Quality of Obturation Achieved by a Non–gutta-percha–based Root Filling System in Single-rooted Canals

Introduction

The present study examined the quality of obturation in root canals filled by an experimental non–gutta-percha–based (NGP) root filling system using warm vertical or cold lateral compaction. The quality of obturation was evaluated by comparing the volumetric percentage of gaps and voids identified from similar canals obturated with gutta-percha and an epoxy resin–based sealer using the same obturation techniques.

Methods

Forty single-rooted premolars with oval-shaped canals were cleaned, shaped, and obturated with 1 of the 4 material/obturation technique combinations (n = 10). Filled canals were scanned with micro–computed tomographic imaging. Reconstructed images were analyzed for the volumetric percentage of gaps and voids at 3 canal levels (0–4, 4–8, and 8–12 mm from the working length). Roots were sectioned at the 4-mm, 8-mm, and 12-mm levels. Scanning electron microscopic images of negative replicas of root sections were examined to quantify the circumferential percentage of interfacial gaps and the area percentage of intracanal voids. Data were analyzed with parametric or nonparametric statistical methods.

Results

A statistically significant difference was found for the volumetric percentage distribution of gaps and voids for “obturation technique” but not for “material.” Significantly higher percentages of gaps and voids were identified in canals obturated with the NGP system using cold lateral compaction. Examination of negative replicas ascribed this difference to a higher area percentage of interfacial gaps rather than more intracanal voids.

Conclusions

Using warm vertical compaction, the NGP system fulfils the objective of 3-dimensional obturation of the canal space in a manner comparable with the results achieved with gutta-percha and a root canal sealer.     

Quality of obturation achieved by an endodontic core-carrier system with crosslinked gutta-percha carrier in single-rooted canals

Objectives

The present study examined the quality of obturation in root canals obturated by GuttaCore, a gutta-percha-based core-carrier system with a cross-linked thermoset gutta-percha carrier, by comparing the incidence of gaps and voids identified from similar canals obturated by cold lateral compaction or warm vertical compaction.

Methods

Thirty single-rooted premolars with oval-shaped canals were shaped and cleaned, and obturated with one of the three obturation techniques (N = 10): GuttaCore, warm vertical compaction or cold lateral compaction. Filled canals were scanned with micro-computed tomography (micro-CT); reconstructed images were analysed for the volumetric percentage of gaps and voids at three canal levels (0–4 mm, 4–8 mm and 8–12 mm from working length). The roots were subsequently sectioned at the 4-mm, 8-mm and 12-mm levels for analyses of the percentage of interfacial gaps, and area percentage of interfacial and intracanal voids, using scanning electron microscopy (SEM) to examine negative replicas of root sections. Data were analysed with parametric or non-parametric statistical methods at α = 0.05.

Results

Both micro-CT and SEM data indicated that canals obturated with GuttaCore core-carriers had the lowest incidence of interfacial gaps and voids, although the results were not significantly different from canals obturated by warm vertical compaction. Both the GuttaCore and the warm vertical compaction groups, in turn, had significantly lower incidences of gaps and voids than the cold lateral compaction group.

Conclusions

Because of the similarity in obturation quality between GuttaCore and warm vertical compaction, practitioners may find the GuttaCore core-carrier technique a valuable alternative for obturation of oval-shaped canals.

Clinical Significance

The quality of obturation achieved by GuttaCore in single-rooted canals is not significantly different from that achieved by warm vertical compaction.     

Gap volume and sealer penetration of C-shaped root canals obturated with cold hydraulic technique and calcium silicate sealer

This study compared the gap volume and sealer penetration in C-shaped root canals prepared with adaptive core rotary files and obturated with cold hydraulic compaction using calcium-silicate sealer, warm vertical hybrid compaction, or lateral compaction using epoxy-resin sealer. Thirty-six extracted mandibular molars with pulpal floor configuration Types I and III were used. The teeth were prepared using XP-Shaper and XP-Finisher and obturated with: group 1: cold hydraulic compaction/calcium silicate, group 2: warm vertical hybrid compaction/epoxy resin, or group 3: lateral compaction/epoxy resin. The gap volume was evaluated using μ-CT. The sealer penetration depth and area were evaluated using confocal laser scanning microscopy. The gap volume in groups 1, 2, and 3 was 0.82%, 0.24%, 0.80%, respectively, which were not significantly different (p > 0.05). The gap volumes in the obturated C-shaped canals were not significantly different among the CHC/CSBS, WHC/ERS, or LC/ERS groups. CHC/CSBS was the most convenient technique.     

