Effect of ethylene diamine tetra-acetic acid, MTAD™, and HEBP as a final rinse on the microhardness of root dentin

Effect of Different Irrigating Solutions on Root Canal Dentin Microhardness-A Systematic Review with Meta-Analysis

The aim of this study was to evaluate the effect of different irrigating solutions as well as their combination and activation modes on root canal dentin microhardness. The protocol was registered in PROSPERO and PRISMA guidelines were followed. The structured question was as follows: "Which type of irrigating solution used in endodontic treatment causes more change in dentin microhardness?" The literature was screened via PubMed, Google Scholar, Scopus, and Science Direct. The last search was carried out in February 2023 with English language restriction. Two reviewers independently performed screening and evaluation of articles. A total of 470 articles were retrieved from all the databases, whereas only 114 articles were selected for full-text analysis. After applying eligibility criteria, 44 studies were evaluated and included in this review. The results showed that with increased contact time with irrigants, dentin microhardness decreases. Increased contact time with sodium hypochlorite (NaOCl) was associated with more reduction in dentin microhardness compared with other irrigants. Other irrigants, with the exception of distilled water, including EDTA, citric acid, herbal irrigants, glycolic acid, phytic acid, etc., in this study significantly decreased dentin microhardness. The maximum reduction in dentin microhardness was seen with 2.5% NaOCl after 15 min of contact time. The use of irrigating solutions alters the chemical composition of dentin, thereby decreasing its microhardness, which affects the clinical performance of endodontically treated teeth.

Is a mix - A fix? "A microscopic analysis of depth of penetration of three combinations of irrigants"

Aims

The aim of the study is to evaluate the penetration depth of irrigants mixed with NaOCl into dentinal tubules at the apical third of the root canal using a confocal laser scanning microscope (CLSM).

Materials and Methods

Thirty-six single-rooted teeth were selected, decoronated, and straight-line access established. Then, the canal was enlarged with hand Protaper till size F3. The samples were divided randomly into three groups: Group 1 was irrigated with 3% NaOCl mixed with 1% phytic acid; Group 2 was irrigated with 3% NaOCl mixed with 18% etidronic acid; and Group 3 was irrigated with 3% NaOCl mixed with chitosan. The samples were subjected to CLSM evaluation. One-way analysis of variance with Tukey's post hoc was used for statistical analysis.

Results

Group 3 (NaOCl with chitosan) showed a greater depth of penetration in comparison to Groups 1 and 2.

Conclusion

Within limitations, it can be concluded that chitosan, in combination with NaOCl can be used as an alternative to the current irrigation protocol.

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.

Effect of prewarming and continuous warming on tissue dissolving ability of Triton™ versus Twin Kleen™: An in vitro study

Context

TwinKleen™ and Triton™ are newer all-in-one irrigants that have simultaneous action on both organic and inorganic contents. Studies comparing their tissue dissolving ability (TDA) either at room temperature (RT) or on prewarming (PW) and continuous warming (CW) are not yet reported.

Aims

To evaluate and compare the effect of 3% sodium hypochlorite (NaOCl), Twin Kleen™, and Triton™, on the bovine TDA.

Materials and Methods

One hundred and twenty tissue specimens (size 4 mm × 4 mm × 2 mm and weight 37 ± 3 mg) were divided into Group 1, normal saline (negative control); Group 2, 3% NaOCl (positive control); Group 3, Twin Kleen™; and Group 4, Triton™ (n = 30) Each group is further divided into three subgroups with ten samples each as sub group a - at room temperature (RT), sub group b - on pre warming (PW) and sub group c- on continuous warming (CW), Tissue specimens were immersed in test tubes with 5 ml of respective irrigants replenished thrice every 15 min. The percentage difference in tissue weights was calculated after 5, 10, and 15 min.

Statistical Analysis Used

Multiple intergroup comparisons were done using Tukey's multiple-comparison test, using SPSS software version 23.0.

Results

Both Triton™ and 3% NaOCl showed significantly higher dissolution than normal saline and Twin Kleen™ on CW followed by PW than at RT. Twin Kleen™ showed significantly less dissolution at all the tested temperatures.

Conclusions

Heating enhances the TDA of Triton™ and 3% NaOCl but not Twin Kleen™. CW showed significantly higher dissolution than PW.

Flexural strength and microhardness of human radicular dentin sticks after conditioning with different endodontic chelating agents

Introduction

The objective of this in vitro study was to examine the impact of different endodontic chelating agents on the flexural strength and microhardness of root dentin.

