The effect of final irrigation on the penetrability of an epoxy resin-based sealer into dentinal tubules: a confocal microscopy study

Dual- or single rinse? The tubular sealer penetration of endodontic chelating agents

INTRODUCTION

In this study, we aimed to compare the effectiveness of various chelating agents, ethilenediaminetetraacetic acid (EDTA), citric acid (CA), and etidronic acid (HEDP) mixed in two different forms, in removing the smear layer and promoting the penetration of an endodontic sealer into the dentinal tubules of extracted single-rooted teeth.

METHODS

The study used 75 teeth divided into five groups: 17% EDTA, 10% CA, 9% HEDP + NaOCl, 9% HEDP + distilled water (DW), and a control (DW) group. Scanning electron microscopy was used to assess smear layer removal and confocal laser microscopy was used to evaluate tubular sealer penetration at different depths from the apical tip.

RESULTS

Sealer penetration was highest with 17% EDTA and 10% CA as compared with the other agents (p<0.001). At the cervical third, the sealer penetration for EDTA, HEDP + NaOCl, and HEDP + DW groups were significantly different than those in DW (p = 0.020). For the middle third, EDTA, CA, and HEDP + NaOCl groups were significantly higher than those of the DW group (p<0.001). Cervical-level values were significantly higher than apical-level values for HEDP + NaOCl, HEDP + DW, and DW (p<0.001). Smear layer removal was lower with 9% HEDP + DW than with 17% EDTA and 10% CA at all depths (p<0.001). A significancy in smear layer removal was observed between 10% CA and control (p = 0.015) in middle depth.

CONCLUSION

Within the limitations of this study, highest values were seen in EDTA and CA in terms of sealer penetration and smear layer removal. In the light of these findings, the use of strong chelating agents highlights better clinical efficiency than dual-rinse or single HEDP irrigation.

Efficacy of Adjunctive Fotoenticine Photodynamic Therapy and Sapindus mukorossi Therapy on Clinical, Radiographic, and Cytokine Profile of Diabetics with Peri-Implantitis

Objective: To evaluate effectiveness of Fotoenticine (FTC)-mediated photodynamic therapy (PDT) and Sapindus mukorossi (SM) as adjunct to mechanical debridement (MD) on peri-implant clinical parameters and levels of proinflammatory cytokines among diabetics. Background: FTC has exhibited robust photodynamic impact against Streptococcus mutans (i.e., an established caries-associated bacterium); however, its efficacy against periodontal pathogens is not known. Methods: One hundred six diabetics with peri-implantitis were randomly categorized into three groups: Group I consisted of 37 participants who were treated with only MD; group II comprised 35 participants who were treated with FTC-mediated PDT, in addition to MD; and group III consisted of 34 participants who were treated with SM, in addition to MD. Peri-implant clinical parameters [plaque index (PI), bleeding on probing (BOP), and probing depth (PD)] and radiographic outcomes [crestal bone loss (CBL)] (PI, BOP, and PD), together with peri-implant sulcular fluid (PISF) interleukin (IL)-1β and IL-6 levels were measured at baseline and 6-month follow-up. Results: In group I (n = 37; 24 males +13 females), group II (n = 35; 20 males +15 females), and group III (n = 34; 17 males +17 females), the mean age of participants was 54.3 ± 4.6, 52.0 ± 5.5, and 50.8 ± 4.5 years, respectively. Significant improvement was observed in the scores of peri-implant PI (p = 0.01), BOP (p = 0.01), and PD (p = 0.02) at the 6-month follow-up among all study groups. Significant improvement in peri-implant CBL among group I subjects at 6-month follow-up compared to baseline (p < 0.05) was observed. PISF levels of IL-1β and IL-6 improved at 6 months. Conclusions: As an adjunct to conventional MD, FTC-mediated PDT and SM might be used as potential therapeutic modalities among diabetics with peri-implantitis.

Effect of antioxidants after post-space irrigation on the adhesive interface of glass fiber post cementation

OBJECTIVE

This study evaluated the effects of antioxidants, 10% sodium ascorbate (SA) or 20% alpha-tocopherol (AT), after post-space irrigation with 2.5% sodium hypochlorite +17% EDTA (SH) or 1% peracetic acid (PA) on the adhesive interface after glass fiber post cementation.

MATERIALS AND METHODS

Sixty bovine roots were endodontically treated. After preparation, the post-space was irrigated with SH or PA followed or not by the use of antioxidants (SA or AT) (n = 10). Push-out bond strength test, failure mode, and dentin penetrability analysis using confocal laser microscope were performed in the cervical, middle, and apical thirds. Data from bond strength and dentinal penetrability were evaluated by one-way ANOVA and Tukey post hoc test (p < 0.05).

RESULTS

SH showed the lowest bond strength regardless of the third (p < 0.05). In apical third, mixed failure was the most incident in all groups. Only in the cervical third of the post-space, SH-AT provided the greatest tag extension of the cementation system into dentin (p < 0.05). However, in the middle and apical thirds, SH-AT, SH-SA, and PA-SA provided the largest tag extensions (p < 0.05), but similar to each other (p > 0.05).

CONCLUSIONS

The use of antioxidants only favored bond strength when SH was used and dentin penetrability of the adhesive and conventional resin cementation, regardless of the solution used to irrigate the post-space.

CLINICAL SIGNIFICANCE

The use of antioxidants (10% sodium ascorbate and 20% alpha-tocopherol) after post-space irrigation with sodium hypochlorite appears to increase the bond strength favoring the glass fiber post-cementation.

