Rational design of EDTA-incorporated nanoflowers as novel and effective endodontic disinfection against biofilms

The ethylenediaminetetradiacetic acid (EDTA) is one of the most commonly used irrigation solutions. Although EDTA has a very low antimicrobial property, it is used to remove inorganic part of smear layer in areas of root canal system. Herein, we developed EDTA-incorporated nanoflowers (EDTA NFs), for the first time, as novel and effective irrigation solution with quite high antimicrobial property to provide complete disinfection in root canal system. We both systematically elucidated the formation of the EDTA NFs with various techniques, and their catalytic and antimicrobial activities in the presence of hydrogen peroxide (H2O2) were documented through intrinsic EDTA property and peroxidase-like activities.

Evaluation of the effect of graphene oxide-based nanocomposites on smear layer by a scanning electron microscope: Laboratory investigation

This study is to examine the effect of graphene oxide (GO) and GO-based nanocomposites (GO_EDTA, GO_CHIT) on the smear layer by scanning electron microscopy (SEM). Sixty human single-rooted anterior teeth were used. Samples were randomly categorised into six groups. Distilled water in group 1, 17% EDTA in group 2, chitosan (CHIT) solution in group 3, GO solution in group 4, GO_EDTA solution in group 5 and GO_CHIT in group 6 were used as irrigation solutions. Photomicrographs were acquired from the coronal, middle and apical parts of the samples by SEM. Statistical analyses were performed using Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests. There was a statistically significant difference among the groups (p < 0.003). Adding GO to CHIT and EDTA did not affect removing the smear layer in all segments (p < 0.003). Incorporating GO into EDTA and CHIT solutions did not change their interaction with the smear layer.

Computational fluid dynamics investigation on the irrigation of a real root canal with a side-vented needle

BACKGROUND

Root canal therapy is one of the main treatments for root canal diseases, and effective irrigation is the key to successful treatment. Side-vented needle is one of the commonly used needle types in clinic. In the real root canal, due to the influence of the curvature of the root canal, the irrigation flow field in different needle directions shows obvious differences. At the same time, changes in root canal curvature and working depth will lead to changes in irrigation efficiency and the flow field. Both the mainstream of the irrigation flow and the shear stress near the wall changes significant. Consequently, either the replacement in the root canal or the removal efficiency of the smear layers is apparently modified.

MATERIALS AND METHODS

In this paper, the permanent root canal of the maxillary first molar prepared until 15/04 were scanned by micro-CT, and then imported into the software for 3D reconstruction. The key parameters of flushing efficiency of 30G side needle at different working depths of 4.75 mm, 5 mm, 5.25 mm and 5.5 mm were compared. Meanwhile, the simulated models with different curvatures of 0°, 5°, 10°, 20° and 30° based on the real root canal were reconstructed to investigate the curvature effect on the irrigation efficiency.

RESULTS

The results show that moderate working depth (such as 4.75 mm and 5.25 mm in present paper) helps to improve the replacement capacity of irrigation flow. At the same time, the apical pressure decreased as the working depth increased. The curvature of the root canal seriously affects the removal depth of the smear layers of the root canal. A root canal with a large curvature (especially 20° and 30°) can significantly improve the difficulty of irrigation.

CONCLUSIONS

(1) Moderate working depth helps to improve the displacement capacity, the ERD of the irrigation flow is generally improved at the working depths of 4.75 mm and 5.25 mm, and the apical pressure will decrease with the increase of working depth. (2) The large curvature of the root canal can significantly improve the difficulty of irrigation. The curvature of the root canal can severely influence the removal depth of the smear layer on the wall. It can be found both the span and the depth of the ESS for little curvatures (5° and 10°) root canals are higher than those for large curvatures (20° and 30°).

Effectiveness of Triton Irrigation Solution in Smear Layer Removal: An in-vitro Study

OBJECTIVE

This in vitro study aimed to compare and evaluate the effectiveness of different irrigation solutions, including Triton, 0.5% Chitosan nanoparticles (CNP), and 17% ethylenediaminetetraacetic acid (EDTA), on the smear layer removal of the root canal walls.

METHODS

Forty extracted sound mandibular premolars were examined; the samples were decoronated to obtain a root length of 14 mm. Each sample was instrumented using ProTaper Next rotary file X4 (40/0.06). The samples were longitudinally sectioned and examined under a scanning electron microscope at 3000x magnification in the coronal, middle, and apical thirds using a four-level scoring system.

RESULTS

Triton demonstrated the lowest mean smear layer removal (p>0.05) compared to the other irrigation solutions at all the levels of the root canal. No significant differences were observed (p>0.05) at the coronal and middle levels of the root canal between the CNP and EDTA groups. CNP demonstrated significantly more smear layer removal at the apical level compared to EDTA.

CONCLUSION

Smear layer removal was least effective with Triton at all the levels of the root canal compared to the other irrigation solutions tested in this study. CNP demonstrated superior smear layer removal at the apical level compared to the other irrigation solutions.

Assessment of the Smear Layer Removal Efficacy of Three Different Agents on Periodontally Compromised Tooth: An In Vitro Study

AIM

The purpose of the present study was to evaluate the smear layer removal efficacy of three various agents on periodontally compromised tooth.

MATERIALS AND METHODS

The current study included 75 molar teeth that were extracted due to periodontal disease. After that, 25 samples were randomly assigned using a simple random technique to the three different agent groups, group A: Scaling and root planing (SRP) and application of SofScale agent, group B: SRP and application of QMix agent, group C: SRP and application of MTAD agent. Using a diamond circular saw, the treated portions were divided into horizontal and vertical halves. All samples were viewed under Scanning Electron Microscope. Every tooth was focused at the coronal third, middle third, and apical third portion with a magnification of 1000×. Data were recorded and statistically analyzed.

RESULTS

The smear layer removal efficacy was more in the QMix agent (3.06 ± 0.04) group followed by MTAD agent (3.28 ± 0.09) and SofScale agent (4.14 ± 0.10) group on the root surface. On intra group comparison, there was a statistically significant difference found in all the intra group agents with all the three levels. On inter group evaluation, at coronal third, there was no significant difference found between the different agents. There was a significant difference found between the different agents at middle and coronal third.

CONCLUSION

On conclusion, the current investigation found that, the root surfaces treated with QMix shown a greater ability to remove smear layers compared to tooth surfaces treated with MTAD and SofScale agent.

CLINICAL SIGNIFICANCE

Conventional therapies such as SRP effectively eliminate calculus, plaque, and necrosed cementum; nevertheless, they leave behind a smear layer that could impede normal healing. In an effort to overcome this, root conditioning agents were applied on the root surface to remove the smear layer. The traditional root conditioning agents such as citric acid have certain disadvantages, though, such as an acidic pH that could harm the root surface. As a result, researchers have been looking for biocompatible root conditioning treatments that are more effective. How to cite this article: Singh DK, BS Raj H, Soans CR, et al. Assessment of the Smear Layer Removal Efficacy of Three Different Agents on Periodontally Compromised Tooth: An In Vitro Study. J Contemp Dent Pract 2024;25(2):156-159.

Effect of EDTA Activation on Blood Clot Structure in Regenerative Endodontics: A Scanning Electron Microscopy Study

INTRODUCTION

EDTA plays a crucial role in regenerative endodontic therapy (RET) because of its significant biological effects. However, EDTA is also recognized as the preferred anticoagulant for hematologic tests. Thus, this study aimed to assess the influence of different EDTA activation techniques on the morphology of blood clots after conditioning the root canal dentin.

METHODS

Forty extracted human teeth were prepared to simulate immature teeth and divided into the following 5 groups: (1) saline solution (negative control), (2) EDTA 17% + saline solution (CNI), (3) CNI + ultrasonic activation, (4) CNI + Easy clean activation, and (5) CNI + XP-endo Finisher activation. After irrigation, the roots were cleaved, and the root canals were filled with human blood to clot formation. The morphology and density of erythrocytes, platelets, and the fibrin network were observed using a scanning electron microscope. The fibrin network density was classified using a 4-point scale. Data were analyzed using the Friedman test and the Kruskal-Wallis test with Bonferroni adjustment (α = 5%).

RESULTS

All groups exhibited consistent blood clot morphology characterized by a high density of erythrocytes, platelets, and white blood cells throughout the entire length of the root canal. The negative control group showed statistically significant high scores of fibrin density compared with the CNI group in all root thirds (P < .05). However, there was no statistical difference in the scores for the fibrin network density between the groups irrigated with EDTA with and without activation (P > .05).

CONCLUSIONS

EDTA may impair the fibrin network formation compared with the saline group. However, EDTA activation did not significantly change the effects on the blood clot in contact with the conditioned intraradicular dentin.

Canal disinfection using photo-chemically activated micro-bubble emulsion, Emblica officinalis, and Nd: YAP laser on smear layer and push-out bond strength of resin-based root canal sealer to the radicular dentin

AIMS

Evaluation of the effects of the latest root canal disinfectants i.e., Micro-bubble emulsion (MBE), Neodymium-doped yttrium aluminum perovskite (Nd: YAP), Emblica officinalis (E. officinalis) on the removal of smear layer (SL) and push out bond strength (PBS) of resin-based root canal sealer to the radicular dentin.

METHODS

The coronal portion of sixty single-rooted human mandibular premolar teeth was precisely sectioned at the cementoenamel junction. The canals were prepared to utilize ProTaper universal rotary files till F3. All the study specimens were divided into four groups based on the disinfection regime (n = 15) Group 1: 5.25% NaOCl, Group 2: MBE, Group 3: Nd: YAP laser and Group 4: E. officinalis extract. All the canals were then finally irrigated using 17% EDTA solution as a final disinfecting agent. SL removal assessment was performed on five samples from each group using a scanning electron microscope (SEM). Ten samples from each group were then filled with root canal filling material and the roots were sectioned. Push-out test and failure mode analysis were performed using the universal testing machine (UTM) and stereomicroscope respectively. The mean scores of PBS and SL removal were compared using a one-way analysis of variance (ANOVA) and Post Hoc Tukey's HSD test p = 0.05.

