Effects of ethylenediaminetetraacetic, etidronic and peracetic acid irrigation on human root dentine and the smear layer

Effect of continuous vs sequential chelation on the mechanical properties of root dentin: An ex vivo study

OBJECTIVES

To evaluate the mechanical properties of root canal dentin treated with sodium hypochlorite (NaOCl) in combination with hydroxyethylidene diphosphonic acid (HEDP) or ethylenediaminetetraacetic acid (EDTA).

METHODS

For testing fracture resistance, 45 single-rooted teeth were instrumented and irrigated with NaOCl/HEDP, NaOCl/EDTA, or distilled water. Fifteen untreated teeth served as control. After obturation, specimens from the experimental groups were thermocycled, dynamically-loaded, and then statically-loaded in a universal testing machine until failure. For flexural strength analysis, 15 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Root segments were sectioned into dentin bars and tested for flexural strength using a universal testing machine. For microhardness evaluation, 20 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Dentin disks from the coronal-third of each root segment were prepared, one before and one after irrigation, for microhardness testing with a Knoop hardness tester.

RESULTS

The highest fracture resistance was recorded in the untreated group, and the lowest in the EDTA group. Although the HEDP group had higher fracture resistance than the EDTA group, the distilled water group demonstrated even greater fracture resistance than the HEDP group. Specimens treated with HEDP had significantly higher flexural strength and microhardness values when compared with those treated with EDTA.

CONCLUSION

The fracture resistance, flexural strength, and microhardness of root canal dentin were higher when root canals were irrigated with NaOCl/HEDP, when compared with NaOCl/EDTA.

CLINICAL SIGNIFICANCE

Irrigating root canals with NaOCl combined with HEDP significantly improves the mechanical integrity of root canal dentin compared to the use of NaOCl with EDTA.

The effect of final irrigation with different solutions on smear layer removal and dentin erosion: A scanning electron microscope study

AIM

This study aimed to compare the effectiveness of initial irrigation with sodium hypochlorite (NaOCl) and final irrigation with QMix, 40% citric acid, and 17% ethylenediaminetetraacetic acid (EDTA) on smear layer removal and dentin erosion.

METHODOLOGY

Forty extracted human mandibular premolar teeth were randomly divided into four groups (n = 10) according to the type of final irrigants used: 17% EDTA, QMix, citric acid, and control (normal saline). Canals were mechanically prepared using ProTaper Next instruments to an apical size of X3. Subsequently, the roots were sectioned in a buccolingual direction. Scanning electron microscopy (SEM) was used to assess the presence of the smear layer and the amount of dentin erosion in the coronal, middle, and apical thirds of the root canals.

RESULTS

In regards to smear layer removal, there was a significant difference between the control group and the other tested groups. Moreover, it was significantly higher in the coronal and middle thirds than in the apical third. However, there were no significant differences between the groups of EDTA, QMix, and citric acid. Concerning dentin erosion, citric acid produced significantly more dentin erosion than the other tested groups.

CONCLUSION

Final irrigation with solutions had a higher ability to remove the smear layer in the coronal and middle thirds compared to the apical third. Of all the solutions tested, 40% citric acid had the most pronounced impact on dentin erosion, followed by 17% EDTA and QMix.

Glycolic acid on push-out bond strength of fiber post and smear removal: an in vitro study

This study aims to investigate glycolic acid (GA) as a final irrigant on push-out bond strength of fiber post and smear removal. Ninety mandibular premolars were stabilized with a silicone key and photographed, and canal cross-section was calculated by image processing software. Round canal morphology was selected. The specimens were divided into five groups (n = 18); 10%GA, 17%EDTA, NaOCl + 10%GA, NaOCl + 17%EDTA, and the control. Fifteen specimens were used for the push-out. Three specimens were evaluated using a scanning electron microscope after post space preparation. Two-way ANOVA and Chi-square were used for statistics. GA presented higher strength than EDTA (p < 0.05). The NaOCl + GA showed higher strength than the NaOCl + EDTA (p < 0.05). The highest values were observed in cervical and lowest in apical thirds (p < 0.05). The most failure type was between dentin and resin (p < 0.05). GA removed the smear in the post space including the apical third. The NaOCl + GA has superiority to NaOCl + EDTA on push-out strength. Glycolic acid improved the bond strength of fiber post when used as a final post space irrigant. The combination of NaOCl and glycolic acid did not negatively affect the bond strength and was more effective compared to the combination with EDTA. Glycolic acid improved the bond strength of fiber post when used as a final post space irrigant. The combination of NaOCl and glycolic acid did not negatively affect the bond strength and was more effective compared to the combination with EDTA.

Comparative Effectiveness of Different Er:YAG Laser-Activated Irrigation Systems on Removing Calcium Hydroxide from Simulated Internal Root Resorption Cavities at Different Root Levels

Objective: To investigate the effectiveness of Er:YAG laser-activated irrigation (LAI) with a short pulse duration for removing calcium hydroxide (CH) from simulated internal root resorption (IRR) cavities at three root levels. Background: Pulse duration is an important parameter during LAI, which ensures the efficiency of irradiation and the corresponding activation process. Short pulses in the range of a few microseconds enable rapid expansion and successive implosion of irrigants, resulting in distinct fluid movement. There have been few reports on CH removal efficacy from IRR cavities of different LAI systems, including those using short pulse duration. Methods: IRR cavities (1.6 mm diameter) were created at the apical, middle, and coronal root levels in 60 mandibular premolars and filled with a radiopaque CH paste. Samples were assigned to the following irrigation groups (n = 12, each): (1) LAI(P)-F, a prototype laser device that operates with short pulse duration (Morita Manufacturing) with a flat tip; (2) LAI(EA)-F, the ErwinAdverl laser device (Morita Manufacturing) with a flat tip; (3) LAI(EA)-T, the ErwinAdverl laser device with a tapered tip; (4) PIPS-T, the Lightwalker laser device (Fotona) with a tapered tip; and (5) SI, the syringe irrigation group. The laser tips were fixed at the canal entrance. The remaining CH volume and surface area were assessed in IRR cavities using micro-computed tomography and scanning electron microscopy, respectively. Data were statistically analyzed utilizing one-way analysis of variance and Tukey's test at 5% significance level. Results: The LAI(P)-F and PIPS-T groups exhibited the highest CH removal rates at three different levels (p < 0.05). The LAI(EA)-F group had a significantly better efficacy of CH removal compared with the LAI(EA)-T group at the middle level (p < 0.05). Conclusion: The LAI(P)-F and PIPS-T groups demonstrated superior efficiency in removing CH from simulated IRR cavities.

Engineering a Microphysiological Model for Regenerative Endodontic Studies

Dental pulp infections are common buccal diseases. When this happens, endodontic treatments are needed to disinfect and prepare the root canal for subsequent procedures. However, the lack of suitable in vitro models representing the anatomy of an immature root canal hinders research on regenerative events crucial in endodontics, such as regenerative procedures. This study aimed to develop a 3D microphysiological system (MPS) to mimic an immature root canal and assess the cytotoxicity of various irrigating solutions on stem cells. Utilizing the Dental Stem Cells SV40 (DSCS) cell line derived from human apical papilla stem cells, we analyzed the effects of different irrigants, including etidronic acid. The results indicated that irrigating solutions diminished cell viability in 2D cultures and influenced cell adhesion within the microphysiological device. Notably, in our 3D studies in the MPS, 17% EDTA and 9% 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) irrigating solutions demonstrated superior outcomes in terms of DSCS viability and adherence compared to the control. This study highlights the utility of the developed MPS for translational studies in root canal treatments and suggests comparable efficacy between 9% HEBP and 17% EDTA irrigating solutions, offering potential alternatives for clinical applications.

Dislodgement resistance and structural changes of tricalcium silicate-based cements after exposure to different chelating agents

This study aimed to evaluate the dislodgement resistance and structural changes of different mineral trioxide aggregate cements (MTA) like Pro-Root MTA, Ortho MTA, and Retro MTA after exposure to sodium hypochlorite (NaOCl), NaOCl-Ethylenediaminetetraacetic acid (EDTA), 1-hydroxyethylidene-1, 1-bisphosphonate (Dual Rinse HEDP), and NaOCl-Maleic acid (MA). The root canal spaces of 150 dentine slices were obturated using tricalcium silicate cements and divided into 3 groups (n = 50): Group1: ProRoot MTA, Group2: Retro MTA, and Group3: Ortho MTA. The samples in each group were further subdivided into four experimental (n = 10) and one control groups (n = 10): 2.5% NaOCl-17% EDTA, Dual Rinse HEDP, 2.5% NaOCl-7% Maleic acid, 2.5% NaOCl, distilled water (control). The dislodgement resistance and structural changes of cements were measured. Use of DR HEDP resulted in higher dislodgement resistance compared to17% EDTA and 7% MA in the samples obturated with Ortho MTA and Pro-Root MTA (p<0.001). In Retro MTA group, samples treated with DR HEDP and 17% EDTA had higher dislodgment resistance compared to 7% MA (p<0.001). On microstructural and elemental analysis of all the three MTA cements, samples treated with 17% EDTA and 7% MA were more amorphous and granular when compared to DR HEDP, which was pettle shaped. Calcium level was decreased more in samples treated with 17% EDTA and 7% MA when compared to DR HEDP.

