Extended Setting Shrinkage Behavior of Endodontic Sealers

Field Emission Scanning Electron Microscope Analysis of the Marginal Adaptation of Various Root Canal Sealers at the Dentin-Sealer and Sealer-Guttapercha Interfaces at Three Root Canal Levels: An In Vitro Study

Aims An in vitro evaluation of the marginal adaptation of four root canal sealer variants at the dentin-sealer and sealer gutta-percha interfaces in the coronal, middle, and apical thirds of root canals was conducted using field emission scanning electron microscope (FESEM) analysis.  Materials and methods In total, 80 extracted human mandibular premolar teeth were used in this study. All teeth were decoronated to standardize the root length to 14 mm. A round bur was used to gain access into canal orifices and the working length was determined. Root canal instrumentation was performed using the crown-down technique with ProTaper Next rotary files up to size X3, along with the use of root canal irrigants. All specimens were then randomly divided into four groups, with 20 specimens per group, depending on the root canal sealer used: Group A consisted of AH Plus (Dentsply Maillefer, Ballaigues, Switzerland), Group B of MTA-Fillapex (Angelus Dental, Londrina, Brazil), Group C of Bio-C Sealer (Angelus Dental), and Group D of GuttaFlow-2 (Coltene Whaledent, Altstatten, Switzerland). All specimens were obturated with size X3 gutta-percha points uniformly coated with respective sealers in the single-cone technique and coronal access was sealed with glass ionomer cement. The specimens were incubated for seven days and then horizontally sectioned at the coronal, middle, and apical thirds of the root canals. On each sample obtained, three points were randomly chosen and both sealer-dentin and sealer gutta-percha interfaces were examined under FESEM at 1000x magnification. The marginal gaps of all four sealers at both interfaces and at three levels of root canals were measured in µm and values were recorded, tabulated, and used for data analysis. One-way analysis of variance (ANOVA) and post hoc Bonferroni tests were used for statistical analysis. A p-value ≤ 0.05 was considered statistically significant. Results Compared to the sealer gutta-percha interface, AH Plus, MTA-Fillapex, and Bio-C sealers at all three levels of the root canals showed more marginal gaps at the sealer-dentin interface with a significant difference (p<0.05). However, the GuttaFlow-2 sealer showed no significant difference (P > 0.05).  Conclusions The marginal adaptation of the GuttaFlow-2 sealer is superior to both dentin and gutta-percha at the coronal, middle, and apical thirds of root canals compared to other sealers used in the study.

Volume and power of expansion of novel polyurethane-based sealers

INTRODUCTION

Shrinkage and lack of interfacial adaptation between endodontic sealers and root canal walls may jeopardize the root canal treatment outcome. This study aimed to evaluate the volume and power of expansion (and the relationship between the two) of three novel root canal sealers (polyurethane expandable sealer (PES), zeolite + PES (ZPES), and elastomeric polyurethane sealer (EPS)) in comparison with an epoxy-resin based sealer (AH Plus) and a calcium silicate-based sealer (EndoSequence BC).

METHODS

This study utilized 36 cylinders (30 plastic graduated cylinders for volume of expansion and 6 steel cylinders for power of expansion) (4x10mm) filled with PES, ZPES, EPS, AH Plus, EndoSequence BC, or water (n=5/group). The plastic graduated cylinders were inserted inside a customized Linear Swell Meter (LSM) apparatus to measure the percentage of volumetric expansion. The steel cylinders were placed inside an LSM apparatus mounted onto a universal testing machine to measure the maximum pressure in psi. Specimens were tested for 72 hours for both volume and power of expansion tests. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Post Hoc Tukey, and Pearson correlation tests (p<0.05).

RESULTS

The volume of expansion of PES, ZPES, and EPS was significantly higher than in AH Plus and EndoSequence BC (p<0.05). For the power of expansion, no significant differences were found between the root-filling materials (p>0.05). No correlation was seen between the volume and power of expansion (p>0.05).

CONCLUSION

Although polyurethane-based sealers showed a significantly higher volume of expansion compared to AH Plus and EndoSequence BC, their power of expansion did not increase significantly.