Regaining Apical Patency after Obturation with Gutta-percha and a Sealer Containing Mineral Trioxide Aggregate

Introduction

MTA Fillapex (Angelus Solucoes Odontologicas, Londrina PR, Brazil) was introduced as a mineral trioxide aggregate (MTA)-based sealer used for endodontic obturation. There is a lack of research that evaluates the ability of different solvents to soften MTA-based sealers during retreatment. This study tested the ability of 4 commonly used endodontic solvents to soften gutta-percha and MTA Fillapex to allow for the re-establishment of apical patency.

Methods

Eighty-six extracted maxillary anterior teeth were instrumented to the working length to a size 45 (.04 taper size). Teeth were divided into 2 groups (n = 43 for each group). MTA Fillapex was placed into all canals. Group 1 was obturated with gutta-percha to the working length, and group 2 was obturated 2 mm short of the working length to ensure the apical 2 mm was filled with sealer only. Both groups were divided into 4 subgroups (n = 10). The remaining teeth served as the control group. Each subgroup was exposed to 1 of the following solvents: chloroform, Endosolv R (Septodont, Saint-Maur, France), Endosolv E (Septodont), or eucalyptol.

Results

Patency was re-established in 100% of the teeth in groups 1 and 2 when tested with chloroform or Endosolv E, 80% of the teeth in group 1 and 90% in group 2 when tested with eucalyptol, and 10% of the teeth in group 1 and 50% in group 2 tested when with Endosolv R. The chi-square test indicated there was a statistical difference between Endosolv R and the other tested solvents for both groups.

Conclusions

Chloroform, Endosolv E, and Eucalyptol soften GP and MTA Fillapex sufficiently to aid in re-establishing apical patency during endodontic retreatment.     

Physical Properties of 5 Root Canal Sealers

Introduction

The aim of this study was to evaluate the pH change, viscosity and other physical properties of 2 novel root canal sealers (MTA Fillapex and Endosequence BC) in comparison with 2 epoxy resin-based sealers (AH Plus and ThermaSeal), a silicone-based sealer (GuttaFlow), and a zinc oxide-eugenol–based sealer (Pulp Canal Sealer).

Methods

ISO 6876/2001 specifications were followed. The pH change of freshly mixed and set sealers was evaluated during periods of 1 day and 5 weeks, respectively. The viscosity was investigated at different injection rates (72, 10, and 5 mm/min) at room temperature by using a syringe-based system that was based on the Instron 3360 series universal testing system.

Results

The flow, dimensional change, solubility, and film thickness of all the tested sealers were in agreement with ISO 6876/2001 recommendations. The MTA Fillapex sealer exhibited a higher flow than the Endosequence BC sealer (P < .05). The MTA Fillapex and Endosequence BC sealers showed the highest film thicknesses among the tested samples. The Endosequence BC sealer exhibited the highest value of solubility, which was in accordance with 3% mass fraction recommended by the ISO 6876/2001, and showed an acceptable dimensional change. The MTA Fillapex and Endosequence BC sealers presented an alkaline pH at all times. The pH of fresh samples of the AH Plus and ThermaSeal sealers was alkaline at first but decreased significantly after 24 hours. The viscosity of the tested sealers increased with the decreased injection rates.

Conclusions

The tested sealers were pseudoplastic according to their viscosities as determined in this study. The MTA Fillapex and Endosequence BC sealers each possessed comparable flow and dimensional stability but higher film thickness and solubility than the other sealers tested.     

Influence of Ultrasonic Activation of 4 Root Canal Sealers on the Filling Quality

Introduction

The purpose of this study was to evaluate the effects of ultrasonic activation on the filling quality (intratubular sealer penetration, interfacial adaptation, and presence of voids) of 4 epoxy resin–based sealers.