Dentinal Tubule Penetrability and Bond Strength of Two Novel Calcium Silicate-Based Root Canal Sealers

BACKGROUND

Once the chemo-mechanical preparation of root canals is finished, achieving a complete seal of the root canal system becomes crucial in determining the long-term success of endodontic treatment. The important goals of root canal obturation are to minimize leakage and achieve an adequate seal. Thus, a material that possesses satisfactory mechanical characteristics, is biocompatible, and has the ability to penetrate the dentine tubules adequately is needed.

AIM

This study aimed to compare the penetrability and bond strength between two calcium silicate-based sealers and an epoxy resin-based sealer, as well as examine the relationship between penetrability and bond strength for the different sealers.

METHOD AND MATERIALS

Thirty-nine recently extracted single-rooted human premolar teeth were instrumented and divided evenly into three groups (n = 13), according to the sealer used for obturation: AH Plus Jet, EndoSequence, and AH Plus Bioceramic Sealer. Three teeth (30 slices) were randomly selected out of each for analysis using confocal laser scanning microscopy to assess penetrability. The remaining ten teeth (90 slices) in each group were subject to push-out tests using a universal testing machine. All teeth were sectioned into nine transverse slices of 0.9 mm thickness for their respective tests (apical, middle, coronal).

RESULTS

AH Plus Jet exhibited significantly lower penetrability and significantly higher bond strength compared to EndoSequence BC sealer (p = 0.002) and AH Plus Bioceramic Sealer (p = 0.006). There was no significant difference between EndoSequence BC sealer and AH Plus Bioceramic Sealer in terms of either penetrability or bond strength. No correlation was found between penetrability and bond strength.

CONCLUSIONS

Within the limitation of this study and regardless of the location in the canal, the bioceramic based root canal sealers appeared to perform better than the epoxy resin-based sealer in terms of dentinal penetration rate. Further studies are required to compare other biomechanical properties of bioceramic sealers including setting characteristics and bacterial leakage.

Calcium Silicate-Based Sealer Dentinal Tubule Penetration-A Systematic Review of In Vitro Studies

The aim of this systematic review was to perform a qualitative synthesis of in vitro studies which evaluate and compare the penetration of calcium silicate-based sealers into dentinal tubules. A systematic advanced search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases on the 1 December 2022. In vitro studies that compared the tubular penetration of at least two calcium silicate-based sealers in extracted human teeth were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias included studies. The search identified a total of 680 preliminary records, among which 12 studies were eligible for review. The most used methodology to evaluate sealer penetration was the use of a fluorochrome together with the tested sealers and the analysis of their penetration under confocal laser microscopy. Regarding the results of the included studies, calcium silicate-based sealers exhibit a favorable dentinal tubule penetration. Tubular penetration, however, can be affected by factors such as the irrigation protocol, sealer activation, the filling method used, and root canal morphology. EndoSequence BC Sealer showed the highest sealer penetration among the tested sealers. The influence of different fluorochromes on the results of dentinal tubule penetration studies should also be further explored. The in vitro nature of the included studies limits the applicability of the results into the clinical setting. Prospero registration: CRD42022383896.

Evaluation of dentinal tubule penetration of Irritrol and chlorhexidine irrigating solutions activated using EDDY and photon-initiated photoacoustic streaming

The aim of the study was to compare the penetration depth and percentage of Irritrol and chlorhexidine (CHX) solutions into dentinal tubules using conventional needle irrigation (CI), EDDY, and photon-induced photoacoustic streaming (PIPS). Sixty oval shaped mandibular premolar teeth were divided into two main groups according to the irrigating solutions as follows; Irritrol and CHX, which were later randomly divided into three subgroups according to the activation technique; CI, EDDY and PIPS (n = 10). Following the irrigation activation procedures, all roots were horizontally sectioned at 3 (apical), 8 (middle), and 13 (coronal) mm from the root apex and then examined with confocal laser scanning microscope (CLSM). Penetration depth (µm) and penetration percentage (%) as determined from the images were analyzed using LSM Image Browser software (Zeiss) and Image J analysis software (V. 1.44p; National Institutes of Health, Bethesda, MD), respectively. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests were performed for multiple comparisons. In both Irritrol and CHX groups, the PIPS activation system demonstrated the highest values for irrigant penetration depth and penetration percentage compared with the other activation methods. Activation of the CHX and Irritrol the final irrigating solutions with PIPS activation technique improved the penetration depth and percentage solutions into the dentinal tubules.

Impact of cleansing protocols to remove endodontic sealer residues on the adhesive interface: Bonding with universal adhesive systems

OBJECTIVE

The aim of this study was to evaluate the effectiveness of cleansing protocols to remove sealer residues using different cleaning strategies and the effect of bond strength of two universal adhesives to dentin impregnated with epoxy resin-based sealer.

MATERIALS AND METHODS

Fifty bovine dentin specimens were impregnated with epoxy resin-based sealer containing calcium hydroxide (Sealer Plus) and submitted to cleansing protocols (n = 10): negative control (NC), positive control (PC), 95% ethanol (ET), xylol (XI), and amyl acetate (AA). Specimens were evaluated by scanning electron microscope (SEM). Other 100 specimens were submitted to the same protocols (n = 20). Each protocol was divided into subgroups (n = 10) according to the universal adhesive system used: Scotchbond Universal (SU); Ambar Universal (AU). Bond strength was evaluated by micro-shear bond test (μSBT). Persistence of residues data were assessed with Kruskal-Wallis and Dunn's tests. μSBT data were analyzed with two-way ANOVA (α = 5%).

RESULTS

ET presented higher persistence of residues compared to AA and XI (p < 0.05). AA and XI were similar from each other (p > 0.05). AU and SU presented similar μSBT values, regardless of the cleansing solution (p > 0.05). SU-NC presented the highest μSBT among all conditions (p < 0.05).