Biological considerations of dental materials as orifice barriers for restoring root-filled teeth

There is ample published literature regarding the technical aspects of restoring root-filled teeth, but little concerning the biological impacts, consequences, and criteria for the selection of direct restorative materials following endodontic treatment. The provision of an effective coronal seal in addition to a sound root filling is known to be important in the prevention of root canal infection. This review seeks to explore the evidence concerning the selection of dental materials in the restoration of root-filled teeth, specifically with a close examination of the properties of commonly used materials as orifice barriers. © 2023 Australian Dental Association.

Comparison of obturation quality in natural and replica teeth root-filled using different sealers and techniques

OBJECTIVES

This study aims to assess the obturation efficacy of sealers placed with different techniques using microcomputed tomography (µCT) and assess the influence of µCT testing parameters on the obturation data obtained.

MATERIALS AND METHODS

Incisors and mesial roots of lower molars with standardized root length were scanned using µCT, and one tooth of each type was 3D printed in acrylic. Two obturation techniques (warm vertical and single cone) and 4 sealer types (AH Plus, BioRoot RCS, Totalfill BC, and Bio-C Sealers) were assessed following storage in Hank's balanced salt solution for 3 and 6 months by assessing gap and void volume percentages on both natural and replica incisor and molar roots. The storage solution was analysed to assess calcium ion leaching. The influence of temperature, tooth positioning, and moisture content of the teeth while µCT scanning was also investigated.

RESULTS

The obturation quality in the incisor group was the same using both natural teeth and replicas (p > 0.05). No changes in void volume were identified when comparing the same sealer using different obturation techniques. The premixed sealers used in single-cone obturation exhibited high void volume in the 3D printed replicas in the long term. The temperature, positioning, and moisture content of the teeth did not affect the outcome of µCT testing.

CONCLUSIONS

BioRoot RCS, Totalfill BC, and Bio-C Sealers are suitable for obturation of both complex and simple root canal systems using different obturation techniques with BioRoot RCS exhibiting the highest calcium ion release. 3D printed acrylic teeth can be used to assess the obturation quality in uncomplicated root canal systems. µCT parameters had no significant effect on the µCT measurement.

CLINICAL RELEVANCE

The single-cone obturation technique with hydraulic sealer is a simple technique that can be used for obturation of all root canal systems.

Evaluation of Bond Strength of Four Different Root Canal Sealers

The purposes of the study were to evaluate the influence of the sealer’s chemical composition on the interfacial strength between root canal dentin and root filling material, for two different classes of endodontic sealers, and to assess their failure modes. Methods: Forty extracted single-rooted teeth were randomly divided into four groups using the following endodontic sealers: RealSeal SE and Resilon (RSSE); EndoSequence BC sealer and BC Point (EBCS); Endoseal MTA and gutta-percha (EDS); Bioroot RCS and gutta-percha (BRS). Teeth were embedded in acrylic resin, and the roots were sectioned horizontally into 1 mm slices. For each slice, the perimeter was measured. A push-out test was performed using an Instron universal testing machine. For each sample, bond strength was calculated. Specimens were examined by SEM investigation in order to analyze the dentin−sealer−core interface. Results were assessed using analysis of variance (ANOVA) and Tukey and Bonferroni test. Results: Statistical analysis revealed that EDS and gutta-percha had significantly higher resistance to dislodgement compared to the other three groups (p < 0.05). EBCS and BC Point showed significantly greater push-out bond strength values compared to RSSE and Resilon (p < 0.05). Conclusions: Bioceramic endodontic sealers showed a higher bond strength to root dentin than methacrylate resin-based endodontic sealer.