Methods

Eighty-four extracted human canines were divided into 4 groups (n = 20) according to the sealer used to obturate the root canals instrumented with F5 ProTaper instruments (50/05) (Dentsply Maillefer, Ballaigues, Switzerland). The canals were filled by the lateral compaction technique. Previously, the sealers were labeled with rhodamine B dye to allow analysis under a confocal microscope. At the time of obturation, the specimens were divided again into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated and nonultrasonically activated groups. All samples were sectioned at 2, 4, and 6 mm from the apex. The percentages of voids, gaps, and dentinal sealer penetration segments of the canal were analyzed.

Results

Regarding the sealer penetration segments, there was a significant increase for the AH Plus (Dentsply Maillefer), Acroseal (Specialités Septodont, Saint Maur-des-Fossés, France), and Sealer 26 (Dentsply Maillefer) at the 4-mm level and the AH Plus and Sealer 26 at the 6-mm level with ultrasonic activation (P < .05). Concerning the gaps, the ultrasonic activation promoted a smaller presence for all sealers at the 4- and 6-mm levels (P < .05). No statistical significant differences were found for the percentages of voids (P < .05).

Conclusions

The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps.     

Effect of three different sealers on the sealing ability of both thermafil obturators and cold laterally compacted Gutta-Percha

The purpose of this study was to assess the seal obtained in straight and curved root canals filled with either laterally compacted gutta-percha or Thermafil obturators. Each technique was used in combination with three different sealers (RSA RoekoSeal, AH Plus, AH 26). Thermafil obturators were also used without sealer, resulting in a total of 14 test groups of 16 teeth each. Sixty teeth served as positive or negative controls. Included in the study were 142 extracted teeth with straight and 142 with curved root canals. All canals were enlarged up to size 40. After obturation, all roots were placed in India ink for 48 h and rendered transparent to measure the maximum linear dye penetration. Canals filled with Thermafil obturators had significantly more extrusion of filling material than canals filled by lateral compaction (p < 0.01). Thermafil without sealer showed significantly greater dye penetration compared with all other groups both in straight and in curved canals (p < 0.05). As long as a sealer was used, the seal obturated with Thermafil was equivalent in terms of dye penetration to lateral compaction. There were no statistical differences in the mean apical dye penetration among the three sealers. The differences between the dye penetration in straight and in curved canals were insignificant for all groups (p > 0.05). Under the conditions of this study, Thermafil obturators achieved seals comparable to lateral compaction, as long as a sealer was used.     

Comparison of the fracture resistance of simulated immature permanent teeth using various canal filling materials and fiber posts

Abstract – Background: The purpose of this study was to compare the fracture resistances of immature teeth treated with MTA along with root canal obturation methods using AH Plus, MetaSEAL, MTA Fillapex sealers + lateral compaction technique, and Unicore quartz fiber posts. Materials and methods: Fifty single‐rooted maxillary anterior teeth were divided into five groups. The crowns were dissected and root canals were enlarged. #6 Peeso reamers were allowed to protrude 1 mm. beyond the apex to simulate immature teeth. The apical 4–5 mm of each tooth was filled using Angelus white MTA. The remaining portions of canals were obturated as follows: Group 1: No backfilling (control), Group 2: AH Plus + gutta‐percha, lateral compaction, Group 3: MetaSEAL + gutta‐percha, lateral compaction, Group 4: MTA Fillapex + gutta‐percha, lateral compaction, Group 5: UniCore Fiber posts luted using PermaFlo DC. The specimens were embedded into self‐curing acrylic poured into identical cylinders which were mounted on a jig providing a 45° angle. A compressive load increasing at 1 mm min^?1 was applied and the maximum load at which fracture occurred was recorded. Statistical analysis was performed using Kruskal–Wallis and Dunn’s multiple tests. Results: The highest fracture resistance was obtained with Group 5 (Fiber posts) whereas Group 4 (MTA Fillapex) yielded the lowest values. The mean fracture resistance value of Group 2 (AH Plus) was significantly higher than Group 4 (MTA Fillapex) (P = 0.001). The mean fracture value of Group 5 (Fiber posts) was significantly higher than Group 2 (AH Plus), Group 3 (MetaSEAL), and Group 4 (MTA Fillapex) (P = 0.02, 0.004, and 0.0001, respectively). Conclusion: Within the limitations of this study, UniCore quartz fiber posts provided the highest resistance. This methodology may specifically be advantageous for teeth with arrest of development at early stages, as these teeth are more susceptible to fracture owing to their excessively weak dentinal walls.     