Effectiveness of continuous chelation irrigation protocol in endodontics: a scoping review of laboratory studies

This scoping review aimed to synthesize and explore the current boundaries and limitations of laboratory research on the effectiveness of continuous chelation irrigation protocol in endodontics. This scoping review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. Literature search was conducted on Pubmed and Scopus to identify all laboratory studies evaluating smear layer and hard-tissue debris removal or, antimicrobial efficacy, or dentine erosion induced by continuous chelation. Two independent reviewers performed the all review steps and the relevant items were recorded. Seventy-seven potentially relevant studies were identified. Finally, 23 laboratory studies met the eligibility criteria for qualitative synthesis. Seven studies focused on the smear layer/debris removal outcome, 10 on antimicrobial activity, and 10 on dentine erosion. In general, the continuous chelation protocol was equally or more effective in the cleanliness of root canals and antimicrobial activity compared with traditional sequential protocol. In addition, etidronate solutions seemed to be milder chelating agents compared to those with EDTA, thus resulting in reduced or no dentine erosion and roughness modification. Yet, the methodological differences among the included studies limit the results' generalizability. The continuous chelation seems to be equally or more effective in all investigated outcomes when compared with the traditional sequential protocol. The methodological variability among the studies and shortcomings in the methods employed limit the generalizability and clinical relevance of the results. Standardized laboratory conditions combined with reliable three-dimensional investigation approaches are necessary to obtain clinically informative findings.

Analysis of the depth of penetration of an epoxy resin-based sealer following a final rinse of irrigants and use of activation systems: An in vitro study

Objective

The objective of the study was to compare and evaluate the depth of penetration of an epoxy resin-based sealer following a final rinse of 17% ethylenediaminetetraacetic acid (EDTA) and 18% 1-hydroxyethylidene 1, 1-diphosphonate (HEDP), with diode laser and passive ultrasonic activation (PUI): an in vitro confocal laser scanning microscopy study.

Materials and Methods

Fifty-two extracted human mandibular premolar teeth with single root and single canal were selected. They were disinfected in 0.1% thymol solution, cleaned of calculus and soft tissues, and stored in 0.1% thymol solution till use. All teeth were radiographed and selected as per the inclusion and exclusion criteria. The teeth were decoronated using a diamond disk under copious water spray to acquire a standardized root length of 14 mm. Working length was established by inserting a size 10-K file into each root canal until it is visible at the apical foramen and by subtracting 1 mm from the recorded length. Instrumentation of the root canal was done till master apical file size of F3 using ProTaper universal, rotary instruments. The canals were irrigated with 2 mL of 3% sodium hypochlorite between successive files. Teeth were randomly divided into four subgroups n = 12 according to the intervention. Passive ultrasonic irrigation and diode laser were used to activate the irrigants. Final irrigation was performed with distilled water. These specimens were examined using confocal laser scanning microscope (OLYMPUS FLUOVIEW FV 3000) for dentinal tubule penetration of the sealer. Two-way ANOVA test and Tukey's multiple post hoc test were used for statistical analysis.

Results

Highly significant difference was seen between the groups with EDTA and HEDP, with HEDP demonstrating the highest penetration. Among the activation techniques used in this study, PUI showed the highest penetration of the sealer. The least penetration was seen with diode laser activation and EDTA.

Conclusions

The irrigation activation techniques significantly influence the penetration of sealer into root dentinal tubules. When penetration of sealer with different irrigation techniques and irrigants was evaluated, significant greater level of sealer penetration was attained with PUI activation of HEDP.

2D and 3D Erosion Landscape Analysis of Endodontic-Treated Teeth Using EDTA and HEDP as Chelating Agents: A High-Resolution Micro-Computed Tomographic Study

This study aimed to assess the amount of erosion during activated endodontic irrigation with either HEDP or EDTA via high-resolution micro-computed tomography. Two root canals of twenty premolars were prepared with ProTaper Next and irrigated with sodium hypochlorite. Palatal canals, which served as control groups, were sealed, while buccal canals were further irrigated with either EDTA (n = 10) or HEDP (n = 10), which served as test groups. Micro-CT was performed to measure erosion depth. For 2D and 3D measurements, non-parametric repeated ANOVA measurements and post hoc tests were performed. 2D analysis showed highly significant differences between the case groups at each position of the root (p ≤ 0.01). The cervical and apical positions showed significant differences in the EDTA group (p = 0.03). The 3D analysis also showed significant differences between both chelating agents (p < 0.01) and the case and control groups (p = 0.01). The mean erosion depths in the cervical, middle, and apical thirds of the EDTA group were 45.75, 41.79, and 32.25 µm, and for the HEDP group were 20.25, 16.40, and 15.96 µm, respectively. HEDP seems to have a significantly less erosive effect. Different irrigation protocols with harsher conditions, as might be the case during endodontic retreatment, could be assessed with micro-CT.

Effect of different chelating agents on the shear bond strength of calcium silicate-based cements to coronal dentin

We evaluated the shear bond strength (SBS) of mineral trioxide aggregate (MTA) and Biodentine (BD) to coronal dentin after treatment with ethylenediaminetetraacetic acid (EDTA), phytic acid (IP6), or etidronic acid (HEDP). Sodium hypochlorite-treated dentin surfaces were randomly divided into four groups according to conditioning protocol namely, 17% EDTA, 2.5% IP6, 9% HEDP, or distilled water (DS). Specimens were further divided according to the type of cement placed on conditioned dentin and SBS was tested. The results showed that DS/MTA and IP6/MTA groups had the highest values, and there was no significant difference between these two groups. IP6/BD group showed a lower SBS value compared to IP6/MTA; however, this did not reach the level of significance. The BS to dentin was influenced by the type of calcium silicate material and chelating agent. IP6 either improved or maintained the bonding while EDTA and HEDP showed a negative or no influence effect.

Scanning Electron Microscopy Analysis of Smear Layer Removal Ability of Conventional Endodontic Irrigation Regimen, MTAD, and QMix™ Versus a Mixture of Azadirachta indica and Citrus limon: An In Vitro Study

INTRODUCTION

Smear layer removal from root canals aid in the penetration of both irrigants and endodontic sealer into the dentinal tubules, thereby improving the efficacy of endodontic treatment. The aim of this in vitro study was to compare the smear layer removal ability of a conventional endodontic irrigation regimen, MTAD (mixture of tetracycline, acid, and detergent), and QMix™ (Dentsply Sirona, Charlotte, North Carolina, United States) with that of a mixture of herbal irrigants, namely, aqueous extracts of Azadirachta indica (neem) and Citrus limon (lemon), evaluated using scanning electron microscopy (SEM).

MATERIALS AND METHODS

We selected 40 extracted human premolar teeth for the study, which we randomly divided into five groups (eight samples each) according to irrigation solution: (i) Group A (normal saline); (ii) Group B (conventional endodontic regimen, 3% sodium hypochlorite (NaOCl) + 17% ethylenediamine tetraacetic acid (EDTA) + 2% chlorhexidine (CHX)); (iii) Group C (MTAD); (iv) Group D (QMix 2-in-1); and (v) Group E (aqueous extracts of Azadirachta indica and Citrus limon). After we prepared the canals with ProTaper Universal nickel-titanium (Ni-Ti) rotary files (Dentsply Sirona) and the respective irrigants, we split the teeth longitudinally to evaluate the amount of remnant smear layer in the coronal, middle, and apical thirds using SEM photomicrographs. We performed statistical analyses of the data using the Kruskal-Wallis and Mann-Whitney U tests, where the level of significance was set at 0.05.

RESULTS

The SEM analysis of the coronal third showed mean values of 3.83 in Group A, 3.67 in Group B, 2.79 in Group C, 3.63 in Group D, and 4.00 in Group E. The SEM analysis of the middle third showed mean values of 4.00 in Group A, 3.88 in Group B, 3.75 in Group C, 3.50 in Group D, and 3.50 in Group E. The SEM analysis of the apical third showed mean values of 3.92 in Group A, 3.63 in Group B, 3.71 in Group C, 3.88 in Group D, and 3.17 in Group E. Therefore, we found that there were significant statistical differences between the groups when an overall comparison was done for the coronal, middle, and apical third, with a p-value of 0.001. On multiple comparisons across the different tooth-section thirds. Groups A and B showed statistically significant differences in the apical third (p-value=0.017). Groups A and C showed statistically significant differences in the coronal third and middle third (p-values=0.001 and 0.010, respectively). Groups A and D showed statistically significant differences in the middle third (p-value=0.001). Groups A and E showed statistically significant differences in all thirds (p-values=0.039, 0.001, and 0.001, respectively) Conclusion: The conventional needle irrigation with MTAD showed the highest level of smear layer removal ability on the root canal surface, followed by QMix 2-in-1, the Azadirachta indica leaf and Citrus limon extract mixture, and the conventional endodontic regimen. Normal saline showed the lowest smear layer removal effect.

Morphological Analyses of Effects of Endodontic Irrigant Solutions Using a Root Canal Model and an Immersion Model

Objective

This study aimed to compare an experimental model simulating clinical root canal irrigation (root canal model) with a conventional experimental model immersing dentin sample to irrigants (immersion model) to evaluate removal of the smear layer and decalcification of the root canal dentin using sodium hypochlorite (NaOCl) and two different concentrations of ethylenediaminetetraacetic acid (EDTA) solution.