CONCLUSION

The bond strength of universal adhesives was not affected by different amounts of sealer residues after different cleaning protocols.

CLINICAL SIGNIFICANCE

Non-polar substances such as amyl acetate and xylol are effective for removing residues from epoxy resin-based endodontic sealers.

Efficacy of antimicrobial photodynamic therapy and Er,Cr:YSGG laser-activated irrigation on dentinal tubule penetration of MTA-based root canal sealer: a confocal microscopy study

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) and laser-activated irrigation (LAI) are adjunctive therapies developed to enhance the effectiveness of root canal disinfection. Sealer penetration into dentinal tubules is significant for preventing re-infection, and the sealer's penetration ability is affected by the chemo-mechanical preparation of the root canal. This study aimed to evaluate the efficacy of aPDT and LAI on dentinal tubule penetration of MTA-based root canal sealer.

METHODS

Forty single-rooted mandibular premolars were divided into four groups (n = 10): control, methylene blue 50 mg/L (MB50), curcumin 500 mg/L (C500), and Er,Cr:YSGG and sodium hypochlorite (LAI). The smear removal efficiency of the groups on intraradicular dentin was evaluated with a scanning electron microscope (SEM). Confocal laser scanning microscopy (CLSM) was performed to determine the depth of penetration of MTA Fillapex into dentinal tubules. Data were analyzed statistically.

RESULTS

The maximum penetration depth of the C500 group was significantly higher than that of the other groups in all three levels of root sections (p<0.05). Regarding mean penetration depth, the highest values were obtained from the C500 group. However, there was no statistically significant difference between the C500 and MB50 groups in the middle and coronal thirds of the root (p>0.05). The LAI group showed the lowest penetrated area percentage in the middle and coronal third of the root (p<0.05). The C500 and LAI groups were more effective in removing the smear layer than the control and MB50 groups.

CONCLUSION

aPDT could enhance the penetration of MTA-based root canal sealer into dentin tubules.

Comparison of Dentinal Tubule Penetration between a Calcium Silicate-Based Sealer with Ultrasonic Activation and an Epoxy Resin-Based Sealer: A Study Using Confocal Laser Scanning Microscopy

OBJECTIVE

 The aim of this study was to compare the degree of dentinal penetration between an epoxy resin-based sealer applied by using two different filling methods and an ultrasonically activated calcium silicate-based sealer via confocal laser scanning microscopy (CLSM).

MATERIALS AND METHODS

 Forty-five extracted permanent maxillary premolars with type II canals (Vertucci's classification) were subjected to the experiment. The root canals were instrumented and distributed randomly into the following three groups: AH Plus + continuous wave technique (AHC group); AH Plus + single cone technique (AHS group); and Endoseal MTA + single cone technique with ultrasonic activation (EMS) group. Each sealer was labeled with rhodamine B dye to allow visualization under CLSM. The sealer penetration depth in each sample was observed at 2 mm and 5 mm from the apex by using CLSM. The data were statistically analyzed by using analysis of variance or Kruskal-Wallis H test according to normality of variable (α = 0.05).

RESULTS

 In all groups, the maximum sealer penetration depth, mean fluorescence intensity, and sum fluorescence intensity values were higher at the 5-mm level than at the 2-mm level. At the 5-mm level, the EMS group showed the lowest value (p = 0.02). At the 2-mm level, there were no statistically significant differences among any of the groups. The AHC group showed higher values than the other groups, but there was no statistically significant difference in the apical area where access of instruments was difficult.

CONCLUSION

 The AHC group showed the highest dentinal tubule penetration, but had questionable filing efficacy in the apical area, which is of particular importance for the success of root canal treatment. Therefore, in areas such as the apical 2 mm of premolars with type II canals, which are difficult to access by using instruments such as heat carriers, other appropriate approaches may be required accordingly.

The Effect of Different Final Irrigation Regimens on the Dentinal Tubule Penetration of Three Different Root Canal Sealers: A Confocal Laser Scanning Microscopy Study In Vitro

This study evaluated the effects of different final irrigation regimens on the dentin tubule penetration of three different root canal sealers using confocal laser scanning microscopy (CLSM). A total of 160 single-rooted extracted mandibular premolar teeth were divided into five groups (n = 32 each) according to the solution used in the final rinse protocol, as follows: 17% ethylenediaminetetraacetic acid (EDTA) (group 1), 17% EDTA and 2% chlorhexidine gluconate (CHX) (group 2), 7% maleic acid (MA) (group 3), 7% MA and 2% CHX (group 4), and 5.25% NaOCl (group 5). Two roots from each group were examined under scanning electron microscopy (SEM) to visualize smear layer removal. Experimental groups were then split randomly into three subgroups (n = 10) and obturated using a cold lateral condensation technique with 0.1% rhodamine B-labelled sealers [either AH Plus (group A), EndoREZ (group E), or Tech BioSealer Endo (group T)] and gutta-percha. Specimens were sectioned and observed by CLSM to evaluate the percentage and maximum depth of sealer penetration at the apical, middle, and coronal levels. Statistical comparison was performed on grouped (apical, middle, and coronal segments) and ungrouped data using two-way ANOVA with Bonferroni post hoc test (p < 0.01). AH Plus showed the greatest tubule penetration while Tech BioSealer Endo showed the least. Resin-based sealers displayed deeper and more consistent penetration. CHX irrigation positively influenced sealer tubule penetration.

