Interfacial Strength of Resilon and Gutta-Percha to Intraradicular Dentin

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).

Fracture resistance of roots obturated with three different materials

OBJECTIVE

The aim of this study was to compare the fracture resistance of roots obturated with different materials.

STUDY DESIGN

Sixty root canals were instrumented and divided into 4 equal groups (n = 15 each). The root canals in group 1 were filled with AH26 sealer and gutta-percha, in group 2 with Resilon and Epiphany, and in group 3 with Ketac-Endo Aplicap and gutta-percha. Fifteen root canals had no obturation. The force required to fracture was recorded. The data was analyzed with analysis of variance and Duncan test.

RESULTS

The mean force of fracture for group 1 was significantly higher than for the other 3 groups (P < .05). There was significant difference between group 2 and group 3 (P < .05). Group 2 and group 3 were not significantly different from the control group (P > .05).

CONCLUSION

The use of AH26 + gutta-percha increased the fracture resistance of instrumented root canals compared with Resilon + Epiphany and Ketac-Endo Aplicap + gutta-percha.

Push-out bond strengths of the dentine–sealer interface with and without a main cone

AIM

To evaluate the push-out bond strength of the dentine-sealer interface with and without main cone for three resin sealers.

METHODOLOGY

Thirty extracted maxillary premolar teeth with two separate canals were prepared using 0.04 taper Profile instruments to size 35-45. Teeth were divided into three groups for filling using AH Plus, EndoREZ or Resilon sealers. In each tooth, one canal was filled with a matching single-cone technique, and other was filled with sealer alone. A 1 mm slice of mid-root dentine was prepared for the push-out test. Failure modes after push-out were examined under microscopy and field emission-scanning electron microscopy. Data were analysed using two-way anova and paired t-tests, with significance set at P < 0.05.

RESULTS

Overall, the epoxy resin-based sealer provided the highest push-out bond strengths. Push-out bond strengths were significantly higher (P < 0.001) when canals were filled with sealer alone than those filled with main cone and sealer (AH Plus 6.6 and 2.0 MPa, respectively; Resilon 3.4 and 0.4 MPa; EndoREZ 0.9 and 0.4 MPa). Sealers appeared to behave differently as thin films in association with a main cone, compared with bulk material. They failed in cohesive mode within the thin film, leaving a layer of sealer on the canal surface. Bulk sealer showed predominantly adhesive failure at the dentine-sealer interface, with a clean dentine wall and with resin tags either partially pulled out or sheared off at the interface.

CONCLUSION

Push-out bond strengths of resin sealers were much lower when the sealer was present as a thin layer.

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.

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.

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.

Cytotoxicity of Epiphany�and Resilon�with a root model

AIM

To record the cytotoxicity of Resilon and Epiphany (Pentron clinical technologies, Wallingford, CT, USA) using a root model.

METHODOLOGY

Thirty teeth with single roots were sectioned at the enamel-cementum junction, the root canals prepared and each root then sterilized before filling with the lateral condensation technique using one of three filling materials (n = 10 per group): Resilon and Epiphany, Sealite (Septodont, Pierre Rolland, Merignac, France) and gutta-percha, Roekoseal Automix (Coltène/Whaledent, Langenau, Germany) and gutta-percha. The roots were stored at 37 degrees C in an incubator to allow for setting of the root filling materials. The apices of the roots were dipped in 1 mL of MEM culture medium for 1, 2, 7 and 30 days renewing the medium every day. After 24 h contact between the medium and the filled roots, the medium was used to measure the cytotoxicity on mouse fibroblasts L 929 with the MTT assay that recorded the mitochondrial activity of the target cells. An additional test according to ISO 10993-5 standards was undertaken to compare Resilon and Epiphany.

RESULTS

The root model showed no statistically significant differences between the sealers at 7 and 30 days (NS). Epiphany and Resilon were the most cytotoxic materials at 1 and 2 days (P < 0.001). Unlike Epiphany, Resilon was not cytotoxic when tested according to ISO 10993-5 standards.