Materials and Methods

Forty-five single-rooted extracted human teeth were prepared using a Ni-Ti rotary file. EDTA, NaOCl, and citric acid were used in the root canal models and the immersion models. After the irrigation protocol, root canal surfaces were observed under scanning electron microscopy. Residual smear and decalcification of the root canal dentin were evaluated objectively by measuring the percentage of the area occupied by visible dentin tubules, the number of visible dentin tubules, and the mean area of a visible single dentin tubule.

Results

Root canal and immersion models with the same irrigation protocol showed significantly different results for smear residues and decalcification of root canal dentin. In the root canal model, neither different EDTA concentrations nor the order of EDTA and NaOCl applications significantly impacted smear residues or decalcification of root canal dentin. Furthermore, no erosion of the root canal dentin surface was observed in any experimental groups in the root canal model using EDTA and NaOCl compared to intact dentin.

Conclusions

Experimental design affected results for residual smear layer and decalcification of root canal dentin. The order of EDTA and NaOCl use and the concentration of EDTA did not affect results. EDTA and NaOCl irrigation did not cause erosion in the root canal model in this study.

Update on citric acid use in endodontic treatment: a systematic review

This systematic review aims to analyse the available evidence concerning the use of citric acid (CA) in endodontics treatment and to assess its results in terms of different considerations: effect on smear layer removal, influence on sealer bond strength, activation effect by means of sonic or ultrasonic devices, effects on dentine surface, antibacterial activity, and effectiveness boost for regenerative procedures, releasing growth factors from dentin. To evaluate the results of CA as a final irrigant and compare them to other chelating agents. This review followed the PRISMA checklist. An electronic search was conducted in MEDLINE (OVID), Scopus (Elsevier) and the Web of Science (Thomson Reuters) databases. Risk of bias of included studies was evaluated using the modified CONSORT checklist and the PRIRATE checklist 2020 guidelines. 39 studies fulfilled the eligibility criteria to be included in this review: 27 in vitro studies using extracted human teeth, 10 in vitro studies using human dentin disks, and 2 RCT. Citric acid has proven to be effective in smear layer removal, showing better results in coronal and middle root thirds, improving its effect when combined with manual dynamic activation. There is no agreement regarding citric acid effect on sealer adhesion and adaptation to root canal walls due to heterogeneity within studies. Citric acid irrigation can decrease dentine microhardness and cause decalcification and erosion, especially when used before NaOCl. Citric acid has proven to be beneficial in regenerative endodontic procedures due to higher TGF-β1 release.Trial registration: Prospero database CRD42021267055.

To evaluate and compare the effect of 17% EDTA, 10% citric acid, 7% maleic acid on the dentinal tubule penetration depth of bio ceramic root canal sealer using confocal laser scanning microscopy: an in vitro study

Background: The main factors that affect the success of an endodontic infection are effective cleaning and shaping of the root canal system including complete disinfection by using chemical irrigating solutions and obturation with an endodontic sealer to provide a fluid-tight seal. Using rotary and hand instruments for shaping and cleaning the root canal along with irrigants produces a smear layer on the surface of the root dentin affecting the penetration of the endodontic sealer into the dentinal tubules. This smear is difficult to remove with the use of only endodontic irrigants, hence, chelating agents were introduced in adjunct with irrigating solutions for irrigation protocol for effective removal of smear layer which affect the penetration of endodontic sealers into the dentinal tubules. Methods: 32 mandibular premolar teeth were used. The biomechanical preparation was done till Protaper F3 size. Irrigation was done with 2.5 mL sodium hypochlorite (NaOCl) solution after each instrumentation change for 1 min. Samples were then divided into 4 groups according to the irrigating solution used as the final rinse used with passive ultrasonic agitation. The groups were: Group I: 5 ml of saline, Group II: 5ml of 17% ethylenediaminetetraacetic acid, Group III: 5 ml of 10% citric acid, Group IV: 5 ml of 7% maleic acid each for one minute. All the canals were obturated with BioRoot tmRCS with gutta-percha using the ultrasonic condensation technique. For staining the samples for Confocal LASER microscopy, BioRoot tmRCS was mixed with Rhodamine B dye. Results: The maximum penetration of bio-ceramic sealer was observed in the coronal region. At the apical third, the maximum sealer penetration was seen with 7% maleic acid. Conclusions: Maximum sealer penetration was seen in the coronal section followed by the middle and apical section. Maximum sealer penetration was seen with 7 % maleic acid at the apical third.

Impact of agitation/activation strategies on the antibiofilm potential of sodium hypochlorite/etidronate mixture in vitro

Background

To investigate the effect of a rotary agitation method or ultrasonically activated irrigation on the antibiofilm effect of a mixture of sodium hypochlorite (NaOCl) and etidronate (1-hydroxyethylidene-1,1-bisphosphonate, HEBP) using a dual-species biofilm model in root canal system.

Methods

Mature dual-species biofilms of Enterococcus faecalis and Streptococcus gordonii were formed in root canals of mandibular premolars. Teeth were randomly allotted (n = 12) to group 1, XP-endo Finisher (XPF); group 2, ultrasonically activated irrigation (UAI); group 3, syringe-and-needle irrigation (SNI). In all groups, canals were instrumented with a rotary instrument (XP-endo Shaper) prior to irrigant agitation/activation. A mixture containing 2.5% NaOCl and 9% HEBP was used throughout the experiment. Bacterial counts from the canal were determined using qPCR before preparation (S1), after preparation (S2), and after final irrigation agitation/activation (S3). Bacterial viability within the dentinal tubules in the coronal, middle and apical root-thirds was quantified using confocal microscopy after Live/Dead staining. The bacterial counts and viability were compared between groups using one-way ANOVA and post-hoc Tukey’s tests. Paired t-test was used to compare the bacterial counts within groups.

Results

Instrumentation alone could significantly reduce the microbial counts in all the groups (P < 0.0001). Subsequent agitation/activation resulted in significant microbial reduction only in XPF and UAI (P < 0.05), both of which reduced significantly more microbial counts than SNI (P < 0.05). Live/Dead staining revealed that XPF and UAI showed significantly greater percentage of dead bacteria within the dentinal tubules than SNI in the coronal third (P < 0.05); UAI resulted in the significantly highest percentage of dead bacteria in the middle third (P < 0.05); while there was no significant difference between the groups in the apical third (P > 0.05).

Conclusions

When using the sodium hypochlorite/etidronate mixture for irrigation, final irrigant agitation/activation with XP-endo Finisher or ultrasonic can improve disinfection of the main root canal space and the dentinal tubules in the coronal third, while ultrasonically activated irrigation appears to exhibit better disinfection within dentinal tubules in the middle third.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02222-1.

Antibacterial efficacy of peracetic acid in comparison with sodium hypochlorite or chlorhexidine against Enterococcus faecalis and Parvimonas micra

Background

The main goal of an endodontic treatment is a complete debridement of the root canal system; however, currently mechanical shaping and chemical cleaning procedures for this purpose have deemed non-satisfactory.

Methods

The efficacy of peracetic acid (PAA; 0.5, 1.0, 2.0%), as a root canal irrigation solution, against Enterococcus faecalis (DSM 20478) and Parvimonas micra (DSM 20468) when compared with the one of sodium hypochlorite (NaOCI; 1.0, 3.0, 5.0%), chlorhexidine digluconate (CHX; 0.12, 0.2, 2.0%) and 0.9% NaCI (as a control solution) was in vitro investigated with the agar diffusion and direct contact methods. The inhibition zone diameters observed with the agar diffusion test were determined. The viable bacterial counts (CFU/ml) were calculated with the direct method.

Results

The agar diffusion test showed that all three root canal irrigation solutions had an efficacy against E. faecalis at all concentrations. The largest inhibition zone diameters against E. faecalis were observed with 5.0% NaOCI. At all three concentrations of PAA, NaOCI, and CHX, the inhibition zone diameter increased with increase in concentration. For P. micra, PAA had a similar inhibition zone diameter despite a concentration increase. In contrast, for NaOCI and CHX, the inhibition zone diameter increased with increasing concentration. 2.0% CHX produced the largest inhibition zone diameter against P. micra. For E. faecalis, only the comparison between 2.0% PAA and 5.0% NaOCI showed statistical significance (p = 0.004). For P. micra the efficacy comparison between the lowest, middle, and highest concentrations of each solution, a statistical significance (p < 0.05) was found for all three solutions. After direct contact with PAA, NaOCI and CHX, no viable bacteria could be determined for either P. micra or E. faecalis.

Conclusions

PAA had a similar antibacterial efficacy as the one of NaOCl and CHX when in direct contact with E. faecalis and P. micra. In the agar diffusion test, PAA showed a similar antibacterial efficacy as the one of CHX and a lower one as the one of NaOCl for E. faecalis.