Materials and Methods

Fourty dentin sticks of (1 mm × 1 mm × 12 mm) were obtained from 10 single-rooted premolars and divided into four groups (n = 10). One stick from each tooth was assigned to one of the experimental groups and was soaked in one of the experimental chelating solutions for 5 min 17% ethylenediaminetetraacetic acid (EDTA), 2.5% phytic acid (PA), 18% etidronic acid, or saline (control group). Following the 5-min soak, the sticks' flexural strength was evaluated using a 3-point loading test using the universal testing machine, and the surface microhardness was tested using a Vickers's microhardness tester.

Results

PA (2.5%) and etidronic acid (18%) showed no significant detrimental effect on either the flexural strength or the surface microhardness of radicular dentin compared to the control. EDTA (17%) exhibited a significant drop in the flexural strength and microhardness of radicular dentin compared to the other groups.

Conclusions

PA and etidronic acid chelators do not compromise the surface and bulk mechanical properties of radicular dentin.

Effects of conventional and herbal irrigants on microhardness and flexural strength of root canal dentin: An in vitro study

Aim:

The aim of this in vitro study was to compare the effects of herbal irrigants with conventional irrigants on microhardness and flexural strength of root dentin.

Materials and Methods:

Sixty extracted permanent maxillary canines were selected. Decoronated roots were sectioned longitudinally into buccal and lingual segments to get 120 specimens. These were embedded in auto polymerizing acrylic resin and further grounded with fine emery papers under distilled water. Of these, 100 root segments without any defects were selected, further divided into four test groups and a control group according to the irrigants used (n = 20). Group 1: 2.5% Sodium hypochlorite, Group 2: Miswak stick extract, Group 3: Cashew leaves extract. Group 4: Mango leaves extract and Group 5: Normal saline (control). All specimens were treated with 5 ml of each irrigant for 10 minutes and rinsed immediately. Dentin microhardness was measured with a Vickers indenter, and the flexural strength test was done using a universal testing machine. The data were analyzed using one-way ANOVA and the intergroup comparison by student t-test.

Results:

The experimental groups showed a significant reduction in microhardness values when compared with the control group. Intragroup comparison among experimental groups, herbal irrigants showed the least reduction in microhardness values at cervical, middle, and apical thirds. When compared to the control group, the flexural strength values decreased significantly with experimental groups.

Conclusion:

Within the limitation of this study, it was concluded that herbal irrigants were least detrimental to root dentin microhardness when compared with conventional irrigant. But the flexural strength was equally reduced by both conventional and herbal irrigants.

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.

Evaluation of the effects of the solution used for electrochemical dissolution of nickel-titanium endodontic files on dentine structure, microhardness and cell viability

AIM

To evaluate the effects of the [NaF 12 g L^-1  + NaCl 1 g L^-1 ] solution used in the electrochemical dissolution process of fractured endodontic files, as well as its NiTi-containing product, on dentine hardness, topography and human fibroblast viability.

METHODOLOGY

Sixty single-rooted human teeth were evaluated for dentine microhardness using the Vickers hardness test and the area and number of dentinal tubules by scanning electron microscopy. The samples were divided according to the dentine surface treatment: distilled water; 17% EDTA; [NaF 12 g L^-1  + NaCl 1 g L^-1 ]; and 17% EDTA + [NaF 12 g L^-1  + NaCl 1 g L^-1 ]. Thirty-six single-rooted human teeth were divided according to the irrigation protocol: Dulbecco's Modified Eagle's Medium + 10% foetal bovine serum; 5.25% NaOCl; [NaF 12 g L^-1  + NaCl 1 g L^-1 ]; and [NaF 12 g L^-1  + NaCl 1 g L^-1  + NiTi]. The extracts in contact with the apical foramen were used in the MTT assay to evaluate human fibroblast viability, with dilutions of 100%, 50%, 25% and 12.5%. Statistical tests used were paired t-tests, one-way anova, Tukey's test, Kruskal-Wallis test and Dunn's post-test.

RESULTS

The [NaF 12 g L^-1  + NaCl 1 g L^-1 ] solution did not modify dentine microhardness or the average dentinal tubule area. However, EDTA induced changes in dentine structure and microhardness (P < 0.05). The [NaF 12 g L^-1  + NaCl 1 g L^-1 ] solution, and its NiTi-containing product had lower cytotoxicity than NaOCl at dilutions of 25% and 50% (P < 0.01).

