Susceptibility of a polycaprolactone-based root canal filling material to degradation. I. Alkaline hydrolysis

Micro-CT assessment of gap-containing areas along the gutta-percha-sealer interface in oval-shaped canals

AIM

To assess the interfacial adaptation (gap-containing areas) of two root canal sealers (EndoSequence BC Sealer and AH Plus) to a conventional gutta-percha (GP) cone (GP-sealer interface) in oval-shaped canals filled using the single cone technique.

METHODOLOGY

Sixteen teeth with oval-shaped canals were selected, scanned in a micro-computed tomographic device, and pair-matched according to the volume, aspect ratio and configuration of root canals. Root canals were then sequentially prepared with WaveOne Gold Primary and Large instruments, followed by filling with WaveOne Large GP points associated with either the premixed calcium-silicate EndoSequence BC Sealer or the epoxy resin-based AH Plus sealer (n = 8 per group) using the single cone technique. After 7 days stored in phosphate-buffered saline solution at 37°C, the specimens were rescanned and the reconstructed images segmented in order to differentiate the filling materials (sealer and GP cone) to the dentine. A total of 453 cross-sectional slices were assessed and categorized according to the presence or absence of gaps at the GP-sealer interface. Mann-Whitney U-test verified the differences between groups and were considered significant at alpha = 5%.

RESULTS

Gaps were non-homogenously distributed in two-dimensional axial cross-section images and none of the specimens showed completely gap-free areas along the entire GP-sealer interface. Root canals filled with EndoSequence BC Sealer and AH Plus displayed 171 (37.75%) and 136 (30.02%) slices with gaps in the GP-sealer interface and these frequencies were statistically significant (p = .000).

CONCLUSIONS

Although none of the specimens had a gap-free area along the entire GP-sealer interface, oval canals filled with AH Plus showed less gaps than the ones filled with EndoSequence BC Sealer.

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.

Critical analysis of research methods and experimental models to study removal of root filling materials

Despite enjoying high favourable outcome rates, root canal treatment is not always successful. Root canal retreatment is a widely practised option for managing a non-healing root treated tooth. A basic distinction between retreatment and initial treatment is the requirement to remove the existing root filling material occupying the root canal space. Only then, can the technical deficiencies and possible causes of failure be addressed. Hence, the successful removal of the root filling material is critical to achieving the objectives of retreatment. Many different materials and techniques have been used for root canal filling, which have been documented in a plethora of studies; these are mainly laboratory studies investigating the removal of root filling materials. To help guide future research, which may then better inform clinical practice in relation to retreatment procedures, the focus of this narrative review is on the research methods and experimental models employed to study the removal of root filling materials. The current available literature demonstrates great variation in the research methodologies used to study the removal of root filling material, including direct visualization by splitting tooth samples or clearing, three-dimensional radiographic imaging including using microcomputed tomography or cone-beam computed tomography, and a combination of these techniques. Depending on the research method employed, variation also exists in quantification of root filling material removal; these include measurements of surface area, volume or weight, and criteria-based (semi-quantitative) assessment. Experimental models, using human teeth or resin models, differ with respect to standardization techniques and replication of the clinical scenario including initial sample preparation, canal filling, allocation and technical aspects of retreatment procedures. Future models should replicate, as closely as possible, the clinical scenario. Currently, microcomputed tomography provides a highly detailed, non-invasive and non-destructive method of objectively assessing and quantifying root filling removal.

Synthesis and Characterization of 2-Decenoic Acid Modified Chitosan for Infection Prevention and Tissue Engineering

Chitosan nanofiber membranes are recognized as functional antimicrobial materials, as they can effectively provide a barrier that guides tissue growth and supports healing. Methods to stabilize nanofibers in aqueous solutions include acylation with fatty acids. Modification with fatty acids that also have antimicrobial and biofilm-resistant properties may be particularly beneficial in tissue regeneration applications. This study investigated the ability to customize the fatty acid attachment by acyl chlorides to include antimicrobial 2-decenoic acid. Synthesis of 2-decenoyl chloride was followed by acylation of electrospun chitosan membranes in pyridine. Physicochemical properties were characterized through scanning electron microscopy, FTIR, contact angle, and thermogravimetric analysis. The ability of membranes to resist biofilm formation by S. aureus and P. aeruginosa was evaluated by direct inoculation. Cytocompatibility was evaluated by adding membranes to cultures of NIH3T3 fibroblast cells. Acylation with chlorides stabilized nanofibers in aqueous media without significant swelling of fibers and increased hydrophobicity of the membranes. Acyl-modified membranes reduced both S. aureus and P.aeruginosa bacterial biofilm formation on membrane while also supporting fibroblast growth. Acylated chitosan membranes may be useful as wound dressings, guided regeneration scaffolds, local drug delivery, or filtration.