Physicochemical properties and penetration into dentinal tubules of calcium hypochlorite with surfactants

Abstract The aim was to assess the physicochemical properties and the penetration into dentinal tubules of calcium hypochlorite solution [Ca(OCl)2], with or without surfactants. The surfactants benzalkonium chloride, cetrimide, Tween 80 and Triton X-100 were mixed at different concentrations with sodium hypochlorite solution (NaOCl), Ca(OCl)2 and distilled water (control). Once the critical micellar concentration (CMC) of the surfactants in Ca(OCl)2 and NaOCl was determined, pH, free chlorine, surface tension and free calcium ions were evaluated. The penetration into dentinal tubules of NaOCl and Ca(OCl)2, with or without benzalkonium chloride and Triton X-100 [surfactants that promoted the lowest surface tension of Ca(OCl)2], was assessed using human premolars stained with crystal violet. The statistical tests were one-way ANOVA and Tukey’s post-test, Kruskal-Wallis and Dunn’s post-test, two-way ANOVA and Bonferroni’s post-test, and t-test; depending on the assay. The addition of surfactants reduced the surface tension of NaOCl and Ca(OCl)2, and did not alter the pH or the free available chlorine of either solution. The addition of all surfactants increased the availability of free calcium ions in Ca(OCl)2, especially benzalkonium chloride. Ca(OCl)2 exhibited lower penetration into dentinal tubules than NaOCl, and the addition of surfactants did not improve the penetration of Ca(OCl)2, but did increase the penetration of NaOCl. It can be concluded that the addition of surfactants to Ca(OCl)2 did not increase the penetration into dentinal tubules, but it did promote lower surface tension, without changing the pH or free available chlorine values, and higher availability of free calcium ions in Ca(OCl)2.

Present status and future directions - irrigants and irrigation methods

Irrigation is considered the primary means of cleaning and disinfection of the root canal system. The purpose of this review was to set the framework for the obstacles that irrigation needs to overcome, to critically appraise currently used irrigants and irrigation methods, to highlight knowledge gaps and methodological limitations in the available studies and to provide directions for future developments. Organization of bacteria in biofilms located in anatomic intricacies of the root canal system and the difficulty to eliminate them is the main challenge for irrigants. Sodium hypochlorite remains the primary irrigant of choice, but it needs to be supplemented by a chelator. Delivery of the irrigants using a syringe and needle and activation by an ultrasonic file are the most popular irrigation methods. There is no evidence that any adjunct irrigation method, including ultrasonic activation, can improve the long‐term outcome of root canal treatment beyond what can be achieved by instrumentation and syringe irrigation. It is necessary to redefine the research priorities in this field and investigate in greater depth the penetration of the irrigants, their effect on the biofilm and the long‐term treatment outcome. New studies must also focus on clinically relevant comparisons, avoid methodological flaws and have sufficiently large sample sizes to reach reliable conclusions. Future multidisciplinary efforts combining the knowledge from basic sciences such as Chemistry, Microbiology and Fluid Dynamics may lead to more effective antimicrobials and improved activation methods to bring them closer to the residual biofilm in the root canal system.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-omputed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Irrigating Solutions and Activation Methods Used in Clinical Endodontics: A Systematic Review

Background

Ex vivo and in vitro studies have demonstrated the effectiveness of some irrigation protocols in reducing the bacterial load in the root canal system. However, standardized protocols have not yet been defined for the real clinical context due to many irrigation procedures available.

Objective

To evaluate the clinical endodontic protocols and limitations of irrigating solutions in the disinfection of the root canal system in patients with apical periodontitis.

Methods

PubMed, Scopus, Embase, Web of Science, and Cochrane databases were searched for randomized controlled trials (RCT) published until January 2021. Hand searching was also performed. Studies focused on evaluating the effectiveness of irrigating solutions and/or irrigation activation methods in reducing the bacterial load in the root canal system were considered. The Cochrane risk-of-bias tool for randomized trials (RoB2) was used to assess the quality of the studies.

Results

Four hundred and twenty eight published articles were identified. After removing the duplicate studies and analyzing full texts, seven RCTs were selected. Two studies compared pure NaOCl with some combination of NaOCl with HEDP and MTAD. Two studies analyzed the antibacterial efficacy of NaOCl and chlorhexidine (CHX). Three studies compared conventional needle irrigation with different irrigation activation methods (PUI, XP-endo finisher, F-file activator, EndoVac activator). The review attained a satisfactory methodology. The main results of each included study were described.

Discussion

Activation methods provide significantly higher biofilm reduction than conventional needle irrigation methods. Combinations of NaOCl with different chelating agents were ineffective in terms of antimicrobial, but it could potentially increase the risk of irrigant extrusion. However, the irrigating protocols were not carefully detailed, especially those regarding the irrigants application time or total volume. The existing literature lacks high-quality studies. The level of evidence is moderate.

Conclusions

The available data is too heterogeneous to compare and identify the superiority of specific valuable irrigation protocols in each clinical context. Application time, volume, and activation methods should be standardized to determine the optimal irrigating procedures to reduce the bacterial load and ensure higher predictability of the endodontic treatment.

Systematic Review Registration

(https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=218555), PROSPERO registration: CRD42020218555.

Microbiological Aspects of Root Canal Infections and Disinfection Strategies: An Update Review on the Current Knowledge and Challenges

The oral cavity is the habitat of several hundreds of microbial taxa that have evolved to coexist in multispecies communities in this unique ecosystem. By contrast, the internal tissue of the tooth, i.e., the dental pulp, is a physiologically sterile connective tissue in which any microbial invasion is a pathological sign. It results in inflammation of the pulp tissue and eventually to pulp death and spread of inflammation/infection to the periradicular tissues. Over the past few decades, substantial emphasis has been placed on understanding the pathobiology of root canal infections, including the microbial composition, biofilm biology and host responses to infections. To develop clinically effective treatment regimens as well as preventive therapies, such extensive understanding is necessary. Rather surprisingly, despite the definitive realization that root canal infections are biofilm mediated, clinical strategies have been focused more on preparing canals to radiographically impeccable levels, while much is left desired on the debridement of these complex root canal systems. Hence, solely focusing on "canal shaping" largely misses the point of endodontic treatment as the current understanding of the microbial aetiopathogenesis of apical periodontitis calls for the emphasis to be placed on "canal cleaning" and chemo-mechanical disinfection. In this review, we dissect in great detail, the current knowledge on the root canal microbiome, both in terms of its composition and functional characteristics. We also describe the challenges in root canal disinfection and the novel strategies that attempt to address this challenge. Finally, we provide some critical pointers for areas of future research, which will serve as an important area for consideration in Frontiers in Oral Health.

Comparative evaluation of decalcifying agents for dissolution of pulp stones: An in vitro study

Background:

Despite constant advances in science, obscurity remains in the efficient removal of pulp stones to aid in successful root canal treatment. In this context, chemical means of dissolving pulp stones were explored.

Aim:

The aim of this study is to evaluate and to compare the efficacy of decalcifying agents on the dissolution of pulp stones.

Materials and Methods:

The study was divided into two groups for pulp stone analysis (21 samples) and dentin analysis (54 samples). Twenty-one pulp stones from patients aged 18–70 who underwent root canal treatment were collected and divided into three subgroups (n = 7) randomly. They were subjected to chemical treatment in a labeled glass container with 5 ml of the respective chemical agents, such as 17% ethylenediaminetetraacetic acid solution (positive control), no treatment (negative control), and newly developed Physiological Simulated Decalcifying Agent (PSDA). At the end of the study period (24 h), the samples were removed, rinsed with deionized water, and subjected to physical analysis, scanning electron microscopy (SEM), and Energy –dispersive X-ray spectroscopy (EDS) analysis. Under dentin analysis, 54 maxillary premolars scheduled for orthodontic extraction without caries or extensive restorations were selected, following which 2-mm thick transverse dentinal sections at the cementoenamel junction level were obtained and randomly divided into two groups for SEM (n = 21) and microhardness analysis (n = 33). The samples were subjected to respective chemical treatment groups similar to pulp stones for 24 h and analyzed using SEM, EDS, and microhardness analysis.

Results:

Postchemical treatment with the newly developed decalcifying solution, the pulp stones showed the absence of nodular crystallites and surface softening under SEM and a decrease in the calcium level under EDS analysis. Concerning the microhardness of dentin, no significant changes could be observed.

Conclusion:

The newly explored PSDA was found to be efficacious in the decalcification of pulp stones at a clinically relevant time of 24 h, without significantly affecting the structural integrity and the hardness values of dentin.

Different formulations of peracetic acid: effects on smear layer removal, dentine erosion, cytotoxicity and antibiofilm activity

Objective:

Methodology:

Results:

Conclusions:

Effect of glycolic acid and EDTA on dentin mechanical properties

The aim of this study was to evaluate the effect of glycolic acid (GA) and EDTA on dentin mechanical properties. For the cohesive strength, flexural strength and fracture strength tests, the hourglass of root dentin, dentin sticks and roots standardised to 1 mm thickness were used respectively. ANOVA and Tukey tests were used for statistical analysis (P < 0.05). The results showed that EDTA and GA 17% reduced the cohesive strength values when compared to distilled water (control; P = 0.0022 and P = 0.0016 respectively), whereas the values for GA 10% group were similar to those of the control group (P = 0.093). No statistically significant difference was found among the groups for the flexural strength test (P = 0.1974). Fracture strength test showed that EDTA and GA 17% were statistically similar to each other (P = 0.7694) and statistically inferior to GA 10% (P = 0.0007 and P = 0.0004 respectively). It was concluded that 10% GA showed fewer negative effects on dentin mechanical properties.