Evaluation of the anti-biofilm effect of poloxamer-based thermoreversible gel of silver nanoparticles as a potential medication for root canal therapy

The purpose of this study was to design silver nanoparticles (AgNPs) poloxamer thermoreversible gel (AgNPs-PL) and investigate whether this gel could provide sustained antibacterial activity against Enterococcus faecalis (E. faecalis) in the root canal. The gels fabricated were characterized in terms of gelatin temperature, particle size, in-vitro Ag⁺ release, and elemental content. Cytotoxicity of AgNPs-PL on primary human periodontal ligament fibroblasts (HPDLFs) was examined by CCK-8 assay. Characterization of AgNPs-PL gel revealed that it contained particles existing as large clumps/fused aggregates of different shapes, with a mean diameter of 21.624 ± 14.689 nm, exhibited sustained release of Ag⁺ for 9 days, and non-toxic to HPDLFs at a low dose (4–32 μg/mL) through 24, 48, and 72 h exposures. The antibacterial effect of 16 and 32 μg/mL concentrations of AgNPs-PL was compared with blank poloxamer gel (PL) and calcium hydroxide (CH) using three methods: (I) agar counting plate, (II) scanning electron microscope (SEM) observations, and (III) confocal laser scanning microscope (CLSM) analysis. AgNPs-PL at the two doses above was more effective than PL and CH in removing E. faecalis biofilm at 1, 3, 9 days. Thus, AgNPs-PL exhibits strong activity against E. faecalis and is easy to produce, with a continuous release profile of Ag⁺. AgNPs-PL gel may be a candidate for a new root canal disinfection.

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

Background

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

Material and Methods

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

Results

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

Conclusions

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

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

Influence of chelating solutions on tubular dentin sealer penetration: A systematic review with network meta-analysis

This systematic review assessed the influence of conventional final irrigation with chelating solutions (CS) on tubular dentin sealer penetration (TDSP). The literature search was conducted in eight electronic databases using MeSH, DeCS, EMTREE and free terms. The study protocol followed the PRISMA guidelines and was registered on the PROSPERO database (CRD42020203080). Twelve studies were included, and a qualitative synthesis and network meta-analysis of the data were performed. The risk of bias of the studies was assessed using an adaptation of the JBI Critical Appraisal tool. QMix was the solution with the highest probability of having the highest percentage of TDSP in the apical (34.1%), middle (86.5%) and coronal (97.7%) thirds. Eleven studies presented a moderate risk of bias, whereas one study presented a high risk of bias. In conclusion, CS improves sealer penetration into the dentinal tubules with QMix demonstrating superior results.

Dentinal Tubule Penetration and Adaptation of Bio-C Sealer and AH-Plus: A Comparative SEM Evaluation

OBJECTIVE

The aim of this study was to compare and evaluate the dentinal tubule penetration and adaptation of a premixed bioceramic sealer and an epoxy-resin based sealer in the three radicular thirds.

METHODS

30 wide roots, with single straight canals and totally formed apexes, were endodontically prepared and divided into two groups (n=14) according to the sealer used for root canal filling: AH-Plus (AHP) and Bio-C Sealer (BIOC). Two samples were left as controls. After the canals were filled, the samples were cut and viewed under Scanning Electron Microscopy by taking images to analyse the tubular penetration and adaptation of the sealers. The results were statistically analysed with the Shapiro Wilk, Levene and Mann-Whitney tests (P<0.05).

RESULTS

BIOC showed significantly higher penetration in dentinal tubules than AHP in the cervical, middle and apical thirds of the root canal (P<0.05) and better adaptation to the dentinal tubule walls.

CONCLUSION

Under the parameters of this study, BIOC exhibits higher penetration and better adaptation to the dentinal tubules compared to AHP.

Intratubular penetration of endodontic sealers depends on the fluorophore used for CLSM assessment

Root canal filling aims at eliminating empty spaces into the root canal system using biologically compatible materials. Three-dimensional root canal obturation must prevent or minimize the reinfection caused by microorganisms' leakage. This study aimed at evaluating whether fluorophore (Rhodamine or Fluo-3) influences the CLSM images of intratubular penetration of four endodontic sealers. Eighty bovine teeth were prepared using K files up to a size #70 and irrigated with 2.5% sodium hypochlorite. All roots were divided into eight groups (n = 10) according to the sealer and fluorophore used: AH Plus/Rhodamine, AH Plus/Fluo-3, Sealer Plus/Rhodamine, Sealer Plus/Fluo-3, Sealer Plus BC/Rhodamine, Sealer Plus BC/Fluo-3, Endosequence/Rhodamine, and Endosequence/Fluo-3. All roots were filled using cold lateral compaction technique. After 7 days, the roots were transversely sectioned, and three slices, one of each canal third, were obtained. Intratubular penetration was evaluated using CLSM. Sealer Plus BC/Rhodamine and Endosequence BC/Rhodamine presented higher intratubular penetration than AH Plus/Fluo-3 and Sealer Plus/Fluo-3 (p ˂ .05). The intragroup analysis showed similar intratubular penetration, regardless of the root third, except for the apical third in AH Plus/Fluo-3 and Sealer Plus BC/Fluo-3 groups. The type of fluorophore influences the calcium silicate sealers' tubular penetration but not of epoxy resin-based ones using CLSM. Bioceramic sealers should not be used associated with Rhodamine for CLSM evaluation. RESEARCH HIGHLIGHTS: The type of fluorophore influences the calcium silicate sealers' tubular penetration but not of epoxy resin-based ones when CLSM is used for assessment. Bioceramic sealers should not be used associated with Rhodamine.