Alkaline conditions can affect the volume and chemical characteristics of dental gutta-percha

The effects of alkaline pH on the size and surface characteristics of gutta-percha were studied. Forty ProTaper Universal-F2 gutta-percha cones (GPC) were stored individually for 8-weeks. GPC were distributed into 2 groups (n = 20) based on the storage solutions' pH (pH7, pH12). The GPC volume was measured after 1,2,3,4 and 8-weeks using water displacement method and compared to the baseline volume. The surfaces of representative GPCs were analysed using Raman spectroscopy and assessed later using Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (EDS). Samples t test was used to compare the change in volume of GPC and a repeated measures Analysis of Variance (ANOVA) was used to compare the effects of storage durations. After 8-weeks, GPCs aged in high-pH exhibited significant drop in their volume (16%) compared with GPCs aged in water (2.5%). The surface of GPCs stored in water or high-pH both demonstrated structural and chemical alterations in comparison with non-aged GPCs.

The Role of Biodegradable Poly-(L-lactide)-Based Polymers in Blood Cell Activation and Platelet-Monocyte Interaction

The main purpose of new stent technologies is to overcome unfavorable material-related incompatibilities by producing bio- and hemo-compatible polymers with anti-inflammatory and anti-thrombogenic properties. In this context, wettability is an important surface property, which has a major impact on the biological response of blood cells. However, the influence of local hemodynamic changes also influences blood cell activation. Therefore, we investigated biodegradable polymers with different wettability to identify possible aspects for a better prediction of blood compatibility. We applied shear rates of 100 s⁻¹ and 1500 s⁻¹ and assessed platelet and monocyte activation as well as the formation of CD62P+ monocyte-bound platelets via flow cytometry. Aggregation of circulating platelets induced by collagen was assessed by light transmission aggregometry. Via live cell imaging, leukocytes were tracked on biomaterial surfaces to assess their average velocity. Monocyte adhesion on biomaterials was determined by fluorescence microscopy. In response to low shear rates of 100 s⁻¹, activation of circulating platelets and monocytes as well as the formation of CD62P+ monocyte-bound platelets corresponded to the wettability of the underlying material with the most favorable conditions on more hydrophilic surfaces. Under high shear rates, however, blood compatibility cannot only be predicted by the concept of wettability. We assume that the mechanisms of blood cell-polymer interactions do not allow for a rule-of-thumb prediction of the blood compatibility of a material, which makes extensive in vitro testing mandatory.

Antimicrobial and ultrastructural properties of root canal filling materials exposed to bacterial challenge

INTRODUCTION

Chemo-mechanical preparation of the root canal leaves behind viable bacteria which can lead to treatment failure. Materials used inside the root canal should possess antimicrobial properties and also resist disintegration in the presence of biofilm.

METHODS

Gutta-percha, three root canal sealers (Pulp Canal Sealer, AH Plus and BioRoot RCS) and materials used to make posts (a metal and a resin) were evaluated. Their antimicrobial activity against Enterococcus faecalis in direct contact was assessed by scanning electron microscopy and live-dead staining using confocal microscopy over a period of eight weeks. The materials' structural integrity was assessed by scanning electron microscopy.

RESULTS

The antimicrobial activity of the materials varied. The metal alloy posts as well as BioRoot RCS sealer did not allow any biofilm accumulation; but gutta-percha, Pulp Canal Sealer and resin from fibre-reinforced posts encouraged thick biofilm accumulation. Microstructural changes were observed in AH Plus (washout) and BioRoot (crystal deposition) in contact with biofilm. The Pulp Canal and BioRoot RCS sealers exhibited a modified ion leaching pattern in contact with microbially loaded media.

CONCLUSIONS

The microbial challenge affected the material microstructure in some of the materials tested and allowed biofilm accumulation. Although clinical success depends on a number of factors, materials that are structurally sound and exhibit antimicrobial properties are preferable for endodontic therapy and tooth restoration involving entry in the root canal.