Effect of intracanal and extracanal heating on pulp dissolution property of continuous chelation irrigant

Context

Extracanal and intracanal heating of sodium hypochlorite (NaOCl) improve its pulp dissolution, but limited literature is available on its effect as a combined single irrigant with etidronate.

Aim

The aim of this study is to compare the effect of temperature on the effectiveness of NaOCl and continuous chelation protocol on the time required for the dissolution of vital and necrotic pulp.

Materials and Methods

Dissolution time of 120 standardized bovine (buffalo) pulp fragments, divided into 12 subgroups based on tissue type (vital/necrotic), irrigant (NaOCl/continuous chelation), and temperature (extracanal, intracanal, and nonheated irrigant), was noted. Conical glass tips mimicking the root canal were considered specimen containers. About 0.2 ml of irrigant corresponding to the irrigation protocol was taken in them and then pulp samples were added to it. Samples were observed using loupes under 2.5 X magnification. Dissolution time was recorded using a stopwatch. The study was approved by the Institutional Ethical Committee (SDC/2019/591).

Statistical Analysis Used

Two-way analysis of variance; statistical product and service solutions version 25. The level of significance was set at P < 0.05.

Results

Time for pulp dissolution by continuous chelation mixture was significantly more as compared to NaOCl alone in all subgroups. Pulp tissue dissolution for both vital and necrotic pulp was improved by the increase in temperature of both irrigants and dissolution time was more for necrotic than vital tissue. Pulp tissue dissolution was significantly better by intracanal heating as compared to extracanal heating.

Conclusion

Although intracanal heating of continuous chelation mixture improves its pulp dissolution capacity significantly as compared to extracanal heating and nonheating protocol but pulpal dissolution capacity of nonheated 5% NaOCl still remains significantly better as compared to intracanal and extracanal heated continuous chelation mixture.

Efficacy of preheated chelating agents on calcium ion removal from instrumented root canals

Background

The heating of chelating agents such as EDTA increases dentin wettability by decreasing surface tension. However, the calcium ion release effect of preheated chelating agents in instrumented root canals has not yet been mentioned. In this study, it was aimed to evaluate the number of calcium ions removed by the pre-heated chelating agents from the root canals.

Material and Methods

After 51 bovine teeth were instrumented, three of them were separated as negative controls and the remaining teeth were divided into six groups according to the temperature of the solution (at 22 or 37ºC): EDTA-22, CITRIC-22, QMix-22, EDTA-37, CITRIC-37 and QMix-37. Following irrigation, calcium ion levels were determined by atomic absorption spectrophotometer in chelating agents collected from the root canals.

Results

QMix solution eliminated significantly more calcium ions than other chelating agents at different temperatures (p< 0.05). Regardless of the heating, QMix and 17% EDTA were significantly superior to 40% Citric acid (p< 0.05) while no significant difference was detected between QMix and 17% EDTA groups (p< 0.05). Heating all chelating agents did not significantly increase their ability to remove calcium ions from pre-instrumented root canals (P< 0.05). In the SEM examination, it was observed that the smear layer was removed from the middle third of the roots, except for the negative control group.

Conclusions

Temperature changes have shown that these agents do not increase the ability of the smear layer to dissolve the inorganic structure. QMix at different temperatures may be recommended to use as the final chelating agent.

Key words:EDTA, citric acid, QMix, calcium ions, temperature.

Effect of Sodium Hypochlorite Concentration in Continuous Chelation on Dislodgement Resistance of an Epoxy Resin and Hydraulic Calcium Silicate Sealer

The conditioning of the root canal wall during chemo-mechanical root canal treatment differentially affects the adhesion of root canal sealers. This investigation evaluated the impact of sodium hypochlorite (NaOCl) concentration as used in a root canal irrigation concept called continuous chelation, with 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) contained in the NaOCl solution that is applied. Fourier-transform infrared spectra of the dentinal wall were gathered. The consequential effects on push-out bond strength of an epoxy resin (AH Plus) versus a hydraulic CaSi sealer (BioRoot RCS) were assessed. Single-rooted extracted human teeth were used and irrigated with pure NaOCl at a concentration of 0% (physiological saline), 2.5%, or 5.25%. Dual Rinse HEDP (9%) was added to the solutions, or not added for further control. Pure NaOCl solutions caused a decrease in the amide III: phosphate ratios, which was counter-acted by the addition of HEDP. It was observed that the adhesion of the epoxy resin sealer under investigation was negatively affected by this NaOCl deproteinization of the canal wall in a dose-dependent manner, while the opposite was observed with the CaSi sealer. HEDP when used in conjunction with NaOCl was beneficial for the adhesion of both sealers.

Effect of post-space irrigation with acid solutions on bond strength and dentin penetrability using a self-adhesive cementation system

Background

The aim of this study was to evaluate the effects of surface treatments with 1% peracetic acid (PA), solution containing 17% EDTA (SmearClear, Kerr Endodontics), solution containing a combination of 17% EDTA with 2% chlorhexidine (QMix, Dentsply Sirona) on the post-space root dentin compared to 2.5% sodium hypochlorite (NaOCl) on bond strength and resin tags length in dentin.

Material and Methods

Forty human-canine roots were endodontically treated and the post space was prepared. The specimens were randomised into four groups (n = 10): control – irrigation with 2.5% NaOCl solution, PA – irrigation with 1% PA, SmearClear – irrigation with SmearClear solution, and QMix – irrigation with QMix solution. The fibre posts were cemented using a self-adhesive resin system (Relyx U200, 3M ESPE). After six months, the specimens were cross-sectioned and subjected to push-out and confocal laser microscopy tests. One-way ANOVA and Tukey’s tests were used to analyse the data (α= 0.05).

Results

PA and QMix presented the highest bond strength values compared to the other groups (p< 0.05). There was no significant difference between the resin tags length in dentin by the groups (p = 0.75).

Conclusions

Irrigation of the post space with 1% PA and QMix showed a positive clinical impact on the adhesion between the fiber post and root dentin. However, these materials had no influence on resin tags length in dentin by self-adhesive resin cement.

Key words:Fiber post, adhesive cementation, self-adhesive resin cement, root dentin, irrigating solutions.

Effect of Irrigants and Irrigating Devices on Disinfection of Root Canal System: A Systematic Review

Aim:

The effective delivery of irrigants into the inaccessible areas of the root canal system is the prerequisite for a proper disinfection of the root canal system. Numerous activation devices that can provide effective delivery of the irrigant and aid in the success of the root canal treatment are available. The activation of irrigants has claimed to be effective in in vitro and clinical trials. Hence, the present systematic review aims to analyze the effect of irrigants and irrigating devices in disinfecting the root canal system.

Materials and Methods:

A literature search was undertaken in PubMed, Cochrane, Web of Science, and Scopus databases. The inclusion criteria included clinical trials, both in vivo and ex vivo. The exclusion criteria included animal studies, textbooks, review articles, and case reports. The patients who required endodontic treatment along with the activation of irrigants were chosen as participants for the review.

Result:

The search strategy screened around 132 articles, out of which only 10 were selected for the present systematic review. The risk of bias was calculated based on the following scores: 3, high; 2, moderate; and 1, low. In the present systematic review, four articles were categorized into low-risk bias, three articles were classified as moderate risk, and three articles belonged to the high-risk category.

Conclusion:

The present systematic review concluded that the use of a mechanical activation device along with the irrigant will help in better removal of the smear layer and debris from the root canal system, improving the cleanliness and helping achieve more successful endodontic treatment.

Effects of heat in the properties of NaOCl alone and mixed with etidronate and alkaline tetrasodium EDTA

AIM

To assess the free available chlorine concentration (FAC), organic tissue dissolution and smear layer removal capacity of sodium hypochlorite (NaOCl) alone and when mixtured with etidronate (HEDP) and tetrasodium EDTA (Na₄ EDTA), and heated to different temperatures.

METHODOLOGY

Mixtures at 1 : 1 ratio of 5% NaOCl with distilled water (considered NaOCl alone), 18% HEDP or 10% Na₄ EDTA were heated to 25 °C, 37 °C, 48 °C and 60 °C. The FAC in the mixtures was assessed at 5, 10, 20, 30, 60 and 120 min. Samples of bovine muscle tissue (n = 10) were prepared with similar size and weighed before and after 5, 10 and 15 min of immersion in the mixtures heated to the different temperatures to verify organic matter dissolution. The intergroup results were compared statistically using one-way analysis of variance (anova) and intragroup by two-way analysis of variance (anova), both followed by Tukey's multiple-comparison test (α < 0.01). Bovine dentine blocks (n = 10) were analysed by scanning electron microscopy before and after immersion in the mixtures, and the time taken to remove the smear layer from the surfaces of the samples was determined. The Friedman test was used to compare the scores of the same group (α < 0.01), and the Kruskal-Wallis test with Dunn's post hoc was used to compare the different groups (α < 0.01). Saline solution was used as a control in the experiments of tissue dissolution and smear layer removal, RESULTS: Heating NaOCl alone did not affect its FAC. The higher the temperature of the mixtures with the chelators, the lower the FAC. Organic tissue dissolution was improved by increases in temperature of NaOCl alone and its mixture with HEDP (P < 0.01); however, the mixture with Na₄ EDTA had no improvement (P > 0.01). Smear layer removal by NaOCl alone was enhanced by heating resulting in lower scores in some samples and became more rapid in the mixtures with the chelators. The saline solution did not promote tissue dissolution nor smear layer removal (P > 0.01).