RESULTS

Group-2 (MBE + EDTA) coronal section (1.50 ± 0.23) exhibited the most effective eradication of SL from the canal space. The apical third of Group-1 (NaOCl+EDTA) (2.68 ± 0.82) samples demonstrated the least effective removal of SL from the radicular canal. The maximum score of PBS of AH plus sealer to the canal dentin was exhibited by the coronal section of Group-2 (MBE + EDTA) (9.55 ± 0.45 MPa) samples. However, the apical third of Group-1 (NaOCl+ EDTA) specimens (5.16 ± 0.32 MPa) demonstrated the minimum EBS.

CONCLUSION

MBE+ EDTA displayed better smear layer removal and bond integrity of AH plus sealer to the root canal dentin. Nd: YAP+ EDTA laser and E.officinalis displayed comparable outcomes to that of control NaOCl+ EDTA.

The comparative of chitosan and chitosan nanoparticle versus ethylenediaminetetraacetic acid on the smear layer removal: A systematic review and meta-analysis of in vitro study

The purpose of this systematic review of meta-analysis was to compare the effectiveness of removing the smearing layer using EDTA versus Chitosan (Ch) and Chitosan nanoparticles (Ch-NPs). A search was performed in four electronic databases (Web of Science, PubMed, Scopus, and Cochrane). The included studies were assessed by two reviewers using Joanna Briggs Institute's critical appraisal checklist for the quasi-experimental studies. Outcomes obtained by scanning electron microscopy (SEM) and conventional methods were presented as standardized mean differences alongside 95% confidence intervals. Seven investigations employed 212 single-root teeth. In the apical section (p = .317, 95% CI = -0.820 to 0.266, Tau2  = 0.387), middle segment (p = .914, 95% CI = -1.019 to 0.912, Tau2  = 1.027), and coronal segment (p = .277, 95% CI = -1.008 to 0.289, Tau2  = 0.378). This meta-analysis found no difference between Ch, Ch-NPs, and EDTA in removing the smear layer in the three segments. This systematic review is designed to show evidence related to the PICO question, in which our outcome is smear layer removal and not the clinical success of such a treatment. RESEARCH HIGHLIGHTS: The study aimed to compare the effectiveness of chitosan and chitosan nanoparticles with ethylenediaminetetraacetic acid (EDTA) in removing the smear layer, a layer of debris and organic material on the tooth surface, through a systematic review and meta-analysis. The removal of the smear layer is crucial for successful dental treatments, as it enhances the adhesion of restorative materials and improves the penetration of antimicrobial agents into dentinal tubules. The researchers conducted a systematic review and meta-analysis, searching various databases of electron microscopy results for relevant in vitro studies comparing the effects of chitosan or chitosan nanoparticles with EDTA on smear layer removal. The results encourage further exploration of chitosan and chitosan nanoparticles for clinical use in dentistry, while considering their specific applications and long-term effects.

Comparison of Easydo Activator, ultrasonic and needle irrigation techniques on sealer penetration and smear layer removal in vitro

The effects of Easydo Activator (EA), a new sonic irrigation system, on sealer penetration at the root apex were compared to needle irrigation (NI) and passive ultrasonic irrigation (PUI) in this study. Forty-two single-rooted teeth were prepared and randomly divided into three groups (n = 14): group 1: NI; group 2: PUI; and group 3: EA. A solution of 3% sodium hypochlorite (NaOCl) was used for irrigation. Nine teeth in each group were filled with AH Plus sealer mixed with CY5 fluorescent dye and a single gutta-percha cone. The sealer penetration area, maximum penetration depth and percentage of sealer penetration at 5 mm and 1 mm from the apex were analyzed by confocal laser scanning microscopy (CLSM). The remaining 5 teeth in each group were subjected to test smear layer scores by scanning electron microscopy (SEM). The CLSM evaluation showed that increases in the area, depth and percentage of sealer penetration were detected at 1 and 5 mm from the root apex in the PUI group compared with the NI group, and greater increases were observed in the EA group (P < 0.05). The SEM experiment showed that the lowest scores for the smear layer and debris removal were achieved by the EA group when compared with the PUI and NI groups (P < 0.05). In conclusion, EA was superior to PUI and NI regarding sealer penetration at the root apex during endodontic treatment, and it could provide a new technical idea for clinical root canal therapy.

In Vitro Evaluation of Smear Layer and Debris Removal and Antimicrobial Activity of Different Irrigating Solutions

OBJECTIVE

The aim of this in vitro study was to compare the smear layer and debris removal and antimicrobial activity of two dual-action irrigating solutions for continuous chelation (Triton; Brasseler, Savannah, USA and Dual Rinse HEDP; Medcem GmbH, Weinfelden, Switzerland) with a dual step irrigation protocol with sodium hypochlorite (NaOCl) followed by ethylenediaminetetraacetic acid (EDTA).

METHODS

Thirty single-rooted single-canal teeth were divided into three groups (n=10) and irrigated with Triton, Dual Rinse HEDP mixed with 6% NaOCl and 6% NaOCl/17% EDTA. The teeth were observed under a scanning electron microscope (SEM) to assess the canal wall cleanliness. In addition, 80 dentine discs were contaminated with Candida albicans and 80 discs with Enterococcus faecalis and irrigated with Triton, Dual Rinse HEDP mixed with 6% NaOCl and 6% NaOCl/17% EDTA or not treated (n=20). Fifteen discs were used to evaluate colony-forming units, while 5 discs were analysed by SEM. Data were analysed using the Shapiro- Wilk, Kruskal-Wallis and One-Way ANOVA tests.

RESULTS

Triton was statistically more effective than Dual Rinse HEDP and NaOCl/EDTA in removing debris (p<0.05), except with NaOCl/EDTA in the coronal third. Triton was more effective than Dual Rinse HEDP in removing the smear layer from the apical and middle thirds (p<0.05). All the irrigation protocols significantly re- duced the number of E. faecalis. The Triton group showed the lowest number of remaining C. albicans (p<0.05).

CONCLUSION

Triton was the most effective irrigation solution in removing debris and as effective as NaOCl/ EDTA in removing the smear layer. Triton showed the highest efficacy against C. albicans. New irrigating solutions that provide continuous chelation may provide an alternative to current irrigation protocols.

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.

Effectiveness of a new endodontic irrigation system for removing smear layer and dissolving simulated organic matter

OBJECTIVES

The study aimed to evaluate the potential for the dissolution of organic tissue in areas of simulated complexity and cleaning of root canal walls of the new iVac® endodontic irrigation system.

MATERIAL AND METHODS

Thirty mandibular premolars were evaluated by scanning electron microscopy before and after biomechanical preparation. Then, they were distributed according to the final irrigation protocol into groups with conventional irrigation, ultrasonic agitation with metallic insert (UA), and iVac® system, and new photomicrographs were obtained. For tissue dissolution analysis, glass capillaries filled with catgut were attached to the cervical and apical thirds of twenty-one prototyped upper incisors. They were weighed before and after the previously mentioned irrigation protocols. The data were statistically compared with a significance level of 5%.

RESULTS

The final irrigation provided greater cleaning of the root canal walls in the cervical, middle, and apical thirds of the root canals (P < 0.05), with no statistically significant difference between UA and iVac®, regardless of the analyzed thirds. Both ultrasonic irrigation protocols dissolved a significantly greater volume than the conventional irrigation protocol (P < 0.05), with no difference between the two protocols (P < 0.05).

CONCLUSIONS

The iVac® system showed root canal wall cleaning and tissue dissolution similar to UA with a metallic insert, and both were superior to conventional irrigation.

CLINICAL RELEVANCE

The new irrigation system iVac is more effective than conventional irrigation and has similar root canal wall cleaning and tissue dissolution to UA.

Comparative Evaluation of the Canal Shaping Ability, Pericervical Dentin Preservation, and Smear Layer Removal of TruNatomy, WaveOne Gold, and ProTaper Ultimate-An Ex Vivo Study in Human Teeth

INTRODUCTION

Innovative file systems have been recently introduced, claiming improved effectiveness and superior ability to preserve the tooth structure, still allowing an efficient preparation and disinfection up to the apical region. Regardless, few data are available on the comparative effectiveness of the most recently developed systems. Thus, this ex vivo study aimed to comparatively evaluate, for the first time, the functionality of WaveOne Gold (WOG), TruNatomy (TN), and ProTaper Ultimate (PU) file systems regarding canal shaping, dentin preservation, and smear layer removal ability.

METHODS

Human maxillary incisors were randomly divided for instrumentation with one of the assayed systems. Canal shaping ability and pericervical dentin preservation were characterized through microtomographic evaluation and morphometric assessment (n = 15). Smear layer removal ability was evaluated by scanning electron microscopy (SEM) (n = 6).

RESULTS

TN and PU presented the lowest canal volume variation upon instrumentation, found to be significantly lower than that attained with WOG (P < .05). Pericervical dentin was reduced in all groups upon instrumentation, with TN evidencing the highest preservation, quantitatively similar to PU, and significantly higher than that attained with WOG (P < .05). SEM imaging revealed the presence of scattered remnants of the smear layer and partially opened dentinal tubules at the apical portion, with no significant differences between systems.

CONCLUSIONS

TN and PU allowed for the highest tissue preservation, reporting the lowest volume variation and the highest preservation of the pericervical dentin. None of the assessed systems provided a complete removal of the smear layer in the apical region.

Comparative evaluation of effect of nisin-incorporated ethylenediamine tetraacetic acid and MTAD on endodontic biofilm eradication, smear layer removal, and depth of sealer penetration

OBJECTIVES

To comparatively evaluate the nisin-incorporated ethylenediamine tetraacetic acid (N-EDTA) and MTAD on cytotoxicity, endodontic biofilm eradication potential, smear layer removal ability, and sealer penetration depth.