Comparison of dentin penetration ability of different root canal sealers used with different obturation methods

This in vitro study aimed to investigate the tubular penetration depth of four different sealers used with two different obturation methods in the apical, middle, and coronal root canal dentin. Eighty-four single-rooted teeth were instrumented until the F4 ProTaper universal rotary file and filled with AH26, AH Plus (Dentsply, DeTrey, Konstanz, Germany), RealSeal (SybronEndo, Orange, CA), and MTA Fillapex (Angelus, Londrina, Brazil) using cold lateral condensation (CLC) and single-cone (SC) obturation techniques. Thereafter, the roots were sectioned longitudinal and prepared for scanning electron microscope evaluation. The maximum and minimum sealers penetration depth into dentinal tubules at the apical, middle, and coronal regions and the average depth of sealer penetration were calculated. The data was statistically analyzed two-way ANOVA and post hoc Tukey and Dunnett tests and independent samples t test using maximum mean values. There was no statistically difference between the obturation methods (p > .05). When the sealers are evaluated within themselves AH26 was affected by obturation methods significantly (p < .05). Also the results revealed a significant difference between root regions (p < .05). AH26 and RealSeal root canal sealers had the highest penetration values with CLC and SC obturation techniques, respectively. The obturation method did not affect the penetration amount of root canal sealers. RealSeal root canal sealer performed better penetration ability than the other sealers. Apical third of the root in all groups showed lowest penetration depth.

The effect of 17% EDTA and QMiX ultrasonic activation on smear layer removal and sealer penetration: ex vivo study

This study aimed to compare the effect of conventional irrigation (CI) and passive ultrasonic irrigation (PUI) with 17% EDTA and QMiX on the maximum depth and percentage of sealer penetration into the dentinal tubules by confocal laser scanning microscopy (CLSM) and to describe the cleaning of root canal walls by scanning electron microscopy (SEM). Eighty single-rooted human mandibular premolars were instrumented and randomly assigned to four groups (n = 20): EDTA + CI, QMiX + CI, EDTA + PUI, and QMiX + PUI. Ten samples from each group were examined by SEM (2,000×) and the remaining 40 roots were filled with a single gutta-percha cone and AH Plus sealer mixed with 0.1% rhodamine B for analysis by CLSM (10×). Images were assessed at distances of 2 mm (apical), 5 mm (middle), and 8 mm (coronal) from the apex with the Leica Application Suite V4.10 software. The EDTA + PUI and QMiX + PUI protocols presented higher rates of debris/smear layer removal in the apical and middle thirds. The PUI was superior to CI in the maximum depth of sealer penetration at the middle third. The QMiX + PUI group had a higher percentage of sealer penetration at the apical third. The PUI and QMiX protocol improved debris/smear layer removal and tubular dentin sealer penetration.

Influence of Different Types of Root Canal Irrigation Regimen on Resin-based Sealer Penetration and Pushout Bond Strength

Introduction

The main objective of root canal treatment is to eliminate the micro-organism from the root canal system and three-dimensional obturation. The proper cleaning and shaping can be accomplished only by using appropriate instruments and effective irrigants during the root canal treatment.

Aim

To evaluate the influence of three different final irrigation regimen on depth of penetration of root canal sealers and push-out bond strength of obturation material.

Materials and methods

Thirty-six extracted single-rooted mandibular premolar human teeth with straight canals were decoronated and instrumented according to groups. Group I: Root canals were irrigated with 3% sodium hypochlorite (NaOCl), then irradiated with 980 nm diode laser (n = 12), Group II: Root canals were irrigated with 3% NaOCl, followed by 17% ethylenediaminetetraacetic acid (EDTA) (n = 12), Group III: Root canals were irrigated with 3% NaOCl, followed by 10% citric acid (n = 12). In each sample, single cone obturation was done with gutta-percha using AH plus sealer incorporated with rhodamine B dye. After seven days coronal, middle and apical thin cross sections were made for evaluation of dentinal tubule sealer penetration depth and pushout bond strength using confocal laser scanning microscope (CLSM) and universal testing machine, respectively. Statistical analysis among the three groups was done by using Kruskal-Wallis and post hoc test.

Results

Mean tubular penetration depth between diode laser (136.57 ± 48 µm), EDTA (130.56 ± 53 µm) and citric acid (113.37 ± 34 µm; P < 0.05) showed statistically highly significant results. Pushout bond strength did not differ significantly between diode laser (1.21 ± 0.48 Mpa), EDTA (1.05 ± 0.45 Mpa) and citric acid (0.93 ± 0.44 Mpa; P > 0.05).

Conclusion

Mean tubular penetration depth of AH plus sealer was better in diode laser than in EDTA and citric acid. Average push-out bond strength of obturation material did not differ significantly between diode laser, EDTA and citric acid.

Dentinal Tubule Penetration of a Calcium Silicate-Based Root Canal Sealer Using a Specific Calcium Fluorophore

This study aimed to evaluate penetrability on dentinal tubule of a new bioceramic sealer through confocal laser scanning microscopy (CLSM). A specific fluorophore (Fluo-3) was mixed with the sealer. Forty distobuccal roots from maxillary molars were selected, and root canal preparation was carried out with Wave One Gold # 35.06 instruments. Roots were randomly assigned to 4 groups according to the filling procedures: Bioceramic/Lentulo (Sealer Plus BC); Bioceramic/EasyClean group, three activation of the sealer (3x20 s) with Easy Clean instrument; Bioceramic/Irrisonic: ultrasonic activation for 30 s; and AHplus/Lentulo: epoxy resin based sealer (AH Plus) was utilized with the same protocol as the BC/LE group. After 72 h, specimens were transversally sectioned at 2 and 7 mm from root apex and then analyzed through CLSM. Sealer penetration area on dentinal tubule was measured by Adobe Photoshop CC2018. Kruskal Wallis and Wilcoxon T tests were carried out. Penetrability results were similar for both sealers regardless of which technique was performed to activate them inside the root canal (p>0.05). It is reasonable to conclude that penetration of bioceramic and epoxy resin based sealers occurred unimpressively. The type of instrument used to activate bioceramic sealer did not affect penetrability. Fluo 3 should be recommended as the fluorophore to evaluate dentinal tubule penetration of bioceramic sealers.