CONCLUSION

In this laboratory study, heating NaOCl alone or when mixed with HEDP improved its capacity to dissolve organic matter and remove the smear layer. However, the mixture with HEDP required frequent refreshment to retain these effects when heated. Due to the acceleration in the reaction between the irrigants, very rapid reductions in the free available chlorine in the mixtures with Na₄ EDTA heated to the different temperatures occurred.

Effect of final irrigation protocols on the fracture resistance of roots with varying dentine thickness

This study evaluated the effects of 9% etidronic acid (HEBP) and 17% ethylenediaminetetraacetic acid (EDTA) used either with conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI) on the fracture resistance of roots with different dentine thickness. The root canals of 120 extracted teeth were widened, leaving dentinal walls with different thicknesses of either 0.75 mm, 1.50 mm, or 2.25 mm with 40 teeth in each group. Within each of these groups, four subgroups (n = 10) were formed according to the final irrigation regimens applied: 2.5% NaOCl-17% EDTA with CSI; 2.5% NaOCl-17% EDTA with PUI; 2.5% NaOCl + 9% HEBP with CSI; 2.5% NaOCl + 9% HEBP with PUI. The irrigated root canals were obturated with AH Plus sealer and gutta-percha cones. A compressive vertical loading was applied to the samples and the force at fracture was recorded. Data were statistically analysed using a multiple linear regression analysis. The most influencing factor for the fracture strength of roots was the remaining dentine thickness, followed by the irrigation method, and then the irrigation solution. The samples irrigated using PUI were statistically significantly more resistant to fracture than those using CSI (mean difference = 116.3 N; 95% CI = [53.9, 178.6] N). The application of HEBP was associated with higher resistance to fracture than the application of EDTA (mean difference = 71.0 N; 95% CI = [8.6, 133.3] N).

Effect of Natural and Artificial Dentin Conditioners on the Release of Vascular Endothelial Growth Factor

INTRODUCTION

The purpose of this study was to observe the release of vascular endothelial growth factor (VEGF) after conditioning with etidronic acid (also known as 1-hydroxyethylidene-1 and 1-bisphosphonate [HEDP]) and phytic acid (inositol hexakisphosphate [IP6]) in comparison with EDTA on human dentin disks and cylinders.

METHODS

Human dentin disks were disinfected and prepared by the standardized method. Seventeen percent EDTA, 9% HEDP, 1% IP6, and distilled water (5 minutes) were used to immerse dentin disks. The dentin cylinders were prepared by following disinfection and the standardized preparation method to achieve a truncated cone-shaped canal with a 1-mm open apex. The dentin cylinder samples were irrigated with sodium hypochlorite (5 mL/5 minutes) and then rinsed with 17% EDTA, 9% HEDP, 1% IP6 and distilled water (5 mL/5 min). Enzyme-linked immunosorbent essay was performed to measure VEGF release. One-way analysis of variance was used to compare the mean release of VEGF between study groups and controls at a significance level of .05. A post hoc Tukey test was used for multiple comparisons between study groups.

RESULTS

Among conditioners, HEDP released more VEGF from both disks and cylinders. In cylinders, VEGF release by HEDP was significantly greater than the other conditioners, whereas in disks the release of VEGF was similar with all conditioners.

CONCLUSIONS

The release of VEGF by 9% HEDP and 1% IP6 was comparable with 17% EDTA from dentin disks; however, HEDP demonstrated more release from dentin cylinders than EDTA and IP6.

Etidronic acid and ethylenediaminetetraacetic acid associated with sodium hypochlorite have limited effect on the compressive fracture resistance of roots ex vivo

Aims:

To assess the effect of etidronic acid (EA) mixed with sodium hypochlorite (NaOCl) and two ethylenediaminetetraacetic acid-containing preparations (EDTA and SmearClear) alternated with NaOCl, as a final rinse, on root fracture resistance to a compressive force.

Materials and Methods:

Seventy-two premolar roots were randomly allocated to the following groups according to the irrigant solutions. For the EA group, 9% EA + 2.5% NaOCl were used throughout the assays (n = 21). The remaining groups received 2.5% NaOCl during and immediately after chemo-mechanical instrumentation. Intermediately, the roots received 17% EDTA (n = 19), or SmearClear (n = 16), or no irrigation (control) (n = 16) plus a final rinse with 2.5% NaOCl. The specimens were subjected to a vertical compressive force loaded at a crosshead speed of 0.02 mm/s parallel to the long axis of the root until fracture occurred. The results were compared statistically using the one-way analysis of variance for intergroup comparisons.

Results:

The negative control presented with the highest values, whereas the SmearClear presented with the lowest values, though no significant differences were found when comparing the different groups (P = 0.82).

Conclusions:

The use of EA + NaOCl or two EDTA formulations in association with NaOCl does not affect the fracture resistance of previously chemo-mechanically prepared roots.

Investigation of the effect of different chelation solutions on penetration of resin-based and bioceramic sealers with a novel method

This study aimed to investigate the effects of different chelation solutions on the penetration of resin-based and bioceramic root canal sealers into dentinal tubules using a device that assembles conventional microplate detection with automated digital microscopy. Eighty-four single-rooted teeth were prepared with 30.07 nickel-titanium instruments and divided into four groups of 21 according to the final irrigation solutions used: saline (control), ethylenediaminetetraacetic acid (EDTA), maleic acid (MA), and etidronic acid (HEBP). The samples were obturated with AH Plus, MTA Fillapex, or EndoSequence BC Sealer using the single-cone technique. The roots were then sectioned horizontally at 2, 6, and 10 mm and examined using a Cytation 5 reader and Gen5 software. Data were compared using two-way analysis of variance followed by univariate analyses and Tukey's multiple comparison test (p < .05). The mean penetration depth in the apical thirds was higher in the MA group than in the other groups (p = .013). The mean depth in the middle and coronal thirds was almost equal in the EDTA and HEBP groups. The mean depth was significantly higher in the coronal thirds of the root canals than in any other section in all final irrigation solution groups (p < .001). EndoSequence BC Sealer displayed higher penetration depth than AH Plus and MTA Fillapex, although the differences between the examined sealers were not statistically significant. The chelation solutions increased root canal sealer penetration into the dentinal tubule.

Effect of final irrigating solutions on penetration depth of resin-based sealers into dentinal tubules

Background:

The goal of root canal therapy depends on chemomechanical debridement and three-dimensional filling of the root canal system.[1]

Aim:

The aim of this study is to assess the effect of NaOCl + Ethylenediaminetetraacetic acid (EDTA) and Twin Kleen as a final irrigating solution on the depth of penetration of AH Plus and Perma Evolution sealers into the dentinal tubules.

Materials and Methods:

Forty mandibular premolars were decoronated and instrumented up to size 30. Moreover, randomly assigned into two groups based on final rinse Group A (n = 20): 5.25% NaOCl + 17% EDTA. Group B (n = 20): Twin Kleen solution. Resin sealers were labeled with few grains of fluorescent rhodamine B dye and subdivided into two subgroups, Subgroup A1and B1 (n¹= 10): AH Plus; Subgroup A2 and B2 (n²= 10): Perma Evolution and obturated. Confocal laser scanning microscopy was used to examine the sections taken 2, 5, and 8 mm from the apex. Images were exported to Image J software to determine the sealer penetration depth.

Statistical Analysis:

Independent t-test and one-way analysis of variance followed by Tukey's HSD post hoc test.

Results:

Maximum depth of sealer penetration was seen in Twin Kleen in all sections. Perma Evolution showed highest sealer penetration at the middle and apical third region of root canal for both groups.

Conclusions:

Final irrigation with Twin Kleen produced highest sealer penetration than with EDTA.

Effect of various calcium hydroxide removal protocols on the dislodgement resistance of biodentine in an experimental apexification model

Background/purpose

Residual calcium hydroxide (CH) in the root canal dentine walls may influence the adhesion of tricalcium silicate-based materials. The aim of this study is to evaluate the effect of various CH removal protocols on the dislodgement resistance of biodentine from simulated immature root canals in an experimental apexification model.

Materials and methods

CH was applied to 120 simulated immature root canals. The samples were divided into 12 experimental groups (n = 10) according to the applied irrigation protocols used for the removal of CH: Group 1: Sodium hypochlorite (NaOCl), Conventional needle irrigation (CNI); Group 2: NaOCl, EndoActivator; Group 3: NaOCl, XP-endo Finisher; Group 4: NaOCl- Ethylenediaminetetraacetic acid (EDTA), CNI; Group 5: NaOCl-EDTA, EndoActivator; Group 6: NaOCl-EDTA, XP-Endo Finisher; Group 7: NaOCl+etidronic acid (HEBP), CNI; Group 8: NaOCl+HEBP, EndoActivator; Group 9: NaOCl+HEBP, XP-endo Finisher; Group 10: NaOCl- Peracetic acid (PAA), CNI; Group 11: NaOCl-PAA, EndoActivator; Group 12: NaOCl-PAA, XP-endo Finisher; Control Group: CH was not applied. Biodentine was placed at the apical thirds of 130 immature root canals. Vertical loading was applied to biodentine fillings inside the dentin discs. Maximum force to dislodge the material was statistically analyzed with ANOVA.