CONCLUSIONS

The [NaF 12 g L^-1  + NaCl 1 g L^-1 ] solution did not alter dentine microhardness or damage the dentine structure. It also demonstrated lower cytotoxicity than NaOCl.

A comparative evaluation of the effect of 8% and 17% ethylenediaminetetraacetic acid exposure for 1 min and 10 min on the fracture resistance of endodontically treated roots: An in vitro study

Objective:

The objective of this study was to evaluate the effect of 8% and 17% ethylenediaminetetraacetic acid (EDTA) exposure for 1 min and 10 min on the fracture resistance of endodontically treated roots.

Methodology:

Sixty human single-rooted teeth were decoronated and divided into six groups (n = 10). Canal preparation was carried out except in negative control group, using the ProTaper rotary file system. Final irrigation was performed using distilled water, 17% EDTA for 1 min and 10 min, 8% EDTA for 1 min and 10 min. Thereafter, roots were obturated with ProTaper F3 Gutta-percha points and AH Plus sealer using a single-cone technique. The specimens were loaded vertically at 1 mm/min crosshead speed until vertical root fracture occurred. Results were evaluated statistically with one-way analysis of variance and post hoc Tukey test.

Results:

Analysis of results showed that the unprepared roots showed the highest fracture resistance and roots irrigated with 17% EDTA for 10 min showed the lowest fracture resistance. The mean fracture resistance of unprepared roots, roots irrigated with 8% EDTA for 10 min and 17% EDTA for 1 min was significantly higher than roots irrigated with 8% EDTA for 1 min, 17% EDTA for 10 min and distilled water.

Conclusion:

From a clinical viewpoint, if EDTA has to be used, it is safer to use higher concentration for a shorter application time or a low concentration with a longer application time. Prolonged use of high concentrations of EDTA might increase the risk of root fracture.

Effect of application time of maleic acid on smear layer removal and mechanical properties of root canal dentin

OBJECTIVES

To evaluate the effect of maleic acid (MA) on the cleaning efficacy and mechanical properties of root canal dentine with respect to different time exposure.

MATERIALS AND METHODS

One hundred and eighty single-canal premolars were instrumented with rotary-files and then randomly assigned to test groups receiving 7% MA for 30 s, 45 s, 1 min, or 3 min or to control groups treated with 0.9% saline or 17% ethylenediaminetetraacetic acid for 45 s. The micro-hardness, nano-hardness and elastic modules were measured before and after treatment, while the amount of smear and erosion in the coronal, middle and apical thirds in root canal were evaluated by scanning electron microscopy, finally, the fracture strength was assessed by vertical root fracture testing.

RESULTS

The efficacy of smear layer removal increased with increasing MA application time. The largest effect was observed at 45 s, even in the apical third, whereas the treatment for 1 min resulted in irreversible erosion of the dentine surface. The micro-hardness and nano-indentation testing confirmed that the micro- and nano-scale mechanical properties were significantly decreased after MA application for 1 min. Furthermore, the specimens treated with MA for 3 min presented the lowest fracture resistance among all groups. In contrast, the 45 s treatment appeared to increase the fracture resistance of the tooth.

CONCLUSIONS

The cleaning efficacy and mechanical properties of root canal dentine varied with MA exposure time. The application of MA for 45 s was found to be the most promising for clinical use.

Comparative evaluation of efficacy of ethylenediaminetetraacetic acid, maleic acid, and dimercaptosuccinic acid against the combination of these with sodium hypochlorite for removal of smear layer: An in vitro scanning electron microscope study

Context:

The effect of dimercaptosuccinic acid (DMSA) and maleic acid (MA) when used alone on smear layer has been evaluated with mixed results, but their effect when combined with sodium hypochlorite (NaOCl) has not been studied.

Aim:

To compare the effectiveness of ethylenediaminetetraacetic acid, MA, and DMSA against the combination of these with NaOCl in the removal of smear layer.

Settings and Design:

n = 4pq/L²

q = 1 − p

p = Incident rate

L = Allowable error

Methods:

One hundred and forty extracted, anterior teeth were radiovisiographically assessed. Access preparation was done; apical patency was established. Cleaning and shaping was accomplished using step-back technique. The specimens were randomly allocated as per the final irrigation protocol. After final irrigation, teeth were prepared for scanning electron microscope analysis, and the middle and apical thirds of radicular dentin were evaluated at ×1000 for evaluation of severity of occlusion of dentinal tubules with smear layer.

Statistical Analysis:

The data were statistically analyzed using the Student's t-test and kappa test.

Results:

For combined irrigation, 10% DMSA + NaOCl was significantly better than all other groups both in the middle third and the apical third. It was more effective in the middle third than at apical third.

Conclusion:

Ten percent DMSA in combination with NaOCl removes the smear layer more effectively at both the middle and apical third.

Effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% ethylenediaminetetraacetic acid, and 18% etidronic acid on Candida albicans: An in vitro study

AIM

The aim of this study was to evaluate the effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% EDTA and 18% etidronic acid against C. albicans.

METHODOLOGY

Dentin powder was prepared from mandibular first premolar using electrical grinder and sterilized. 3% NaOCl, 2%CHX, 17% EDTA and 18% etidronic acid were tested against C. albicans in the presence and absence of dentin, in eppendorf tubes. Group 1 (presence of dentin):- 100ul dentin powder + 100ul C. albicans suspension + 100ul irrigating solution. Group 2 (absence of dentin):- 100ul C. albicans suspension+ 100ul irrigating solution.

CONTROL GROUP

- 100ul C. albicans suspension.+ 100ul sterile saline Suspension was thoroughly mixed, submitted for serial dilution upto10-5 after 1 min and colony forming units were counted.

RESULTS

In group 2 (without dentin powder), 3% NaOCl and 2% CHX showed the lowest bacterial count compared to group 1 (with dentin powder). Dentin had a significant inhibitory effect on 3% NaOCl (P < 0.001) and 2% CHX (P<0.001). 17% EDTA showed lowest bacterial count in group 1 (with dentin powder) compared to group 2 (without dentin powder). 18% Etidronic acid showed similar bacterial counts in the both the groups. No reduction was observed in the control group.

CONCLUSION

NaOCl & EDTA showed measurable antimicrobial effect even in the presence of dentin which can be promising in the reduction of C. albicans in root canal therapy.

Dentine microhardness changes following conventional and alternate irrigation regimens: An in vitro study

AIM

To compare the changes in microhardness of root dentin caused by two novel irrigation regimens with conventional irrigation.

MATERIALS AND METHODS

Forty extracted human permanent incisor teeth were selected. Decoronated roots were separated longitudinally to get 80 specimens that were embedded in autopolymerizing acrylic resin and grounded flat with silicon carbide abrasive papers. Of these, 60 root segments without any cracks or defects were selected and divided into four groups according to the irrigation regimen used (n = 15). Group I: 5% sodium hypochlorite (NaOCl) + 17% ethylenediaminetetraacetic acid (EDTA) + 0.2% chlorhexidine digluconate (CHX) (conventional). Group II: 6% Morinda Citrifolia Juice + 17% EDTA (MCJ). Group III: 5% NaOCl + Q Mix 2 in 1 (QMix). Group IV: Distilled water (control). Irrigation regimens were performed for 5 minutes. Dentin microhardness was measured with a Vickers indenter under a 200-g load and a 20-s dwell time at the midroot level of root dentin. The data were analyzed using Kruskal Wallis test and Dunn's multiple comparison tests.

RESULTS

A significant difference was seen in the median values of the four groups. The control group showed the least reduction in microhardness when comparison with the other groups. Except for Group III (Q Mix), the other groups that were tested (MCJ and conventional regimens) showed statistically significant difference from the control group.

CONCLUSION

Within the limitation of this study, it was concluded that NaOCl + Q Mix were least detrimental to root dentin microhardness when compared with MCJ and conventional irrigation regimens.

Comparative Evaluation of the Effect of EDTA, EDTAC, NaOCl and MTAD on Microhardness of Human Dentin - An In-vitro Study

AIM

The aim of this study was to evaluate the microhardness of human dentin by using four irrigating solutions. Materials and Methodos: A total of 40 extracted mandibular premolars were selected and sectioned horizontally in the middle third of the root. Forty specimens of 4 mm thickness were embedded in acrylic resin and polished. Four test groups, each group containing ten specimens were immersed in respective irrigating solution and subjected to vicker's microhardness test at T0, T2 and T5min.

STATISTICAL ANALYSIS

The data obtained were analyzed using the one way ANOVA followed by Tukey HSD method with ap=0.05 as the level for statistical significance.

RESULTS

Suggested that there was no statistically significant difference in mean values between four experimental irrigating solutions.

CONCLUSION

Mixture of Tetracycline isomer i.e. Doxycycline, Citric acid and a Detergent (Tween 80) MTAD not altered the microhardness of root canal dentin significantly and seems to be an appropriate irrigating solution, because of its harmless effect on the microhardness of the root canal dentin.

Comparative evaluation of the efficacy of different irrigants including MTAD under SEM

Context:

During biomechanical preparation, a smear layer is formed which occludes the openings of dentinal tubules and disfavors the penetration of irrigants. Hence, such layers should be removed. It becomes more challenging when we approach the apical third of the root canal.

Aim:

The aim was to compare the efficacy of different irrigants including ethylenediaminetetraacetic acid (EDTA), EDTA along with ultrasonication, citric acid, and mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final irrigants where sodium hypochlorite (NaOCl) was used in each experimental group during root canal preparation with special emphasis on the apical third.

Settings and Design:

Forty-five human upper anterior teeth were selected and divided into one control group (group 1) and four experimental groups (group 2 to group 5), each containing nine teeth. All the four experimental groups were irrigated with 5.25% NaOCl solution during preparation, whereas test irrigants (5 mL) as the final solution used in each experimental group were 17% EDTA, 17% EDTA along with ultrasonication, 25% citric acid, and MTAD, respectively. The samples were prepared and observed under a scanning electron microscope (SEM). The photomicrographs were recorded and evaluated with a scoring system.

Statistical Analysis Used:

Data were analyzed using Kruskal-Wallis test and Dunn's test (P = 0.05).

Results:

None of the combined irrigants was found completely effective. All the test irrigants including MTAD worked well in the middle and cervical third, whereas MTAD showed excellent results in the apical third as compared to the other groups.

A new weak chelator in endodontics: effects of different irrigation regimens with etidronate on root dentin microhardness

This study investigated the effect of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic (EDTA), etidronic (HEBP), and citric acid (CA) associated in different irrigation regimens on root dentin microhardness. Forty-five root halves of single-rooted teeth were sectioned into thirds that were embedded in acrylic resin, polished, randomly assigned into 3 groups, and treated as follows: G1: saline solution; G2: 5% NaOCl + 18% HEBP, mixed in equal parts; and G3: 2.5% NaOCl. After measurements, the G3 samples were distributed into subgroups G4, G5, and G6, which were submitted to 17% EDTA, 10% CA and 9% HEBP, respectively. Following the new measurements, these groups received a final flush with 2.5% NaOCl, producing G7, G8, and G9. Microhardness was measured with Knoop indenter under a 25 g load for 15 seconds, before and after treatments. The data were statistically analyzed using paired Student's t-test (α<0.05) to compare values before and after treatments and analysis of variance (ANOVA) (α<0.05) to detect any differences among thirds. Except G1, all tested irrigation regimens significantly decreased the microhardness. There were no differences between root thirds before treatments, and all root thirds exhibited equal responses to same treatment. Except saline, all tested irrigation regimens reduced the root dentin microhardness.

Chitosan: effect of a new chelating agent on the microhardness of root dentin

The effect of solutions of 0.2% chitosan, 15% EDTA and 10% citric acid on the microhardness of root dentin was evaluated comparatively in this study. Thirteen sound human maxillary central incisors were selected and decoronated at the cementoenamel junction. Ten roots were set into rapid polymerization acrylic resin and the root/resin block was fitted to the cutting machine to obtain slices from the cervical third. The first slice was discarded and the second slice was divided into four quadrants. Each quadrant was used to construct a sample, so that 4 specimens were obtained from each root slice, being one for each chelating solution to be tested: 15% EDTA, 10% citric acid, 0.2% chitosan and distilled water (control). The specimens were exposed to 50 μL of the solution for 5 min, and then washed in distilled water. A microhardness tester (Knoop hardness) with a 10 g load was used for 15 s. Data were analyzed statistically by one-way ANOVA and Tukey-Kramer test (α=0.05). The other 3 roots had the canals instrumented and irrigated at the end of the biomechanical preparation with the test solutions, and then examined by scanning electron microscopy (SEM) for qualitative analysis. All solutions reduced the microhardness of root dentin in a way that was statistically similar to each other (p>0.05) but significantly different from the control (p>0.05). The SEM micrographs showed that the three solutions removed smear layer from the middle third of the root canal. In conclusion, 0.2% chitosan, 15% EDTA and 10% citric acid showed similar effects in reducing dentin microhardness.