Resilon: Assessment of Degraded Filling Material in Nonhealed Cases

INTRODUCTION

The Resilon obturation system (Pentron Clinical Technologies, Wallingford, CT) was discontinued a few years after its introduction as an alternative to traditional gutta-percha and sealer. Ex vivo models support anecdotal reports of degraded Resilon filling material; however, there is no previous clinical report of this degradation. This may represent a significant health concern for the patient and contribute to a higher clinical failure rate of Resilon-obturated root canals. The aim of this study was to determine the proportion of Resilon degradation in nonhealed endodontic cases compared with gutta-percha and sealer.

METHODS

Patients previously treated with Resilon or gutta-percha who had a nonhealed root canal that needed retreatment were enrolled. Upon access, the previous filling material was classified as either degraded or intact. If there was a lack of solid, dense material remaining within the canal confirmed by passively placing a size 15 K-file to the working length, the filling material was considered to be degraded.

RESULTS

The proportion of degradation between the 2 materials was statistically significant, with Resilon having a higher likelihood of degradation than gutta-percha in the bivariate analysis (P = .0003).

CONCLUSIONS

This clinical observational study indicates that Resilon has a higher rate of degradation when compared with gutta-percha in nonhealed cases.

Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction

The aim of this study was to evaluate the ability of gutta-percha and a thermoplastic synthetic polymer (Resilon) to fill simulated lateral canals, using warm vertical compaction. Forty-five single-rooted human teeth were prepared using the rotary crown-down technique. Artificial lateral canals were made at 2, 5, and 8 mm from the working length (WL) in each root. The specimens were divided into three groups (n = 15), according to the filling material: Dentsply gutta-percha (GD), Odous gutta-percha (GO), and Resilon cones (RE). The root canals were obturated using warm vertical compaction, without endodontic sealer. The specimens were subjected to a tooth decalcification and clearing procedure. Filling of the lateral canals was analyzed by digital radiography and digital photographs, using the Image Tool software. The data were subjected to the Kruskal-Wallis and Dunn tests at 5% significance. RE had the best filling ability in all root thirds (p < 0.05), with similar results for GO in the coronal third. In the middle and apical thirds, GD and GO had similar results (p > 0.05). Resilon may be used as an alternative to gutta-percha as a solid core filling material for use with the warm vertical compaction technique. The study findings point to the potential benefit of the warm vertical compaction technique for filling lateral canals, and the study provides further information about using Resilon and gutta-percha as materials for the warm vertical compaction technique.

Temperature Profiles Along the Root with Gutta-percha Warmed through Different Heat Sources

OBJECTIVES

To evaluate temperature profiles developing in the root during warm compaction of gutta-percha with the heat sources System B and System MB Obtura (Analityc Technology, Redmond, WA, USA). Thirty extracted human incisor teeth were used. Root canals were cleaned and shaped by means of Protaper rotary files (Dentsply-Maillefer, Belgium), and imaging was performed by micro-CT (Skyscan 1072, Aartselaar, Belgium).

METHODS

Teeth were instrumented with K-type thermocouples, and the roots were filled with thermoplastic gutta-percha. Vertical compaction was achieved through the heat sources System B and System MB, and temperature profiles were detect-ed by means of NI Dac Interface controlled by the LabView System. With both heat sources, higher temperature levels were recorded in the region of the root far from the apex. When the warm plugger tip was positioned at a distance of 3 mm from the root apex, temperature levels of about 180°C were used to soften gutta-percha, and no statistically significant differences were observed between peak temperatures developed by the two heating sources at the root apex. However, a temperature level higher than 40°C was maintained for a longer time with System MB.

RESULTS

Statistically significant differences were observed in peak temperature levels recorded far from the root apex. Thus, with a temperature of about 180°C and the warm plugger positioned at 3 mm from the root apex, both heating sources led to a temperature slightly higher than 40°C at the apex of the root, suggesting that the gutta-percha was properly softened.

SIGNIFICANCE

A temperature level higher than 40°C was maintained for a longer time with System MB, thus providing an ad-equate time for warm compaction of the gutta-percha.

Influence of pH change and water storage on the sealing ability of two resin-based root-filling materials

AIM

To evaluate the Influence of pH change and water storage up to 90 days on the sealing ability of two resin-based root-filling materials.