Results

The control, NaOCl+HEBP (CNI, EndoActivator, XP-endo Finisher) and NaOCl-PAA (EndoActivator, XP-endo Finisher) groups exhibited the lowest dislodgement resistance values (p < 0.001). When used CNI, irrigation with NaOCl+HEBP resulted in lower resistance to dislodgement of biodentine compared to NaOCl, and NaOCl-EDTA (p < 0.001).

Conclusion

Adhesion of apical barrier materials to root canal dentine can be influenced by the irrigation protocols used for CH removal.

The effects of sequential and continuous chelation on dentin

OBJECTIVE

Proteolytic and demineralizing agents have a profound influence on the dentin ultrastructure, which plays a key role in the mechanical integrity of the tooth and integrity of dentin-biomaterial interfaces. In-depth characterization of dentin treated with a novel root canal irrigation protocol comprising sodium hypochlorite (NaOCl) and etidronate (HEDP) is lacking. This study comprehensively characterized and compared the effects of the continuous chelation (NaOCl/HEDP) and sequential chelation (NaOCl/EDTA) protocols on dentin.

METHODS

Dentin blocks, dentin powder and root canals of mandibular premolars were distributed into Group 1, Saline (control); Group 2, NaOCl/EDTA; and Group 3, NaOCl/HEDP. Ultrastructural characteristics of the treated dentin were investigated using electron microscopy and light microscopy, while the surface roughness was analyzed using atomic force microscopy. Chemical compositional changes were characterized using Fourier transform infrared spectroscopy (FTIR) and energy-dispersive-X-ray spectroscopy (EDS), while collagen degradation was determined using ninhydrin assay. Data were statistically analyzed using multiple-factor one-way ANOVA and Tukey HSD tests (P = 0.05).

RESULTS

NaOCl/HEDP resulted in partially degraded, yet mineralized collagen fibers, with minimal alteration to the subsurface matrix. Conversely, NaOCl/EDTA dissolved the hydroxyapaptite encapsulation, exposing collagen fibre bundles. There was no significant difference in the surface roughness between the two protocols (P > 0.05). NaOCl/HEDP resulted in homogenous distribution of organic and inorganic components on the treated surface.

SIGNIFICANCE

This study highlighted that continuous chelation (NaOCl/HEDP) resulted in a frail surface collagen layer while sequential chelation (NaOCl/EDTA) exposed bare collagen fibres. These surface and sub-surface effects potentially contribute to structural failures of dentin and/or dentin-biomaterial interfacial failures.

A laboratory study of root canal and isthmus disinfection in extracted teeth using various activation methods with a mixture of sodium hypochlorite and etidronic acid

AIM

To evaluate in a laboratory setting the antibiofilm activity of several irrigating protocols including conventional irrigation, ultrasonic activation and XP-endo Finisher, with a mixture of sodium hypochlorite and etidronic acid in infected isthmuses and root canals of extracted human mandibular molar teeth.

METHODOLOGY

Fifty-six mesial roots of mandibular molars, half of them with a continuous isthmus from the cervical to the apical third between the two root canals (type 1), and the other half with a continuous isthmus from the cervical to the middle third and one canal in the apical third (type 2), were included. The root canals were contaminated for 7 days with an Enterococcus faecalis suspension. There were three experimental groups plus a control group (n = 7 per type of root canal anatomy). All the root canals, except for the control group that was not treated, were chemomechanically prepared and then assigned to one of the experimental groups according to the final adjunctive procedure: conventional irrigation, ultrasonic activation or XP-endo Finisher activation. The irrigating solution used was a combination of 2.5% sodium hypochlorite and 9% etidronic acid, and the final protocols were applied for three cycles of 30 s with a 3 mL volume. The antibiofilm activity was evaluated at each location (root canal and isthmus) and third (cervical, middle and apical) using confocal laser scanning microscopy and the live/dead technique. Statistical analysis was performed using SPSS (descriptive statistics) and SUDAAN (P-value calculations).

RESULTS

Root canals had significantly lower biovolume values than the isthmuses (P < 0.05). The biovolume in the root canals was significantly reduced in all the experimental groups in all the thirds except for conventional irrigation in the apical third (P > 0.05). In the cervical and middle thirds, ultrasonic activation was associated with the lowest biovolumes (P < 0.05), followed by XP-endo Finisher. In the isthmus, disinfection was similar in all the thirds for all the protocols. Conventional irrigation was associated with intermediate values with no significant differences from the control group or from the activated protocols (P > 0.05), although the latter were significantly different from the control group (P < 0.05). No differences were found between ultrasonic activation and XP-endo Finisher in the middle and apical thirds (P > 0.05) in the isthmuses.

CONCLUSIONS

In this laboratory study on extracted teeth, the isthmus was more difficult to disinfect than root canals. In the root canals, ultrasonic activation and XP-endo Finisher had a greater effectiveness than conventional irrigation. In the isthmuses, no differences were observed between the two activation techniques and conventional irrigation.

Comparison of Three Endodontic Irrigant Regimens against Dual-Species Interkingdom Biofilms: Considerations for Maintaining the Status Quo

Endodontic infections are often interkingdom biofilms, though current clinical management rarely considers this phenomenon. This study aimed to evaluate new and standard endodontic antimicrobial regimens against simple and complex Candida albicans and Enterococcus faecalis mono- and dual-species biofilms. C. albicans and E. faecalis mono- and dual-species biofilms were grown upon Thermanox™ coverslips and treated for 5 min with 3% NaOCl, 3% NaOCl followed by 17% EDTA, or 9% HEDP dissolved in 3% NaOCl. The number of cells remaining immediately after treatment at 0 h and after 72 h of regrowth were assessed using real-time quantitative PCR. All three treatment arms showed a similar positive antimicrobial effect on C. albicans and E. faecalis in both mono- and dual-species biofilms following initial treatment, resulting in ≥98% reduction in colony forming equivalent (CFE). Regardless of species or biofilm type (mono- or dual- species), the antimicrobial effect of NaOCl:HEDP mixture was comparable to that of NaOCl alone, with both showing significant regrowth after 72 h, whereas sequential treatment with NaOCl and EDTA consistently prevented significant regrowth. Our data suggest that sequential irrigation with NaOCl and EDTA remains the antimicrobial strategy of choice as it significantly reduces biofilm persistence and regrowth in our experimental dual-species biofilm conditions.

Resistance to compressive force in continuous chelation

Continuous chelation involves the simultaneous use of sodium hypochlorite and a chelating agent. Given the combination of a proteolytic agent and a demineralising chelator, this study aimed to investigate whether mixtures containing the weak chelators etidronate or clodronate and sodium hypochlorite could adversely affect the mechanical strength of teeth compared to the sequence sodium hypochlorite/EDTA/sodium hypochlorite. Matching pairs of bovine teeth were tested on a universal testing machine, and the compressive load at fracture was recorded. One root from each pair was prepared with the sequence, and the matching tooth was prepared with either water, the clodronate mixture or the etidronate mixture. No differences in load at fracture were seen between either mixture and the sequence. However, loads were higher in the teeth irrigated with water compared to the sequence. The results indicated that the continuous chelation mixtures did not alter tooth mechanical properties compared to the standard sequence.

Nanohardness reduction and root dentine erosion after final irrigation with ethylenediaminetetraacetic, etidronic and peracetic acids

AIM

To evaluate the nanohardness reduction and erosion in root canal dentine after application of 17% ethylenediaminetetraacetic acid (EDTA), 9% etidronic acid (HEBP) and 2% peracetic acid (PAA) either alone or combined with sodium hypochlorite (NaOCl).

METHODOLOGY

One hundred and sixty single-rooted teeth were decoronated and their root canals were chemomechanically prepared. For the nanohardness evaluation, 80 roots with instrumented canals were split longitudinally into two halves. Dentine blocks with a length of 7 mm were obtained from the middle third of one half of each tooth and were embedded in epoxy resin blocks exposing the root canal walls. Initial nanohardness values of root canal dentine were measured for each specimen using a nanoindenter with a Berkovich tip. The specimens were divided into seven experimental (n = 10) and one control (n = 10) group according to the final irrigation regimens: Group 1: 2.5% NaOCl, Group 2: 17% EDTA, Group 3: 2.5% NaOCl-17% EDTA, Group 4: 2% PAA, Group 5: 2.5% NaOCl-2% PAA, Group 6: 9% HEBP, Group 7: 2.5% NaOCl + 9% HEBP and Group 8: Distilled water (control). The measurement of the nanohardness values was repeated for each specimen after being exposed to the irrigants. The nanaohardness reduction of each sample was calculated and recorded. The other 80 instrumented root canals were used for scanning electron microscope (SEM) evaluation. First, they were irrigated with the same protocols stated above and longitudinally split into two halves. One half of each root canal was viewed using SEM for the amount of erosion. The erosion scores were recorded. Data were analysed statistically using Kruskal-Wallis and Bonferroni-adjusted Mann-Whitney U-tests with a significance level of 0.05.

RESULTS

Use of etidronic acid and NaOCl + HEBP reduced the nanohardness values significantly more than the other experimental solutions (P < 0.05). There was no significant difference between the values for the nanohardness reduction in the samples irrigated with a single chelator and chelator combined with NaOCl (P > 0.05). Peritubular and intertubular erosion were observed in the samples irrigated with HEBP and NaOCl + HEBP.

CONCLUSION

Final irrigation of root canals using etidronic acid alone or combined with NaOCl was associated with structural alterations in root canal dentine of extracted teeth.

The effect of root canal irrigants on dentin: a focused review

Despite the vast literature on the effects of root canal irrigants on the dentin characteristics, the precise effects of clinically relevant irrigation sequences remain unclear. In this review, we systematically dissect the role of different sequential irrigation approaches that are used in clinical endodontics. Using a systematic search strategy, we attempt to answer the question: ‘Which irrigating sequence has the most deleterious effects on dentin structure and properties?’ The effect of irrigants on the dentin composition and mechanical properties have been reviewed. A wide variety of concentrations, duration and techniques have been employed to characterize the effects of chemicals on dentin properties, thus making it impossible to draw guidelines or recommendations of irrigant sequences to be followed clinically. It was apparent that all the studied irrigation sequences potentially result in some deleterious effects on dentin such as decrease in the flexural strength, microhardness, modulus of elasticity and inorganic content and organic-inorganic ratio of the dentin. However, the literature still lacks comprehensive investigations to compare the deleterious effect of different irrigation sequences, using a wide variety of qualitative and quantitative methods. Such investigations are essential to make clinical recommendations and strategize efforts to minimize chemically-induced damage to dentin characteristics.

Influence of the Chelating Solutions in the Resistance of Glass Fiber Posts to the Root Dentin

Objective  This study aimed to evaluate the influence of chelating agents (EDTA, citric acid and Tetraclean) on glass fiber posts adhesion to root dentin.

Materials and Methods  Forty mandibular premolars single canals, with complete apical root, straight, circular cross sections were selected, accessed and had the cervical third prepared with Gates-Glidden drills, then included in resin, instrumented with ProTaper Universal and the root canal obturation was carried out. After, the samples were randomly divided into 4 groups (n = 10) to test the final irrigation solutions: G1:17% EDTA; G2:10% citric acid; G3: Tetraclean and G4: saline solution (control). After 30 days of storage (36.5° C and 100% humidity), the post preparation was performed leaving 4 mm of apical endodontic filling. Then, a fiber-glass post previously selected was coated with ED Primer adhesive system and resin sealer Panavia, installed and stored for 24 hours at 37°C. The samples were subjected to a tensile test with a constant speed of 1 mm/min with 2000 Kgf. The results were analyzed with the ANOVA test.

Results  The statistical analyzes indicated no significant differences between the groups (p > 0.05).

Conclusion  The type of chelating agent used in the final irrigation of the endodontic treatment did not influence the tensile strength of the fixation system used to sealer the glass fiber posts to the intracanal dentin.

Debris and Smear Layer Removal from Oval Root Canals Comparing XP-Endo Finisher, EndoActivator, and Manual Irrigation: A SEM Evaluation

Objective  This study aimed to assess and compare XP-Endo Finisher (XP) cleaning efficiency with respect to the amount of remaining debris and smear layer versus Max-I-Probe needle (CI), EndoActivator device (EA), and combination of XP-Endo Finisher file with EndoActivator device (XP+EA) in oval root canals.

Materials and Methods  This in vitro study was performed on 36 extracted single root/canal mandibular premolars. Radiographic images were taken in buccolingual and mesiodistal projections to evaluate the shape of the root canal and determine whether it met exclusion criteria. All teeth were decoronated and prepared using Reciproc (R40). The samples were divided randomly into four groups: CI, EA, XP, and XP + EA. The root canals were irrigated with 5 mL of 17% EDTA and 2.5% NaOCl, respectively. Apart from the CI group, both solutions were activated by using the tested techniques for 1 minute.

The teeth were split longitudinally, and the best visible identified sections of the roots were used as the representing samples for scanning electron microscope (SEM) evaluation. Each half was divided into the following three parts: 1 mm from the anatomic apex and a standardized photomicrograph with 500x and 1500x magnifications for debris and smear layer were obtained. A five-grade scoring system was utilized to quantify the results at the coronal, middle, and apical regions. Statistical analysis was performed by using the Kruskal–Wallis and Mann–Whitney U tests.

Results  Group differences in debris and smear layer scores were found statistically significant for all locations as well as for overall assessment, except for the coronal third. Intragroup comparison of debris and smear layer in CI, EA, and XP had the minimum score at the middle third, with no significant difference compared with the coronal and apical thirds. XP + EA had less debris and smear layer score at the coronal third, significantly different from apical third.

CI and EA had less debris and smear layer compared with XP and XP + EA at all locations with a significant difference at the middle and apical third ( p < 0.05).

Conclusion  EA and CI showed less debris and smear layer than XP and XP + EA in the middle and apical third. The use of the XP in conjunction with the present irrigation protocol failed to have debris-free dentin surface in the apical portion of most of the root canals.

Influence of sodium hypochlorite/etidronic acid combination and SmearOFF on push-out bond strength of fiber posts to root dentin

The aim was to evaluate the effects of different irrigation protocols on the bonding ability of fiber posts on root canal dentin through push-out test and the dentin tubule penetration of luting cement by confocal laser scanning microscope (CLSM). Forty-eight single-rooted premolars were divided into six groups (n=8) based on post space irrigation protocols: Saline 0.85%; Etidronate 18% (HEBP); EDTA 17%; NaOCl 5.25%+EDTA 17%; NaOCl 2.5%/HEBP 9% combination; SmearOFF. Two specimens per group were assessed with CLSM. The push-out test and the failure analysis were performed. Whilst EDTA had the highest bond strength at the coronal and middle thirds, it was not statistically significant compared to saline, HEBP, and NaOCl/HEBP at the middle third (p>0.05). Cement/dentin adhesive failures were predominant (41.9%) and the intratubular fluorescence intensity was significant among the groups (p<0.05). EDTA resulted in highest bond strength values and dentinal penetration.

Cytotoxic effects of alkaline tetrasodium EDTA irrigating solutions

The aim of this study is to determine the cytotoxic effects of tetrasodium ethylenediaminetetraacetic acid (EDTANa₄) when used alone or when combined with sodium hypochlorite (NaOCl), with and without the addition of cetrimide (CTR). Human pulmonary fibroblast cell line was exposed to the following irrigating solutions: group 1, 2.5% NaOCl; group 2, 10% EDTANa₄; group 3, 20% EDTANa₄; group 4, 2.5% NaOCl/5% EDTANa₄; group 5, 2.5% NaOCl/10% EDTANa₄; group 6, 2.5% NaOCl/5% EDTANa₄/0.2% CTR; group 7, 2.5% NaOCl/10% EDTANa₄/0.2% CTR; group 8, control, cells in Dulbecco's modified Eagle's medium. Methyl thiazol tetrazolium assay was used to determine the viability of cells after 1 and 24 h. Viability percentages were analyzed for global comparison using the Welch test followed by the Games-Howell test to determine groups with similar viability, and the Student's t test was used to compare the two times. The lowest viability was obtained with a 2.5% NaOCl solution at both time periods. The association of NaOCl with EDTANa₄ increased the cellular viability in direct relation with the concentration of the chelating agent. Globally, after 24 h of exposure, cell viability reduced. The solutions of EDTANa₄ showed moderate cytotoxic effects when compared with NaOCl alone.

Effect of different chelating agents and their surface tension on the amount of apically extruded debris

Background/purpose

During root canal preparation apical extrusion is an undesirable situation that can cause postoperative complications. The aim of the present study is to evaluate the effect of the presence of different chelators in root canals during preparation on the amount of apically extruded debris and to investigate the effect of surface tension of irrigant on the apical extrusion.

Materials and methods

Ninety extracted mandibular incisor teeth were included. Prior to canal preparation, the teeth were mounted to Eppendorf tubes. Root canals of the samples were prepared with Reciproc instruments in the presence of different chelating agents (17% EDTA-liquid, 17% EDTA-gel, 7% maleic acid, 2.25% peracetic acid, 10% citric acid) and 5% NaOCl. Apically extruded debris was collected in Eppendorf tubes and weighted with an electronic balance. The surface tension of solutions was calculated with the ring method using a du Noüy ring digital tensiometer. The statistical analysis was performed with Tamhane's T2 test for apical extrusion and the Tukey for surface tension. The correlation between apical extrusion and surface tension was compared using Pearson's coefficient.

Results

The least amount of apically extruded debris was with EDTA-gel, peracetic acid and citric acid which were similar to each other. NaOCl had the highest surface tension whereas peracetic acid and EDTA-liquid had the lowest. There was no significant correlation exists between apical extrusion and surface tension.

Conclusion

The presence of EDTA-gel, citric acid and peracetic acid in root canals during preparation decreased the amount of apically extruded debris compared to other solutions. The investigated irrigation solutions have no significant effect on the amount of apical debris extrusion.