Effect of ultrasonic and sonic activation of root canal sealers on the push‐out bond strength and interfacial adaptation to root canal dentine

Effectiveness of supplementary protocols for filling material removal after sealer ultrasonic activation - a laboratory investigation

Ultrasonic activation of the endodontic sealer makes it difficult to remove the material during endodontic reintervention. Therefore, supplementary removal protocols should be tested to optimize the removal of the remaining filling material. This study assessed the effectiveness of supplementary protocols for filling material removal after sealer ultrasonic activation (UA). Sixty teeth were prepared and distributed into two groups: UA and No UA of the sealer before obturation. Teeth were re-instrumented and two supplementary removal protocols were tested, resulting in six groups (n = 10): NoUA; NoUA+XP (XP-endo Finisher); NoUA+CS (Clearsonic-R1); UA; UA+XP; and UA+CS. Root canals were analyzed under stereomicroscopy and scanning electron microscopy for quantification of the remaining filling material. Considering the total root canal area, the NoUA+CS group had the lowest remaining filling material compared to NoUA+XP, UA+XP and UA+CS groups (p < 0.05). When the root thirds were compared, there was no statistical difference among groups (p > 0.05). The XP-endo Finisher instrument demonstrated the lowest effectiveness when used as a supplementary step. In contrast, the Clearsonic-R1 insert exhibited the highest performance.

Influence of sonic activation of epoxy-resin and calcium silicate sealer on postoperative pain: a patient-blinded, parallel group, randomized clinical trial

BACKGROUND

This clinical study aims to compare postoperative pain after single-visit root canal treatment of teeth with asymptomatic apical periodontitis using epoxy-resin-based AH Plus and calcium silicate-based Endosequence BC sealers with or without sonic activation.

METHODS

This study included 72 individuals with one first or second mandibular premolar tooth with asymptomatic apical periodontitis. They were randomly divided into four groups according to the root canal sealer (AH Plus or Endosequence BC) and activation protocol (sonic activation or non-activation) (n = 18). The participants were ask to rate their postoperative pain intensity on a NRS scale as none, minimal, moderate, or severe after 24 h, 48 h, 72 h, and 7 days following treatment. Patients were also asked to record the number of prescribed analgesic medication tablets (400 mg of ibuprofen) taken. Statistical analysis were performed using the Mann-Whitney U test, the Friedman test, the Spearman's correlation test, the Chi-square test. Significance level was established at 0.05.

RESULTS

There was no statistically significant difference in postoperative pain scores or analgesic intake between AH Plus and Endosequence BC sealers regardless of the activation protocol (p > 0.05). There was no statistically significant difference in postoperative pain scores between the sonic activation and non-activation groups (p > 0.05). A weak positive correlation was detected between Endoactivator sonic activation and sealer extrusion (r = 0.36).

CONCLUSIONS

AH Plus and EndoSequence BC root canal sealers showed similar results in terms of prevalance and intensity of postoperative pain. Sonic activation and non-activation groups had similar postoperative pain scores.

CLINICAL TRIAL REGISTRATION

The study was retrospectively registered with ClinicalTrials.gov (NCT06403293). Date of Registration: 07/05/24.

Retreatability of calcium silicate-based sealers based on micro-computed tomographic evaluation - A systematic review

Introduction

Endodontic retreatment procedures with calcium silicate-based sealers (CSS) have been receiving greater credibility in clinically challenging situations. The objective of this systematic review was to analyze the published in vitro studies for the retrievability of CSS in comparison to resin-based sealers evaluated using micro-computed tomography (micro-CT) in terms of the volume of the residual root canal filling materials, time taken, efficacy of the solvent, and different systems used during the retreatment procedure.

Methods

The study protocol was registered in the International Prospective Register of Systematic Reviews and conducted in adherence to PRISMA 2020 checklist. Accordingly, an electronic literature search was done to identify studies published in English language, within the time frame from January 2004 to June 2024. The search was conducted through popular databases including PubMed (Medline - National Library of Medicine), Scopus (Science Direct), EMBASE and Google Scholar following the inclusion and exclusion criteria answering the research question in focus.

Results

After thorough scrutiny, 15 studies qualified for the systematic review. Following retreatment, in all of the studies pre-treatment working length was achieved, with both the types of endodontic sealers. However, none of the micro-CT studies reported complete removal of endodontic filling material from the root canals. Irrespective of the sealer type used, within each root canal, apical third had the greatest amount of remaining filling material, followed by the middle and coronal thirds.

Conclusions

Retreatment of canals obturated with bioceramic sealers is feasible in most cases using traditional instruments and techniques. Active irrigation and supplemental mechanical removal, which employs lasers, XP-Finisher, and ultrasonics, adds advantage to maximize material removal.

Can the addition of surfactants to NaOCl irrigation impact on the percentage of voids of root canal filling?

This study evaluated the impact of canal irrigation using surfactants associated to NaOCl on the percentage of voids of root canal filling through micro-computed tomographic (micro-CT) analysis. 27 mandibular mesial roots with Vertucci type II canal configuration with isthmus were selected and scanned in a micro-CT device. The specimens were assigned to three groups (n = 9), according to the irrigation solution during instrumentation: 2.5% NaOCl without additives (control), 2.5% NaOCl with 0.1% Benzalkonium Chloride and 2.5% NaOCl with 0.1% Tween 80. After obturation, the specimens were rescanned, and the percentage of voids were calculated. Data were analysed using one-way ANOVA with a significance level of 5%. The percentage of voids were similar among the groups (p > 0.05). None of the specimens showed completely voids-free areas. The addition of surfactants to NaOCl irrigation did not improve the quality of root canal filling of mandibular mesial root canals.