MATERIALS AND METHODS

N-EDTA was prepared and characterized using high-performance liquid chromatography (HPLC). Minimum inhibitory, minimum bactericidal, and minimum biofilm inhibitory concentration (MBC, MIC, and MBIC) were determined on Enterococcus faecalis (E. faecalis) strain. The cytocompatibility of N-EDTA and MTAD was evaluated using 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based colorimetric assay. Dentin specimens (n = 88 for antibacterial analysis, n = 170 for sealer penetration depth) were prepared and subjected to the classical irrigating strategy and obturation, respectively. The scanning electron microscopic evaluation (SEM) was done for the evaluation of biofilm disruption and smear layer removal. Confocal laser scanning microscopy (CLSM) evaluation was done for determining percentage of bacterial viability and sealer penetration depth. Statistical analysis of one-way ANOVA and Tukey's HSD post hoc tests for bacterial viability and Kruskal-Wallis test and Mann-Whitney test for smear layer removal and depth of penetration were done with the significance level set at p < 0.05.

RESULTS

MTAD and N-EDTA showed cytocompatibility without any statistical differences from each other. For N-EDTA, the MIC and MBC values were 12.5 μg/ml (1:8), and MBIC values were 36 μg/ml. Biofilm disruption and killed bacterial percentage of N-EDTA was statistically higher than MTAD, whereas both the materials showed similar efficacy in the removal of the smear layer and sealer penetration depth.

CONCLUSION

N-EDTA had negligible cytotoxicity with similar smear layer removal ability, sealer penetration, and better antibiofilm potential than MTAD.

CLINICAL RELEVANCE

N-EDTA can serve as a viable alternative endodontic irrigant.

Effectiveness of three auxiliary irrigation methods for cleaning the internal walls of root canals of curved isolated teeth

OBJECTIVES

This study aimed to compare the effectiveness of ultrasound and acoustic and laser cleaning of curved root canals.

METHODS

A total of 92 molars with independent root canals with a curvature of 20°-40° were prepared and standardized at 04 25# and stained with gentian violet solution for 72 h. Among them, 52 were randomly divi-ded into four groups for final rinsing (n=13): NI group, PUI group, EDDY group, and PIPS group. Ten samples in each group were cut horizontally along the long axis perpendicular to the root and divided into curved upper, curved, and apical segments. Images were taken with a stereomicroscope and Image J measurements were taken to calculate the depth of rinse penetration. The remaining three samples from each group were split along the long axis of the dentin, photographed by scanning electron microscope to record the dentin tubule exposure and staining layer, and scored for staining layer by double-blind method. SPSS 26.0 software was used to perform statistical analysis and select the best flushing method. An extra 40 samples were randomly divided into four groups for detection of flushing fluid penetration depth (n=10): 10, 20, 30, and 40 s.

RESULTS

In the upper part, the mean depth of infiltration was not significantly different between the experimental and control groups (P>0.05). The PIPS group had a significantly lower smear layer score than the control group and the EDDY group (P<0.01). In the curved segment, the mean depth of infiltration was significantly greater in the PUI group than in the control group (P<0.05); the tarnish layer score was lower in each experimental group than in the control group. At the top, the mean depth of infiltration was greater in the PUI and PIPS groups than in the control group (P<0.05), and the smear layer score was lower in the PIPS group than in the other groups (P<0.05). After the time was changed, the depth of infiltration of PUI increased only in the apical segment as the flushing time increased.

CONCLUSIONS

The PUI and PIPS methods facilitate the penetration of irrigation solution into the dentin canal in curved root canals, especially in the apical segment. The PIPS technique is effective in removing the smear layer in curved root canals.

Evaluation of Effect of Natural Extract Sodium Gluconate on Smear Layer and Dentine Decalcification Compared with EDTA - An In-vitro Study

OBJECTIVE

Mechanical instrumentation of the root canal system generates a smear layer on the canal walls which are removed most commonly with the help of chelators such as ethylenediaminetetraacetic acid (EDTA) but can potentially cause severe dentinal erosion. Considerable research has been conducted to find an al- ternative to EDTA which removes the smear layer without causing dentinal erosion. The current study aimed at evaluating the ability of sodium gluconate compared with that of 17% EDTA in smear layer removal along with its effect on dentine decalcification when used as a final irrigant.

METHODS

Twenty single-rooted mandibular premolars were collected and prepared based on the pre-set criteria. Following preparation, the specimens were exposed to the test solutions as a final irrigant. Then the specimens were subjected to (Scanning electron microscope) SEM analysis at 1000x for evaluating the smear layer and 5000x for evaluating the dentinal erosion, and a Vickers microhardness tester was used for evaluat- ing the reduction in dentine microhardness post-treatment. The values obtained were analysed using SPSS software for a statistically significant difference with Mann-Whitney U test for evaluating of smear layer remov- al and dentinal erosion and using one-way (Analysis of variance) ANOVA test for microhardness evaluation.

RESULTS

The smear layer removal capability of sodium gluconate was as effective as EDTA on the contrary so- dium gluconate did not cause any dentinal erosion compared to EDTA with a statistically significant difference (p=0.002 in middle third and p=0.001 in apical third of the canal). Microhardness reduction caused by sodium gluconate was less compared to EDTA, however, no statistically significant difference (p=0.113) was noted.

CONCLUSION

Sodium gluconate, therefore, can produce a balance between smear layer removal and dentinal decalcification and can be considered a potential alternative to EDTA. (EEJ-2023-01-017).

Efficacy of using chitosan and chitosan nanoparticles as final irrigating solutions on smear layer removal and mineral content of intraradicular dentin

Background

This study evaluated the effect of using chitosan, nano-chitosan, and ethylenediaminetetraacetic acid (EDTA) as final irrigating solutions on smear layer cleanliness and Ca/P ratio of dentin.

Methodology

Forty-eight decoronated human single-rooted teeth were used. They were divided randomly into four groups (n = 12) based on the final irrigating solution used as follows: (a) control group (IA; n = 6) normal saline, (IB; n = 6) were left unprepared; group II - 0.2% chitosan; group III - 0.2% nano-chitosan; and group IV - 17% EDTA. Samples were prepared using ProTaper Next and irrigated with 2.6% NaOCl 5 ml after each instrument using 31-gauge needle. Final rinse was used 5 ml/3 min according to the assigned group. The specimens were prepared for evaluation.

Results

Best smear layer removal was observed in group IV. No statistically significant differences (P > 0.05) were observed between the experimental groups (II, III, and IV) coronally; however, a statistically significant difference (P < 0.05) was observed between groups II and IV at middle and apical thirds. Intragroup comparison showed that apical third exhibited the highest mean smear layer score among all experimental groups. The highest mean Ca/P ratio was in the 0.2% nano-chitosan group, while the highest calcium loss was in the 17% EDTA group.

Conclusions

17% EDTA is a potent chelating agent that can successfully remove the smear layer but compromises the Ca/p ratio of dentin. However, 0.2% chitosan and its nanoparticles have comparable chelating effects and induce remineralization of the root canal dentin.

Cleaning efficacy of EDDY versus ultrasonically-activated irrigation in root canals: a systematic review and meta-analysis

BACKGROUND

Ultrasonically-activated irrigation (UAI) is effective in root canal irrigation but may damage canal walls. EDDY is a sonic activation system with flexible working tips that cause no harm to dentinal walls. This review explores the intracanal cleaning efficacy of EDDY compared with UAI in vitro.

METHODS

The systematic review was registered in the PROSPERO database (CRD42021235826). A literature search was conducted in six electronic databases. In vitro studies that compared the removal of smear layer, debris, soft tissue or microbes in root canals between EDDY and UAI were included. Data extraction and quality assessment were performed. Meta-analyses were conducted on smear layer removal and debris elimination with the standardized mean difference (SMD). Heterogeneity was measured using the I² test and the Chi² test. The random-effect model was used when I² > 50%, or p < 0.1, otherwise the fixed-effect model was applied. The level of significance was set at p < 0.05.

RESULTS

19 articles were included in this systematic review and 7 articles were included in meta-analyses. Meta-analyses on smear layer removal showed unimportant differences between EDDY and UAI at any canal third (coronal [SMD = 0.08, 95% confidence interval (95%CI): -0.29 to 0.45; p = 0.44, I² = 0%]; middle [SMD = 0.02, 95% CI: -0.44 to 0.47; p = 0.94, I² = 0%]; apical [SMD = 0.01, 95%CI: -0.35 to 0.38; p = 0.70, I² = 0%]). Meta-analyses on debris removal evaluated by scanning electron microscope (coronal [SMD = 0.03, 95% CI: -0.41 to 0.46; p = 0.27, I² = 23%]; middle [SMD = -0.24, 95% CI: -0.83 to 0.35; p = 0.80, I² = 0%]; apical [SMD = 0.24, 95%CI: -0.20 to 0.67; p = 0.36, I² = 2%]) and micro-CT (SMD = 0.36, 95% CI: -0.67 to 1.40; p = 0.03, I² = 70%) both found insignificant differences. No meta-analysis was undertaken on soft-tissue removal and disinfection due to the various study designs, but the qualitative analyses implied that EDDY achieved similar performance to UAI in both aspects.

CONCLUSIONS

Limited evidence indicated that EDDY was comparable to UAI in removing smear layer, debris, soft tissue and microbes ex vivo. Considering UAI may damage canal walls, EDDY might be a substitute for UAI in irrigation activation. But more randomized clinical trials are required to explore the clinical extrapolation of the results in this review.

Investigation of the effectiveness of sonic, ultrasonic and new laser-assisted irrigation activation methods on smear removal and tubular penetration

The aim of this study was to examine the effectiveness of different irrigation activation methods on smear layer removal and tubular penetration. One hundred-five distal roots of mandibular molar teeth in total; 50 for smear removal efficiency (n = 10) analysis using scanning electron microscopy (SEM), and 55 roots were used to examine tubular penetration using confocal laser scanning microscope (CLSM). Five different irrigation activation methods were used in this study; conventional needle irrigation (CNI), sonic irrigation device of EDDY, passive ultrasonic irrigation (PUI), PIPS and SWEEPS techniques, which are two different laser irrigation activation methods. The obtained data were statistically analyzed and the significance level was determined as p < 0.05. At the apical level, the cleanest canal walls were observed when laser methods PIPS and SWEEPS were used, while in the middle third, there was no difference in smear removal efficiencies between all groups except for the CNI (p > 0.05). Penetration depths and percentages increased from apically to coronally in all groups. The PUI and EDDY generally showed similar penetration depths and percentages to the CNI, except at the coronal root level (p > 0.05). In all groups, when PIPS was used, it showed greater penetration depth and percentage (p < 0.05). PIPS and SWEEPS techniques showed lowest and similar smear scores compared to PUI and EDDY in the apical area where access and effectiveness of the irrigation solution are difficult.