MATERIALS AND METHODS

Forty-four human mandibular single-rooted teeth were instrumented and filled with gutta-percha/ AH Plus or Resilon/Epiphany SE (n=20 per group). Two teeth each were used as positive and negative controls. Specimens were set for 7 days under 100% humidity at 37°C. They were allocated into two subgroups (n=10) according to whether they were tested immediately or stored for up to 90 days in water before testing. Sealing ability was evaluated by passive dye penetration. Absorbance at 630 nm (in μg/ml) was measured by spectrophotometry. The pH values were obtained in triplicate. Data were submitted to ANOVA by post-hoc Tukey's test (α=0.05).

RESULTS

Specimens filled with Resilon/Epiphany SE exhibited more leakage than specimens filled with gutta-percha/AH Plus at the immediate time point (p<0.001). No differences were detected between the groups after storage, or between the materials with pH changes after 30, 60 and 90 days (p>0.05).

CONCLUSION

Gutta-percha/AH Plus provided superior sealing at the immediate time point. Water storage and pH changes did not Influence the sealing ability of tested materials.

CLINICAL SIGNIFICANCE

These results suggest that Resilon/ Epiphany SE sealer offered no apparent advantage over the more conventional gutta-percha/AH Plus sealer technique in terms of sealing ability.

Penetration of a resin-based filling material into lateral root canals and quality of obturation by different techniques

The aim of this study was to evaluate the penetration of a resin/polyester polymer-based material (Resilon Real Seal; SybronEndo Corp., Orange, USA) into simulated lateral canals, and the quality of obturations by different techniques. A total of 30 standardized simulated canals were divided into three groups according to the technique of obturation used: MS (McSpadden), SB (SystemB/Obtura II), and LC (Lateral Condensation). To analyze the penetration of the filling material, the simulated canals were digitalized and the images were analyzed using the Leica QWIN Pro v2.3 software. The data of the middle and apical thirds were separately submitted to analysis of variance (ANOVA), followed by the Tukey's test for the comparison of the techniques. Results showed a significant difference (p < 0.05) between groups (LC < SB) in the middle third, and a significant difference (p < 0.05) between groups (LC < SB and MS < SB) in the apical third. To analyze the quality of the obturations, the canals were radiographed and evaluated by three examiners. The Kappa test on interexaminer agreement and the nonparametric Kruskal-Wallis test indicated no significant difference between filling techniques. It was concluded that Resilon achieves greater levels of penetration when associated with thermoplastic obturation techniques.

Fabrication and characterization of polymer composites for endodontic use

AIM

To develop a low-density polyethylene-hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material.

METHODOLOGY

Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in simulated body fluid (SBF), using a universal testing machine. The radiopacity of the fibres was determined using digital radiography. The interaction of the composites with eugenol was evaluated and compared with gutta-percha. Data of the tensile test were submitted to two-way anova and Bonferroni tests (P < 0.05).

RESULTS

The endothermic peaks obtained from the DSC studies showed that the melting point of the HA/PE composites ranged between 110.5 and 111.2 °C, whereas gutta-percha exhibited a melting point at 52 °C. The tensile strength and elastic modulus of the silanated HA/PE composites were significantly higher than those of gutta-percha (P < 0.0001) under dry conditions and 1 month storage in SBF. The gutta-percha in eugenol showed a significant increase in the polymer molar mass, whereas the silanated HA/PE composites were unchanged. Radiological evaluations demonstrated that silanated HA/PE fibres were sufficiently radiopaque.

CONCLUSION

Promising materials for endodontic applications have been developed, offering relevant benefits over the traditional materials in terms of mechanical and chemical properties.

Comparative evaluation of the fracture resistance of teeth prepared with rotary system, filled with single cone gutta-percha and laterally condensed with zinc oxide eugenol and resin based (AH26) sealers to that of Resilon

AIM AND OBJECTIVE

To compare the fracture resistance of teeth prepared with rotary system and filled with single cone guttapercha followed by lateral condensation with different sealers like zinc oxide eugenol and resin based (AH26) to that of resilon.

MATERIALS AND METHODS

A total number of 70 extracted intact human permanent maxillary incisors were selected. All prepared samples were divided into one control group (n = 10) and three experimental groups (n = 20 per group). Group 1 control. This group received no obturation; the root canal opening was sealed with a temporary filling material (Cavit, Premier Dental Products, Plymouth Meeting, PA) Group 2: Gutta-Percha and zinc oxide Eugenol sealer. Group 3: Gutta-Percha and AH26 sealer. (DiaDent, Korea) dipped in AH26 sealer. Group 4: Resilon cones and RealSeal Resin Sealer. Obturation was accomplished using a 0.06 taper size 40 gutta-percha master point. All the root samples were stored in 100% humidity at 37 °C for 2 weeks to allow the sealer to set completely. The root samples were then prepared for mechanical testing and the data was recorded and analyzed statistically.