Effect of ultrasonic activation on setting time, pH and calcium ion release, solubility, and chemical structure of calcium silicate sealers

This study evaluated the setting time, pH, calcium ion release, solubility, and chemical structure of four calcium silicate sealers after ultrasonic activation (UA). Five sealers were evaluated: Sealer Plus (SP - control); Sealer Plus BC (SPBC), Bio C Sealers (BCS), Endosequence BC Sealer (EBC), and BioRoot RCS (BR). Ten groups were created based on the use or not of ultrasonic activation: SP; SP/UA; SPBC; SPBC/UA; BCS; BCS/UA; EBC; EBC/UA; BR; and BR/UA. Setting time was performed based on ISO 6876:2012 and ASTM C266-07 specifications. Solubility at 24hs, based on ISO 6876:2012. pH and calcium release were evaluated at 1, 24, 72, and 168hs. Raman spectroscopy was used to evaluate structural changes. Quantitative data were analyzed using One-Way ANOVA and Tukey post-hoc test (α=5%). Raman spectroscopy results were qualitatively analyzed. Setting times and solubility of all sealers were not affected by UA (p>0.05). The highest solubility was found for BCS, BCS/UA; and BR, BR/UA (p<0.05). After 24hs, calcium silicate sealers had higher pH than SP and SP/UA (p<0.05). BR and BR/UA had the highest pH at all time points. SP and SP/UA had stable pH at all time points. SP and SP/UA had the lowest calcium release values at all time points (p<0.05). EBC and EBC/UA calcium release significantly differ at 24,72 and 168hs (p<0.05). No chemical changes were observed during Raman spectroscopy. In conclusion, ultrasonic activation affected calcium ion release only for EndoSequence BC Sealer. Ultrasonic activation did not influence the initial and final setting time, solubility, pH, and chemical structure of any investigated sealers.

The use of sonic and ultrasonic activation of endodontic sealer to improve sealer filling quality in the root canal: a scoping review

This scoping review aimed to map whether the use of sonic and ultrasonic methods to activate the endodontic sealer improves the sealer filling quality in the root canal, considering the bond strength and intratubular penetration to the root dentin as evaluation criteria. The study protocol was prospectively registered and is available online ( https://osf.io/x5fma/ ). Reporting was based on PRISMA Extension for Scoping Reviews. The search was performed in Embase, PubMed, Scopus, and Web of Science. We selected studies without time and language restrictions that used sonic or ultrasonic methods to activate endodontic sealer, whose outcomes were bond strength and intratubular penetration. Three researchers independently selected the articles and collected data. Of 1422 articles, 19 were read in full and 13 studies were included. The vast majority of studies opted for direct activation of the endodontic sealer. The most investigated sealers were the epoxy resin-based sealers, and the ultrasonic activation method was the most explored. For the bond strength outcome, there was a trend toward higher values when the sealer was activated ultrasonically, but the findings seem to be divergent. The sonic activation was not effective for its intended purpose. For the outcome of intratubular penetration, the vast majority of studies indicate that the use of sonic and ultrasonic methods to activate the endodontic sealer is capable of increasing intratubular penetration. The use of sonic and ultrasonic methods to directly activate the endodontic sealer can increase the intratubular penetration of the sealer, but their benefits on the bond strength are uncertain.

Ultrasonic activation of the endodontic sealer enhances its intratubular penetration and bond strength to irradiated root dentin

To evaluate the effect of ultrasonic activation of the endodontic sealer on its intratubular penetration and bond strength to irradiated root dentin. Forty human teeth were distributed into 4 groups (n = 10), according to the radiation therapy (RT) exposure-70 Gy-and ultrasonic activation (UA) of the endodontic sealer: RT/UA-irradiated teeth and sealer UA; RT/no-UA-irradiated teeth and no sealer UA; no-RT/UA-non-irradiated teeth and sealer UA and no-RT/no-UA-non-irradiated teeth and no sealer UA. Push-out bond strength test was performed in a Universal Testing Machine. Failure modes and adhesive interface were analyzed under Scanning Electron Microscopy. The data were statistically compared (two-way-ANOVA and posthoc Games-Howell test; Fisher's exact test - α = 5%). The different experimental conditions (radiation and UA) and the root third had a significant effect on push-out bond strength, and the interaction of these factors was significant (p < 0.05). UA of the sealer significantly increased its bond strength to both irradiated and non-irradiated dentin (p < 0.05). The irradiated groups mostly presented adhesive-type failure of the sealer (p < 0.01). Regardless of the irradiation, the ultrasonically activated groups showed a more homogeneous adhesive interface, with the presence of sealer tags in greater density and depth. Ultrasonic activation enhanced the intratubular penetration and the bond strength of the endodontic sealer to irradiated dentin. The impact of ultrasonic activation of the endodontic sealer on teeth undergoing radiotherapy is a gap in the scientific literature that needs to be bridged.

Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy

OBJECTIVE

This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin.

MATERIALS AND METHODS

Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface.

RESULTS

Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure).

CONCLUSION

Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition.

CLINICAL RELEVANCE

Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Evaluation of various obturation techniques with bioceramic sealers in 3D-printed C-shaped canals

This in vitro study compared various obturation techniques with bioceramic sealers for filling C-shaped 3D-printed replicas. A mandibular molar with a C-shaped root canal with a C1 configuration was obtained. After instrumenting with M3 Pro Gold files (United Dental, Shanghai, China) up to size #30/0.04, a CBCT scan of the tooth was taken. Sixty 3D-printed replicas of the tooth were created. The samples were obturated with EndoSeal TCS sealer (E. TCS; Maruchi, Wonju, Korea) or EndoSeal MTA (E. MTA; Maruchi, Wonju, Korea) (n = 30). The samples in each group were obturated with the following techniques (n = 10): (1) single-cone technique (SC), (2) SC with ultrasonic activation (UA), and (3) cold hydraulic compaction (CHC). Following incubation, the replicas' apical, middle, and coronal thirds were inspected under a digital microscope, and the proportion of filling material and void were calculated. Also, the obturation time and sealer extrusion were recorded. Data were analyzed using ANOVA, LSD post-hoc, and the chi-square tests (α = 0.05). The results indicated that in the apical third, E. TCS-SC, E. TCS-UA, and E. MTA-UA had the lowest void percentage among groups (p < 0.05). In the middle thirds, samples obturated with E. TCS-UA showed a significantly lower void percentage among all groups (p < 0.05). However, in the coronal third, E. TCS-CHC showed the least void percentage (p < 0.05), followed by E. TCS-UA and E. MTA-CHC. The E. TCS-SC and E. TCS-UA were the least time-consuming methods (p < 0.05). Sealer extrusion significantly differed among the groups, with E. MTA-UA and E. TCS-UA showing higher incidence (p = 0.019). It was concluded that E. TCS-UA was the most convenient obturation technique. However, care must be taken when obturating the canals with high flow and ultrasonic activation near the vital anatomical landmarks.