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.

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 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 effect 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.

Cleaning efficacy of various root canal irrigants in primary teeth: a scanning electron microscopic study

Root canal irrigation plays an important role in debridement and disinfection of the root canal system. The present study aimed to evaluate the efficacy of 17% ethylenediaminetetraacetic acid (EDTA), 2% iodine-potassium iodide (IKI), and 1% and 3% concentrations of sodium hypochlorite (NaOCl) for root canal irrigation in the anterior primary teeth. A total of 60 anterior primary teeth were selected and assigned to 1 of 4 irrigation groups (n = 15): 1, 17% EDTA; 2, 3% NaOCl; 3, 2% IKI; and 4, 1% NaOCl. The root canals in all groups were subsequently irrigated with normal saline following a 30-minute incubation period. The prepared specimens were cut longitudinally and imaged using scanning electron microscopy to evaluate the cleaning efficacy in the coronal, middle, and apical thirds. Data were analyzed using descriptive statistics as well as nonparametric Kruskal-Wallis and Mann-Whitney U tests. Group 2 (3% NaOCl) showed the greatest efficacy for cleaning the entire root canal (P < 0.01). Analysis of the different parts of the root canal revealed that group 2 also demonstrated the greatest efficacy in achieving a clean apical portion (P < 0.01). According to the results of the present study, 3% NaOCl offered a better performance in irrigating the root canals of primary teeth.

Addition of metal chlorides to a HOCl conditioner can enhance bond strength to smear layer deproteinized dentin

OBJECTIVES

To evaluate the effect of smear layer deproteinization using hypochlorous acid (HOCl) with/without metal chlorides (SrCl₂ and ZnCl₂) on the microtensile bond strength (µTBS) of two simplified adhesives to dentin.

METHODS

Human dentin surfaces with a standardized smear layer were pretreated using a 105 ppm HOCl solution with/without SrCl₂ (0.05 M, 0.1 M, 0.2 M, 0.4 M) or ZnCl₂ (0.05 M, 0.1 M, 0.2 M) for 5 s, 15 s, or 30 s. After the deproteinizing solution was washed out with water for 5 s, 15 s, or 30 s, pretreated surfaces were bonded with one-step self-etch adhesive Bond Force II or universal adhesive Clearfil Universal Bond Quick, and µTBS was measured after 24 h. Additionally, the deproteinizing effects of HOCl solutions with/without the metal chlorides were compared by measuring changes in the amide:phosphate ratio using attenuated total reflection Fourier transform infrared spectroscopy. Statistical analysis was performed using multifactor ANOVA, Tukey's post hoc tests and t-tests (p < 0.05).

RESULTS

Pretreatment with pure HOCl for 15 s and 30 s significantly decreased the amide:phosphate ratio (p < 0.05), indicating effective deproteinization, but the µTBS of both adhesives increased significantly only if HOCl was washed out for 30 s (p < 0.05). Increasing the concentrations of metal chlorides enabled shortening of the wash-out time down to 5 s while maintaining the improved µTBS (p < 0.05). The deproteinizing effect of HOCl was not significantly altered by the addition of metal chlorides (p > 0.05).

SIGNIFICANCE

The effectiveness of smear layer deproteinization using HOCl can be improved by the addition of metal chlorides, as their increasing concentration allowed to shorten the wash-out time from 30 s down to 5 s.

An In Vitro Evaluation of the Smear Layer Removal Efficacy of Three Different Chemical Decalcifying Agents on Periodontally Compromised Root Surfaces: A Scanning Electron Microscopy Study

AIM

Aim of the current research was to assess the smear layer removal efficacy of SofScale, Carisolv gel, and QMix chemical decalcifying substances on periodontally weakened radicular surfaces.

MATERIALS AND METHODS

The sample size constituted 60 recently extracted periodontally compromised teeth having a poor prognosis. The samples were allocated at random to one of the following three groups (20 in each): Group I: Scaling and root planing (SRP) with SofScale, Group II: SRP with Carisolv gel, and group III: SRP with QMix. The surfaces thus subjected to treatment were washed with 20 mL of saline and the crown portion was detached at the cementoenamel junction (CEJ). Following this, samples were horizontally and vertically segmented employing a diamond circular disk with 150-200 μm thickness. Every sample segment was subjected to rinsing in normal saline and positioned in 2.5% glutaraldehyde solution in 0.1 M phosphate buffer at a pH of 7.4 for at least 24 hours. Samples were evaluated in a scanning electron microscopy (SEM) at a magnification of 2000×, and photomicrographs were assessed to establish the degree of radicular biomodification by eliminating the smear layer.

RESULTS

QMix group showed the highest smear layer elimination at 3.56 ± 0.13 in pursuit by Carisolv gel at 3.64 ± 0.11 and SofScale group with 4.68 ± 0.08. The differences amid the groups were statistically significant with p <0.001. On multiple contrast assessments of smear layer elimination effectiveness of the dissimilar chemical decalcifying substances employing Tukey's HSD, statistically significant differences were noted between group I and group II, as well as group I and group III (p <0.001). However, there were no significant differences between group II and group III (p >0.001).

CONCLUSION

In conclusion, QMix was noted to have a superior smear layer elimination capacity in comparison with the radicular surfaces conditioned with Carisolv and SofScale.

CLINICAL SIGNIFICANCE

Modifying the surface of teeth by radicular conditioning causes the enhanced attachment of connective tissues coupled with progression in the final aim of reconstructive periodontal therapy. The utility of chemical substances along with physical management characterizes the probability of reduced trauma during treatment, avoiding the sacrifice of radicular portions of teeth.

Application of Sulfinate Agent in Conjunction with HOCl Smear-Layer Deproteinization Improves Dentin Bonding Durability of One-step Self-etch Adhesives

PURPOSE

To evaluate the effect of a sulfinate agent on the bonding durability of one-step self-etch adhesives (1-SEAs) to smear-layer-covered dentin deproteinized with hypochlorous acid (HOCl).

MATERIALS AND METHODS

Human coronal dentin disks with a standardized smear layer were deproteinized with 100 ppm HOCl solution for 0 s (control), 15 s or 30 s. After rinsing with water for 30 s and air drying, half of the specimens were treated with a sulfinate agent (Scotchbond Universal Dual Cure Activator; SDA) prior to the application of a 1-SEA (Bond Force II [Tokuyama Dental] or Clearfil Universal Bond Quick [Kuraray Noritake]). Microtensile bond strength (µTBS) was measured after 24 h or 10,000 thermal cycles (TC). The data were analyzed by three-way ANOVA with Tukey's post-hoc tests and t-tests at the 0.05 significance level.

RESULTS

The 24-h µTBS of both adhesives increased statistically significantly with the HOCl pretreatment for 15 s or 30 s (p < 0.05), but it was not statistically significantly affected by the application of SDA (p > 0.05). However, after TC, the groups treated with the combination of HOCl and SDA maintained their µTBS (p > 0.05), as opposed to untreated dentin and dentin treated with either HOCl or SDA, whose µTBS decreased significantly (p < 0.05).

CONCLUSION

The application of the sulfinate agent did not statistically significantly affect the immediate bond strength of 1-SEAs, and it could not prevent a significant decrease in the bond strength to untreated dentin after thermocycling. However, the sulfinate agent significantly improved the bonding durability of 1-SEAs to HOCl smear-layer deproteinized dentin.

Effect of Clinically Relevant Smear Layers and pH of Universal Adhesives on Dentin Bond Strength and Durability

PURPOSE

To evaluate the effects of different smear layers on the microtensile bond strength (µTBS) of a reference two-step self-etch adhesive and two universal adhesives.

MATERIALS AND METHODS

Mid-coronal dentin of 90 teeth was exposed and divided into three bur groups (coarse diamond, fine diamond, or tungsten carbide). Each bur-prepared group was further divided into three adhesive groups: Clearfil SE Bond (SE, Kuraray Noritake), Single Bond Universal (SB; 3M Oral Care), and G-Premio Bond (GP, GC). After adhesive application, 4-mm-thick resin composites were built up. Half of the teeth in each bur-adhesive group were used in immediate µTBS testing, and the others were tested after thermal aging (n = 5). Rectangular sticks were prepared using a low-speed diamond saw. For each tooth, 6 central sticks were used in the µTBS test. Statistical analysis was performed using three-way ANOVA and Bonferroni tests (α = 0.05).

RESULTS

SE presented higher µTBS than universal adhesives and SB presented higher µTBS than GP regardless of dentin surface preparation and thermal aging (p ˂ 0.05). For SE and SB, the tungsten carbide bur demonstrated higher immediate and aged µTBS than did the extra-fine diamond bur (p ˂ 0.05). The immediate µTBS was similar for GP with all bur types (p ˃ 0.05); the tungsten carbide and extra-fine diamond burs presented higher µTBS than did the coarse-diamond bur after thermal aging (p ˂ 0.05).

CONCLUSION

Dentin surface preparation and adhesive type had significant effects on µTBS. The smear layer created with an extra-fine diamond or tungsten carbide bur is favorable when mild and ultra-mild self-etch adhesives are used.

[Comparison of the clinical value of three reciprocating single nickel-titanium instruments in preparation of simulated curved root canals]

PURPOSE

To explore the application value of three reciprocating single nickel-titanium instruments in preparation of simulated curved root canals.