RESULTS

One-way ANOVA and Post hoc test (Duncan Multiple range test) were employed to determine possible statistical variation among the groups tested in this study. The force for group 2 was significantly greater than that for the control group 1 (no obturation).The force for group 3 was significantly greater than that for group 2. The force for group 4 was significantly greater than that for group 3. All other groupwise comparisons were not significant at 5% level. Group 4 seemed to have the greatest force among the three groups of interest in the study.

CONCLUSION

Root canals filled with Resilon increased the in vitro resistance of single canal extracted teeth compared to other experimental groups. The mean fracture resistance value for the experimental groups in ascending order was as follows: Root canals instrumented but not filled, filled with gutta-percha and zinc oxide eugenol sealer, filled with gutta-percha and AH26 sealer and filled with Resilon.

CLINICAL SIGNIFICANCE

Resilon is a promising material for reinforcement of endodontically treated teeth.

Dissolving efficacy of different organic solvents on gutta-percha and resilon root canal obturating materials at different immersion time intervals

Background Aim:

The purpose of this study was to compare and evaluate the dissolving capability of various endodontic solvents used during endodontic retreatment on resilon and gutta-percha at different immersion time intervals.

Materials and Methods:

160 ISO no. 40 cones (0.06 taper), 80 each of resilon and gutta-percha were taken as samples for the study. Both resilon and gutta-percha were divided into eight experimental groups of 20 cones (four groups each of resilon and gutta-percha) for immersion in xylene, tetrachloroethylene, refined orange oil and distilled water. Each group was further divided into two equal subgroups (n=10) for 2- and 5-minute immersion time intervals at room temperature to investigate the potential of these solvents for clinical use in dissolving resilon and gutta-percha. Each sample was weighed initially before immersing in the solvent on a digital analytical scale. Distilled water served as a control. Samples were removed from the respective solvents after the specified immersion period and washed in 100 ml of distilled water and allowed to dry for 24 h at 37°C in a humidifier. The samples were then again weighed after immersion in the specific solvent on a digital analytical scale. The extent of gutta-percha or resilon removed from the specimen was calculated from the difference between the original weight of gutta-percha or resilon sample and its final weight. Means and standard deviations of percentage loss of weight were calculated at each time interval for each group of specimens. The values were compared by statistical parametric tests using SPSS 16.0 Software. The data was subjected to paired ‘t‘ test, independent ‘t’ test, one-way ANOVA test and multiple comparisons with Scheffe's test.

Results:

There was no significance in the amount of gutta-percha dissolved at 2- and 5-minute immersion time intervals in all groups (P>0.05) except the tetrachloroethylene group (P=0.00). There was a very high significance in the amount of resilon dissolved at 2- and 5-minute immersion time intervals in all groups (P=0.00) except the xylene and distilled water (Control) groups (P>0.05).

Conclusion:

The results showed that xylene, refined orange oil and tetrachloroethylene can be used for softening gutta-percha/resilon during retreatment with various techniques- xylene being the best solvent both for gutta-percha and resilon.

Physicochemical properties, sealing ability, bond strength and cytotoxicity of a new dimethacrylate-based root canal sealer

BACKGROUND/PURPOSE

Resin-based root canal sealer can bond to dentin and establish a hermetic seal. The aim of this study was to evaluate the physicochemical properties, sealing ability, cytotoxicity and bond strength of a new resin-based root canal sealer (NRCS).

METHODS

The physicochemical properties were assessed by the flow, setting time, solubility, film thickness, radiopacity and dimensional changes. Sixty premolar root samples were filled with either Resilon/NRCS or Resilon/Epiphany and sectioned perpendicularly at the long axis at 2 mm below the cemento-enamel junction into 1-mm serial slices. The bond strength was tested by a universal testing machine. The glucose microleakage model was used to test the sealing ability. Elutes of NRCS and Epiphany were co-cultured with human periodontal ligament cells to test the cytotoxicity.

RESULTS

All the physicochemical properties of NRCS conformed to ISO 6876:2001(E). The root samples filled with Resilon/NRCS had significantly less leakage (p < 0.01) and greater bond strength (p < 0.001) than the Resilon/Epiphany group had. Environmental scanning electron microscopy showed that Resilon/NRCS filling material was intimately bonded to the root dentin. Although NRCS was slightly toxic to human periodontal ligament cells, its cytotoxicity was significantly less than that of Epiphany (p < 0.01)

CONCLUSION

NRCS has better physicochemical and sealing properties, as well as lower cytotoxicity and microleakage than Epiphany has.

