p<0.05). There was correspondence between the presence of gaps and microleakage (p<0.05). Microleakage was similar among the root-filling materials (p>0.05).

Conclusions

The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.     

Influence of endodontic irrigants on resin sealer bond strength to radicular dentin

The present study evaluated the influence of 2% chlorhexidine and 2.5% sodium hypochlorite on the resin sealer/dentin interface bond strength of AH Plus/gutta-percha and Epiphany/Resilon. Seventy-two extracted bovine incisors were randomly distributed into 6 groups according to irrigant and sealers: G(S+AH)=physiologic saline solution+AH Plus/gutta-percha; G(S+Ep)=physiologic saline solution+Epiphany/Resilon; G(H+AH)=2.5% sodium hypochlorite (NaOCl)+AH Plus/gutta-percha; G(H+Ep)=2.5% NaOCl+Epiphany/Resilon; G(C+AH)=2% chlorhexidine (CHX)+AH Plus/gutta-percha; and G(C+Ep)=2% CHX+Epiphany/Resilon. After 7 days at 37°C and 100% humidity, the roots were cut transversally on the long axis of the tooth in 0.8 mm (±0.09)-thick slices; these slices were then subjected to the push-out test. Data were analyzed using a 2-way ANOVA and Tukey tests at 5% significance. The AH Plus/gutta-percha groups showed significantly higher bond strength than the Epiphany/Resilon groups, regardless of the irrigant used (p<0.001). Sodium hypochlorite adversely affected bond strength in the AH Plus group, whereas chlorhexidine did not influence the push-out bond strength of either sealer (p<0.05). Two percent chlorhexidine did not adversely affect the bond strength of the sealers, whereas 2.5% sodium hypochlorite solution damaged AH Plus/gutta-percha bond strength.     

In vitro evaluation of the cleansing working time and analysis of the amount of gutta-percha or Resilon remnants in the root canal walls after instrumentation for endodontic retreatment

The present study assessed the obturation removal and reinstrumentation working time of canals filled with Resilon/Real Seal in comparison with canals filled with gutta-percha/AH Plus. Thirty human extracted canines were instrumented. In group 1 (n = 15) root canals were filled with Resilon/Real Seal and in group 2 (n = 15) with gutta-percha/AH Plus sealer. The obturations were removed from both by using chloroform and irrigation with 2.5% NaOCl, and the canals were manually reinstrumented. The teeth were radiographically analyzed. Specimens without obturation material remnants visible in the radiographic examination were selected for analysis under scanning electron microscopy. The Resilon/Real Seal system was removed in greater quantities from the canal walls compared with the gutta-percha cones and the AH Plus cement. Time was not a significant factor. Under scanning electron microscopy analysis, the teeth presented material remnants in the 3 analyzed thirds. Resilon was better removed from the canal than the gutta-percha cones and the AH Plus.     

Bond strength of different endodontic sealers to dentin: push-out test

Objective

The aim of this in vitro study was to evaluate the bond strength of different root canal sealers to dentin.

Material and Methods

Forty extracted single-rooted human teeth were examined and the coronal and middle thirds of the canals were prepared with a 1.50 mm post drill (FibreKor Post System, Pentron). The teeth were allocated in two experimental groups, irrigated with 2.5% NaOCl+17% EDTA or saline solution (control group) and instrumented using Race rotary files (FKG) to a size #40 at the working length. Then, the groups were divided into four subgroups and filled with Epiphany sealer (Group 1), EndoREZ (Group 2), AH26 (Group 3) and Grossman''s Sealer (Group 4). After 2 weeks of storage in 100% humidity at 37ºC, all teeth were sectioned transversally into 2-mm-thick discs. Push-out tests were performed at a cross-head speed of 1 mm/min using a universal testing machine. The maximum load at failure was recorded and expressed in MPa.

Results

Means (±SD) in root canals irrigated with 2.5% NaOCl and 17% EDTA were: G1 (21.6±6.0), G2 (15.2±3.7), G3 (14.6±4.5) and G4 (11.7±4.1).Two-way ANOVA and Tukey''s test showed the highest bond strength for the Epiphany''s group (p< 0.01) when compared to the other tested sealers. Saline solution decreased the values of bond-strength (p<0.05) for all sealers.

Conclusion

Epiphany sealer presented higher bond strength values to dentin in both irrigating protocols, and the use of 2.5% NaOCl and 17% EDTA increased the bond strength values for all sealers.     

Ex vivo microbial leakage after using different final irrigation regimens with chlorhexidine

Objective:

To assess the influence of final irrigation protocols with chlorhexidine in the coronal leakage of Enterococcus faecalis in filled root canals.

