The Effect of Endodontic Irrigants on the Microtensile Bond Strength of Dentin Adhesives

IntroductionThe purpose of this study was to evaluate the microtensile bond strength of a total etch (XP-Bond) and a self-etch (Clearfil SE Bond) adhesive system to dentine surfaces treated using endodontic irrigants.MethodsTwenty-four freshly extracted third molars were used. After creating a smear layer on the coronal midthird portion of the crowns, the teeth were divided into three groups and surfaces were irrigated with distilled water, 5.25% NaOCl + 17% EDTA, and 1.3% NaOCl + BioPure MTAD, respectively. Each group was divided into two subgroups, and a self-etching adhesive and an etch-and-rinse adhesive were applied respectively. The teeth were restored with a composite material and sectioned to produce sticks for microtensile bond testing.ResultsThe microtensile bond strength of the MTAD + Clearfil SE group was found to be significantly lower than the microtensile bond strength of the distilled water + Clearfil SE Bond group and the NaOCl, EDTA, + Clearfil SE Bond group (p = 0.0001, p = 0.009).ConclusionsBecause of the significant reduction of Clearfil SE Bond to coronal dentine after MTAD application, an etch-and rinse adhesive such as XP-Bond may be preferred if this irrigant has been chosen during endodontic treatment.     

Soft chelating irrigation protocol optimizes bonding quality of Resilon/Epiphany root fillings

This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n = 10): G1: NaOCl, G2: NaOCl + 17% EDTA, G3: NaOCl + BioPure MTAD (Dentsply/Tulsa, Tulsa, OK), and G4: NaOCl + 18% HEPB. The teeth were obturated and then prepared for micropush-out assessment using root slices of 1 mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey multiple comparisons were used to compare the results among the experimental groups. EDTA- and MTAD-treated samples revealed intermediate bond strength (0.3-3.6 MPa). The lowest bond strengths were achieved in NaOCl-treated samples (0.3-1.2 MPa, p < 0.05). The highest bond strength was reached in the HEBP-treated samples (3.1-6.1 MPa, p < 0.05). Under the present in vitro conditions, the soft chelating irrigation protocol (18% HEBP) optimized the bonding quality of Resilon/Epiphany (Resilon Research LLC, Madison, CT) root fillings.     

Effect of endodontic irrigants on the shear bond strength of epiphany sealer to dentin

This study examined the effects of commonly employed endodontic irrigants on Epiphany-dentin bond strengths. Smear layers were created on dentin discs obtained from human third molars. Five groups of 10 discs each were treated with one of the following: (a) water; (b) 2% chlorhexidine; (c) 6% sodium hypochlorite (NaOCl); (d) 6% NaOCl followed by EDTA and water; or (e) 1.3% NaOCl followed by MTAD. The treated surfaces were air-dried and treated with Epiphany primer. Hollow steel tubes were placed on the dentin surfaces, and Epiphany sealer was applied to dentin inside the tubes. Samples were tested for shear bond strengths after 7 days of storage. Representative specimens were examined using scanning electron microscopy. One-way ANOVA and Tukey's test revealed significant differences among the groups (p<0.05). Using water or chlorhexidine as an irrigant resulted in significantly lower bond strengths when compared with NaOCl, NaOCl/EDTA, or NaOCl/MTAD. Neither EDTA nor MTAD significantly improved Epiphany-dentin bond strengths when compared with NaOCl used alone.     

The Effect of Different Irrigating Solutions on Bond Strength of Two Root Canal–filling Systems

The bond strength of ActiV GP root canal filling system and gutta-percha/AH plus sealer when used after final rinse with different irrigation protocols was evaluated in this study. Forty roots were randomly divided into four groups (n = 10) according to the final irrigation regimen: group 1, 5 mL 17% EDTA; group 2, 5 mL 17% EDTA followed by 5 mL 2% chlorhexidine gluconate (CHX); group 3, 5 mL MTAD; and group 4, 5 mL MTAD followed by 5 mL 2% CHX. Each group was further subdivided into two subgroups (n = 5): in subgroup a, the root canals were filled using warm gutta-percha and AH plus sealer, and in subgroup b, the root canals were filled using the ActiV GP obturation system. Two-millimeter thick horizontal sections from the coronal and midthirds of each root were sliced for the push-out bond strength measurement. EDTA/CHX/ActiV GP (2.46 ± 1.02 MPa) yielded significantly the highest mean bond strength value. The significantly lowest bond strength was recorded for EDTA/ActiV GP (1.12 ± 0.72 MPa). It was concluded that the bond strength of ActiV GP was improved by using 2% CHX in the final irrigation after 17% EDTA, whereas CHX did not enhance the effect of MTAD on the bond strength of the material. The bond strength of gutta-percha/AH plus was adversely affected by MTAD and MTAD/CHX.     

Effects of different irrigating solutions and disinfection methods on push-out bond strengths of fiber posts

Objective. The aim of this study was to evaluate the effects of various irrigating solutions and photoactivated disinfection (PAD) on the push-out bond strengths of fiber posts to root dentin. Materials and methods. Thirty-two human teeth were divided into eight groups, as follows: (1) irrigation with physiologic saline (control), (2) NaOCl irrigation, (3) chlorhexidine (CHX) irrigation, (4) ethanol (EtOH) irrigation, (5) NaOCl followed by 17% EDTA irrigation, (6) NaOCl-EDTA supplemented with CHX irrigation, (7) NaOCl-EDTA supplemented with EtOH irrigation and (8) NaOCl-EDTA irrigation supplemented with PAD. After the posts were cemented, the roots were transversally sectioned to obtain four slices (1 mm thick) (n = 16). Push-out tests were conducted by applying a load at 0.5 mm/min, types of fracture failures were recorded and data were analyzed with one-way ANOVA and Tukey post-hoc tests (p = 0.05). Results. Push-out bond strength was significantly affected by the type of irrigating solution and the disinfection protocol (p < 0.05). The bond strength of the EtOH, NaOCl and NaOCl-EDTA-CHX irrigated groups was significantly higher than that of the other groups. The highest bond strength was observed in the EtOH irrigated group and the lowest was the NaOCl-EDTA irrigated group. Conclusions. Irrigation with NaOCl and EDTA combined caused lower bond strength than observed in the control group. However, supplementing this combination with CHX improved the post-dentin bond strengths; supplementing with PAD did not.     

Adhesion of Epiphany self-etch sealer to dentin treated with intracanal irrigating solutions

Introduction

This in vitro study assessed the adhesion of Epiphany self-etch (SE) root canal sealer to dentin treated with different irrigation regimens.

Methods

Flat dentin surfaces were obtained from human third molar teeth; smear layer was created on each sample. Five groups of 10 samples each were conditioned with one of the following regimens: (1) deionized water for 10 minutes; (2) 5% sodium hypochlorite (NaOCl) for 10 minutes; (3) 5% NaOCl for 10 minutes and then 10% sodium ascorbate (Na-Ascr) for 10 minutes; (4) 5% NaOCl for 10 minutes and then 2% chlorhexidine (CHX) for 5 minutes; or (5) 5% NaOCl for 10 minutes and then 10% Na-Ascr for 10 minutes, followed by 2% CHX for 5 minutes. The conditioned dentin surfaces were dried with absorbent paper points. The Epiphany SE sealer was placed on each dentin surface with the use of hollow stainless steel tubes with specific diameter and height. The samples were stored in 100% humidity at 37°C for 7 days and then tested for shear bond strength in a universal testing machine.

Results

Shear bond strength data were analyzed by one-way analysis of variance and Tukey post hoc tests (P < .05). There were statistically significant differences among the groups.

Conclusions

NaOCl decreased the bond strength of Epiphany SE sealer to dentin, whereas the use of Na-Ascr reversed this negative effect of NaOCl. CHX had neither negative nor positive influence on the bond strength.     

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 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.     

Effect of post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts

The aim of this study was to evaluate the effect of different post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push‐out test. Data were statistically analysed with anova (P = 0.05). After push‐out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.     

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).     

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.     

The effect of different irrigation protocols on smear layer removal in root canals of primary teeth: a SEM study

Objective: The purpose of this study was to compare the efficacy of different irrigation protocols on smear layer removal in root canals of primary teeth by scanning electron microscopy (SEM).

Material and methods: The study was conducted with 40 extracted maxillary primary incisor teeth divided into four groups (n?=?10) as 1% sodium hypochlorite (NaOCl), 10% ethylenediaminetetraacetic acid (EDTA)+1% NaOCl, 6% citric acid (CA)+1% NaOCl, and 0.9% physiological saline (PS). After the irrigation procedures, root canal walls were examined by SEM and the efficacies of irrigation solutions in smear layer removal were scored and compared. Data were analyzed using Kruskal–Wallis, Friedman and Siegel Castellan tests.

Results: The smear layer removal was found to be statistically more effective in groups of 10% EDTA + 1% NaOCl and 6% CA + 1% NaOCl when compared with the other groups (p?<?.05). Smear removal efficacy was statistically significantly higher in coronal and medium thirds when compared with the apical regions in the experimental groups.

Conclusions: It was concluded that 10% EDTA + 1% NaOCl and 6% CA + 1% NaOCl could be alternative irrigation protocols regarding smear layer removal. However, due to the absence of erosive dentinal changes, it might be suggested that using 6% CA + 1% NaOCl can be recommended compared to 10% EDTA + 1% NaOCl in primary root canals.     

Effect of Photoactivated Disinfection on Bond Strength of Root Canal Filling

IntroductionThe aim of this in vitro study was to assess and compare the effect of photoactivated disinfection (PAD) on the bond strength of root canal sealers to human root canal dentin using the push-out test.MethodsFifteen extracted human mandibular premolar teeth with single and straight roots were used. After the clinical crowns were removed from the cementoenamel junction, root canals were prepared with the ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) rotary system to the size of the F3 file. The smear layer of the roots was removed using 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl) and distillate water. The roots were then randomly divided into 3 groups (n = 5) according to the final irrigation regimen. In group 1, PAD (FotoSan; CMS Dental, Copenhagen, Denmark) was applied to the root canals and light cured for 20 seconds. Group 2 was finally irrigated with a 2% solution of chlorhexidine gluconate, and group 3 served as the control group (NaOCl + EDTA). All the canals were then obturated with the lateral condensation technique using gutta-percha and AH Plus sealer (Dentsply Maillefer) sealer. One-millimeter-thick horizontal sections from the coronal and midthirds of each root (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. The data were converted to megapascals and statistically analyzed using 1-way analysis of variance and the post hoc Tukey test.ResultsThere was no significant difference among the bond strength of PAD, chlorhexidine gluconate, and NaOCl (P > .05).ConclusionsWe conclude that PAD does not adversely affect the bond strength of the AH Plus sealer to root canal dentin and that it can be used for the final disinfection of root canals.     

Smear Layer Removal Using Passive Ultrasonic Irrigation and Different Concentrations of Sodium Hypochlorite

IntroductionThe present study evaluated the effect of passive ultrasonic activation (PUI) of EDTA solution followed by conventional irrigation with 2 concentrations of sodium hypochlorite (NaOCl) on smear layer removal.MethodsFifty single-root mandibular premolars were chemomechanically prepared with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments and 1% NaOCl. The roots were cleaved, and the dentin surfaces were analyzed with scanning electron microscopy operated at a low vacuum. Images were obtained from previously demarcated areas in each root canal third. The teeth were reassembled and distributed into 5 groups according to the final irrigation protocols (n = 10): group 1, EDTA/PUI + 1% NaOCl; group 2, EDTA/PUI + 5% NaOCl; group 3, EDTA/CI + 1% NaOCl; group 4, EDTA/CI + 5% NaOCl; and group 5 (negative control), saline solution/PUI. After irrigation, the teeth were reseparated and prepared for conventional high-vacuum scanning electron microscopy of the same dentin surface that was previously analyzed. The amount of debris was classified using a 4-point scoring system. Data were analyzed with Kruskal-Wallis and Dunn tests at α = 0.05.ResultsGroups 1 and 2, which used PUI and different concentrations of NaOCl, were not significantly different; however, they differed significantly from group 3 (P < .05). With respect to canal cleanliness at different root thirds, all groups showed the worst cleaning at the apical third.ConclusionsPUI activation of the EDTA irrigant is required when canal debridement is performed with EDTA and a lower concentration of NaOCl.     