CONCLUSIONS

The cytotoxicity of Resilon + Epiphany, due mainly to Epiphany, decreased after 2 days to reach a level comparable with commonly used root canal sealers.

An In Vitro Comparison of the Intraradicular Dentin Bond Strength of Resilon and Gutta-Percha

The purpose of this study was to compare the micropush-out bond strength of Resilon to that of gutta-percha. Extracted human anterior teeth were used for evaluation. The crowns were removed and the root canals were instrumented with Gates Glidden drills and 0.06 Profile rotary files. Instrumentation was performed with 5.25% sodium hypochlorite irrigation and a final rinse of 17% EDTA. The teeth were randomly divided into two groups. Gutta-percha group: obturation with gutta-percha and Kerr Pulp Canal Sealer EWT. Resilon group: obturation with Resilon points, Epiphany Primer, and Root Canal Sealant. The teeth were cut perpendicular to their long axis to obtain a series of 1.0 mm thick disks (n = 15 per group). Micropush-out bond strengths to root canal dentin were measured. The results show that the mean bond strength to root canal dentin was significantly higher (p < 0.05) in the Resilon/Epiphany group as compared to the gutta-percha/Kerr Pulp Canal Sealer EWT group.

Self-Etching Adhesives Increase Collagenolytic Activity in Radicular Dentin

Endogenous matrix metalloproteinases (MMPs) release from crown dentin and their activation results in degradation of hybrid layers created by dentin adhesives. This study tested the hypothesis that instrumented intraradicular dentin possesses latent collagenolytic activity that is activated by mild self-etching adhesives. Root dentin shavings were produced from 50 cleaned and shaped, saline-irrigated root canals using Gates Glidden drills and rinsed with sodium azide to prevent bacterial growth. Dried dentin powder aliquots were treated with two clinically-relevant MMP inhibitors, 2% chlorhexidine for 10 minutes and 17% EDTA for 1 minute. Additional dentin powder was mixed with Clearfil Liner Bond 2V or Clearfil Tri-S Bond for 1 minute followed by extracting the adhesives with acetone. Dentin powder was also treated with 2% chlorhexidine for 10 minutes before or after adhesive application. Collagenolytic activities of the nine groups were assayed with a fluorometer in 96-well plates, by recording the changes in fluorescence before and after addition of fluorescein-labeled type I collagen. Epoxy resin-embedded powders were examined with TEM for the extent of demineralization. Instrumented, mineralized intraradicular dentin possessed low but detectable collagenolytic activity that was inhibited by chlorhexidine (p < 0.001) and EDTA (p < 0.001). Both adhesives partially demineralized the dentin powder and activated latent MMPs, with 14- to 15-fold increases in collagenolytic activities (p < 0.001) that were significantly (p < 0.001) but incompletely inactivated after 10 min application of chlorhexidine. Mild self-etching adhesives activate latent MMPs without denaturing these enzymes, and may adversely affect the longevity of bonded root canal fillings and posts.

The Effect of Immediate Versus Delayed Cementation on the Retention of Different Types of Fiber Post in Canals Obturated Using a Eugenol Sealer

Post can be placed immediately after the completion of the endodontic procedure or at a later stage after setting of the sealer. In this in vitro study, post space preparation and post cementation were performed immediately (group 1), 24 h (group 2), and 7 days (group 3) after root filling. A control group with no root canal obturation was included (group 4). Each group was further divided into three subgroups, according to the post type and to the materials used for luting the post. A push-out test was performed to evaluate post-root canal dentin interfacial strength. Differences among experimental groups were analyzed with two-way ANOVA and the Tukey test. Significant differences (p < 0.05) in interfacial strengths were observed for the factors post cementation interval and post type. Clinicians should be careful in performing immediate cementation of fiber posts, as delayed cementation shows higher post-dentin interfacial strengths irrespective of the post type.

