Susceptibility of a Polycaprolactone-Based Root Canal Filling Material to Degradation. II. Gravimetric Evaluation of Enzymatic 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.

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.

Synchrotron-Based in Situ Characterization of the Scaffold Mass Loss from Erosion Degradation

The mass loss behavior of degradable tissue scaffolds is critical to their lifespan and other degradation-related properties including mechanical strength and mass transport characteristics. This paper presents a novel method based on synchrotron imaging to characterize the scaffold mass loss from erosion degradation in situ, or without the need of extracting scaffolds once implanted. Specifically, the surface-eroding degradation of scaffolds in a degrading medium was monitored in situ by synchrotron-based imaging; and the time-dependent geometry of scaffolds captured by images was then employed to estimate their mass loss with time, based on the mathematical model that was adopted from the literature of surface erosion with the experimentally-identified model parameters. Acceptable agreement between experimental results and model predictions was observed for scaffolds in a cylindrical shape, made from poly(lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL). This study illustrates that geometry evaluation by synchrotron-based imaging is an effective means to in situ characterize the scaffold mass loss as well as possibly other degradation-related properties.

Advances in endodontics: Potential applications in clinical practice

Contemporary endodontics has seen an unprecedented advance in technology and materials. This article aimed to review some of the challenges and advances in the following sections: (1) endodontic imaging, (2) root canal preparation, (3) root canal disinfection, (4) root canal filling, and (4) regenerative endodontic procedures (REPs). Jointly, these advances are aimed at improving the state of the art and science of root canal treatment.

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.

Bacterial entombment by intratubular mineralization following orthograde mineral trioxide aggregate obturation: a scanning electron microscopy study

The time domain entombment of bacteria by intratubular mineralization following orthograde canal obturation with mineral trioxide aggregate (MTA) was studied by scanning electron microscopy (SEM). Single-rooted human premolars (n=60) were instrumented to an apical size #50/0.06 using ProFile and treated as follows: Group 1 (n=10) was filled with phosphate buffered saline (PBS); Group 2 (n=10) was incubated with Enterococcus faecalis for 3 weeks, and then filled with PBS; Group 3 (n=20) was obturated orthograde with a paste of OrthoMTA (BioMTA, Seoul, Korea) and PBS; and Group 4 (n=20) was incubated with E. faecalis for 3 weeks and then obturated with OrthoMTA–PBS paste. Following their treatments, the coronal openings were sealed with PBS-soaked cotton and intermediate restorative material (IRM), and the roots were then stored in PBS for 1, 2, 4, 8 or 16 weeks. After each incubation period, the roots were split and their dentin/MTA interfaces examined in both longitudinal and horizontal directions by SEM. There appeared to be an increase in intratubular mineralization over time in the OrthoMTA-filled roots (Groups 3 and 4). Furthermore, there was a gradual entombment of bacteria within the dentinal tubules in the E. faecalis inoculated MTA-filled roots (Group 4). Therefore, the orthograde obturation of root canals with OrthoMTA mixed with PBS may create a favorable environment for bacterial entombment by intratubular mineralization.

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.

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.

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 retrospective study comparing clinical outcomes after obturation with Resilon/Epiphany or Gutta-Percha/Kerr sealer

The purpose of this retrospective study was to evaluate the treatment outcome of root canal systems obturated with gutta-percha and Kerr Pulp Canal Sealer compared with Resilon and Epiphany sealer. One hundred three teeth treated in a private endodontic practice were included in the study. Clinical outcomes (healed versus nonhealed) were assessed by using the Periapical Index determination and clinical evaluation at recall appointments. The magnitude of the association between obturation materials used and outcome measured was evaluated with univariate and multivariate logistic regression analysis. Univariate analysis indicated that pulpal vitality, presence of a preoperative lesion, and length of recall times were statistically significant in predicting the outcome. Logistic regression analysis showed that age, tooth position, and length of recall times were statistically significant in predicting the outcome. Root canal systems obturated with gutta-percha and Kerr Pulp Canal Sealer or Resilon and Epiphany sealer had statistically indistinguishable differences in clinical outcome.

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).