METHODS

One hundred and fifteen single-curved resin simulation root canals were selected and divided into Reciproc group (group A, 28), One file group (group B, 29), Wave One group (group C, 29) and control group (group D, 29) by random graph method. The simulated root canals were prepared according to the specifications of the instructions, root canal preparation, resin removal, root canal cleaning effect, center positioning ability and root canal width were compared. SPSS 22.0 software package was used for statistical analysis.

RESULTS

There was no significant difference in quality and curvature among four groups(P＞0.05). The difference in root canal preparation time among the four groups was statistically significant (P＜0.05), and the root canal preparation time in group B was the shortest(P＜0.05). Comparison of resin removal at the root canal orifice and the midpoint of the bending start point among four groups, the difference was statistically significant(P＜0.05). The root canal wall debris scores and smear layer scores in four groups were significantly different(P＜0.05). Compared with group A, B and D, the root canal wall debris scores of the crown, middle and tip of group C were the lowest, the scores of smear layer on the crown and middle of the root canal wall was the lowest(P＜0.05). There was no significant difference in the center positioning ability of the four groups at 5 mm, 6 mm and 7 mm from the apical foramen(P＞0.05). There was no significant difference in root canal width among four groups (P＞0.05).

CONCLUSIONS

Reciproc, One file and Wave One reciprocating single nickel-titanium instruments can maintain the original shape of the simulated root canal. Compared with Reciproc and Wave One, One file has better root canal shaping ability and cleaning effect.

Evaluation of Free Available Chlorine of Sodium Hypochlorite When Admixed with 0.2% Chitosan: A Preliminary Study

AIM AND OBJECTIVE

The aim of the study was to evaluate the changes in free available chlorine (FAC) when 6% sodium hypochlorite (NaOCl) is admixed with irrigants 17% ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine (CHX), and 0.2% chitosan in varying proportions of 90:10, 80:20, and 50:50.

MATERIALS AND METHODS

The 25 mL aliquots of 6% NaOCl were admixed in varying proportions of 90:10, 80:20, and 50:50 with secondary irrigation solutions: (a) 17% EDTA, (b) 2% CHX, (c) 0.2% chitosan. Iodometric titration was done to evaluate the change in FAC.

STATISTICAL ANALYSIS USED

Kruskal-Wallis and Mann-Whitney tests.

RESULTS

On titration, the mean FAC value of NaOCl at baseline was 1.99 g%. On mixing NaOCl with EDTA, the FAC decreased in all the three proportions and the values were 0.17 g%, 0.17 g%, and 0.06 g% at 90:10, 80:20, and 50:50 ratios, respectively. pH obtained was 9.55 at 50:50 ratio. On mixing NaOCl with CHX, FAC reduced and the values were 1.84 g%, 1.72 g%, and 0.27 g% at 90:10, 80:20, and 50:50 ratios, respectively. pH obtained was 10.87 at 50:50 ratio. On mixing NaOCl and chitosan, the FAC remained unaltered in all the three proportions and the values were 1.64 g%, 1.51 g%, and 1.63 g% at 90:10, 80:20, and 50:50 ratios, respectively. pH obtained was 11 at 50:50 ratio.

CONCLUSION

Combination of NaOCl and chitosan did not lead to a reduction in FAC and the pH of the solution remained unaltered, suggesting that tissue-dissolving property of NaOCl might be preserved.

CLINICAL SIGNIFICANCE

The combination of chitosan with NaOCl is advantageous in two ways. Firstly, FAC remained unaltered and the pH of the solution was also maintained at 11.05 indicating that the tissue-dissolving property of NaOCl prevailed. Secondly, chitosan is known for its chelating property and is effective in smear layer removal. With further in vivo and in vitro studies, a combination of chitosan and NaOCl can be proposed as a novel irrigant.

Post-Space Treatment Influences the Bond Strength In Endodontically Treated Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies

OBJECTIVES

This systematic review of in vitro studies investigated the influence of the post-space treatment used to remove the smear layer on the bond strength of the post to root canal dentin.

METHODS AND MATERIALS

In vitro studies included in this study were identified from PubMed/MEDLINE, Lilacs, and Scopus databases up until March 2019, without limits on publication year or language. Two reviewers independently selected the studies based on the inclusion and exclusion criteria, extracted the data, and evaluated the risk of bias of all studies. A random effects model was used for pairwise meta-analyses (control vs. post-space preparation groups) at a significance level of p<0.05.

RESULTS

Of the 2,832 potentially eligible studies, 453 studies were selected for full-text analysis, and 75 were included in this systematic review. Only one study was considered to have a low risk of bias. Overall, post-space treatment significantly improves the bond strength to root canal dentin (p<0.00001).

CONCLUSION

Post-space treatment has a positive influence on the bond strength of the post to root canal dentin. In this review, the post-space treatments that improve the adhesive resistance of the post were ethanol, sodium hypochlorite, and ethylene diamine tetra-acetic acid (NaOCl + EDTA), NaOCl + EDTA + ultrasound, erbium-doped yttrium aluminium garnet laser (Er:YAG laser), neodymium-doped yttrium aluminium garnet laser (Nd:YAG laser), and diode laser.

Efficacy of different instruments for the mechanical removal of the smear layer in immediate post preparations: a comparative study

Adhesively cemented fiber-reinforced composite posts are commonly used to reconstruct endodontically treated teeth. Adhesion to intraradicular dentin is complex, and close contact between the resin cements and the dentin is essential. The removal of the smear layer following post space preparation (secondary smear layer) can improve this integration. Different mechanical systems have been used to activate the irrigant inside the root canal. The purpose of this study was to compare, ex-vivo, the removal of the smear layer from the walls of the immediate post space preparation by the action of three mechanized instruments. Forty premolar specimens with a single root canal were selected, endodontically treated, and shaped for glass fiber post cementation with Peeso reamer #1 (Dentsply Sirona, Switzerland) and Macrolock finishing drill #3 (RTD, France). The specimens were randomly divided into 4 groups (n=10): Group C (control); Group PUI (passive ultrasonic irrigation); Group CEP (Rotoprox brush, Hager Werken, Germany) and Group XP (XP-endo Finisher, FKG Dentaire, Switzerland). Post space surfaces were cleaned with 3mL of distilled water; each specimen root split longitudinally to expose the root canals, and prepared for examination in a scanning electron microscope at magnification 350X. The results were analyzed using the Kruskal-Wallis and Friedman tests (p>0.05). RESULTS: Statistically significant differences (p<0.05) were found between Groups C and XP in all three root regions, but not between Groups C, CEP and PIU. Of these, Group CEP showed a better trend in the results of the coronary and middle thirds, without significant difference with Group XP. Although it was difficult to achieve a clean dentin surface after preparation for the fiberglass post, the XP-endo Finisher was the most efficient in removing secondary smear layer, followed by the Rotoprox conical brush.

In vitro study on conditioned dental root surfaces: evaluation of wettability, smear layer, and blood clot adhesion

OBJECTIVES

The aim was to investigate the efficacy of citric acid and ethylenediaminetetraacetic acid (EDTA)-based treatments on smear layer removal and blood clot formation and stabilization.

METHOD AND MATERIALS

After scaling and root planing, 126 root samples were divided into seven groups treated with: deionized water; saline; citric acid solution; Ultradent Citric Acid gel; EDTA solution; EDTA-based PrefGel; or untreated. Each group was divided into three subgroups: I for the evaluation of smear layer removal and surface wettability, II and III for the evaluation of blood clot formation and stabilization in static or dynamic rinsing conditions.

RESULTS

Conditioning agent treatments increased surface wettability with respect to untreated samples (Ultradent: 45 ± 1 degrees, P = 6.2 × 10-3; EDTA: 36 ± 5 degrees, P = 8.9 × 10-7; PrefGel: 47 ± 7 degrees, P = 3.2 × 10-2). Smear layer removal (30% to 60% with respect to untreated samples) was observed for all the conditioning agents. Clot was absent on untreated samples and samples treated with deionized water. Clot quality was significantly higher for samples treated with conditioning agents (P < .05) and similar between group II and III (P > .05). A statistically significant difference (P = .027) was observed for clot coverage of the saline group, comparing static and dynamic rinsing, confirming the positive effect of treatments on clot stabilization.

CONCLUSIONS

The use of conditioning agents improves smear layer removal and clot formation and stabilization with respect to scaling and root planing procedure only, which is, however, considered an essential procedure to promote wound healing in periodontal surgery.

A Comparative Evaluation of Smear Layer Removal by Using Four Different Irrigation Solutions like Root Canal Irrigants: An In Vitro SEM Study

BACKGROUND

The present study aimed to evaluate and compare the efficacy of 17% ethylenediaminetetraacetic acid (EDTA), 18% etidronic acid, 10% citric acid, and 7% maleic acid in the removal of smear layer at the apical third of the root canals.

MATERIALS AND METHODS

Sixty single-rooted teeth were equally divided into four study groups (n = 15), according to the type of irrigant used (17% EDTA, 18% etidronic acid, 10% citric acid, and 7% maleic acid) to remove the smear layer effectively from apical third of root canal. In each group, respective irrigant was used with 5.25% of sodium hypochlorite during instrumentation. Each study sample was then sectioned longitudinally and removal of smear layer was observed using a scanning electron microscope (SEM) at 2000×.

RESULTS

A 7% maleic acid revealed better smear layer removal than all other three groups at apical third. A 10% citric acid was found to be more efficient than EDTA and etidronic acid. The intergroup comparison was performed using Mann-Whitney U test, and there was no significant difference between all the study groups, except maleic acid.

CONCLUSION

The present study compared the effect of various irrigants as an adjunct with 5.25% of sodium hypochlorite for root canal irrigation during and after instrumentation. The use of irrigants aids in the removal of the smear layer from the root canals, thereby increasing the success rate of endodontic therapy.