An automated method to analyze root filling voids and gaps using confocal microscopy images

This study evaluated the feasibility of an automated method to delimit the required area to quantitatively analyze root filling voids and gaps from cross-sectional confocal laser scanning microscopy (CLSM) images. Root canals of maxillary canines were prepared with rotary instruments and filled by lateral compaction technique using gutta-percha and AH Plus sealer. The roots were stored (100% humidity, 37 °C) for a period of 24 h and then transversally sectioned to obtain 2-mm-thick slices from the apical and middle thirds. The areas corresponding to filling materials, gaps, and voids were manually delimited or automatically demarked by ImageJ software after converting the images to the RGB color system. Based on manual and automatic delimitations, the percentages of voids and gaps were calculated. Data of voids and gaps between middle and apical thirds were individually compared by paired t-test. Pearson`s correlation test was used to assess the correlation of data between the methods. Irrespective of the method of area delimitation, no difference was observed between the root thirds for both voids and gaps, while the p-values calculated for each method were similar. Almost perfect correlations between the methods were observed for both outcomes. The proposed method to automatically delimit the areas corresponding to filling material, voids, and gaps appears to be a valid method to facilitate the quantitative analysis of defects in root canal fillings using topographic CSLM images.

Effect of different sealer activation techniques on dentinal tubule penetration

The aim of this study was to evaluate the influence of different activation techniques on dentin tubule penetration of root canal sealer. Seventy-five teeth with single canals were chemomechanically prepared. A calcium silicate-based sealer was stained with a fluorescent dye (rhodamine B), placed into the canals and activated according to the following groups: control (no activation), EDDY, EndoActivator, ultrasonic and XP-Endo Finisher. Then, the samples were obturated. The percentages of sealer penetration at various depth levels of root sections were measured with confocal laser scanning microscopy. XP-Endo Finisher presented the highest penetration at 50 μm (p < 0.05). XP-Endo Finisher showed similar penetration with EDDY at 100 and 200 μm (p > 0.05) while presented higher penetration than the other groups (p < 0.05). At 500 μm, XP-Endo Finisher presented higher penetration than EndoActivator (p < 0.05) while similar penetration with the other groups (p > 0.05). XP-Endo Finisher can be recommended for activation during sealer placement for better penetration into dentin tubules.

Effect of ultrasonic agitation on marginal adaptation, intratubular penetration and bonding strength of calcium-silicate-based endodontic sealers: A laboratory study

The effect of ultrasonic activation (UA) on marginal adaptation, intratubular penetration and bond strength provided by three calcium silicate-based sealers was evaluated. Ninety-six distobuccal root canals of maxillary molars were randomly divided into 8 groups (n = 12) according to the sealer and UA application: EndoSequence BC sealer (ESBC), Sealer Plus BC (SPBC) and Bio-C Sealer (BCS), using AH Plus (AH) as a control group. The specimens were sectioned at 2, 4 and 6 mm from the apex. The data were statistically analysed using Kruskall-Wallis, Dunn, Mann-Whitney and chi-squared tests. UA improved the marginal adaptation of ESBC (6 mm), SPBC (all levels), BCS (2/4 mm) and AH (4 mm) (p < 0.05); the bond strength of SBPC (2 mm) and BCS (6 mm) were also improved (p < 0.05). The UA of endodontic silicate-based sealers improved the marginal adaptation in all levels and the bond strength of SBPC and BCS sealer.

Analysis of the adhesive interface of dentine treated with carbodiimide and chitosan before cementation of fiberglass posts with different resin cements

The objective of this study is to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and chitosan (CHI) on the adhesive interface of resin cements to root dentine. Forty-five upper canines were sectioned, endodontically treated, prepared and divided into three groups according to dentine treatment (distilled water-DW, CHI 0.2% and EDC 0.5) and in three subgroups according to resin cement: RelyX ARC, Panavia F 2.0 or RelyX U200. Slices were obtained, with five slices of each third submitted to the analysis of the adaptation of the adhesive interface through scores and the perimeter with gaps in confocal laser scanning microscopy and one slice of each third later evaluated qualitatively in scanning electron microscopy. The results were analyzed using with Kruskal-Wallis and Spearman correlation tests. There was no difference in adaptation for the different resin cements (p = .438). EDC presented better adaptation when compared to the groups treated with DW and CHI (p < .001), while the CHI and DW presented similar adaptation values (p = .365). No difference was observed in the perimeter referring to the gap areas for the different resin cements (p = .510). EDC showed a lower percentage of perimeters with gaps when compared to CHI (p < .001), with the percentage of perimeter with gaps of teeth treated with CHI being lower than DW (p < .001). A positive correlation coefficient equal to 0.763 was obtained between the perimeter with gaps and the adaptation data of the adhesive interface (p < .001). EDC resulted in better adaptation of the adhesive interface and a lower percentage of perimeters with gaps compared to chitosan.

Effect of sodium/calcium hypochlorite on adhesion and adaptation of fiber posts luted with a dual resin cement

This study aimed to evaluate the effect of different concentrations of sodium hypochlorite (NaOCl) and calcium hypochlorite [Ca(OCl)2] on the bond strength and adaptation of glass fiber posts luted with a dual-curing resin cement. Fifty decoronated premolars were sectioned 14 mm from the apex and endodontically treated. The root canal filling was partially removed. The specimens were divided into 5 groups (n=10) according to the irrigant for post space irrigation: 0.9% sodium chloride (NaCl), (control); 2.5% NaOCl; 5.25% NaOCl; 2.5% Ca(OCl)2; and 5.25% Ca(OCl)2. For each group, irrigation was performed with 5 ml of solution. Afterward, the posts were luted with a dual-curing resin cement. One slice from each third was obtained and submitted to the push-out test and failure modes analysis. An additional slice from the middle third was submitted to confocal images for analysis of adaptation failures (gaps). Two-way ANOVA, Tukey's post-hoc, Kruskal-Wallis with Bonferroni adjusted, and chi-square tests, analyzed data. The group treated with 5.25% NaOCl showed lower bond strength values and generated more cohesive failures compared to the control (p < 0.05). Bond strength decreased from coronal to apical in the post space (p < 0.001). The groups treated with NaOCl had the highest percentages of gaps compared to the control (p < 0.05). Regardless of concentration, Ca(OCl)2 did not influence the bond strength and the occurrence of gaps (P > 0.05). Ca(OCl)2 is a good option for irrigating the post space before luting a fiber post with a dual-curing resin cement.