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.

Antibacterial properties of four endodontic sealers

The purpose of this study was to evaluate the antimicrobial effects of root canal sealers. The direct contact test (DCT) was used to assess the antibacterial properties of AH plus, Apexit Plus, Epiphany SE, and RoekoSeal when in contact with Enterococcus faecalis. The materials were examined immediately after setting and 1, 2, 7, and 14 days after aging in phosphate-buffered-saline. Statistical analysis with two-way analysis of variance, one-way analysis of variance, and Tukey multiple comparison was applied to the data. Apexit Plus had a short-term antibacterial effect of 1 day on E. faecalis, whereas Epiphany SE enhanced bacterial growth for at least 7 days. AH plus and RoekoSeal were ineffective.

Microbial Leakage of Gutta-percha and Resilon™ Root Canal Filling Material: A Comparative Study Using a new Homogeneous Assay for Sequence Detection

The sealing ability of gutta-percha/sealer root canal filling was compared to a new thermoplastic synthetic polymer-based obturation material (Resilon TM), using a microleakage model and a new sequence detection assay One Cut Event AmplificatioN (OCEANTM). Eighty-eight extracted human teeth, shaped with K-Files and the ProTaper Technique, were randomly assigned to four groups (n = 22) and obturated in the apical 5 mm. Group R were obturated with the Resilon/Epiphany technique; group GP were obturated with gutta-percha and Zinc oxide eugenoe sealer; group RCH and GPCH received calcium hydroxide intracanal medication before being obturated. Sterilized specimens were inoculated with Enterococcus faecalis and incubated in sterile medium for 47 days. DNA extracted from the specimens was amplified by PCR and then identified by the OCEAN technique. Samples obturated with Resilon root canal filling material showed a greater number of microleakage events than the other groups (p = 0.036). Calcium hydroxide medication did not have a relevant impact on the quality of the apical seal (p = 0.044).

An evaluation of the sealing ability of a polycaprolactone-based root canal filling material (Resilon) after retreatment

OBJECTIVE

The aim of this study was to evaluate the sealing ability of Resilon after retreatment.

STUDY DESIGN

Sixty-six single-rooted mandibular premolars were enlarged to apical size 45 and then obturated with Resilon. The roots were randomly divided into 3 groups (n = 22/group). In group 1 no further treatment was done. Groups 2 and 3 were reinstrumented to apical size 60 using K-files and ProFile, respectively. In each group, 4 samples were kept for environmental scanning electron microscopy (ESEM) analysis. The remaining roots from groups 2 and 3 were refilled with Resilon. Sixteen roots from each group were then evaluated for microleakage; two roots served as controls. Data were analyzed statistically by Kruskall-Wallis test.

RESULTS

There were no significant differences between the experimental groups (P > .05). The ESEM showed new attachment of resin tags on the dentin surface of retreated roots.

CONCLUSION

Resilon can be used for retreatment, but it still allowed microleakage.

Apical sealing ability of Resilon/Epiphany versus gutta-percha/AH Plus: immediate and 16-months leakage

AIM

To compare the long-term apical sealing ability of gutta-percha/AH Plus and Resilon/Epiphany.

METHODOLOGY

The root canals of 90 single-rooted human mandibular premolars with single narrow root canals were prepared with ProFile 0.4 taper instruments to apical size 40. After each instrument, the canals were irrigated with 1% sodium hypochlorite. Subsequently, the teeth were randomly divided into four groups containing 20 teeth each. Additionally, 10 prepared premolars served as positive and 10 counterparts with intact crowns as negative controls. The root canals were filled with gutta-percha/AH Plus or Resilon/Epiphany using lateral or vertical compaction. Specimens were allowed to set for 7 days at 37 degrees C and 100% humidity. Subsequently, the root fillings were removed down to the apical 4 mm. Fluid movement was then assessed using a fluid transportation model and re-evaluated after 16 months of water storage. Leakage within and between groups was compared using nonparametric tests.