Assessment of the Sealing Ability of a New Root Canal Obturation Material

This study was designed to compare the leakage allowed by different obturation materials, using a fluid-transport method. Sixty-six single-rooted human anterior teeth were fully instrumented by using the "step-back" technique and irrigated with 5.25% sodium hypochlorite. The smear layer was removed by washing in 10 ml of 17% EDTA. The specimens were randomly divided into three experimental groups of 18 teeth each, plus two groups of 6 teeth each for positive and negative controls. The specimens were obturated by the lateral condensation technique, with gutta-percha and AH 26 or AH plus sealers, or Epiphany sealer and Resilon core material. The fluid transport method used in this study gave quantitative results and allowed nondestructive evaluation of the specimens. The teeth filled with gutta-percha and AH 26 exhibited the most leakage. The least leakage was seen with Epiphany sealer and Resilon core material. The differences in leakage among the groups were statistically significant (p < 0.05). It was concluded that of the materials tested under the conditions of this study, Epiphany allowed the least leakage.

Push-out bond strengths: the Epiphany-Resilon endodontic obturation system compared with different pairings of Epiphany, Resilon, AH Plus and gutta-percha

AIM

To assess the bond strength of the new resin-based Epiphany-Resilon root canal filling system, and to compare this with bond strengths of different pairings of AH Plus, gutta-percha, Epiphany and Resilon.

METHODOLOGY

A total of 65 extracted human single-rooted teeth were used. All teeth were instrumented using a set of ProTaper rotary instruments. Irrigation was performed with 15 mL of 1.25% NaOCl between each instrument and the smear layer was removed during and after instrumentation with 5 mL of 17% EDTA. The canal spaces were filled with different combinations of core and sealer using lateral condensation, as follows: group 1, AH Plus + gutta-percha; group 2, AH Plus + Resilon; group 3, Epiphany + Resilon; group 4, Epiphany + gutta-percha; group 5 (control), gutta-percha only. Cylinders of root dentine 1.13 (0.06)-mm long were prepared from the coronal sections of the 65 teeth. The test specimens were subjected to the push-out test method. After adhesion testing, the remaining sections were examined under a stereomicroscope at x 25 magnification to determine the nature of bond failure. The values of bond strength were analyzed by one-way analysis of variance (ANOVA) and the post hoc Tukey's test, with significance set at P < 0.05.

RESULTS

The respective mean push-out test values for groups 1-5 were: 2.000 +/- 0.369, 1.380 +/- 0.154, 1.706 +/- 0.340, 2.857 +/- 0.523 and 0.078 +/- 0.027 MPa. Significant difference (P < 0.001) occurred between the groups. Multiple paired comparisons (Tukey's test) revealed that group 4 (Epiphany + gutta-percha) had significantly (P < 0.001) greater bonding strength than all the other groups; group 1 (AH Plus + gutta-percha) had significantly (P < 0.05) greater bonding strength than group 2 (AH Plus + Resilon); and group 5 (control) had significantly (P < 0.05) lower bonding strength than all the other groups. Inspection of the surfaces revealed the bond failure to be mainly adhesive to dentine for all groups.

CONCLUSIONS

The Epiphany-Resilon combination (group 3) was not superior to that of the AH Plus-gutta percha combination (group 1).

A Comparison of Cohesive Strength and Stiffness of Resilon and Gutta-Percha

The purpose of this study was to compare the cohesive strength and stiffness of Resilon and gutta-percha under dry conditions and after 1 month of water storage to determine if they are stiff enough to reinforce roots. Dog-bone shaped specimens were created and pulled to failure at 3 mm/min in a Vitrodyne universal tester. The apparent modulus of elasticity, percent elongation, and yield stress were measured. Cohesive strength was defined as the yield stress. The data were analyzed using a two-way ANOVA for each outcome (alpha = 0.05). The results of this study show that the cohesive strength (that is the tensile stress when they begin to flow or break) and modulus of elasticity (or stiffness) of gutta-percha and Resilon are relatively low. Although the results showed statistically significant differences between the physical properties of gutta-percha and Resilon under varied conditions, these differences were not clinically significant. In conclusion, the stiffness of Resilon and gutta-percha is too low to reinforce roots after root canal therapy.