Effect of Calcium Hydroxide and Double and Triple Antibiotic Pastes on the Bond Strength of Epoxy Resin–based Sealer to Root Canal Dentin

Introduction

The aim of this study was to evaluate the effects of calcium hydroxide (CH) and triple (TAP) and double (DAP) antibiotic pastes on the bond strength of an epoxy resin–based sealer (AH Plus Jet; Dentsply DeTrey, Konstanz, Germany) to the root canal dentin.

Methods

Sixty-four single-rooted human mandibular premolars were decoronated and prepared using the rotary system to size 40. The specimens were randomly divided into a control group (without intracanal dressing) and 3 experimental groups that received an intracanal dressing with either CH, DAP, or TAP (n = 16). The intracanal dressing was removed by rinsing with 10 mL 17% EDTA followed by 10 mL 2.5% sodium hypochlorite. The root canals were then obturated with gutta-percha and AH Plus Jet sealer. A push-out test was used to measure the bond strength between the root canal dentin and the sealer. The data were analyzed using 2-way analysis of variance and Tukey post hoc tests to detect the effect of the independent variables (intracanal medicaments and root canal thirds) and their interactions on the push-out bond strength of the root canal filling material to the root dentin (P = .05).

Results

The push-out bond strength values were significantly affected by the intracanal medicaments (P < .001) but not by the root canal thirds (P > .05). In the middle and apical third, the bond strength of the TAP group was higher than those of the CH and DAP groups (P < .05).

Conclusions

The DAP and CH did not affect the bond strength of the epoxy resin–based sealer. Additionally, the TAP improved the bond strength of the epoxy resin–based sealer in the middle and apical thirds.     

Penetration of Epiphany, Epiphany self-etch, and AH Plus into dentinal tubules: a scanning electron microscopy study

Introduction

The purpose of this study was to measure the average depth of dentinal tubule sealer penetration in the middle third of teeth obturated with gutta-percha/AH Plus (Dentsply, DeTrey, Konstanz, Germany), Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon/Epiphany self-etch (SE) using scanning electron microscopy (SEM).

Methods

The root canals of 36 extracted single-rooted human teeth were prepared and randomly divided into three groups. Obturations were performed with the following filling materials using the lateral compaction technique: group 1, gutta-percha/AH Plus; group 2, Resilon/Epiphany; and group 3, Resilon/Epiphany SE. The specimens were prepared for SEM examination. The average depth of sealer penetration into the dentinal tubules was measured. Data were analyzed by one-way analysis of variance and a post hoc Tukey test.

Results

The mean (± standard deviation) values for the average depth of sealer penetration in the middle third of the roots were 22.07 ± 6.92 μm, 31.56 ± 6.80 μm, and 21.50 ± 9.25 μm for AH Plus, Epiphany, and Epiphany SE, respectively. The average penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). There was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05).

Conclusions

It could be concluded that the average penetration for Epiphany into dentinal tubules within the middle third of the roots was significantly deeper than that of Epiphany SE and AH Plus.     

Maxillary Premolar with 4 Separate Canals

Introduction

Recognition of anatomic variations is a challenge for clinicians regardless of which tooth is treated. Maxillary premolars usually have 2 root canals, but the presence of 3 distinct root canals has been reported in 1%–6% of cases.

Methods and Results

This report describes the case of a maxillary right second premolar with 4 separate canals: 1 mesial, 1 palatal, and 2 distal canals. This was confirmed by using cone-beam computed tomography and was successfully treated with rotary files and obturated by using a warm vertical compaction technique.

Conclusions

The clinical significance of the present case is that this is the first report of 3 roots and 4 separate canals in a maxillary premolar. Precise knowledge of root canal morphology and its variation is also underlined. Cone-beam computed tomography examination and the operating microscope are excellent tools for identifying and managing these complex root canal systems.     

Investigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source

Introduction

During warm vertical compaction of gutta-percha, root canal sealers with different chemical compositions absorb the heat generated inside the root canal. The aim of this research was to assess physicochemical modifications of sealers subjected to the System B heat source (Analytic Technology, Redmond, WA) and to evaluate the effect that the use of different sealers has on the heat transfer to the external root surface.

Methods

Three proprietary brand sealers (AH Plus [Dentsply International, Addlestone, UK], Pulp Canal Sealer [Kerr Corporation, Orange, CA], MTA Fillapex [Angelus Dental Solutions, Londrina, PR, Brazil]) and a prototype sealer based on Portland cement were assessed. The heat generated on the surfaces of System pluggers and the heat dissipation at different levels (apical, midroot, and cervical) over root surface while using different sealers was assessed using thermocouples. Data were collected in 3 different environmental conditions with the tooth suspended in air, immersed in Hank's balanced salt solution, or gelatinized Hank's balanced salt solution. Chemical changes in the sealers induced by the heat were monitored by Fourier transform infrared spectroscopy. The effect of heat changes on the setting time and compressive strength of the sealers was also assessed.

Results

The continuous wave plugger sustained a rise in temperature at a maximum of 80°C at the instrument shank. The highest change in temperature on the external root surface was recorded after 1.5 minutes from the start of heating, and it was restored to body temperature by 6 minutes. Environmental conditions affected heat dissipation for all the sealers in the midroot and cervical regions and the highest increase in temperature (∼60°C) recorded in air. In the midroot and cervical regions, the type of sealer used did not affect the rise in temperature. In the apical region, AH Plus obturations resulted in a greater rise in temperature, and the chemical composition of this sealer was affected by high temperature; it also induced a reduction in sealer setting time and strength.

Conclusions

It could be concluded that surrounding conditions, such as temperature and humidity, exerted influence on heating dissipation during the continuous wave of the condensation obturation technique and that root canal sealers presented different conductive/isolating properties. Furthermore, the physical and chemical properties of AH Plus were negatively affected by the changes in temperature.     

The Effect of Primary Root Canal Treatment on Dentinal Tubule Penetration of Calcium Silicate–based Sealers during Endodontic Retreatment

IntroductionThe aim of this study was to evaluate the effect of previous root canal treatment on dentinal tubule penetration of calcium silicate–based sealers during endodontic retreatment and to compare 2 different (commonly used and modified) tubule penetration depth measurement techniques.MethodsThe crowns of mandibular premolar teeth were removed, and root canals were prepared (ProTaper Universal; Dentsply Sirona, York, PA) and obturated using AH Plus (AH; Dentsply DeTrey, Konstanz, Germany), MTA Fillapex (MTAF; Angelus, Londrina, Brazil), and WellRoot ST (WRST; Vericom, Gyeonggi-do, South Korea); 0.1% red Rhod-2 dye (Chemodex, St Gallen, Switzerland) was added to the sealers. After storage for 3 weeks (37°C, 100% humid), the following sealer combination subgroups were created (the sealer used during the primary root canal treatment/the sealer used during the retreatment, n = 8): AH/AH, AH/MTAF, and AH/WRST; MTAF/AH, MTAF/MTAF, and MTAF/WRST; and WRST/AH, WRST/MTAF, and WRST/WRST. Green Fluo-3 dye (0.1%) was added to the sealers during retreatment. Sealer penetration depths were measured at 8 points and averaged, and the ratio of the retreatment sealer to the initial sealer was recorded as the mean tubule penetration depth ratio in the first technique, whereas the percentage of the circumferential penetration area ratios of the retreatment and initial sealers was calculated in the second technique. Statistical analyses were performed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests.ResultsThe mean penetration depth of AH and MTFA was found to be higher at the coronal third region in the control groups (P < .05). Both methods showed a significant difference among the groups at the coronal and median regions (P < .05). The AH/WRST, MTAH/AH, MTAF/MTAF, MTAF/WRSTS, and WRST/WRST groups showed deeper tubule penetration (first technique, P = .01). Both techniques showed that the penetration depth of the sealers was the same at the apical region (P > .05), whereas a difference was found among the techniques at the coronal and median regions. The sealers used in the previous root canal treatment limited the penetration depth of the sealers used during the retreatment process (P < .05). When MTAF was used as the initial sealer, the penetration depth of the second sealer did not change, whereas if WRST was the initial sealer, the penetration depth of the sealers at the median and apical regions is negatively affected during the retreatment process (P < .05).ConclusionsPrevious root canal treatment affects the penetration depth of calcium silicate–based sealers. The use of AH Plus and MTA Fillapex during the retreatment process showed an advantage. Both measurement techniques showed similar performances at the apical region, whereas the results varied at the coronal and midcoronal regions; therefore, a more stable sealer penetration measurement technique is still necessary.     

Coronal leakage of sealer-only backfill: an in vitro evaluation

We tested the hypothesis that AH Plus and Roeko Seal Automix (RSA) sealers alone are no less effective in preventing coronal microleakage than gutta-percha compacted with sealer. Freshly prepared sheep incisor root canals were obturated with warm gutta-percha alone, AHPlus or RSA alone, or warm gutta-percha with AH Plus or RSA (n = 20 each group). Coronal leakage was assessed under vacuum conditions with Indian ink and tooth clearing. Sealer-only backfills with AH Plus and RSA yielded significantly more dye-free canals than backfills of gutta-percha alone or with sealer (p < 0.001). Warm gutta-percha with or without sealer kept no more canals sealer free than the positive control. Mean dye penetration was 0.92% of canal length for AH Plus and RSA backfills, 27.42% for gutta-percha only backfills, 26.47% for gutta-percha with RSA and 13.92% for gutta-percha with AH Plus. Sealer only backfills allowed significantly less leakage than those including warm gutta-percha (p < 0.001). Sealer-only backfills may be a viable alternative to traditional gutta-percha and sealer compaction methods.     

Comparison of Sealer Penetration Using the EndoVac Irrigation System and Conventional Needle Root Canal Irrigation

Introduction

The aim of this study was to compare the effect of the EndoVac irrigation system (SybronEndo, Orange, CA) and conventional endodontic needle irrigation on sealer penetration into dentinal tubules.

Methods

Forty single-rooted, recently extracted human maxillary central incisors were randomly divided into 2 groups according to the irrigation technique used: conventional endodontic needle irrigation and EndoVac irrigation. All teeth were instrumented using the ProFile rotary system (Dentsply Maillefer, Ballaigues, Switzerland) and obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) labeled with fluorescent dye. Transverse sections at 1, 3, and 5 mm from the root apex were examined using confocal laser scanning microscopy. The total percentage and maximum depth of sealer penetration were then measured.

Results

Mann-Whitney test results showed that EndoVac irrigation resulted in a significantly higher percentage of sealer penetration than conventional irrigation at both the 1- and 3-mm levels (P < .05). However, no difference was found at the 5-mm level. The 5-mm sections in each group showed a significantly higher percentage and maximum depth of sealer penetration than did the 1- and 3-mm sections (P < .05).

Conclusions

The EndoVac irrigation system significantly improved the sealer penetration at the 1- to 3-mm level over that of conventional endodontic needle irrigation.     

Human tooth germ stem cell response to calcium-silicate based endodontic cements

Objective

The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer.

Material and Methods

To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO₂ for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods.

Results

On the 1^st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p<0.008). No significant difference was observed between the other tested materials at this period (p>0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface.

Conclusions

Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.     

Efficacy of Reciprocating Instruments in Retreatment of Bioactive and Resin-Based Root Canal Sealers