RESULTS

Negative controls revealed no fluid movement and positive controls displayed gross fluid movement at both times of observation. At the immediate measurement, there were no significant differences between the experimental groups (Kruskal-Wallis, P > 0.05). Gutta-percha/AH Plus fillings retained their seal after 16-months storage (Wilcoxon, P > 0.05), whilst the Resilon/Epiphany groups lost their sealing capacity (Wilcoxon, P < 0.001). In these groups, 29 of the 40 specimens exhibited gross leakage similar to positive controls.

CONCLUSION

Initially, Resilon/Epiphany root fillings prevented fluid movement to the same degree as gutta-percha/AH Plus counterparts, but showed more fluid movement when tested at 16 months.

Endodontic materials

This article presents a review of materials currently used in the practice of endodontics. Current endodontic materials include those that have been thoroughly tested by scientific investigation, clinical usage, and time, as well as others that are the result of new knowledge in the field of dental materials. Article sections are devoted to obturation materials, sealers, irrigation materials, smear layer removal, root-end filling materials, and intracanal medicaments. Knowing the particular qualities of materials can aid the clinician in choosing those that are appropriate for a given situation. Properties, components, and rationale for the materials' use are presented to aid the clinician in choosing materials for a particular need.

Enterococcus faecalis type strain leakage through root canals filled with Gutta-Percha/AH plus or Resilon/Epiphany

The aim of this in vitro study was to compare leakage of Enterococcus faecalis ATCC 29212 through root canals of single-rooted extracted human mandibular premolars filled with either gutta-percha/AH Plus or Resilon/Epiphany using the continuous wave of condensation technique. Test and control teeth were suspended in an experimental bacterial leakage setup for 50 days. Kaplan-Meyer curves showed a tendency of the gutta-percha/AH Plus root fillings to prevent leakage better than Resilon/Epiphany counterparts. This tendency, however, was not statistically significant (log-rank test, p = 0.141). The estimated mean time for turbidity to occur in the broth below the suspended root was 35 days (SD = 5 days) in the gutta-percha/AH Plus and 33 days (SD = 4 days) in the Resilon/Epiphany group. It was concluded that within the limitations of this study, there was no apparent advantage of using Resilon/Epiphany over gutta-percha/AH Plus.

Leakage along apical root fillings with and without smear layer using two different leakage models: a two-month longitudinal ex vivo study

AIM

To compare two different experimental models when measuring leakage along root fillings with or without smear layer.

METHODOLOGY

One hundred and twenty single-rooted teeth were prepared to size 50 and allocated to two groups: fluid transport model (n = 60) and glucose penetration model (n = 60). The roots in each group were divided into three subgroups of 20 teeth each. Smear layer was left in place in group 1 but removed in groups 2 and 3. In groups 1 and 2 canals were filled with laterally compacted gutta-percha cones and AH 26. Group 3 was laterally compacted with Resilon cones and Epiphany sealer. The coronal portion of the filling was removed to assure only 4 mm of filling remained in the canal. Leakage of glucose was evaluated by measuring its concentration once a week for a total period of 56 days using a glucose penetration model. Fluid transport was evaluated by measuring the movement of an air-bubble using a fluid transport model, 1 and 8 weeks after canal filling. Differences between the groups in glucose concentrations and fluid transport were statistically analysed with the Kruskal-Wallis and the Mann-Whitney tests. The level of significance was set at alpha = 0.05.

RESULTS

Glucose penetration was significantly different between the three groups after the first 8 days (P < 0.05). Resilon leaked the most throughout the experiment period. No significant difference (P > 0.05) existed between the two gutta-percha groups at all time intervals (Mann-Whitney test). In the fluid transportation model, no statistically significant differences were observed between all three experimental groups (P > 0.05) at either 1 or 8 weeks after filling (Kruskal-Wallis test).

CONCLUSIONS

Under the conditions of this study, the glucose penetration model was more sensitive in detecting leakage along root fillings. Removing the smear layer before filling did not improve the sealing of the apical 4 mm of filling. Resilon allowed more glucose penetration but the same amount of fluid transport as the gutta-percha root fillings.

Evaluation of the thermoplasticity of different gutta-percha cones and Resilon�

The goal of this study was to evaluate the thermoplasticity of conventional and thermoplastic gutta-percha and Resilon, a polyester polymer-based material. Specimens with standardised dimensions were made from the following materials: conventional and thermoplastic gutta-percha (Dentsply), conventional and thermoplastic gutta-percha (Endopoints) and Resilon. After 24 h, the specimens were placed in water at 70 degrees C for 60 s, and thereafter positioned between two glass slabs. Each set was compressed by a 5-kg weight. Digital images of the specimens before and after compression were obtained and analysed. The thermoplasticity of each material was confirmed by the difference between final and initial areas of each sample. The data were analysed statistically by anova and Tukey's test at a 5% significance level. Resilon had the highest thermoplasticity means (P < 0.05). Among the gutta-percha cones, Endopoints TP (thermoplastic) presented the highest thermoplasticity means and differed significantly from the other commercial brands (P < 0.05). Resilon had good thermoplasticity, endorsing its use as a thermoplastic root canal filling material.