Comparison of Two Root Canal Filling Techniques: Obturation with Guttacore Carrier Based System and Obturation with Guttaflow2 Fluid Gutta-Percha

Introduction: The aim of the present study was to compare the quality of the root canal obturation obtained with two different techniques, i.e., thermoplastic gutta-percha introduced through a carrier (GuttaCore) and fluid gutta-percha (GuttaFlow2). Materials and Methods: The study included 40 permanent single-rooted human teeth, divided into two groups and obturated with Guttaflow (group G) and with GuttaCore (group T). The teeth were fixed and transversely sectioned, they were examined by scanning electron microscopy. The dentin–cement–gutta–percha interface and the percentage of voids produced by the two techniques were statistically analyzed. Results: GuttaCore showed a better filling in the apical third of the canal with a percentage of voids equal to 5%. GuttaFlow showed a lower percentage of voids in the middle and coronal thirds of the canal, 1.6% of coronal voids. Statistical analysis showed a statistically significant difference in the percentage of voids in the two groups (GuttaCore and Guttaflow2) in each portion. Conclusions: GuttaFlow2 seems to flow optimally in the middle and coronal third of the canal, with greater difficulty in filling the apical third. Due to the rigidity of the carrier, GuttaCore is able to reach better the most apical portions of the canals, with greater difficulty in creating the three-dimensional seal at the level of the middle third and coronal third.

The evaluation of physical properties of a polyurethane expandable endodontic sealer: a preliminary study

Endodontic sealers play a vital role in providing 3-dimensional (3D) filling of complex root canal system (RCS). This study intended to compare the physical properties of a Polyurethane Expandable Sealer (PES), AH Plus and EndoSequence. Three properties including setting time, radiopacity and flow (rheology) were evaluated based on ISO 6876 standard. For evaluation of each of these physical properties, five samples from experimental groups: AH Plus, EndoSequence, PES (controlled expansion) and PES (high expansion) were used (n = 5). Data were analysed by one-way ANOVA and Post Hoc Tukey tests (a = 0.05). EndoSequence showed the longest setting time (P < 0.000); AH Plus showed that highest radiopacity (P < 0.000); and PES (high expansion) showed the highest flow (diameter and surface area) (P < 0.000). EndoSequence and PES (controlled expansion) showed promising and comparable physical properties to the AH Plus sealer in terms of flow, setting time and radiopacity.

Novel Calcium Zirconate Silicate Cement Biomineralize and Seal Root Canals

This study evaluated the sealing ability of gutta-percha (GP) with a calcium silicate-based sealer and a novel calcium zirconate containing calcium silicate cement (ZC). The root canals of the extracted premolars were prepared, which were then randomly allocated to three experimental groups (12 root canals per group) for obturation by continuous wave of condensation with the GP and AH 26 sealer (CW); obturation using a single GP with a calcium silicate-based EndoSequence BC sealer (SC); or obturation with ZC. The roots were inserted into sterile Eppendorf tubes, which were inoculated coronally with Porphyromonas gingivalis. The amount of endotoxin leakage into the apical reservoirs were measured using the Limulus Amebocyte Lysate (LAL) assay over 21 days, with comparisons made using one-way ANOVA and Scheffe’s tests (α = 0.05). After 21 days, 75% of the canals that had been obturated by SC, 50% of those obturated by CW and 42% of those obturated by ZC showed endotoxin leakage. The amount of leakage was higher in the SC canals than in the CW (p = 0.031) or ZC (p = 0.03) canals, although there was no significant difference in the amount of leakage for CW and ZC (p > 0.05). X-ray diffraction revealed the presence of tricalcium silicate (Ca₃SiO₅) and calcium zirconate (CaZrO₃) in the synthesized ZC. Scanning electron microscopy revealed mineralized precipitates on the dentin of canals obturated by ZC. The novel calcium zirconate silicate cement appears to promote biomineralization and seal root canals at least as effectively as the conventional sealer.

Expansion of Gutta-percha in contact with various concentrations of zinc oxide-eugenol sealer: A three-dimensional volumetric study using spiral computed tomography

Aim:

The purpose of this study was to evaluate the three-dimensional expansion of Gutta-percha (GP), at various powder/liquid ratios, of a zinc oxide-eugenol (ZOE)-based sealer using spiral computed tomography (SCT).