Material and Methods:

Seventy single-root canals from extracted teeth were prepared using ProTaper instruments. The irrigation protocol accomplished an alternating irrigation with 5 mL of 2.5% sodium hypochlorite (NaOCl) and 17% EDTA between each file. The teeth were randomly divided into four experimental groups (n=15) according to the final irrigation regimen: group 1, without final irrigation; group 2, irrigation with 10 mL 2.0% chlorhexidine (CHX); group 3, with a final application of EC40^TM; and group 4, irrigation with the combination (1:1) of 0.2% CHX + 0.1% cetrimide (CTR). All the teeth were mounted in a two-chamber apparatus and the coronal access was exposed to E. faecalis. The presence of turbidity in the BHI broth over a period of 180 days was observed. The Friedman test was used for statistical analysis.

Results:

EC40^TM varnish showed the least leakage at 180 days, and was statistically similar to 2% CHX. No significant differences were observed between the group without final irrigation and the 2% CHX group or 0.2% CHX + 0.1% CTR.

Conclusions:

In this ex vivo study, EC40^TM showed the longest delayed coronal leakage of E. faecalis, although without significant differences from 2% CHX.     

Effect of disinfectant solutions on the surface free energy and wettability of filling material

Introduction

Gutta-percha (GP) and Resilon (Res) cones are usually disinfected by the use of solutions such as sodium hypochlorite (NaOCl) and chlorhexidine (CHX). The aims of this study were to evaluate the surface free energy of GP and Res cones after disinfection procedures and to investigate the wettability of endodontic sealers in contact with these surfaces.

Methods

GP and Res flat smooth surfaces were prepared. Thirty-six samples of each material were used. The samples were divided into 6 groups as follows: Control group GP, immersed in Milli-Q water (MQW); CHX group GP, immersed in 2% CHX solution and then washed with MQW; NaOCl group GP, immersed in 5.25% NaOCl and then washed with MQW; Control group Res, immersed in MQW; CHX group Res, immersed in 2% CHX solution and then washed with MQW; and NaOCl group Res, immersed in 5.25% NaOCl and then washed with MQW. Samples were analyzed first with a goniometer to measure the contact angle between the test surfaces and 3 solutions (water, ethylene glycol, and diiodomethane) to determine the surface free energy. Then the contact angle between surfaces and each one of the sealers tested, AH Plus and Real Seal SE, was measured. Data were statistically analyzed.

Results

The results showed that when disinfectant solutions were used, the surface free energy was greater. When evaluating the interaction between materials and sealers, the use of CHX presented lower values of contact angle, followed by NaOCl.

Conclusions

It was concluded that the solutions used in decontamination increase the surface free energy, promoting high interaction between GP/Res and sealers.     

Monitoring the effectiveness of root canal procedures on endotoxin levels found in teeth with chronic apical periodontitis

Objective:

The aim of this study was to monitor the effectiveness of root canal procedures by using different irrigants and intracanal medication on endotoxin levels found in root canals of teeth with chronic apical periodontitis.

Material and Methods:

Thirty root canals of teeth with pulpal necrosis associated with periapical lesions were selected and randomly divided into groups according to the irrigants used: GI - 2.5% NaOCl, GII - 2% chlorhexidine (CHX) gel, and GIII - saline solution (SS) (all, n=10). Samples were collected with sterile/apyrogenic paper points before (S1) and after root canal instrumentation (S2), after use of 17% ethylenediaminetetraacetic acid (EDTA) (S3), and after 30 days of intracanal medication (Ca(OH)₂+SS) (S4). A turbidimetric kinetic Limulus Amebocyte Lysate assay was used for endotoxin measurement.

Results:

Endotoxins were detected in 100% of the root canals investigated (30/30), with a median value of 18.70 EU/mL. After S2, significant median percentage reduction was observed in all groups, irrespective of the irrigant tested: 2.5% NaOCl (99.65%) (GI), 2% CHX (94.27%) (GII), and SS (96.79%) (GIII) (all p<0.05). Root canal rinse with 17% EDTA (S3) for a 3-minute period failed to decrease endotoxin levels in GI and a slight decrease was observed in GII (59%) and GIII (61.1%) (all p>0.05). Intracanal medication for 30 days was able to significantly reduce residual endotoxins: 2.5% NaOCl (90%) (GI), 2% CHX (88.8%) (GII), and SS (85.7%) (GIII, p<0.05). No differences were found in the endotoxin reduction when comparing s2 and s4 treatment groups.