Do Contaminating Substances Influence the Rheological Properties of Root Canal Sealers?

INTRODUCTION

This study evaluated the effect of residual substances derived from irrigant solutions and intracanal medications on the rheological properties of a silicone, gutta-percha, and bioactive glass-based sealer in comparison with an epoxy resin-based sealer.

METHODS

Thin films of contaminants (0.5 μL) (3% sodium hypochlorite [NaOCl], chlorhexidine digluconate [CHX], 17% EDTA, calcium hydroxide, 40% citric acid, or distilled water [DW]) were applied along with freshly mixed GuttaFlow Bioseal (GFB; Coltene/Whaledent, Langenau, Germany) or AH Plus Jet (Dentsply DeTrey, Konstanz, Germany) on the lower plate of a dynamic rheometer. Rheological measurements were performed in oscillating mode at the strain amplitude, angular frequency, and constant temperature of 0.01%, 10 rad/s, and 37°C, respectively. Samples without contaminants served as controls. All measurements were performed 5 times. The Kolmogorov-Smirnov test and 1-way analysis of variance followed by the Student-Newman-Keuls test were performed to analyze the results (P < .05).

RESULTS

The contaminants did not alter the setting time of GFB compared with the controls; however, CHX and calcium hydroxide decreased its complex viscosity (ƞ*) (P < .05). The setting time of AH Plus Jet was increased by DW, CHX, citric acid, and EDTA (P < .05). All contaminants decreased its ƞ* at the setting point (P < .05). NaOCl led to the greatest alteration of its rheological parameters.

CONCLUSIONS

Irrigant solutions and intracanal medications adversely affected at least 1 of the tested rheological properties of both sealers, except for DW and 3% NaOCl, which did not alter any rheological property of GFB.

Effect of fiber post space irrigation with different peracetic acid formulations on the bond strength and penetration into the dentinal tubules of self-etching resin cement

STATEMENT OF PROBLEM

The post space must be irrigated with solutions that do not interfere with the bond strength and enhance penetration into the dentinal tubules of self-etching resin cement. Which solution is best is unclear. Peracetic acid with different formulations appears to be a good option.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of irrigating the fiber post space by using 1% peracetic acid (PA) at low (LH) or high (HH) hydrogen peroxide concentration on the bond strength and penetration into the dentinal tubules of RelyX U200 self-etching resin cement.

MATERIAL AND METHODS

After intraroot preparation for fiber posts in 60 endodontically treated teeth, the specimens were divided into 4 groups (n=15) according to the irrigation protocol: CG (control), distilled water; NA (NaOCl), 2.5% sodium hypochlorite; LHPA, PA with a low concentration of hydrogen peroxide; and HHPA, PA with a high concentration of hydrogen peroxide. The fiber posts were then cemented with self-etching resin cement labeled with rhodamine. Cross sections of the thirds were obtained by confocal scanning microscopy and submitted to the push-out and cement penetration tests. The data obtained in the push-out tests were evaluated by using ANOVA and the Tukey post hoc test, and those data obtained in the confocal screening were evaluated by using the Kruskal-Wallis and Dunn (Bonferroni correction) tests (α=.05).

RESULTS

Bond strength values in the cervical third of the CG were higher than those in NA (P=.035) but similar to those of the other groups (P=.05). In the other thirds, CG and LHPA values were similar to one another (P=.05) but higher than those of NA and HHPA (P<.001). The penetration rate assessed by confocal scanning microscopy revealed similar results in the cervical third for all groups (P=.075), except for NA which provided the lowest penetration. In the remaining thirds, CG and LHPA provided the highest penetration rate (P=.015).

CONCLUSIONS

The LHPA group had no negative effects on the bond strength and penetration into the dentinal tubules of the self-etching resin cement.

The Penetration Ability of Calcium Silicate Root Canal Sealers into Dentinal Tubules Compared to Conventional Resin-Based Sealer: A Confocal Laser Scanning Microscopy Study

The purpose of this study was to compare the penetration ability of calcium silicate root canal sealers and conventional resin-based sealer using confocal laser scanning microscopy (CLSM). A total of 60 recently extracted single-rooted human premolars were used in this study. The root canals were prepared to a size 40/0.06 taper with ProFile rotary instruments and irrigated with NaOCl and EDTA. After drying all canals, the specimens were randomly divided into three experimental groups (n = 20): Group 1, gutta-percha (GP)/AH Plus with continuous wave compaction; group 2, GP/BioRoot RCS with a single-cone technique; and group 3, GP/Endoseal MTA with a single-cone technique. All experimental samples were sectioned perpendicular to their long axis using a low-speed diamond wheel at the apical, middle, and coronal third levels. The penetration abilities of all samples were evaluated using CLSM. A Kruskal⁻Wallis analysis and a series of Mann⁻Whitney U post hoc tests were performed. A higher intensity level was found in the coronal area and a lower intensity level in the apical area in all the experimental groups. The AH Plus group showed higher sum fluorescence intensity in the apical and coronal thirds compared with the BioRoot RCS and Endoseal MTA groups, whereas the BioRoot RCS group showed a higher intensity level in the middle third, similar to the AH Plus group. The maximum sealer penetration depth was low in the apical area and high in the coronal area in the AH Plus and Endoseal MTA groups. In the BioRoot RCS group, maximum sealer penetration was observed in the middle third. In conclusion, there were significant differences in sealer penetration pattern and distance according to the root level and sealer type.