Buckling resistance, torque, and force generation during retreatment with D-RaCe, HyFlex Remover, and Mtwo retreatment files

Objectives

This study compared the buckling resistance of 3 nickel-titanium (NiTi) retreatment file systems and the torque/force generated during retreatment.

Materials and Methods

The buckling resistance was compared among the D-RaCe (DR2), HyFlex Remover, and Mtwo R25/05 retreatment systems. J-shaped canals within resin blocks were prepared with ProTaper NEXT X3 and obturated by the single-cone technique with AH Plus. After 4 weeks, 4 mm of gutta-percha in the coronal aspect was removed with Gates-Glidden drills. Retreatment was then performed using DR1 (size 30, 10% taper) followed by DR2 (size 25, 4% taper), HyFlex Remover (size 30, 7% taper), or Mtrwo R25/05 (size 25, 5% taper) (15 specimens in each group). Further apical preparation was performed with WaveOne Gold Primary. The clockwise torque and upward force generated during retreatment were recorded. After retreatment, resin blocks were examined using stereomicroscopy, and the percentage of residual filling material in the canal area was calculated. Data were analyzed using 1-way analysis of variance with the Tukey test.

Results

The HyFlex Remover files exhibited the greatest buckling resistance (p < 0.05), followed by the Mtwo R25/05. The HyFlex Remover and Mtwo R25/05 files generated the highest maximum clockwise torque and upward force, respectively (p < 0.05). The DR1 and DR2 files generated the least upward force and torque (p < 0.05). The percentage of residual filling material after retreatment was not significantly different between file systems (p > 0.05).

Conclusions

NiTi retreatment instruments with higher buckling resistance generated greater clockwise torque and upward force.

Does ultrasonic activation improve the bond strength and root canal filling quality of endodontic sealers?

This study aimed to investigate the effect of ultrasonic activation (UA) of three endodontic sealers on the bond strength to root dentin and root canal filling quality. Ninety six bovine incisors were instrumented and root canal filling was carried out using AH Plus (AP), Sealer Plus (SP), or Sealer Plus BC (BC), with or without UA (n=16/group). Two 1.5-mm slices were obtained from each root third. The first slice was subjected to push-out testing and failure mode analysis, while the second was observed under a stereomicroscope for filling quality assessment. Data were analyzed by Kruskal-Wallis, Mann-Whitney and Friedman tests (α=0.05). SP showed higher bond strength and fewer voids than BC in the apical third and when root thirds data were pooled. SP also had higher bond strength compared with AH Plus in the apical third. UA improved the bond strength when BC was used but did not affect the filling quality of any sealer. There were no significant differences between the ultrasonically activated sealers regarding bond strength and filling quality. When root thirds were compared, the bond strength was similar along the root, but there was a tendency to worsen filling quality, with more voids, in the apical segment. In conclusion, UA was effective in increasing the bond strength of the calcium silicate-based sealer but did not improve its filling quality. For the epoxy resin-based sealers, these properties were not affected by UA.

Efficacy of sonic and ultrasonic activation during endodontic treatment: a Meta-analysis of in vitro studies

OBJECTIVE

To ensure a successful endodontic treatment, it is important to have a proper disinfection of the root canal. The current study compares the root canal cleanliness and smear layer score between sonic and ultrasonic activation.

METHOD

Systematic literature review was implemented, using 12 databases. All in vitro studies comparing the efficacy of sonic and ultrasonic activation and reporting at least one outcome of interest were included.

RESULTS

At the apical level, pooling the data in the random-effects model (I²=64%, p = .1) revealed a statistically significant lower smear layer score within the sonic activation group (MD-0.48; 95% CI-0.92, -0.04; p = .03). Furthermore, there was a statistically significant lower push-out bond strength value among the sonic group, in contrast to the ultrasonic group at the middle (MD-0.69; 95% CI-1.13, -0.25; p = .002) and at the apical levels (MD-0.78; 95% CI-1.09, -0.46; p < .0001) of the root canal.

CONCLUSIONS

Sonic activation accomplished advancement relative to ultrasonic agitation in removing the smear layer, while ultrasonic activation resulted in significant cohesion between the sealers and the dentine tubules, decreasing the vulnerability of apical leakage and tooth fracture.

A critical analysis of research methods and experimental models to study root canal fillings

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11,000 articles, an impressive number that is much higher than "root canal disinfection" (5,544 articles) or even the popular "root canal preparation" (8,527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. Since filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology-based review, this paper aims to present an in-depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long-term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long-term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques.

Physico-Chemical Properties of Calcium-Silicate vs. Resin Based Sealers-A Systematic Review and Meta-Analysis of Laboratory-Based Studies

INTRODUCTION

The aim of this systematic review is to analyse the effect of physico-chemical properties of calcium silicate-based sealers in comparison to epoxy resin sealers in permanent teeth using a single-cone obturation technique.

METHODS

The study was conducted according to the guidelines of Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Literature search was performed using the PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ, Open Gray with no language restrictions until October 2020. Two reviewers assessed the studies for eligibility. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was carried out to assess the evidence. Meta-analysis of the pooled data with subgroups was performed using the RevMan software (p < 0.05).

RESULTS

Results from the 28 included studies showed that the mean difference in adaptation to root canal walls (marginal adaptation, interfacial gaps and void volume) for both sealers were non-significant. However, void volume values showed a significant mean difference (p < 0.00001) favouring the calcium silicate-based sealers. The pooled meta-analysis reported statistically significant differences for apical microleakage (p = 0.0007) whilst there were non-significant mean differences for fracture resistance (p = 0.09) and push-out bond strength (p = 0.63). The heterogeneity among the included studies was 97% (I²).

CONCLUSIONS

Within the limitations of this review, calcium silicate-based sealers demonstrated a similar or superior performance in comparison to resin-based sealers in terms of the physico-chemical properties.