Materials and Methods:

Thirty-five freshly extracted human mandibular premolars were selected for this study. Cleaning and shaping were performed in all the teeth initially with hand K-files up to #25 and finally with RaCe rotary instruments (25/06). Teeth were randomly divided into five groups of 7 teeth each. Specimens were scanned using SCT. They were then viewed both cross-sectionally and longitudinally, with a constant thickness of 1 mm/slice. The volume of root canal in each tooth was estimated. Obturation was performed by GP points (25/04) and ZOE-based root canal sealer in all groups with different powder-liquid ratio. Groups 1, 2, 3, and 4, had powder/liquid ratio of 1:1, 1:2, 1:3, and 1:4, respectively, while in the control group, no sealer was used. The obturation was performed by sealer coated single cone GP. A second SCT scan was performed to determine the volume of GP and sealer in all four groups 1 day after obturation. The third and fourth SCT scans were taken 7 and 30 days after obturation, respectively. The mean volume of GP per group was calculated. Data were statistically analyzed using one-way ANOVA. Inter-group comparisons were done using Scheffe post hoc multiple comparisons test.

Results:

All groups with sealer showed expansion of GP at both 7^th day and 30^th day, which was statistically significant from the GP volume at 1^st day. Groups 2 and 3 with powder/liquid ratio of 1:2 and 1:3 gave the highest mean volume values during 30 days period and showed significant expansion in comparison with Groups 1 and 4 with powder/liquid ratio of 1:1 and 1:4, respectively.

Conclusion:

Increasing the ratio of eugenol in sealer resulted in the volumetric expansion of GP. However, further studies should be performed to confirm the expansion of GP, leading to the achievement of fluid impervious seal.

Ability of Three Endodontic Sealers to Fill the Root Canal System in Association with Gutta-Percha

Introduction:

The present study compared the ability of the endodontic sealers AH Plus, Pulp Canal Sealer and EndoREZ to fill the root canal system in association with gutta-percha.

Methods:

Ninety mandibular premolars were accessed, prepared and divided into three groups of 30 teeth each, according to the sealer used to fill the canals: AH Plus, Pulp Canal Sealer and EndoREZ. All the teeth were filled using the continuous wave of condensation technique. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators with 8x magnification. Chi-squared test (χ², p < 0.05) was used to compare the groups in relation to the totally filled, the partially filled and the non filled ramifications. The same test was used to compare the directions of filled ramifications and the number of ramifications among the three thirds of the roots.

Results:

EndoREZ filled a significantly higher number of ramifications than AH Plus and Pulp Canal Sealer (χ², p < 0.05). All the groups showed higher number of totally filled ramifications than partially filled and unfilled ramifications. The ramifications were more frequently detected in the apical third, followed by medium and coronal thirds, respectively (χ², p < 0.05). The ramifications were more frequently detected towards lingual direction (χ², p < 0.05).

Conclusion:

EndoREZ presented higher ability to fill the root canal system in association with gutta-percha when compared to AH Plus and Pulp Canal Sealer. The ramifications were more frequently detected in the apical third, running in a lingual direction.

Comparison of bacterial leakage resistance of various root canal filling materials and methods: Confocal laser-scanning microscope study

This study evaluated the bacterial leakage resistance and root canal lining efficacy of various root canal filling materials and methods by using confocal laser-scanning microscope (CLSM). Sixty extracted human premolars with mature apex and single root canal were randomly divided into 2 control groups and 4 experimental groups. Group CW was filled with continuous wave technique using gutta-percha and AH Plus sealer. Group GC was coated with AH-Plus sealer and then obturated with soften GuttaCore. Group GF was obturated using GuttaFlow and gutta-percha. Group EM was filled with EndoSeal MTA and gutta-percha using ultrasonic vibration. The AH-Plus, GuttaFlow, and EndoSeal were labeled with Hoechst 33342 to facilitate fluorescence. The obturated root tip was incubated with Carboxyfluorescein diacetate succinimidyl ester (CFSE)-stained E. faecalis for 14 days. CLSM was performed to evaluate the sealer distribution and bacterial leakage for the apical 1-, 2-, 3-mm specimens. Statistically significant differences were determined by 1-way ANOVA with Tukey's post-hoc test and Pearson's correlation analysis. Group EM showed the better sealer distribution score than the other groups (p < 0.05). Group CW and group GC exhibited the less bacterial leakage than the group GF, while group EM showed the similar bacterial leakage score with the groups CW and GC. There was no significant correlation between the sealer distribution and bacterial leakage (p > 0.05). Under the conditions of this study, different root canal filling materials and methods showed different efficacy for canal distribution and bacterial leakage resistance.

Sealing efficacy of a single-cone root filling after post space preparation

Objectives

The aim of the present study was to compare the sealing efficacy of root fillings made by a single-cone technique with three different sealers and a cold lateral compaction technique with an epoxy sealer.

Materials and methods

Eighty extracted single-rooted human teeth were assigned to four experimental groups: group 1, single-cone and epoxy sealer; group 2, single-cone and calcium silicate-based sealer; group 3, single-cone and methacrylate resin-based sealer; and group 4, cold lateral compaction and epoxy sealer. Twenty extra teeth served as negative and positive controls. After preparation of a coronal post space, the sealing efficacy of the root fillings was assessed on a fluid transport setup. The results were analyzed using Kruskal-Wallis and Mann-Whitney U test.

Results

No fluid transport was detected for the negative controls whereas all the positive controls showed rapid fluid transport. No significant difference was detected between groups 1, 3, and 4 whereas group 2 demonstrated significantly more fluid transport than all the other experimental groups.

Conclusions

Root fillings made by a single-cone technique with the epoxy or methacrylate-based sealers were as effective after post space preparation as those made by a cold lateral technique with the epoxy sealer in sealing the root canal.

Clinical Relevance

Specific root canal sealers in combination with single-cone technique represent a noteworthy alternative to the use of cold lateral compaction technique when a post space is required. The use of effective endodontic procedures with simplified technical implementation may positively affect endodontic outcome.

Ability of new obturation materials to improve the seal of the root canal system: a review

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.

Evaluation of coronal leakage and pathway of dye leakage after obturation with various materials for open apical foramina

The aim of this study was to investigate coronal leakage after obturation with mineral trioxide aggregate (MTA), resin-based sealer, and silicon-based sealer for open apical foramina and to evaluate pathway of leakage. Twenty-eight maxillary premolars were used, and instrumented to ISO size #80. Teeth were randomly divided into four groups as follows: Group A filled with MTA, Group B with gutta-percha and resin-based sealer, Group C with polymer-based material and resin-based sealer, and Group D with gutta-percha and silicon-based sealer. All samples were evaluated for coronal leakage with methylene blue solution and spectrophotometry. After leakage testing, samples were cut, and sections were observed. Dye leakage of Group A was significantly lowest among all groups at 15 days and 30 days. Defects which induced coronal leakage in resin-based sealer were observed at 7 mm from the apex. Coronal leakage after obturation with MTA for open apical foramina was significantly lower than resin-based sealer and silicon-based sealer.

Sealing ability of three single-cone obturation systems: An in-vitro glucose leakage study

AIM

The aim of this study is to compare the corono-apical sealing ability of three single-cone obturation systems using a glucose leakage model.

MATERIALS AND METHODS

A total of 90 extracted maxillary single rooted teeth were selected and their crowns were cut. The root canal of each sample was instrumented using a rotary crown down technique and then divided into four experimental (n = 20 each) and two control groups (n = 5 each). Samples in the experimental groups were filled as follows: Group 1, cold lateral condensation using Gutta-percha/AH Plus; Group 2, single-cone Gutta-percha and AH Plus; Group 3, single-cone Gutta-percha/and GuttaFlow2; Group 4, single-cone Resilon/RealSeal SE after 7 days, the sealing ability of root canal fillings was tested at different time intervals using glucose leakage model. Glucose leakage values were measured using a spectrophotometer and statistically analyzed.

RESULTS

The four experimental groups presented significantly different glucose leakage values at all test periods (P < 0.05). At the end of the observation period, the cumulative glucose leakage values of Groups 3 and 4 were significantly lower than those of Groups 1 and 2 (P < 0.05).

CONCLUSION

Gutta-percha/GuttaFlow2 or Resilon/RealSeal SE combinations provided the superior sealing ability over the lateral condensation technique.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique

OBJECTIVES

The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1.

MATERIALS AND METHODS

Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth.

RESULTS

Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region.

CONCLUSIONS

These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system.

CLINICAL RELEVANCE

These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

Interfacial adaptation of an epoxy-resin sealer and a self-etch sealer to root canal dentin using the System B or the single cone technique

The aim of this laboratory study was to compare the interfacial adaptation of an epoxy-resin and a self-etch sealer in mesial root canals of mandibular molars filled using the System-B/Elements Obturation Unit. Sixty mesial root canals of mandibular molars were prepared using the K3 rotary system up to 35.04 instrument and then filled with the aid of the System-B/Elements Obturation Unit using either gutta-percha/ThermaSeal Plus (n=15) or Resilon/Real Seal SE (n=15). The single cone technique using both materials was used as control. The sealers were stained with Rhodamine B dye and the teeth were filled and sectioned at 2, 4 and 6 mm from the apex. The interfacial marginal adaptation of sealers was evaluated using confocal microscopy. Statistical analyses were performed by the Kruskall-Wallis test (α=0.05). In general, microscopic analysis showed a quite regular gap distribution pattern at sealer-dentin interfaces, mainly for the two groups filled with Real Seal SE. This means that both nonbonding root-filling groups (ThermaSeal Plus) showed significantly higher amount of gap-free regions regardless of the filling technique (p<0.05). Better marginal adaptation was obtained with gutta-percha and epoxy resin-based sealer using either the system B or the single cone technique.

Expansion of gutta-percha in contact with various concentrations of zinc oxide-eugenol sealer: a three-dimensional volumetric study

INTRODUCTION

Successful endodontic treatment depends on achievement of a fluid-tight seal that is not possible solely with gutta-percha and requires the use of a root canal sealer. Eugenol, which is a principal component in zinc oxide-eugenol (ZOE) based sealers, is reported to produce a volumetric expansion of gutta-percha. The aim of this study was to evaluate the three-dimensional expansion of gutta-percha at various powder/liquid ratios of ZOE-based sealer by using spiral computed tomography (SCT).

METHODS

Fifty freshly extracted premolars with single canal were decoronated and instrumented by using RaCe rotary instruments (35/06). The teeth were divided into 5 groups of 10 each, and volume of the canal was measured by using SCT. The teeth were then obturated with gutta-percha cones (35/04) in groups ZE 1:1 to ZE 1:4 with Pulp Canal Sealer EWT (ZOE-based) with powder/liquid ratio of 1:1, 1:2, 1:3, and 1:4, respectively, and gutta-percha alone in control group (no sealer group). The filled volume in each canal was measured by using SCT 1 day, 7 days, and 1 month after obturation, and percentages of obturated volume and of volume changes in groups over time were calculated. The data were statistically analyzed by using one-way analysis of variance and post hoc multiple comparison tests.

RESULTS

The groups ZE 1:2 and ZE 1:3 gave the highest mean volume values during a 1-month period and were significantly different in comparison with groups ZE 1:1 and ZE 1:4 (P < .05).

CONCLUSIONS

Increasing the ratio of eugenol in sealer resulted in volumetric increase of gutta-percha. However, further studies should be performed to confirm the expansion and sealing ability of gutta-percha of the size corresponding to the prepared canal, leading to the achievement of fluid impervious seal.

A comparative evaluation of 3 root canal filling systems

OBJECTIVE

This in vitro study was conducted to evaluate and compare the microbial leakage of a new obturation system: Guttaflow with resin-based Resilon cones and Epiphany sealer, keeping gutta-percha with AH plus sealer as the standard.

STUDY DESIGN

The microbial leakage was tested using Enterococcus faecalis ATCC 29,212 as the bacterial marker in the microbial leakage test. These results were supplemented with scanning electron microscopy (SEM).

RESULTS AND CONCLUSION

The microbial leakage test indicated good sealing abilities for Resilon and Guttaflow, with the latter resisting microbial leakage for a longer period. AH plus with gutta-percha showed poor sealing ability. Results of the scanning electron microscopy correlated with the microbial leakage test. This study indicates that newer obturation systems like Guttaflow and Resilon cones with Epiphany provide better seal against microbial leakage than the standard obturation material, gutta-percha used with AH plus sealer.