Comparative study of the cytotoxic effect of resilon against two cell lines

Resilon is a new material that is a candidate to replace gutta-percha as a root filling material. This study evaluated the antiproliferative effect of Resilon and two commercially available gutta-percha points (Roeko, Dentsply). Two established cell lines (L929 and RPC-C2A) were used for the experiment. Cell survival fraction was estimated by the sulforhodamine-B assay, in reference to controls after 48-h exposure. Non-parametric tests (Kruskal-Wallis followed by Dunn's multiple comparisons) were used to evaluate the statistical significance of the results (α=0.05). Cytotoxicity in a descending order was: Resilon > Roeko gutta-percha > Dentsply gutta-percha. At 24-h exposure, no statistically significant differences (p>0.05) were observed between tested materials in both cell lines. At 48-h exposure, statistically significant differences (p<0.05) were found between Resilon and the other materials in the L929 cell line. In the RPC-C2A cell line Resilon was significantly more cytotoxic than Dentsply gutta-percha (p<0.05), but no statistically significant differences (p>0.05) were found between Resilon and Roeko gutta-percha. The cytotoxicity of Resilon increased significantly from 24 h to 48 h in both cell lines. Resilon points were more cytotoxic than gutta-percha points. The cytotoxicity was time dependent and increased after 48 h.

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.

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.

Comparison of 5.25% Sodium Hypochlorite, MTAD, and 2% Chlorhexidine in the Rapid Disinfection of Polycaprolactone-Based Root Canal Filling Material

The purpose of this investigation was to compare the effectiveness of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of Resilon pellets. Resilon pellets were randomly selected, contaminated with Enterococcus faecalis, and disinfected with 5.25% sodium hypochlorite, MTAD, or 2% chlorhexidine. Positive and negative controls were used. All samples were air dried, washed in sterile water, placed in centrifuge tubes containing BHI broth, and incubated at 37 degrees C for up to 7 days. Broths were visually checked for turbidity and scored for growth. Samples from each experimental and control group were randomly chosen, plated, incubated at 37 degrees C, and checked visually for growth. If growth occurred, a gram stain was performed to identify bacterial species. Results indicate that 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine were all effective in the rapid disinfection of Resilon and gutta-percha pellets, and a 1-minute immersion was sufficient to disinfect.

The physical characterization of a thermoplastic polymer for endodontic obturation

OBJECTIVE

To analyze a new endodontic sealer material commercially known as Resilon and to describe in detail the experimental techniques employed that lead to the identification of the composite material.

METHODS

An extensive structural, thermal, and physical characterization was used to identify a new endodontic sealer material using the following techniques: Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) analysis, X-ray fluorescence spectrometry (XRF) technique, X-ray diffraction (XRD) measurement, thermo-gravimetric analysis (TGA) and a differential scanning calorimeter (DSC). The surface morphology was analyzed using a scanning electron microscope (SEM).

RESULTS

The material was identified as a composite of polycaprolactone, which is a polymer of the polyester family and bioactive glass, which is radiopaque filler.

CONCLUSIONS

The Resilon sealer material is a thermoplastic synthetic degradable polymer (polycaprolactone), it contains bioactive glass. Its properties, such as strength, modulus, shape-memory effect and biodegradability depend on the crystalline fraction, which is affected in turn by conditions of crystallization. Investigation of the crystallization kinetics of PCL is of practical significance. It is especially necessary to study its the dynamic and non-isothermal crystallization process.

Initial In Vitro Biological Response to Contemporary Endodontic Sealers

The objective of this study was to evaluate the cytotoxicity of three endodontic sealers (AH Plus/Maillefer-Dentsply, Epiphany/Pentron, GuttaFlow, Coltene-Whaledent). Materials were mixed according to the manufacturer instructions and packed into Teflon molds (10 x 1 mm). For cytotoxicity testing (MTT method), the specimens were placed in contact with cultured cells, then evaluated at two subsequent time points (24 or 72 h). In addition to testing the mixed materials, 5 microl of primer liquid (GuttaFlow and Epiphany) and resin solvents (HEMA, ethanol, sterile water, or acetone) were added directly in culture for 24 and 72 h. The results showed that most materials pose significant cytotoxic risks and that cytotoxicity generally increased with time. At 72 h, GuttaFlow became significantly less toxic than AH Plus, Epiphany sealer, and Resilon. The current results support the need to continue to develop better endodontic sealers that combine the excellent sealing and bonding properties of resins with acceptable biological properties for endodontic applications.