Evaluation of Injectable Hyaluronic Acid-Based Hydrogels for Endodontic Tissue Regeneration

Dental pulp tissue engineering (TE) endeavors to regenerate dentin/pulp complex by combining a suitable supporting matrix, stem cells, and biochemical stimuli. Such procedures foresee a matrix that can be easily introduced into the root canal system (RCS) and tightly adhere to dentin walls to assure the dentin surface’s proper colonization with progenitor cells capable of restoring the dentin/pulp complex. Herein was investigated an injectable self-setting hyaluronic acid-based (HA) hydrogel system, formed by aldehyde-modified (a-HA) with hydrazide-modified (ADH), enriched with platelet lysate (PL), for endodontic regeneration. The hydrogels’ working (wT) and setting (sT) times, the adhesion to the dentine walls, the hydrogel’s microstructure, and the delivery of human dental pulp cells (DPCs) were studied in vitro. Hydrogels incorporating PL showed a suitable wT and sT and a porous microstructure. The tensile tests showed that the breaking point occurs after 4.3106 ± 1.8677 mm deformation, while in the indentation test after 1.4056 ± 0.3065 mm deformation. Both breaking points occur in the hydrogel extension. The HA/PL hydrogels exhibited supportive properties and promoted cell migration toward dentin surfaces in vitro. Overall, these results support using PL-laden HA injectable hydrogels (HA/PL) as a biomaterial for DPCs encapsulation, thereby displaying great clinical potential towards endodontic regenerative therapies.

The Effect of Ultrasonic Agitation on the Porosity Distribution in Apically Perforated Root Canals Filled with Different Bioceramic Materials and Techniques: A Micro-CT Assessment

The present study evaluated the effect of ultrasonic agitation on the porosity distribution of BioRoot RCS/single gutta-percha cone (BR/SC) and MTA Flow (MF) root canals fillings used as apical plugs in moderately curved and apically perforated roots. Eighty mesial root canals of mandibular first molars were enlarged up to ProTaper NEXT X5 rotary instrument 2 mm beyond the apical foramen, simulating apical perforations. Specimens were randomly divided into four experimental groups (20 canals per group) according to the material and technique used for root canal obturation: BR/SC, BR/SC with ultrasonic agitation (BR/SC-UA), MF and MF with ultrasonic agitation (MF-UA). The ultrasonic tip was passively inserted into the root canal after the injection of flowable cement and activated for 10 s. The specimens were scanned before and after obturation with a high-resolution micro-computed tomography scanner, and the porosity of the apical plugs was assessed. The differences between groups were analyzed using the Kruskal-Wallis and Mann-Whitney tests, with the significance level set at 5%. None of the obturation materials and techniques used in this study was able to provide a pore-free root canal filling in the apical 5 mm. Considerably higher percentages of open and closed pores were observed in the MF and MF-UA groups, with the highest porosity being in the MF-UA group (p < 0.05). No significant differences were observed between the BR/SC and BR/SC-UA groups, where the quantity of open and closed pores remained similar (p > 0.05).

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.

Effect of the several epoxy resin-based sealer compositions on adhesion interface in radicular dentin after calcium hydroxide intracanal medication removal

Background

This study evaluated the effects of several epoxy resin-based sealer compositions (AHP, AH Plus; ADS, Adseal; SPL, Sealer Plus) on bond strength and intratubular dentin penetration of the endodontic obturation, in root canal previously treated with calcium hydroxide intracanal medication (CH) and removed by continuous ultrasonic irrigation (CUI).

Material and Methods

Forty-five maxillary canines were prepared up to F5 (ProTaper system), filled with CH, coronally sealed, and stored at 37ºC. After 1 week, CH was removed using 2.5% sodium hypochlorite energized by CUI. The specimens were randomly distributed in three groups (n=15) and root canal obturated, according to epoxy-based resin sealer composition (AHP, ADS or SPL). The roots were transversally sectioned in cervical, middle, and apical thirds. In each radicular third, push out bond strength using universal machine and intratubular dentin using confocal laser scanning microscopy (CLSM) and Image J Program were evaluated. Bond strength and intratubular dentin penetration were statistically evaluated by ANOVA one-way and Tukey tests and Kruskal Wallis test, respectively (α = 0.05).

Results

In middle and apical thirds, AHP showed higher bond strength values (p<0.05), and ADS and SPL were similar each other (p>0.05). All epoxy resin-based sealers presented similar intratubular dentin penetration, independently of the radicular thirds (p>0.05). Cohesive and mixed failures were predominant in the cervical thirds. In the middle and apical thirds, AHP showed more cohesive type failures, while ADS and SPL showed more adhesive-type failures.

Conclusions

AHP has the highest bond strength in middle and apical radicular thirds, after calcium hydroxide intracanal medication removal using continuous ultrasonic irrigation, although intratubular dentin infiltration being similar among epoxy resin-based sealer with several chemical composition. Key words:Continuous ultrasonic irrigation, endodontic sealers, epoxy resin-based sealers, root canal obturation.

Effect of Sonic Activation on Push-Out Bond Strength of Fiber Post: An In Vitro Study

This study aimed to evaluate the effectiveness of conventional and sonic activation techniques on push-out bond strength of fiber post cemented with two different monomers containing self-adhesive resin cement (SARC). Four groups (n = 19 each) were made based on the type of SARC (Rely X U200 and Panavia SA) and technique (conventional and sonic activation). After placing the fiber post, each root was sectioned into 2 mm coronal, middle, and apical portions, and a push-out bond strength test was performed using a universal testing machine. The least push-out bond strength (13.0 ± 0.9 MPa) was found in Rely X U200 conventional technique and highest with Panavia SA sonic activation technique (15.4 ± 0.9 MPa). A significant difference was found in push-out bond strength at coronal (p = 0.002), middle (p = 0.002), and apical (p = 0.001) root sections using Rely X U200 cement with sonic activation as compared to the conventional technique. However, no difference (p > 0.05) was noticed between conventional and sonic activation techniques in Panavia SA cement at any root level. Sonic activation can be used as an adjunct with a manual technique to increase bond strength. However, it was noted that 10-MDP monomer containing SARC performed well regardless of techniques.

Comparison of Various Root Canal Filling Materials and Obturation Techniques for Primary Teeth Using Microcomputed Tomography

Aim:

The aim of this study was to compare the effectiveness of different filling materials and obturation techniques for root canal obturation in primary teeth.