The Effect of Chlorhexidine and Dimethyl Sulfoxide on Long-Term Microleakage of Two Different Sealers in Root Canals

Objective

The aim of root canal obturation is to prevent leakage and inhibit microbial invasion. This study aimed to determine the effect of chlorhexidine (CHX) and dimethyl sulfoxide (DMSO) as final irrigants on microleakage of root filling immediately and after 18 months. The hypothesis was that either CHX or DMSO would not affect the immediate or long-term microleakage.

Methods

A total of 120 human third molar root canals were obturated with RealSeal SE or Topseal and gutta percha. Before obturation, the canals were irrigated with saline (control), 2% CHX or 5% DMSO. Microleakage of half of each groups (n=10) was measured after 3 days, and of the other half was measured after 18 months with fluid filtration method.

Results

In immediate measurements, RealSeal SE performed significantly better in CHX-irrigated group (p=0.035; Mann-Whitney test). For both sealers, DMSO had the lowest mean microleakage values, which were also statistically significantly lower than with CHX irrigation within sealers (p<0.009 for Topseal and p=0.04 for RealSeal SE; Mann-Whitney test). With RealSeal SE, the microleakage with CHX was significantly higher than that in controls (p=0.022; Mann-Whitney test).

Conclusion

Neither final irrigant showed statistically significant differences in the immediate microleakage within the two sealers. Irrigation with DMSO caused significantly less microleakage than CHX for both sealers after 18 months.

The effect of smear layer removal on E. faecalis leakage and bond strength of four resin-based root canal sealers

BACKGROUND

The aim of the study was to assess bacterial sealability and bonding ability of methacrylate-based Resilon (RS, SybronEndo), Endo Rez (ER, Ultradent Products Inc), and epoxy-based AH Plus (AH, Dentsply/DeTrey), MTA Fill Apex (MTAF, Angelus Soluções Odontológicas) root canal sealers, and the effect of the smear layer removal on the sealability.

METHODS

One hundred thirty root segments were instrumented up to apical size #60 and rinsed with 2.5% NaOCl. Half of the roots were rinsed with 5ml 17% EDTA to remove the smear layer. All the roots were filled with AH, ER, MTAF sealers and gutta-percha, or RS with Resilon cones. After storage at 37°C for 7 days the samples were mounted into bacterial leakage assay for 50 days. Another 100 roots were instrumented and rinsed as described above, split longitudinally, cut into the cervical, middle and apical parts. The sealers were injected through the plastic mould on the dentin surface. After 7 days of incubation at 37°C, bond strength was tested using a notched-edge test fixture (Crosshead, Ultradent Products Inc.) and a universal testing machine (Lloyd Instruments).

RESULTS

AH revealed the longest mean time for bacterial resistance by 29.4 and 36.8 days (with and without smear layer, respectively) followed by RS (15.1 and 24.7 days, respectively). The difference between materials was significant (p<0.001). Bond strength values ranged from 0.2± 0.1 to 3.5± 0.7 MPa and increased from the apical to the cervical third. In the apical third, AH showed the highest mean (SD) bond values 1.4 (0.4) MPa and 1.7 (0.6) MPa (with and without smear, respectively, followed by RS, 0.5 (0.1) MPa and 0.8 (0.1) MPa, respectively. The difference between materials was significant (p=0.001).

CONCLUSION

The effect of the smear layer removal on the sealability was material-dependent.

Influence of Nd:YAG laser on the penetration of a bioceramic root canal sealer into dentinal tubules: A confocal analysis

OBJECTIVE

The aim of this in vitro study, is to evaluate the penetration of a bioceramic root canal sealer into dentinal tubules at 3 mm and 5 mm from the apex after Nd:YAG laser irradiation.

METHODS

Forty freshly extracted human mandibular premolars were prepared using Reciproc® and irrigated with 17% ethylenediaminetetraacetic acid (EDTA). Teeth were divided into 4 groups: group 1, obturated with control sealer (AH Plus®); group 2, obturated with bioceramic sealer (Endosequence BC Sealer®); group 3, Nd:YAG laser + control sealer (AH Plus®); and group 4, Nd:YAG laser + bioceramic sealer (Endosequence BC Sealer®). The samples were transversely sectioned 3 mm and 5 mm from the apex and examined using confocal laser scanning microscopy. Two parameters were measured: 1) sealer penetration into dentinal tubules of the root canal and 2) sealer penetration into the perimeter of the root canal walls.

RESULTS

Penetration analysis showed that bioceramic sealer had a higher penetration at depths of 3 and 5 mm than that of the control sealer, regardless of laser use (p <0.05). Perimeter analysis showed that there was no difference between both sealers at a depth of 3 mm (p <0.05), regardless of laser use. At a depth of 5 mm, bioceramic sealer and laser showed a greater perimeter of penetration (p <0.05) than the control sealer.

CONCLUSION

The use of Nd:YAG laser did not compromise the penetration of bioceramic sealer into dentinal tubules of root canals at 3 mm and 5 mm from the apex.

Effects of different peracetic acid formulations on post space radicular dentin

STATEMENT OF PROBLEM

The optimal irrigating solution with antimicrobial and dentin cleansing properties for post space preparation for fiber posts is unclear. Peracetic acid is one option but is available in various chemical formulations that require evaluation.

PURPOSE

The purpose of this in vitro study was to evaluate dentin surface cleanliness based on the presence of a smear layer and the number of open dentin tubules. It also investigates the chemical composition of residues after canal irrigation with a 1% peracetic acid solution (PA) at low or high concentration of hydrogen peroxide during the preparation of intracanal fiber posts.