ObjectiveTo compare the effectiveness of reciprocating instruments in removing gutta-percha and bioactive-based (BioRoot RCS and MTA Fillapex) and epoxy resin-based (AH Plus) sealers from root canals based on filling residues and the time required for root canal revision.Material and methodsRoot canals of 90 teeth were instrumented with Reciproc R40. All root canals were obturated using the single-cone technique with Reciproc R40 gutta-percha and with one of the selected sealers. Samples with oval, straight canals were used and randomly divided into three groups: (i) filled with AH Plus sealer and gutta-percha (n=30); (ii) filled with MTA Fillapex and gutta-percha (n=30); (iii) filled with BioRoot RCS and gutta-percha (n=30). Each group was divided into two subgroups (n=15) according to the retreatment instrument used (Reciproc M-Wire R25/R40 or Reciproc blue RB25/RB40). Root canals were longitudinally split and analyzed with a stereomicroscope at 15 × magnifications in the coronal, middle, and apical third. Computational analyses were performed with the Image J software. Data were compared using the Kruskal-Wallis test and Mann-Whitney U test.ResultsWhile no statistically significant differences in the residual material surface were found for Reciproc Blue, Reciproc M-Wire showed significantly higher residual material surface for AH Plus and MTA Fillapex compared to BioRoot RCS. For AH plus. Residual material surface was significantly lower for Reciproc Blue than for Reciproc M-Wire. In contrast, BioRoot RCS showed a significantly higher residual material surface for Reciproc Blue.ConclusionsCalcium silicate-containing sealers were more retrievable compared to AH Plus, with fewer sealer remnants and shorter retreatment time. Retreatment with Reciproc M-Wire instruments was superior to Reciproc blue instruments in retreatment of BioRoot RCS. However, none of the sealers were removed completely.     

Interface of dentine to root canal sealers

Objective

Root canal sealers can interact physically or chemically with dentine. The aim of this study was to characterize the dentine-root canal sealer interface of experimental sealers based on Portland cement using an epoxy-based vehicle in comparison to an epoxy resin sealer, AH Plus.

Methods

Root canals were biomechanically prepared and filled with any one of the four experimental epoxy sealers containing Portland cement with micro- and nano-particles of either zirconium oxide or niobium oxide radiopacifers, or AH Plus. The dentine-sealer's interfaces were assessed by coronal penetration of fluorescent microspheres, the penetration of sealers labelled with Rhodamine B inside the dentine tubules (following obturation with gutta–percha and sealers using System B technique) assessed by confocal laser scanning microscopy, and the chemical characterization of dentine-sealers interface by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) line scans.

Results

No penetration of fluorescent microspheres at the root-dentine to sealer interface was recorded for all test materials. Sealers presented greater ability to penetrate within the dentinal tubules at the coronal and mid-root thirds. The experimental sealers containing radiopacifier nano-particles exhibited a more homogeneous microstructure along the whole length of the canal. EDS-line scans results showed a migration of silicon and niobium into dentine. Peak overlap between zirconium and the phosphorous compromised the identification of the migration of the zirconium oxide into dentine.

Conclusions

All five sealers promoted coronal sealing. The experimental sealers exhibited promising characteristics and were comparable to AH Plus sealer. Elemental migration of the experimental sealers suggests material interaction with dentine which was not displayed by AH Plus.     

Radiographic Identification of Separated Instruments Retained in the Apical Third of Root Canal–filled Teeth

Introduction

The aim of the study was to compare the diagnostic ability to radiographically detect separated stainless steel (SS) versus nickel-titanium (NiTi) instruments located at the apical third of filled root canals with either AH 26 (Dentsply DeTrey GmbH, Konstanz, Germany) or Roth sealer (Roth International Ltd, Chicago, IL).

Methods

Sixty single-rooted extracted human teeth with 1 straight root canal were instrumented to a size 25 apical diameter. In 40 teeth, apical 2-mm segments of SS (n = 20) or NiTi (n = 20) files were intentionally fractured in the apical part of the root canal. The remaining 20 teeth without fractured files served as a control group. Subsequently, the root canals were filled using laterally condensed gutta-percha and either AH 26 sealer (AH) or Roth sealer (Roth). All teeth were radiographed using conventional Kodak film (Eastman Kodak Co, Rochester, NY) and a charge-coupled device digital sensor. The evaluation of the images for the presence of a fractured instrument was performed independently by 2 blinded observers. The data were statistically analyzed using McNemar and Fisher exact tests.

Results

The kappa values were 0.76 and 0.615 for the first and second observers, respectively, and 0.584 between the observers. There were no significant differences in the diagnostic ability between digital and conventional radiography or the different root canal sealers (AH vs Roth, P > .05). The sensitivity to detect fractured SS was significantly higher than NiTi (P < .05).

Conclusions

It may be difficult to radiographically detect a retained separated instrument. It is easier to radiographically detect fractured SS than NiTi instruments retained at the apical third of the root canal.