A laboratory evaluation of the physical and mechanical properties of selected root canal sealers

AIM

To evaluate and compare the porosity, degree of conversion (DC) and hardness of two resin-based sealers; RealSeal and EndoRez, and a silicon-based sealer; GuttaFlow to that of a traditional zinc oxide-based sealer; TubliSeal.

METHODOLOGY

For porosity, four samples from each sealer were prepared and scanned using a SkyScan 1072 Micro-CT. Porosity was then calculated using specialized software. For DC, 10 samples from each sealer were prepared and placed onto a Fourier transform infrared spectroscopy spectrometer. Spectra readings were carried out before and after curing of the sealers, and the DC for each sealer was calculated. For hardness, 10 samples from each sealer were prepared and then tested using a Wallace hardness tester. SPSS software was used for statistical analysis of the data using one-way anova and independent t-tests.

RESULTS

TubliSeal had the highest percentage porosity (3.52%), whilst RealSeal had the lowest percentage porosity (0.41%). Statistically significant differences (P = 0.01) in porosity were present between all groups except between RealSeal and EndoRez groups. RealSeal exhibited a significantly higher DC% than EndoRez (P = 0.01), whereas EndoRez had the highest hardness number [28.54 Vickers hardness number (VHN)] whilst TubliSeal showed the lowest (13.57 VHN). Statistically significant differences in hardness were found between all groups (P = 0.01) except between RealSeal and EndoRez groups.

CONCLUSIONS

Resin-based sealers had less porosity, greater hardness and a high DC.

A comparative study on the frequency, location, and direction of accessory canals filled with the hydraulic vertical condensation and continuous wave of condensation techniques

The present study compared the frequency, location, and direction of accessory canals filled with two different filling techniques. Sixty-four mandibular first molars were accessed, prepared, and divided into two groups of 32 teeth each. The teeth from group A and group B were filled using the hydraulic vertical condensation technique and the continuous wave of condensation technique, respectively. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators. There was no significant difference (t test, p < 0.05) between the two groups in relation to the total number of filled ramifications. Moreover, there was no significant difference among the three thirds of the roots in relation to the number of filled ramifications (analysis of variance, p < 0.05). The filled ramifications were more frequently detected toward lingual, buccal, distal-lingual, and distal-buccal directions. It was concluded that the two filling techniques are not different in relation to the frequency, location, and direction of the ramifications filled.

Effect of immediate and delayed post preparation on apical microleakage by using methacrylate-based EndoREZ sealer with or without accelerator

The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the apical sealing ability of EndoREZ, a methacrylate-based dual-cured resin sealer, with or without accelerator. Fifty extracted human teeth were endodontically prepared and randomly divided into 6 groups. Teeth in experimental groups 1, 2, 3, and 4 (n = 10) were filled with resin-coated gutta-percha and either EndoREZ with accelerator (A+) or EndoREZ without accelerator (A-) by the lateral compaction technique. In group1 (A+) and group2 (A-), the post space was prepared immediately at the time of obturation. In groups 3 (A+) and 4 (A-), the post space was prepared after storage in 100% humidity at 37 degrees C for 1 week. Groups 5 and 6 (n = 5) represented positive and negative control groups, respectively. Leakage was determined by computerized fluid filtration device. Complete leakage was observed in group 5, and no leakage was evident in group 6 (P = 1.000). In experimental groups, mean apical microleakage values (microL/cmH(2)O/min(-1)) were as follows: group 1, 2.77 +/- 0.79(a); group 2, 2.88 +/- 1.38(a); group 3, 19.95 +/- 7.85(c); group 4, 6.20 +/- 2.09(b) (different letters indicate significantly different groups, P < .005). Immediate post space preparation achieved better sealing than delayed post preparation at the apical end, regardless of whether the EndoREZ accelerator was used. There was no significant difference between the (A+) and (A-) in immediate post space preparation. However, more leakage was found when using (A+) than (A-) in delayed post preparation. Under the conditions of this study, it was concluded that EndoREZ accelerator seems not to provide clinicians with any advantage for rapid transition from endodontic treatment to post-endodontic restorative procedures immediately after completion of root canal therapy.