CLINICAL SIGNIFICANCE

This study supports the hypothesis that a thorough use of root canal irrigants can efficiently remove the smear layer which is the key for successful root canal treatment. The present study helps in choosing an appropriate irrigant that can ensure complete root canal debridement from all thirds, especially from the apical third of the root canal. How to cite this article: Mankeliya S, Singhal RK, Gupta A, et al. A Comparative Evaluation of Smear Layer Removal by Using Four Different Irrigation Solutions like Root Canal Irrigants: An In Vitro SEM Study. J Contemp Dent Pract 2021;22(5):527-531.

SEM Evaluation of Various Intracanal Irrigation Devices on Smear Layer Removal: A Comparative Study

AIM

The present study aimed at assessing the effectiveness of different intracanal irrigation devices on the removal of the smear layer.

MATERIALS AND METHODS

The recently extracted 80 lower premolars having single canal were chosen for this in vitro study. A round diamond bur was used to gain endodontic access and the root canal was entered with a #15 K-file until the tip was just seen at the apical foramen. Manual instrumentation of root canals of all teeth was done using the step-back method. The samples were later divided randomly into four groups. Later, each sample was exposed to final irrigation by using four different irrigation systems, group 1: conventional needle irrigation, group 2: irrigation with ultrasonic activation, group 3: irrigation with EndoVac system activation, group 4: irrigation with EndoActivator. The samples were next mounted and visualized under scanning electron microscope (SEM) for the absence or presence of the smear layer.

RESULTS

Irrigation with EndoVac system activation showed the presence of least smear layer (2.40 ± 0.32), followed next by EndoActivator (3.24 ± 0.46) and ultrasonic activation (4.96 ± 0.54) and conventional needle irrigation (5.20 ± 0.10). No statistically significant difference was found in the apical and coronal thirds of the root canal in removal of the smear layer on an intragroup comparison. However, a statistically significant (p < 0.001) difference was seen between the groups at the apical and coronal thirds on an intergroup comparison.

CONCLUSION

This study demonstrated the EndoVac system group to be efficient in removal of the smear layer when compared to the EndoActivator system, ultrasonic activation, and conventional needle irrigation group.

CLINICAL SIGNIFICANCE

The definitive objective of endodontic therapy is to transform the affected teeth to a healthy and functional state. The irrigants can reach the working length when delivered by an effective irrigation delivery system. This type of delivery system should deliver adequate volume of irrigants all the way up to the working length and have sufficient flow and be efficient at debridement of complete canal system.

Assessment of Effectiveness of Erbium:Yttrium-Aluminum-Garnet Laser, GentleWave Irradiation, Photodynamic Therapy, and Sodium Hypochlorite in Smear Layer Removal

AIM AND OBJECTIVE

To compare the effectiveness of erbium:yttrium-aluminum-garnet laser, GentleWave irradiation, photodynamic therapy (PDT), and sodium hypochlorite in smear layer removal and dentin permeability with a scanning electron microscope (SEM).

MATERIALS AND METHODS

Seventy-five recently extracted single-rooted teeth (maxillary second premolars) were randomly divided into 5 groups of 15 each. Group I teeth was the control group in which conventional root canal preparation (RCP) [17% ethylenediaminetetraacetic acid (EDTA)] was done without laser irradiation, group II teeth underwent RCP and GentleWave™ treatment, group III teeth were subjected to Er:YAG laser irradiation, group IV uses low-level 660 nm (PDT), and group V samples were irrigated with 5.25% NaOCl. All samples were viewed under the SEM. Images at the coronal, middle, and apical part of the root canal were obtained at ×1000. A scoring system for smear layer removal and debris removal scoring was used for analysis.

RESULTS

Smear layer removal was significantly higher at different points (coronal, middle, and apical area) in group I, followed by V, IV, II, and group III in declining order (p < 0.05). Intercomparison between the groups at different points indicates a significant difference in smear layer removal score between group I and group V at coronal, middle, and apical third. The result was not significant at coronal third and middle third, between group I and V, II and III, II and IV. The result was not significant at apical third between I and V, II and III, and II and IV (p < 0.05). Ethylenediaminetetraacetic acid and sodium hypochlorite are effective in smear layer removal followed by the Er-YAG laser technique.

CONCLUSION

Ethylenediaminetetraacetic acid and NaOCl are effective in smear layer removal. Er:YAG laser-activated RCP was comparatively efficient in cleaning the smear layer and opening dentinal tubules.

CLINICAL SIGNIFICANCE

Er:YAG laser-activated RCP was comparatively efficient in cleaning the smear layer and it can be used for effective removal of smear layer for clinical usage.

Post preparation: cleanness achieved by different irrigating protocols

The aim of this study was to evaluate the ability of different irrigation protocols to remove from the walls of the root canal and entrance to dentinal tubules the smear layer produced during preparation for a fiber post. Fifty decoronated human lower premolars were treated endodontically and the apical third of the canal was filled with a single gutta-percha point using warm vertical compaction. Ten millimeters were left free for post preparation, which was done by sequential use of a Largo #1 drill and Exacto #3 pilot drill (Angelus, Brazil), with irrigation with distilled water upon each instrument change. Samples were distributed randomly into 5 groups (n=10). G 1: No irrigation after post preparation. G 2: Distilled water activated for 60 s + distilled water. G 3: 5.25% NaOCl 15 s+ distilled water. G 4: 17% EDTA (Farmadental, Argentina) 60 s + 5.25% NaOCl 15 s + distilled water. G 5: 10% polyacrylic acid (Densell) 15 s + distilled water. Irrigant was activated mechanically with a low-speed conical brush. Roots were then split longitudinally in vestibular-lingual direction. Each surface was observed under SEM in its different thirds. Microphotographs were taken at 150X and 600X magnification and results analyzed statistically using Kruskall Wallis and Friedman tests (p<0.05). The results [mean (standard deviation)] were: for 150X: G1 11.00 (1.33), G2 7.50 (3.13), G3 6.30 (2.58), G4 2.20 (2.80), G5 4.30 (1.50), and for 600X G1 11.40 (0.84), G2 10.00 (1.94), G3 7.70 (3.33), G4 5.80 (3.70), G5 7.20 (2.65). The statistical analysis showed significant differences between irrigants (p<0.05) but not between root thirds (p>0.05). The EDTA+NaOCl combination and polyacrylic acid showed greater capacity to remove the smear layer created during post preparation.

Impact of Different Root Conditioning Agents on Periodontally Affected Root Surface: A Scanning Electron Microscope Study

AIM

The present study aimed to evaluate the effect of various root-conditioning agents on root surfaces that are periodontally affected.

MATERIALS AND METHODS

A total of 90 human teeth having single root that were extracted because of chronic periodontitis were chosen. The extracted teeth were cleaned of saliva and blood using a soft-bristled brush and distilled water. The investigational groups were categorized into group I-doxycycline HCl, group II-ethylenediaminetetraacetic acid, and group III-tetracycline HCl. Samples were readied for histological study by scanning electron microscope (SEM). The SEM was used to assess the effectiveness of smear layer removal, amount of patent dentinal tubules out of the totality of dentinal tubules present, and the appreciation of collagen fiber-like structures inside the intertubular area.

RESULTS

The highest efficacy for smear layer removal was seen for group III-tetracycline HCl samples (1.80 ± 0.148) followed next by group II-EDTA (1.36 ± 0.230), and group I-doxycycline HCl (1.30 ± 0.283). The highest number of patent dentinal tubules were seen in group III-tetracycline HCl (44.50 ± 0.18) followed immediately by group II-EDTA (38.10 ± 0.42), and group I-doxycycline HCl (34.90 ± 0.23). The highest number of appreciation of collagen-like structures was recorded in group III-tetracycline HCl (2.64 ± 0.04) followed next by group I-doxycycline HCl (1.88 ± 0.10) and group II-EDTA (1.76 ± 0.28).

CONCLUSION

The present in vitro study concludes tetracycline HCl root-conditioning agent to be significantly more efficient in smear layer removal, exposing collagen fibers and amount of patent dentinal tubules than doxycycline HCl and EDTA.

CLINICAL SIGNIFICANCE

The modification of the root surface of human teeth with the use of root conditioning agents leads to enhanced attachment by connective tissue resulting in improved reconstructive periodontal treatment goals.

Bond Strength of Self-Adhesive Restorative Materials Affected by Smear Layer Thickness but not Dentin Desiccation

PURPOSE

To use shear bond strength (SBS) testing to determine the effect of surface moisture and smear layer thickness on the adhesion of self-adhesive restorative materials and a universal adhesive.

MATERIALS AND METHODS

One single-step self-etch universal adhesive, Prime & Bond Active (PA), was used to bond Ceram.x Spectra ST HV composite resin to dentin and enamel using the self-etching technique. Three commercially available restorative materials and one newly developed material with self-adhesive properties, Activa (A), Fuji II LC(F), Equia Forte (E), and ASAR-MP4 (S), respectively, were also bonded to enamel and dentin prepared moist and dry and to dentin prepared with a thick smear layer. Shear bond testing was performed using an Ultradent bonding apparatus.

RESULTS

The universal adhesive generated the highest SBS to dentin and enamel, followed by the newly developed material. None of the materials tested were significantly affected by the moisture conditions on enamel or dentin. The thickness of smear layer significantly affected SBS to dentin for S, F, and E. However, S and F still exhibited higher shear bond strength to dentin with the thicker smear layer compared to the other self-adhesive materials. Only the universal adhesive in self-etch mode was not affected by the thicker smear layer and maintained significantly higher SBS.

CONCLUSION

None of the materials tested were affected by bonding to overdried dentin or enamel. All of the self-adhesive materials exhibited lower SBS to specimens with a thicker smear layer. The newly developed material ASAR-MP4 compared favorably to the other self-adhesive materials tested under all test conditions.

The effects of alternate irrigation of root canals with chelating agents and sodium hypochlorite on the effectiveness of smear layer removal

BACKGROUND

After the mechanical preparation of a root canal, the canal walls are covered with a smear layer. In order to deeply clean the dentinal tubules, removal of the smear layer is recommended. There is no consensus on the length of time of rinsing with chelating agents or irrigation with alternating chelating agents and sodium hypochlorite (NaOCl).

OBJECTIVES

The aim of the study was to evaluate the effectiveness of smear layer removal using 4 irrigation protocols.