Monoblocks in root canals: a hypothetical or a tangible goal

The term monoblock has become familiar in the endodontic literature with recent interest in the application of dentin adhesive technology to endodontics. Endodontic monoblocks have generated controversial discussions among academicians and clinicians as to whether they are able to improve the quality of seal in root fillings and to strengthen roots. This review attempts to provide a broader meaning to the term monoblock and to see how this definition may be applied to the materials that have been used in the past and present for rehabilitation of the root canal space. The potential of currently available bondable materials to achieve mechanically homogeneous units with root dentin is then discussed in relation to the classical concept in which the term monoblock was first employed in restorative dentistry and subsequently in endodontics.

Influence of resin-based adhesive root canal fillings on the resistance to fracture of endodontically treated roots: an in vitro preliminary study

OBJECTIVE

The aim was to investigate the root reinforcing capability of the resin-based RealSeal.

STUDY DESIGN

In two groups (n=36) canals were instrumented with nickel-titanium rotary GTfiles or with hand K-files. Twelve teeth from each group were obturated with lateral compaction using either gutta-percha and AHPlus or RealSeal. The canals of twelve teeth of both groups were instrumented but not filled. Group 3 (n=12) acted as uninstrumented controls. The force required to fracture the roots was measured. ANOVA and Scheffé test were used for statistical analysis.

RESULTS

The intact roots were significantly stronger than both groups with instrumented and unobturated roots (P<.05). Between the roots of both groups obturated with RealSeal and the intact roots there were no significant differences (P>.05). The roots obturated with RealSeal were significantly stronger than those obturated with gutta-percha and AHPlus (P<.05).

CONCLUSIONS

An obturation with RealSeal significantly increases the fracture resistance of instrumented roots.

Sealing Ability of New Adhesive Root Canal Filling Materials Measured by New Dye Penetration Method

The sealing ability of new adhesive root canal filling materials was evaluated using a new dye penetration method. Twenty-eight single-rooted mandibular premolars were randomly divided into four groups of seven teeth each and filled by lateral condensation using one of these combinations: Resilon point with Epiphany sealer (RE); gutta-percha point with Sealapex sealer (GS); gutta-percha point with dentin activator and Superbond sealer (GDS); or gutta-percha point with Accel primer, dentin activator, and Superbond sealer (GADS). Amount of 0.06% methylene blue dye solution (MB) that leaked from the coronal portion to the apical area was measured with a spectrophotometer at one, four, eight, 15, and 30 days in an accumulative manner. The total amount of leaked MB on day 30 was significantly higher for GDS than the other combinations (p < 0.05).

The penetration of RealSeal primer and Tubliseal into root canal dentinal tubules: a confocal microscopic study

AIM

To compare penetration depth into dentinal tubules of RealSeal with that of a well-established endodontic sealer (Tubliseal) by means of confocal microscopy.

METHODOLOGY

Twenty sound extracted, single-rooted premolars were selected. Following completion of root canal instrumentation, the teeth were divided into two groups using a stratified sampling method, ranking teeth according to size. In group 1, 10 teeth were filled with Gutta-percha and Tubliseal using cold lateral condensation. In group 2, 10 teeth were filled with RealSeal. Both sealers were labelled with Rhodamine B dye. The teeth were sectioned parallel to their long axis resulting in 20 specimens per group. Confocal microscopy was used to assess the penetration depths of the sealers at three sites for each specimen (coronal, middle and apical). Data were analysed statistically using Stata Release 9.1.

RESULTS

The penetration depth of RealSeal in each one of the thirds of the root canal was found to be higher than that of Tubliseal (P < 0.05). The penetration depths of the two sealers was found to be significantly different (P = 0.001). The mean penetration value for the RealSeal group was 908.8 microm whereas the mean value for the Tubliseal group was 139.5 microm.

CONCLUSIONS

The penetration depth of RealSeal into the root dentinal tubules is significantly greater than that of Tubliseal.