Conclusion:

Our findings demonstrated the effectiveness of the mechanical action of the instruments along with the flow and backflow of irrigant enduring root canal instrumentation for the endotoxin removal from root canals of teeth with chronic apical periodontitis. Moreover, the use of intracanal medication for 30 days contributed for an improvement of endotoxin reduction.     

Apical sealing of root canal fillings performed with five different endodontic sealers: analysis by fluid filtration

Objectives

To evaluate the sealing ability of five root canal sealers, including two experimental cements (MBP and MTA-Obtura) using the fluid filtration method.

Material and Methods

Teeth were divided into 5 study groups: G1-AH Plus; G2-Acroseal; G3-Sealapex; G4-MBP; G5-MTA-Obtura; and two controls. Chemical-mechanical preparation was performed with ProFile rotary nickel-titanium instruments 1 mm short of the apical foramen. The sealing ability was evaluated by fluid filtration at 15, 30, and 60 days.

Results

The statistical analysis showed significant difference between the materials at different periods (p<0.05). AH Plus and MBP had similar leakage values at 15 and 60 days, alternating with significant reduction at 30 days, while the other materials showed progressive increase in leakage values. Acroseal and Sealapex presented the best results at 15 days and the worst at 60 days.

Conclusions

All sealers evaluated presented fluid leakage, with AH Plus and MBP showing the best results at the end of the experimental period. Acroseal, Sealapex, and MTA-Obtura presented increase in leakage values at longer observation periods.     

Bond strength to root dentin and fluid filtration test of AH Plus/gutta-percha,EndoREZ and RealSeal systems

Objectives

To investigate the bond strength and seal ability produced by AH Plus/gutta-percha, EndoREZ and RealSeal systems to root canal dentin.

Material and Methods

Sixty extracted single-root human teeth, instrumented manually to size 40, were divided into three groups (n=20) according to the sealer used; G1: AH Plus, G2: EndoREZ, and G3: RealSeal sealers. After filling using the lateral condensation technique, each sealer group was randomly divided into two subgroups according to the tests applied (n=10 for µPush-out test and n=10 for fluid filtration test). A fluid filtration method was used for quantitative evaluation of apical leakage. Four 1-mm-thick slices (cervical and medium level) were obtained from each root sample and a µPush-out test was performed. Failure modes were examined under microscopy at 40x, and a one-way ANOVA was applied to analyze the permeability. Non-parametrical statistics for related (Friedman''s and Wilcoxon''s rank tests) or unrelated samples (Kruskal-Wallis'' and Mann-Whitney''s tests) allowed for comparisons of µPush-out strength values among materials at the different levels. Statistical significance was accepted for p values <.05.

Results

There are no significant differences among fluid filtration of the three sealers. The sealer/core material does not significantly influence the µPush-out bond strength values (F=2.49; p=0.10), although statistically significant differences were detected with regard to root level (Chi²=23.93; p<0.001). AH Plus and RealSeal obtained higher bond strength to intraradicular dentin in the medium root slices.

Conclusions

There are no significant differences between the permeability and global µPush-out bond strength to root canal dentin achieved by AH Plus/gutta-percha, EndoREZ and RealSeal systems.     

The effect of root canal sealers and timing of cementation on the microlekage of the parapost luted with resin cement

Objectives

The objectives of the study were to study the effect of root canal sealers either eugenol or non-eugenol and timing of cementation on microleakage of the parapost luted with resin cement.

Materials and methods

Seventy extracted human, single-rooted teeth were instrumented using a crown-down technique. All teeth were instrumented up to a size 50 .04 taper ProFile followed by the use of Gates Glidden drills from size 2 up to 5. Following instrumentation, the teeth were randomly divided into four experimental groups of fifteen teeth each, based on type of root canal sealer (eugenol or non-eugenol sealer) and timing of post cementation (immediate or delayed). The remaining ten teeth were divided into two control groups with five teeth per group. All teeth were tested for microleakage using a fluid filtration method.

Results

The microleakage of the paraposts luted with resin cement increased over time, irrespective of sealer type or timing of post cementation. Immediate post cementation following obturation with AH26 (non-eugenol sealer) produced the least microleakage at all three time periods at 24 h, 2 months and 3 months.

Conclusions

The microleakage paraposts luted with resin cement was not influenced by either sealer type or timing of post placement. All experimental groups demonstrated a significant increase in microleakage over time as well as the presence of voids at the resin–dentin interface.     

A fluid filtration comparison of gutta-percha versus Resilon, a new soft resin endodontic obturation system

The purpose of this study was to compare the sealing ability of gutta-percha and AH Plus sealer versus Resilon and Epiphany Resin Root Canal sealer using three different final irrigants with the fluid filtration model. There were 140 teeth prepared using a crown-down method to a size 50 file. The teeth were randomly divided into two groups: (A) GP and AH Plus and (B) Resilon and Epiphany. After removal of the smear layer each group was irrigated with either 5.25% NaOCl, 0.012% chlorhexidine (CHX), or 2% CHX for 10 minutes. Obturation was performed using the continuous wave of condensation. The teeth were stored for 20 days in 100% humidity before testing. Two-way ANOVA analysis indicated significantly less leakage (p < 0.05) using Resilon with Epiphany sealer compared to gutta-percha and AH Plus sealer. There was no statistical significance between any of the irrigants used for either obturation group.     

终末冲洗方案对根管封闭剂与根管壁牙本质粘接强度的影响

目的：比较不同终末冲洗方案对根管封闭剂 AH Plus 及 GuttaFlow 与根管壁牙本质之间粘接强度的影响。方法：60颗单根离体人牙截冠后用冠向下法进行常规根管机械化学预备,按终末冲洗方案随机分为3组（n ＝20）。组1：17％乙二胺四乙酸（EDTA）＋2％氯己定（CHX）;组2：5．25％次氯酸钠（NaOCl）＋17％ EDTA;组3：0．9％生理盐水（NS）对照组。每组根据使用的根管封闭剂分为2个亚组（n ＝10）：组 a．AH Plus;组 b．GuttaFlow。每个牙根自冠方向根方获取3个厚度约为2mm 的水平切片进行薄片推出实验。体视显微镜下观察断裂形式。结果：3种冲洗方案,AH Plus 的粘接强度均显著高于GuttaFlow（P ＜0．05）。使用 AH Plus 根管充填时,组1、组2和组3的粘接强度分别为（5．37±2．80）MPa、（8．81±4．38） MPa、（9．07±2．77）MPa（组1与组2或组3比较,P ＜0．05,组2与组3间比较,P ＞0．05）。使用 GuttaFlow 根管充填时,组1、组2和组3粘接强度分别为（1．40±0．59）MPa、（1．26±0．62）MPa 和（1．05±0．27）MPa（两两比较,P ＞0．05）。各组试件均以混合型断裂为主要断裂方式,但 GuttaFlow 组内粘接型断裂形式所占比例显著高于 AH Plus 组。结论：GuttaFlow 对牙本质的粘接强度显著低于 AH Plus。17％ EDTA ／2％ CHX 终末冲洗方案可显著降低 AH Plus 与根管壁牙本质的粘接强度,但对 GuttaFlow 的粘接性能无显著影响。     

Coronal microleakage of endodontically treated teeth with intracanal post exposed to fresh human saliva

Objective

The aim of this study was to investigate the coronal microleakage of endodontically treated teeth prepared to receive an intracanal post and teeth with an intracanal post but without a prosthetic crown and exposed to contamination by fresh human saliva.

Material and Methods

A mechanical-chemical preparation following the step-back technique was carried out in 35 extracted single-rooted human teeth. The teeth were randomly divided into five groups: G1=root canals instrumented, obturated, and prepared to receive an intracanal post (N=10); G2=root canals with cemented posts but without coronal sealing (N=10); PC1=positive control root canals instrumented and open (N=5); PC2=positive control 2 root canals without instrumentation and open (N=5); and NC=negative control healthy teeth (N=5). The crowns were removed except for the control group of intact teeth. The root canals were obturated and sterilized with cobalt 60 gamma irradiation and were then adapted in an apparatus using a Brain Heart Infusion (BHI) medium and fresh human saliva for contamination. Microbial growth was indicated by the presence of turbidity in the BHI liquid medium.

Results

Data were submitted to the Kaplan-Meier Survival Analysis and the Holm-Sidak statistic method, which observed an index of 90% of microleakage in root canals after 24 hours for G1 and 70% of microleakage in samples at the end of 40 days for G2.

Conclusion

The results show that root canals with an intracanal post but without a prosthetic crown can be recontaminated when exposed to fresh human saliva in a short period.     

An in vitro evaluation of the apical sealing ability of a new resin-based root canal obturation system

The purpose of this study was to assess the apical sealing ability of the new resin-based Epiphany-Resilon root canal filling system, and to compare this with the sealing abilities of different pairings of AH plus, gutta-percha, Epiphany, and Resilon. Seventy extracted human single-rooted teeth were used. All teeth were instrumented using a set of ProTaper rotary instruments. The canal spaces were filled with different combinations of core and sealer using lateral condensation, as follows: group 1, AH Plus + gutta-percha; group 2, AH Plus + Resilon; group 3, Epiphany + Resilon; group 4, Epiphany + gutta-percha. Apical leakage quantity was measured with the computerized fluid filtration meter. Statistical analysis indicated that Epiphany gutta-percha combination had the least amount of microleakage than all the other groups; AH Plus gutta-percha combination proved to have second least amount of microleakage among the groups. AH Plus-Resilon combination demonstrated the greatest amount of microleakage. There were a significant difference between Epiphany gutta-percha and AH Plus-Resilon combinations (p < 0.05). It was found that there were no significant differences between Epiphany-Resilon combination and all the other groups (p > 0.05).     

The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

Objective

The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)₂] from root canals.

Material and Methods

Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)₂-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)₂ removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)₂ was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)₂ (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)₂ were evaluated in the middle and apical thirds using a 5-score system.

Results

None of the techniques completely removed the Ca(OH)₂ dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)₂ in the middle (P=0.11) and the apical (P=0.23) thirds.

Conclusion

The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)₂ from mandibular incisor root canals.     

CLEANING ABILITY OF CHLORHEXIDINE GEL AND SODIUM HYPOCHLORITE ASSOCIATED OR NOT WITH EDTA AS ROOT CANAL IRRIGANTS: A SCANNING ELECTRON MICROSCOPY STUDY

The aim of this study was to evaluate the cleaning efficacy of 2% chlorhexidine gluconate gel (CHX) compared to 2.5% sodium hypochlorite solution (NaOCl) associated or not with 17% EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5% NaOCl, G3 - 2% CHX, G4 - 2.5% NaOCl + EDTA and G5 - 2% CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1% significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2% chlorhexidine gluconate gel alone is not able to remove the smear layer.     

Push-out Bond Strength of RealSeal SE and AH Plus after Using Different Irrigation Solutions

Introduction

The aim of this investigation was to evaluate the influence of different endodontic irrigants (sodium hypochlorite [NaOCl], chlorhexidine [CHX], and EDTA) on the push-out bond strength of the obturation materials RealSeal SE (SybronEndo, Orange, CA) and AH Plus (Dentsply International Inc, York, PA).

Methods

Two hundred human root canals were prepared and divided into 2 groups according to the filling material (RealSeal SE vs AH Plus). Each group was subdivided into 5 groups according to the irrigation protocol (0.9% saline [control], 3% NaOCl, 3% NaOCl with saline, 17% EDTA, and 2% CHX). After obturation, roots were sliced into 1-mm discs for push-out assessment. Compressive loading was performed using an universal testing machine at a speed of 0.5 mm/min. Two-way analysis of variance and the Kruskal-Wallis test were performed for pair-wise comparisons to assess the differences between the experimental groups.

Results

AH Plus exhibited a significantly higher bond strength than RealSeal SE (mean = 2.53 and 1.53 MPa, respectively; P < .05), except with saline alone (P > .05). Within the AH Plus groups, no significant differences existed between the irrigants and saline alone (P > .05). The bond strength of RealSeal SE with saline alone or with NaOCl and saline did not differ from that of AH Plus with saline alone (P > .05). However, the push-out bond strength of RealSeal SE decreased by approximately half (P < .05 compared with RealSeal SE with saline alone) after rinsing with NaOCl alone, EDTA, or CHX.

Conclusions

The bond strength of RealSeal SE is highly influenced by the irrigant used.     

Effect of root canal filling materials on dimensions of cone-beam computed tomography images

Objective

To evaluate the discrepancy of root canal filling (RCF) measurements obtained from original root specimens and cone-beam computed tomography (CBCT) images.

Material and Methods

Seventy-two human maxillary anterior teeth were prepared up to an ISO #50 K-File 1 mm short of the apical foramen. Thus, the teeth were randomly divided into 8 groups, according to the root canal filling material: Sealapex^®, Sealapex^®+gutta-percha points, Sealer 26^®, Sealer 26^®+gutta-percha points, AH PlusTM, AH PlusTM+gutta-percha points, Grossman Sealer, and Grossman Sealer+gutta-percha points. After root canal preparation and RCF, CBCT scans were acquired and the specimens were sectioned in axial, sagittal and coronal planes. The RCF measurements were obtained in different planes and thicknesses to determine the discrepancy between the original root specimens (using a digital caliper) and the CBCT images (using the scanner''s proprietary software). One-way analysis of variance and Tukey tests were used for statistical analyses. The significance level was set at α=5%.

Results

Measurements of the different endodontic filling materials were 9% to 100% greater on the CBCT images than on the original root specimens. Greater RCF dimensions were found when only sealers were used, with statistically significant difference among the groups.

Conclusions

RCF dimensions were greater on CBCT images than on the original root specimens, especially when only sealer was used.