MATERIAL AND METHODS

We prepared 42 straight root canals to size ISO40/04 and assigned them into 4 study groups (n = 10) and a control group (n = 2). The root canals were irrigated as follows: in the control group, 180 s with 5.25% NaOCl; in group 1, 60 s with 40% citric acid (CA) and 120 s with NaOCl; in group 2, 120 s with CA and 120 s with NaOCl; in group 3, 30 s CA, 30 s with NaOCl, 30 s CA and 120 s with NaOCl; and in group 4, 60 s with CA, 30 s with NaOCl, 60 s with CA, and 120 s with NaOCl. The roots were split longitudinally and the root canals were observed under ×200-500 magnification. The root canal walls were analyzed in areas 2 mm, 6 mm and 10 mm from the apex.

RESULTS

In the apical and medial sections, the best effects were achieved in groups 3 and 4. In coronal sections, no significant differences between experimental groups were found.

CONCLUSIONS

Within the limitations of this study, it can be concluded that irrigation with alternating NaOCl and CA was the most effective at smear layer removal, regardless of the irrigation time.

[The influence of endodontic rinsing liquids activation methods on the root dentin structure and effectiveness of root canal cleaning]

The study was aimed to conduct a morphological assessment of the influence exerted by a certain method of activation of endodontic rinsing liquid on the root dentin structure and canal cleaning effectiveness in an ex vivo experiment. The study was performed on 20 single-rooted teeth removed due to complicated caries in people aged 25-44 years. A devised method of vacuum-jet irrigation was used to carry out the final antiseptic treatment and to activate a rinsing liquid in the group No. 1 (n=10), and an endodontic syringe with ultrasonic activation was used in the group No. 2 (n=10). Optical and scanning electron microscopy data were used to assess dentin histostructure, presence or absence of organic inclusions in the root canal lumens, quality of preparation and contour lines of their sides. An analysis of scans demonstrates that the vacuum-jet irrigation method effectively cleans the root canal lumen in the apical area in 90% of the cases, while irrigation with an endodontic syringe and ultrasound activation has been effective in 67% of the cases. The smear layer throughout the root canals in the samples of the group No. 1 was removed in 100% of the cases. At the same time, the smear layer in the canal apical area was not completely removed in either of the samples of the group No. 2. An analysis of photomicrographs of histotopographic cross sections of the dental roots in group No. 2 under consideration revealed numerous cavities in the circumpulpal dentin, which form nidi of destruction up to 10-15 mcr in diameter merging in the cervical and middle third of the root. At the same time, a typical structure of the circumpulpal dentin with a well-developed network of dentinal tubules and intact peritubular and intertubular matrix was observed throughout the dental roots in the samples of the group No. 1. These investigational studies allow us to conclude that vacuum-jet irrigation of root canals provides better cleaning, completely removes the smear layer and does not damage the root dentin structure.

Manual vs. rotary instrumentation in endodontic treatment of permanent teeth: A systematic review and meta-analysis

PURPOSE

To systematically review all studies comparing manual instrumentation with at least one rotary instrument in the preparation of the root canal of permanent human teeth.

METHODS

The electronic databases PubMed, EMBASE, LILACS, IBECS and BBO were searched. In vitro studies published until 27 of September, 2016 were included. For statistical analysis, we used the Comprehensive Meta-Analysis software (Biostat), considering P< 0.05 significant.

RESULTS

A total of 1,104 articles published until September 27, 2016 were obtained, with 57 meeting the eligibility criteria. The studies were grouped according to the main methodology used (computerized tomography, periapical radiography, image amplification and scanning electron microscope). Due to the wide variability of the methodologies and evaluated parameters, a subgroup analysis was performed based on the evaluated parameter. The meta-analysis revealed that rotary instruments caused a significant reduction in instrumentation time and a smaller change of the canal curvature than manual instruments. The rotary instrumentation presented better results regarding root canal transportation, ability of centralization within the canal path and shaping of the canal. Manual instrumentation performed better with regard to the smear layer and debris production, more instrumented canal surfaces and fewer dentin defects.

CLINICAL SIGNIFICANCE

An increasing number of studies have compared the efficiency of manual and rotary instrumentation in endodontic treatment of permanent teeth. This study helps elucidate which method is more efficient in the endodontic treatment of permanent teeth.

Effectiveness of Etching by Three Acids on the Morphological and Chemical Features of Dentin Tissue

AIM

The purpose of this study was to evaluate the microscopic and chemical effects of phosphoric acid gel, phosphoric acid liquid, and polyacrylic acid application for 15 seconds (s) on coronal dentin.

MATERIALS AND METHODS

Twelve extracted teeth were selected. Three etching acids were used to prepare the dentin surfaces. Scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDX) were used to analyze the chemical and morphological changes of the dentinal surfaces, including the depth of demineralization. Collected data were statistically analyzed by the one-way analysis of variance test.

RESULTS

Dentin etched with phosphoric acid gel or liquid showed greater peritubular dentin dissolution, including complete removal of the smear layer. In addition, there were many silica particles on the dentin etched by phosphoric acid gel 37%. The dentin that was etched with 25% polyacrylic acid for 15 seconds showed no smear layer removal. Chemical analysis (EDX) showed that dental surfaces etched with phosphoric acid liquid 37% for 15 seconds showed the strongest mineral dissolution at the calcium surface, with a calcium content of 5.25%. On the other hand, EDX analysis of the dental surface etched with 25% polyacrylic acid showed more surface enrichment in calcium (17.19%).

CONCLUSION

Although phosphoric acid (gel or liquid) 37% cleans the dental surface, phosphoric acid gel precipitates silica particles on the etched dentin surface. These particles cannot be removed by rinsing off this acid. The application of polyacrylic acid for 15 seconds does not noticeably demineralized dentin, nor remove the smear layer.

CLINICAL SIGNIFICANCE

The clinician should use phosphoric acid (gel or liquid) to clean dental surfaces to prepare them for the bonding process. The low demineralizing effects of the polyacrylic acid permits its use near the pulp.

Comparative analysis of cleaning ability of two rotary instrument systems: Mtwo and ProTaper® universal. An in vitro scanning electron microscopic study

This study is to compare the cleaning effectiveness of two Ni-Ti files systems. Thirty single-rooted human teeth were selected and two NiTi rotary systems were used. Group A: canal shaping with ProTaper® Universal (Dentsply Tulsa Dental Specialties, Tulsa, OK) (PTU); Group B: (n=15) canal shaping with Mtwo Ni-Ti instruments (Sweden and Martina, Padova, Italy) and apical finishing with Mtwo Apical Ni-Ti instruments (Sweden and Martina, Padova, Italy). The amount of debris and smear layer were quantified on a basis of a numerical evaluation scale. The data established for scoring the debris and the smear layer was recorded separately and statistically analysed using the Kruskal-Wallis test. No significant differences were found for debris. Mtwo instruments resulted in significantly less smear layer (P less than 0.05) compared with ProTaper® Universal. Under the conditions of this study, Mtwo resulted in significantly less smear layer compared with canal preparation with ProTaper® Universal.

Root canal preparation using S5, Mtwo, and ProTaper Universal nickel-titanium systems: a comparative ex-vivo study

OBJECTIVES

To examine various parameters of root canal preparation using three rotary nickel-titanium systems (S5, Mtwo, and ProTaper Universal [PTU]).

METHOD AND MATERIALS

One hundred and twenty curved root canals were prepared to size 30. The following parameters were evaluated: straightening, changes of root canal cross-section, safety issues, cleanliness of canal walls, and working time. Statistical analysis was performed with the Kruskal-Wallis test, Wilcoxon-Mann-Whitney test, and analysis of variance (P < .050).

RESULTS

All three systems maintained the curvature well with no significant difference between the groups. With regard to the cross-section, no significant differences for any of the root canal thirds (coronal, P = .589; medial, P = .898; apical, P = .474) were found. Preparation with S5 resulted in two, with Mtwo in one, and with PTU in three procedural incidents. Debris scores 1 and 2 were found in 56% (S5), 46% (Mtwo), and 60% (PTU) of the specimens, respectively. Smear layer scores 1 and 2 were found in 85% (S5), 73% (Mtwo), and 78% (PTU). Results for removal of debris and smear layer were not significantly different between the three groups. Mean working time was significantly shorter for Mtwo (293 seconds) than for S5 (329 seconds) (P = .001) or PTU (369 seconds) (P = .001).

CONCLUSION

All three systems respected the original root canal curvature well and were safe to use. None of the three systems was able to prepare the entire circumference of the root canals, and to remove debris and smear layer completely.

EFFICIENCY OF CHELATING IRRIGATION AGENTS FOR REMOVING A LUBRICATED DENTIN LAYER OF ROOT CANAL

The study is aimed at investigating the smear layer, formed on the walls of dental root canals as a result of endodontic treatment, by using scanning electron microscope (SEM) and determining its removal and/or modification quality after applying water solution of 18% ethylenediaminetetraacetic acid (EDTA) and gel. 50 extracted teeth preliminary prepared using Step-Back technique has been studied. Experimental teeth were randomly divided into the following 3 groups: control group (20 teeth), study group I (15 teeth) and study group II (15 teeth), respectively, irrigated by water solution of 18% ethylenediaminetetraacetic acid (EDTA). SEM examination was carried out for 3 different areas of preliminary prepared separated dental roots: coronal, middle and apical portions. The entire study was based on the analysis of 900 electron microscope photo- images. SEM study revealed formation of the thick smear layer on the surface of root canal dentin, practically covering the openings of canal tubules. Both the water solution and/or gel of 18% ethylenediaminetetraacetic acid provided partial or complete removal of the mentioned smear layer; among them, EDTA 18% water solution appeared to be more effective for coronal and middle thirds of dental root (P<0.05). Removal of the smear layer from root canals by using the chelating agents was less effective in the apical third. Having studied these areas, the portions covered with the smear layer and blocked dentinal tubules on canal surfaces were revealed.