Materials and Methods:

Eighty maxillary primary incisors were included in this in vitro study. After biomechanical preparation, all samples were scanned using microcomputed tomography (micro-CT) and root canal volumes were calculated. Samples were grouped according to filling materials and obturation techniques, with ten samples in each group. The samples were filled with zinc oxide eugenol (ZOE) and Vitapex using four different obturation techniques (local anesthesia syringe, lentulo spiral, pastinject, and lentulo spiral–ultrasonic activation). After filling, samples were scanned a second time using micro-CT and root canal volumes were calculated. The statistical analysis was performed using SPSS version 24.0. Data were analyzed by Kruskal–Wallis and Mann–Whitney U tests.

Results:

When the ZOE and Vitapex were compared, it was observed that there were no significant differences between their postobturated volumes, percentage obturated volume (POV), internal void (IV), and percentage of internal void volume (PIV) ( P > .05). The local anesthesia syringe group had a significantly lower postobturated volume and POV, and a significantly higher IV and PIV for both filling materials than that by the other groups ( P < .05). There was no significant difference between the other obturation techniques ( P > .05). For the local anesthesia syringe group, postobturated volume and POV were significantly higher and IV and PIV were significantly lower with Vitapex than with ZOE ( P < .05). There was no significant difference between the other obturation techniques filled either with ZOE or Vitapex ( P > .05).

Conclusion:

Except for the syringe technique, no difference was observed between the ZOE and Vitapex materials. The syringe technique used in the primary root canal filling was less effective than the other techniques, which had similar efficacy, and in this technique, more effective canal filling was achieved with Vitapex.

Ultrasonic vibration and thermo-hydrodynamic technique for filling root canals: Technical overview and a case series

AIM

To present a novel root canal filling technique: Ultrasonic Vibration & Thermo-Hydrodynamic Obturation (VibraTHO), and its rationale with a series of cases.

SUMMARY

The VibraTHO technique was used to fill the root canals of three clinically challenging cases: A C-shaped mandibular molar with complex anatomy, a C-shaped mandibular molar with an infected root canal system and a periapical lesion that required retreatment, and apically bifurcating mesiobuccal canals with a common orifice in a maxillary second molar. The cases were followed up for 15, 7 and 37 months, respectively. After follow-up, normal periapical status was observed without any noticeable radiographic change in the root canal fillings in each case. Periapical radiographs revealed complete healing of the periapical area in cases with pre-operative periapical lesions.

Root Canal Filling Quality Comparison of a Premixed Calcium Silicate Endodontic Sealer and Different Carrier-Based Obturation Systems

Background: The number of voids within the root canal obturation is a relevant parameter to describe the quality of the technique, as well as to predict long-term prognosis. The aim of this study was to evaluate the quality of root canal obturation in curved root canals filled with Thermafil, GuttaCore, GuttaFusion and lateral compaction with AH Plus and EndoSequence BC sealer, by means of percentage of gutta-percha and sealer filled area. Methods: 200 curved canals of mandibular molars were divided in five groups (n = 40). Each specimen was evaluated at 3, 6 and 9 mm from the apex. A total of 600 samples were analyzed. Obturation was performed with either Thermafil (TH), GuttaCore (GC), GuttaFusion (GF) or lateral compaction (LC), using AH Plus as sealer. In another group EndoSequence BC sealer (BC) was used. Subgroups (n = 20) were made depending on the use of sonic activation during the placement of the sealer. The percentage of total obturation material was analyzed as an indirect measurement of percentage of voids. Results: GF showed a better performance at the apical level, while GC showed the higher percentage of total obturation at the coronal area. No differences were observed for the activation of sealers in any of the groups. Statistical analysis was performed by using two-way ANOVA. Statistical significance was set at CI: 95% (p < 0.05). Conclusions: Sonic activation of sealers did not show any benefit to avoid the presence of voids within obturation of curved canals. Following the manufacturer recommendations, we found that TH did not show benefits when applied to curved canals.

Does the ultrasonic activation of sealer hinder the root canal retreatment?

OBJECTIVES

To evaluate if the ultrasonic activation of sealer hinders the root canal retreatment.

MATERIALS AND METHODS

Thirty mandibular premolars were prepared using the ProTaper Universal system (Dentsply) until the instrument F3 (0.30/0.09). The canals were distributed into 2 groups (n = 15), according to the filling technique: NUact group - sealer without ultrasonic activation + gutta-percha cones and Uact group - sealer with ultrasonic activation + gutta-percha cones. The canals were re-instrumented with Largo burs, followed by the instrument R50 (0.50/0.05) of the Reciproc system. The time required to perform re-instrumentation was recorded (s). The roots were longitudinally cleaved, and the total area of root canal and remaining filling material were quantified (%). The ANOVA test was applied to the data and complemented by Student's t test (P < 0.05).

RESULTS

Uact group had higher percentage of remaining filling material than NUact group (P < 0.05). When the root thirds were considered, there was statistically significant difference only for Uact group at the apical third (P < 0.05). There was no difference between groups regarding the time required to perform re-instrumentation (P > 0.05).

CONCLUSIONS

Ultrasonic activation of sealer leads to a higher percentage of remaining filling material attached to the root canal walls. However, it did not affect the retreatment time.

CLINICAL SIGNIFICANCE

Ultrasonic activation increases sealer penetration into dentinal tubules, improving its resistance to dislodgement. However, there is no scientific evidence to prove if ultrasonic activation of sealer hinders its removal when root canal retreatment is necessary.

Retrievability of bioceramic-based sealers in comparison with epoxy resin-based sealer assessed using microcomputed tomography: A systematic review of laboratory-based studies

Aim:

The objective was to evaluate the retrievability of bioceramic sealers in comparison with epoxy resin-based sealers assessed using microcomputed tomography.

Materials and Methods:

Four reviewers independently conducted a systematic literature search in four electronic databases. The risk of bias was assessed using modified Joanna Briggs Institute Critical Appraisal tools for Quasi-Experimental Studies.

Results:

Ten articles were included in this review and all had a moderate risk of bias. The results across the included articles were inconsistent with some indicating easier/difficult removal of bioceramic sealers, while others indicate no difference. The studies varied in terms of the type of bioceramic sealer used, root canal anatomy, and retreatment techniques followed. Due to heterogeneity, only a qualitative analysis was performed and no meta-analysis was conducted.

Conclusion:

The quality of evidence is low and no definitive conclusion could be derived regarding the retrievability of bioceramic sealer/AH plus sealer from the root canals during retreatment procedures.

Calcium hydroxide paste removal strategies and bond strengths of epoxy- and silicate-based sealers

This study evaluated the syringe/needle (SN), passive ultrasonic irrigation (PUI) and XP-endo Finisher (XP) in the removal of Ca(OH)₂ -based paste and the bond strength (BS) values of an epoxy resin (AH Plus) and silicate (MTA)-based sealers to root dentin. Eighty lower premolars were assigned: control group (CT), SN, PUI and XP, and subdivided according to the sealer (n = 10) for BS. SN has the lowest removal followed by PUI and XP. AH Plus had higher BS for CT compared with SN in all root thirds. CT and XP presented similar BS in the apical and middle thirds and higher than SN and PUI. For MTA, similar BS was observed in the cervical and apical thirds, and in the middle third, CT, PUI and XP presented similar values and higher than SN. PUI and XP methods presented higher efficiency in the Ca(OH)₂ removal, and the residual Ca(OH)₂ provides a reduction in BS of the AH Plus.

Temperature changes affect the rheological properties of a silicone-based and an epoxy resin-based root canal sealers

To evaluate temperature changes on the rheological properties (setting time and complex viscosity (η*)) of GuttaFlow Bioseal (GFB) and AH Plus Jet (AHPJ). Rheological measurements were performed in oscillating mode at the strain amplitude and angular frequency of 0.01% and 10 rad s^-1 , respectively. Each sealer (n = 5) was tested running a temperature ramp (rapid increase to 80°C, 1 min constantly at 80°C, and slower decrease to 37°C). Control groups (n = 5) were tested at a constant temperature of 37°C. Kolmogorov-Smirnov and one-way ANOVA (P < 0.05) statistical tests were performed. The temperature ramp reduced setting time of GFB (24.85 to 4.45 min) (P < 0.05), but did not alter that of AHPJ (P > 0.05). GFB exhibited an increased η*, whereas the AHPJ η* was decreased when heated (P < 0.05). Rheological properties of sealers were negatively affected by temperature changes.

Effect of Ultrasonic Activation of Endodontic Sealers on Intratubular Penetration and Bond Strength to Root Dentin

INTRODUCTION

This study aimed to evaluate the effect of ultrasonic activation (UA) of endodontic sealers on dentin tubule penetration and the bond strength to root dentin.

METHOD

One hundred single-rooted teeth were prepared with 40.06 nickel-titanium instruments and divided into 2 groups: with or without UA. Three resin-based sealers (MTA Fillapex [Angelus Dental Solutions, Londrina, PR, Brazil], Sealer Plus [MK Life Medical and Dental Products, Porto Alegre, RS, Brazil], and AH Plus [Dentsply, DeTrey GmbH, Konstanz, Germany]; n = 20) and 2 calcium silicate-based sealers (Sealer Plus BC [MK Life Medical and Dental Products] and EndoSequence BC [Brasseler, Savannah, GA], n = 20) were used and subdivided (n = 10) according to the protocols. Fluo-3 (Thermo Fisher Scientific, Waltham, MA) and rhodamine B dyes were added to the calcium silicate- and resin-based sealers, respectively. In the UA groups, the activation was performed for 40 seconds followed by lateral compaction. Samples were transversely sectioned to evaluate the dentin tubule penetration and the bond strength to root dentin. The penetration data were analyzed with the Student t test, 1-factor analysis of variance, and Bonferroni tests. Bond strength was evaluated using the Student t test, Kruskal-Wallis, and Dunn post hoc test.

RESULTS

Resin-based sealers showed the highest tubule penetration without UA (P < .05). UA significantly enhanced MTA Fillapex and Endosequence BC dentin tubule penetration (P < .05). AH Plus and Sealer Plus BC improved their bond strength to root dentin after UA (P < .05). AH Plus/UA, Sealer Plus/UA, and Sealer Plus BC/UA presented the highest bond strength values (P < .05). Adhesive failures were predominant in all groups regardless of the use of ultrasound.

CONCLUSIONS

UA interferes with tubule penetration and the bond strength to root dentin of resin- and calcium silicate-based sealers.

Retreatability of BC Sealer and AH Plus root canal sealers using new supplementary instrumentation protocol during non-surgical endodontic retreatment

OBJECTIVE

The aim of this study was to evaluate the efficacy of supplementary techniques (ultrasonic tip/XP-endo Finisher R) in removing remaining filling materials (gutta-percha/AHPlus/BCSealer) from oval-shaped root canals during non-surgical endodontic retreatment.

MATERIAL AND METHODS

Twenty-eight distal roots of human mandibular molars with single and oval-shaped canals were initially shaped with a R40 instrument and filled with gutta-percha points and AH Plus (n = 14) or BC Sealer (n = 14) followed by an initial micro-CT scanning. Initial filling material removal was performed in all 28 samples with an R50 instrument, and all samples submitted to a second micro-CT. Supplementary techniques with ultrasonic tips or XP-endo Finisher R instruments were performed in each sealer group, and all samples submitted to a third micro-CT. The volume of remaining filling material was calculated for the entire canal as well as for the coronal, middle, and apical thirds. Statistical analyses were performed using T, ANOVA 3-way, and Tukey tests.

RESULTS

Lower values of remnant filling material were found for BC Sealer (16.06 ± 14.34) compared to AH Plus (28.30 ± 10.54) (P < 0.001), and considering the supplementary technique, lower values of remnant filling material were found for the ultrasonic tip (18.95 ± 11.05) compared to XP-endo Finisher R (25.41 ± 15.81) (P = 0.025). Ultrasonic instruments significantly reduced the percentage of remaining filling material for both AH Plus (P = 0.04) and BC Sealer (P = 0.02) while XP-endo Finisher R was effective for AHPlus only (P = 0.04). The remaining filling material was observed in all samples regardless the filling material or the supplementary technique employed.

CONCLUSIONS

Supplementary techniques increased filling material removal; however, none of them was able to render root canals completely free from root fillings. Ultrasonic tips should be considered a good option for endodontic retreatment, especially for bioceramic cases.

CLINICAL RELEVANCE

Supplementary instrumentation techniques are effective tools to reduce the amount of filling materials during root canal retreatment.

Correlation between Bond Strength to Dentin and Sealers Penetration by Push-Out Test and CLSM Analysis

This study correlated the bond strength (BS) and dentin penetration of different sealers by push-out test and Confocal Laser Scanning Microscopy (CLSM) analysis. Forty-five root canals were prepared according to the crown-down technique and filled with gutta-percha associated to the following sealers (n=15): Endofill, AH Plus and MTA Fillapex. Five canals of each group were filled with the sealers added with 0.1% Rhodamine B dye. Next, the specimens were transversely sectioned and submitted to the push-out test (n=10) and CLSM analysis (n=5). The BS data showed the following means (MPa) and standard deviation: AH Plus (4.17±1.86); MTA Fillapex (3.13±1.96) and Endofill (2.10±1.03). Statistical analysis (two-way ANOVA, α=0.05) showed significant difference among sealers (p<0.001) and root canal thirds (p<0.001). The BS results of Endofill and MTA Fillapex were statistically similar (p>0.05), however, they were statistically different from AH Plus (p<0.001). The regional analysis of BS showed similarity between middle and apical thirds (p>0.05), and both were different from coronal portion (p<0.001). CLSM analysis verified tags formation in all groups and higher penetration of the specimens filled with AH Plus (p<0.05). The Kendall test (correlation between BS to dentin and sealer penetration into dentinal tubules) and the Pearson test (between failures pattern and sealer penetration into dentinal tubules) did not show correlation between the variables evaluated for all the tested sealers (p>0.05). AH Plus group had higher BS to dentin, and deeper tags formation than the other sealers. There was no significant correlation between BS and intratubular penetration of the tested sealers.

Effect of ultrasonic activation on dentinal tubule penetration of calcium silicate-based cements

This study investigated the dentinal tubule penetration of mineral trioxide aggregate (MTA), NeoMTA Plus and Biodentine placed by either manual condensation or ultrasonic activation in simulated open apex model. Standardized divergent open apex models were created using palatal roots of 60 human maxillary molars and divided into six groups according to the used cements and activation methods (n = 10): MTA-manual condensation, MTA-ultrasonic activation, NeoMTA Plus-manual condensation, NeoMTA Plus-ultrasonic activation, Biodentine-manual condensation, Biodentine-ultrasonic activation. For the measurement of penetration, the cements were mixed with 0.1% Rhodamin B and 6-mm apical portions of each root canal were obturated in an orthograde direction. The roots were embedded into acrylic blocks, and 1-mm-thick sections were obtained at 3 mm from the apex. Specimens were mounted onto glass slides and scanned under a confocal laser scanning microscope (CLSM) and stereomicroscope. Dentinal tubule penetration areas, depth and percentage were measured using LSM and ImageJ software. The data were analyzed using two-way analysis of variance (anova) with Bonferroni correction (α = 0.05). No correlation was found between stereomicroscope and CLSM analyses (p > .05). CLSM analysis showed no significant differences between MTA, NeoMTA Plus, and Biodentine groups when manual condensation was used (p > .05). Ultrasonic activation did not increase the tubular penetration of MTA, NeoMTA Plus or Biodentine as compared to manual condensation of each material (p > .05). MTA, NeoMTA Plus and Biodentine showed similar tubular penetration when manual condensation was used. Ultrasonic activation of these cements had no effect on tubular penetration of each material as compared to the manual condensation counterparts.

Design Variability of the Push-out Bond Test in Endodontic Research: A Systematic Review

INTRODUCTION

There is limited literature on the impact of testing variables on the push-out bond test (POBT). This review identified designs of the POBT used in the endodontic literature and aimed to determine which experimental variables may influence the push-out bond strength (POBS).

METHODS

A systematic review based on PRISMA guidelines was performed by searching the PubMed, SCOPUS, and Cochrane library databases using terms including push-out and dislocation resistance and descriptions of endodontic materials. Test variables assessed included method of root preparation, timing of sectioning compared with filling, thickness, diameter and taper of sections, and plunger size and velocity. The POBS of 3 common materials (gutta-percha and AH Plus, mineral trioxide aggregate, and Biodentine) were collected from investigations, and a comparison was attempted.

RESULTS

One hundred thirty-three studies assessed the POBS of root-filling materials, 68 assessed root repair cements/root-end filling materials, and 16 assessed orifice barrier materials other than mineral trioxide aggregate. There was significant variation in all of the assessed variables, resulting in a large range of reported values for the POBS of the various materials. Because of this heterogeneity in study design, no further statistical analysis of the impact of the test variables on POBS was possible.

CONCLUSIONS

There was considerable variation in the POBT design used in endodontic research. Greater standardization is required for future research as well as accurate reporting for all test variables to assess the impact of specific design variables on POBS.

Apically extruded debris during the removal of canal filling material from root canals using three techniques

AIM

In the present study, we evaluated the effect of the single-cone technique (SCT), cold lateral compaction (CLC), and wave vertical compaction (WVC) technique performed using two different sealers on the amount of apically extruded debris (AED) produced during the removal of canal filling material.

METHODS

Ninety extracted mandibular premolars were prepared with ProTaper instruments. The teeth were then randomly assigned to six groups (N = 15) for root canal filling: (a) group 1, CLC+AH Plus; (b) group 2, SCT+AH Plus; (c) group 3, WVC+AH Plus; (d) group 4, CLC+MTA Fillapex; (e) group 5, SCT+MTA Fillapex; and (f) group 6, WVC+MTA Fillapex. In all groups, the removal of canal filling material was performed with ProTaper retreatment instruments. The mean weight of the AED was assessed with an analytical balance.

RESULTS

The amount of AED was lowest in groups 2 and 5 (P < .05), with no difference between these groups (P > .05). Groups 3 and 6 produced the greatest amount of extruded debris (P < .05); there was no difference between these groups (P > .05). Additionally, there was no difference between groups 1 and 4 (P > .05). There was no significant difference among the groups regarding sealer type (P > .05).

CONCLUSIONS

The canal filling technique used affected the amount of AED produced during the removal of canal filling material, but not sealer type.