Bond strength of self-adhesive resin cement to root dentin. Comparison of photon-initiated photoacoustic streaming technique with needle and ultrasonic irrigation

Abstract

Objective. The aim of this study was to investigate the effects of photon-initiated photoacoustic streaming (PIPS) with various irrigating solutions on the bond strength of a self-adhesive resin cement to root dentin. Materials and methods. Seventy-two mandibular premolar roots were divided into six groups after post space preparation and treated with a needle irrigation with distilled water and NaOCl, ultrasonic irrigation with NaOCl, PIPS with NaOCl, PIPS with EDTA and PIPS with distilled water at 0.3 W, 15 Hz and 20 mJ per pulse for 60 s. Fiber posts were cemented with a newly marketed, self-adhesive resin cement. The data obtained from the push-out tests were analyzed using analysis of variance (ANOVA) and LSD post-hoc tests (p = 0.05). Results. PIPS with distilled water resulted in higher push-out values than those of needle (with both distilled water and NaOCl) and ultrasonic irrigation (p < 0.05). Conclusions. The use of PIPS may provide higher bond strength of self-adhesive resin cement to root dentin than needle and ultrasonic irrigation techniques.     

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.     

Effect of sodium hypochlorite irrigation with or without surfactants on the bond strength of an epoxy-based sealer to dentin

Objectives

This study evaluated the effect of sodium hypochlorite (NaOCl) irrigation with or without surfactants on the bond strength of an epoxy-based sealer to the root canal dentin.

Materials and methods

Eighty decoronated single-rooted human mandibular premolars were instrumented using the rotary system. The roots were subsequently rinsed with 5 ml 17 % EDTA for 1 min and then randomly divided into 3 test groups (n = 20) and 1 control group (n = 20) according to the type of irrigation with experimental 5 % NaOCl (Wizard, RehberKimya, Istanbul, Turkey) solutions: Group 1: NaOCl-0.1 % benzalkonium chloride; Group 2: NaOCl-0.1 % Tween 80; Group 3: NaOCl-0.1 % Triton X-100; control group: NaOCl without any surfactants. Five samples from each group were prepared for scanning electron microscopy to examine the surface of root canal dentin. The 15 samples remaining in each group were obturated with gutta-percha and AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany) using the cold lateral compaction technique. A push-out test was used to measure the bond strength between the sealer and root canal dentin. Data were analyzed using two-way analysis of variance and Tukey’s post hoc tests (P = 0.05).

Results

The NaOCl-0.1 % Triton X-100 group demonstrated the highest mean bond-strength values in all root thirds among the groups (P < 0.05). However, the bond strength of the sealer in the NaOCl-0.1 % benzalkonium chloride and NaOCl-0.1 % Tween 80 groups did not differ from that in the control group (P > 0.05). Additionally, the bond-strength values decreased in the corono-apical direction for all groups (P < 0.05).

Conclusions

NaOCl solution with Triton X-100 can provide higher bond strength of the epoxy resin-based sealer to root dentin compared to NaOCl solution wiithout any surfactant.

Clinical relevance

The bond strength of sealer to dentin can be improved by the addition of the surfactants to NaOCl solution.

     

Effect of chemical irrigants on the bond strength of a self-etching adhesive to pulp chamber dentin

The aim of this study was to evaluate the influence of endodontic irrigants on adhesion to pulp chamber dentin. Seventy crowns of bovine incisors were cut to expose the pulp chamber. Specimens were divided into seven groups, according to the irrigant solution used: G1, 0.9% sodium chlorite (control); G2, 5.25% NaOCl; G3, 5.25% NaOCl + 17% EDTA; G4, 2% chlorhexidine solution; G5, 2% CHX solution + 17% EDTA; G6, 2% chlorhexidine in a gel base; and G7, 2% CHX gel + 17% EDTA. After irrigation, Clearfil SE Bond was applied to pulp chamber dentin, followed by Filtek Z250 composite. Six rectangular sticks were obtained from each specimen and dentin/resin interface was tested in tension. Bond strength means were analyzed by ANOVA and Tukey test. There was a significant decrease in bond strength associated to NaOCl, whereas chlorhexidine irrigation showed no effects on adhesion. It was concluded that endodontic irrigants affected differently bond strength to pulp chamber dentin.     

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.     

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.