Evaluation of the Apical Seal of Mineral Trioxide Aggregate in the Absence and Presence of Smear Layer

AIM

The aim of this study was to in vitro evaluate the apical sealability of mineral trioxide aggregate (MTA) when used as an orthograde root filling material, and to evaluate whether smear layer removal has any influence on the apical seal of this material.

MATERIALS AND METHODS

Forty single-rooted human mandibular premolars were selected in this in vitro study. The selected teeth were randomly divided into two equal groups (n = 20) based on the irrigation type. Group 1 was irrigated using distilled water to keep the smear layer intact, and group 2 was irrigated using NaOCl 5.25% and ethylenediaminetetraacetic acid (EDTA) 17% to remove the smear layer. All teeth were instrumented using a step-back technique and obturated using white MTA. Microleakage of 0.2% rhodamine B solution at the tooth-material interface was evaluated to assess the apical seal of MTA. The data were analyzed statistically using Mann-Whitney test U-test (p = 0.05).

RESULTS

When the smear layer was present, MTA revealed less leakage compared to the group of MTA without smear layer with statistically significant difference (p <0.05).

CONCLUSION

The apical seal produced by MTA when smear layer is left intact was better than the apical seal of MTA when smear layer is removed.It can be stated that MTA is a promising root canal filling material with good sealing ability in the presence of a smear layer.

CLINICAL SIGNIFICANCE

Using white MTA material for the obturation of root canals is a useful procedure. It could be done without complexity in irrigation during root canal treatment and cause no discoloration to the teeth.

Smear Layer Removing Ability of Root Canal Irrigation Solutions: A Review

AIM

The purpose of this review is to address the smear layer removing the ability of root different canal irrigants including ethylenediaminetetraacetic acid (EDTA), a mixture of tetracycline, acid and detergent (MTAD), tetraclean, citric acid, Q-Mix, maleic acid, and smear clear.

BACKGROUND

Smear layer is a layer which is produced during instrumentation. It contains both organic and inorganic materials. It may also contain bacteria and their byproduct considering the root canal situation. This layer may prevent the penetration of the healing material introduced to the canal to the interior of the dentinal tubules. In addition, it can affect the adaptation of sealing materials to the root canal walls.

REVIEW RESULTS

The smear layer removal ability of MTAD is superior and faster than EDTA. Tetraclean is similarly composed of an acid, an antibiotic, and a detergent. The presence of doxycycline is believed to help the smear layer removal ability of these irrigants. Antibiotics such as tetracycline had similar smear layer removal ability as even citric acid. EDTA is an amino acid with a chelating ability that sequestrates metal ions. Some believed EDTA smear layer removing ability is better than MTAD, tetraclean, SmearClear, and 20% citric acid which is controversial in case of comparison between MTAD and EDTA. Phosphoric acid is efficient enough to be comparable to EDTA in removing the smear layer. Maleic acid is an organic compound with acid etching smear layer removal. Its ability seems to be similar or even better than EDTA. Citric acid as another organic acid is believed to be used as smear removing agent. HEBP is another chelating agent that can be used in combination with NaOCl; however, HEBP is a weak decalcifying agent compared to EDTA and hence cannot be applied as a mere final rinse. QMiX is a combination of CHX, EDTA, and detergent and should be used at final rinse. It is believed that QMiX is as efficient as EDTA. Smear clear is a 17% EDTA solution including an anionic and cationic (cetrimide) surfactant. The ability of QMiX is similar to EDTA.

CONCLUSION

There are different canal irrigation solutions with various smear layer removal ability that some should be used as a mere final rinse and some should not.

CLINICAL SIGNIFICANCE

The usage of canal irrigation solutions depends on the clinical situation and preference of the dentists. This study provides a good guide for clinician of the field.

Effects of Double Application of Contemporary Self-Etch Adhesives on Their Bonding Performance to Dentin with Clinically Relevant Smear Layers

PURPOSE

To evaluate the effects of double application of self-etch adhesives on their microtensile bond strength (μTBS) to dentin, as well as the hardness (H) of resin-dentin interfacial structures.

MATERIALS AND METHODS

Midcoronal dentin surfaces (n = 45) were polished with 180-grit SiC paper and randomly allocated to 9 groups based on three adhesives - Scotchbond Universal Adhesive (SB), G Premio Bond (GP), and Clearfil Megabond 2 (MB) - and three application modes: single application (S), double application with light curing after each application (DL), and double application with light curing only at the end (D). Following composite-resin build up and water storage (37°C; 24 h), μTBS were obtained. The hardness of adhesive, resin-dentin interface and dentin were evaluated by nanoindentation. The μTBS and H data were analyzed by two-way ANOVA to demonstrate the effects of adhesive and application mode as well as their interaction, followed by Tukey's test (α = 0.05). Fracture modes were determined using a stereomicroscope.

RESULTS

μTBS and H were significantly affected by the adhesives and their application modes (p ˂ 0.001). Double application significantly increased the µTBS and H of adhesive and resin-dentin interface (p ˂ 0.05). SB and MB showed significantly higher µTBS than GP (p ˂ 0.05).

CONCLUSION

Double applications during bonding of dentin having clinically relevant smear layers were beneficial for three contemporary self-etch adhesives. The improvement in bonding performance is believed to be the result of increased chemical interaction, better solvent removal, and improved resin infiltration, leading to improved mechanical properties of the resin-dentin interface or thicker adhesive layers providing improved stress distribution.

Smear layer removal efficiency using apple vinegar: An in vitro scanning electron microscope study

PURPOSE

To evaluate and compare the smear layer removal efficacy using two different concentrations of apple vinegar.

METHODS

48 single-rooted human teeth with conical roots and canals were randomly divided into four groups and prepared by using a nickel-titanium rotary system (Flexmaster). The final irrigation regimens used were: Group A (negative control group) in which distilled water only was used: Group B (positive control group) in which 2.5% NaOCL was used during instrumentation and 17% EDTA as a final irrigant; Group C (experimental group) in which the 5% apple vinegar was used as a root canal irrigant during instrumentation and as a final irrigant; and Group D (experimental Group 2) in which the diluted apple vinegar was used as a root canal irrigant during instrumentation and as a final irrigant. Specimens were then examined under a scanning electron microscope and scored for smear layer removal on the coronal, middle and apical thirds.

RESULTS

5% apple vinegar was significantly more effective in smear layer removal only in the apical third (P< 0.001). However, diluted apple vinegar was comparable to 5% apple vinegar and 2.5% NaOCl and 17% EDTA, within the coronal and middle levels of the root canal (P<0.05).

CLINICAL SIGNIFICANCE

5% apple vinegar was significantly more effective in smear layer removal only in the apical third. Diluted apple vinegar demonstrated comparable results to the control groups. Thus, it is possible to use diluted apple vinegar as an irrigant after investigating its antimicrobial efficiency and the effect on sealing ability.

[Influence of the dentin smear layer trait on the bond strength of the self-adhesive resin cements]

OBJECTIVE

This work aimed to evaluate the influence of smear layer on the bonding effectiveness and durability of the self-adhesive resin cements to dentin.

METHODS

A total of 48 fresh caries-free third molars with exposed dentin surface were divided into two groups. The dentin surfaces were treated using a standard grit diamond bur (group A) or further polished using a fine grit diamond bur (group B) and then bonded with either of the two self-adhesive resin cements, namely, Clearfil SA Cement (CSA, Kuraray) and Multilink Speed (MS, Ivoclar Vivadent). After 24 h or 2-year water storage, a microtensile bond strength test was performed.

RESULTS

In group A, the dentin surface was rough, the smear layer was thick, and the dentin tubule orifice detritus showed low embolism value. In group B, the dentin surface roughness decreased, the embolism proportion increased, and the smear layer became thin. The initial bonding strengths of CSA and MS in group A were significantly lower than those in group B (P<0.05). The bonding strengths of CSA and MS significantly decreased after two years of water storage (P<0.05). For CSA, the bond strength of group B was significantly lower than that of group A (P<0.05). For MS, the differences in the bonding strength between groups A and B were insignificant (P>0.05).

CONCLUSIONS

The properties of the smear layer and the types of self-adhesive resin cement used affected the bond strength and durability.

Evaluation of Influence of Widening Apical Preparation of Root Canals on Efficiency of Ethylenediaminetetraacetic Acid Agitation Protocols: Study by Scanning Electron Microscopy

AIM

The purpose of this study was to evaluate the influence of widening the apical root canal preparation (RCP) on the efficiency of different ethylenediaminetetraacetic acid (EDTA) agitation protocols on smear layer removal: EDTA; EDTA + Easy Clean in rotary movement (ECROT); EDTA + Easy Clean in reciprocating movement (ECREC); and EDTA + Passive ultrasonic irrigation (PUI).

MATERIALS AND METHODS

A total of 80 mandibular premolars had their crowns sectioned and then were divided into two groups according to widening: size 25 or 40, 0.08 taper. Sequentially they were once again allocated to subgroups according to the agitation protocol performing eight experimental groups (n = 10). Ten additional teeth were prepared for controls (C+/C-). The specimens were then submitted to the cleaning protocols and thereafter cleaved and microphotographed by variable pressure scanning electron microscopy (SEM) at previously determined points along their root thirds (750*). Scores were attributed to the images, and data were analyzed by the Kruskal-Wallis, Student-Newman-Keuls and Friedman tests.

RESULTS

A higher widening was observed to have a positive influence on cleaning efficiency offering significant differences in global and apical third evaluations (p < 0.05). Relative to the agitation, significant differences were observed mainly in the apical third, with PUI and ECROT providing the best results (p < 0.05); no difference for C+ was observed when higher widening was employed.

CONCLUSION

A greater widening of the apical third provided a significant improvement in the action of the agitation/activation protocols. Moreover, the PUI and ECROT activation methods were shown to be superior to the use of EDTA solely, particularly in the apical third.

CLINICAL SIGNIFICANCE

The findings of this study reinforce the need for clinical use of additional methods to complement cleaning. Therefore, it is important for professionals to have knowledge and command of these protocols to obtain more satisfactory results.