MATERIAL AND METHODS

After filling the root canals of 40 mandibular incisors, a rotary instrument was used for intracanal preparation to place fiber posts. The teeth were divided into 4 groups (n=10) according to the post space irrigation protocol as follows: CG (control): distilled water; NA (NaOCl): 2.5% sodium hypochlorite; LH: PA with low concentration of hydrogen peroxide; and HH: PA with high concentrations of hydrogen peroxide. After irrigation, the teeth were sectioned, and the intracanal dentin surface was subjected to analysis using energy dispersive spectroscopy to evaluate chemical composition and to scanning electron microscopy (×500) to evaluate the presence of the smear layer. The number of open dentin tubules was measured by scanning electron microscopy analysis (×2000) using photo-editing software. ANOVA and the Tukey test (α=.05) were used to evaluate the data, except for the presence of a smear layer, for which the Kruskal-Wallis and Dunn tests were used (α=.05).

RESULTS

The highest concentrations of oxygen in the dentin residues were detected in LH and HH (P<.05); CG and NA showed similar oxygen concentrations (P>.05). NA had a higher concentration of chlorine (P<.05), whereas LH had a lower amount of smear layer and a larger number of open dentin tubules than the other groups (P<.05). These were equivalent to each other (P>.05), except for HH, which also had a larger number of open dentin tubules than CG and NA (P<.05).

CONCLUSIONS

PA 1% with a low concentration of hydrogen peroxide yielded a lower amount of smear layer and a larger number of open dentin tubules in the dentin of the post space when compared with PA 1% with a high concentration of hydrogen peroxide, despite maintaining a similar oxygen concentration in these dentin residues.

Effect of novel chelating agents on the push-out bond strength of calcium silicate cements to the simulated root-end cavities

To compare the effects of different chelating agents on the push-out bond strength of calcium silicate-based cements to the simulated root-end cavities. Root-end cavities were prepared on the roots of fifty extracted maxillary anterior teeth. The specimens were then randomly divided into 5 groups (n = 10) based on the final irrigation regimen: Group 1: 17% EDTA, Group 2: 7% maleic acid, Group 3: QMix, Group 4: 2.25% peracetic acid (PAA), Group 5: 0.9% saline. Then, the samples from each group were subdivided into two groups (n = 5) based on the apical filling material. In group 1, root-end cavities of all samples were filled with Biodentine and in group 2, with MTA. Each sample was horizontally sectioned to produce two discs of ∼1 mm thick per specimen. The maximum load required for the dislodgement of 100 retrofillings was recorded. The specimens were examined under scanning electron microscope after debonding to assess the type of bond failure. Data were statistically analyzed using Kruskal Wallis and Mann Whitney U tests. Irrigation with saline resulted in higher bond strength compared to the other irrigants in the retrograde cavities obturated with MTA or Biodentine (p < .05). In MTA group, there was no significant difference between the test irrigants (p > .05). EDTA and PAA groups showed higher dislodgement resistance values than the other test irrigants, when Biodentine was used as a filling. The type of irrigation solution influences the bond strength of the root-end fillings.

Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth

INTRODUCTION

The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth.

MATERIALS AND METHODS

A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols.

RESULTS

G2 presented the lowest fracture resistance (p < 0.05). The other groups were similar to each other (p > 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05).

CONCLUSION

A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed.

CLINICAL SIGNIFICANCE

The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

[Research progress on QMix properties in root canal irrigation]

Mechanical instrumentation preparation alone is insufficient to completely remove root canal infection, and chemical irrigation is essential to eliminate infected remnants. An ideal root canal irrigant should completely remove the smear layer, lubricate the root canal, efficiently kill bacteria, induce mild or no inflammatory response in the tissues, and avoid damaging the dentin structure. However, a commercial irrigant that meets all these requirements is currently lacking. QMix is a root canal irrigation mixture of ethylenediamine tetraacetic acid (EDTA), chlorhexidine (CHX) and surfactant. This mixture can remove the smear layer efficiently, and it possesses strong antibacterial effect and good biocompatibility with minimal cytotoxicity. Furthermore, the influence of QMix on the color and micro-hardness of dentin is low, and it can improve the wettability of root canal sealant without affecting its adhesive properties. This review compares the efficiencies of QMix with other irrigants (sodium hypochlorite, CHX, EDTA, SmearClear, and MTAD) in term of smear layer removal, dentine and root canal sealing, cell cytotoxicity, and bacterial growth inhibition.

Influence of the Calcium Hydroxide Intracanal Dressing on Dentinal Tubule Penetration of Two Root Canal Sealers

Objective

The aim of this study was to evaluate the effect of a calcium hydroxide (CH) dressing on the tubular penetration of two endodontic sealers, AH Plus (Dentsply Maillefer, Ballaigues, Switzerland) and MTA Fillapex (Angelus, Londrina, Brazil).

Methods

Seventy-two mandibular premolars with a single root canal were prepared with ProFile.04 rotary instruments (Dentsply Maillefer) and divided into four groups. In two groups, an intracanal CH dressing was placed for 15 days. The obturations were performed with lateral condensation of gutta-percha in combination with one of the tested sealers. The roots were transversely sectioned at the apical and middle levels. The percentage of sealer penetration in the root canal walls and the percentage of impregnated dentin area in the transverse sections were obtained using confocal laser scanning microscopy. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Games-Howell test.

Results

The CH dressing reduced the mean value of tubular penetration in the middle third of teeth obturated with AH Plus (P<0.01), whereas no difference was observed at the apical sections for both sealers.

Conclusion

The CH dressing did not interfere with the apical penetration of both tested sealers, however, decreased the tubular penetration in the middle third of the AH Plus root canal fillings. Overall, MTA Fillapex presented higher tubular penetration than AH Plus obturations.

In vitro remineralization of hybrid layers using biomimetic analogs

Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey's honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation.