Cytotoxicity of Different Concentrations of Three Root Canal Sealers on Human Mesenchymal Stem Cells.

This study assessed the dose-dependent effect on the cytotoxicity of BioRoot RCS (BR) and Endosequence BC (BC) sealers in human bone marrow mesenchymal stem cells (hMSCs) compared to those of the AH Plus sealer. Cells were exposed to different dilutions of extracts from freshly prepared sealers (1:2, 1:8, 1:32). Unexposed cells acted as the negative control. Cytotoxicity was evaluated by an alamar blue assay. Cell morphology was analyzed by using scanning electron microscopy after exposure to the different sealers' extracts. Statistical analysis was performed using a one-way analysis of variance and the Bonferroni post hoc test (p < 0.05). The cytotoxicities of BC and BR were less than that of AH Plus. In the presence of 1:2 BR, the cell proliferation was significantly lower than the control. At 1:8 and 1:32 concentrations, both the tricalcium silicate sealers led to similar cellular proliferation. Cells in BC and BR sealers' extracts spread better than those in AH Plus extract.

Effect of Sodium Hypochlorite on Push-out Bond Strength of Four Calcium Silicate-based Endodontic Materials when used for repairing Perforations on Human Dentin: An in vitro Evaluation.

AIM: This study aimed to evaluate the push-out bond strength of NeoMTA Plus (NMTA), EndoSequence root repair material fast set putty (ERRMF), biodentine (BD), and ProRoot white mineral trioxide aggregate (PMTA) when used as perforation repair materials after exposure to 2.5% sodium hypochlorite (NaOCl) during the early setting phase. MATERIALS AND METHODS: Horizontal midroot sections were prepared from single-rooted human teeth. Sections (n = 144) were randomly divided into four groups: PMTA, BD, NMTA, and ERRMF. Materials were condensed and allowed to set for 10 minutes. The groups were further divided into two subgroups. The NaOCl group included specimens that were immersed in 2.5% NaOCl for 30 minutes, and the control group included specimens on which a wet cotton pellet was placed over the test material. After 48 hours, the highest force applied to the materials at the time of dislodgement was recorded. Slices were then examined under a digital microscope to evaluate the nature of the bond failure. The surfaces of two specimens from each subgroup were observed by scanning electron microscopy. Data were statistically analyzed with two-way and one-way analysis of variances, independent t-tests, and chi-square tests. The statistical significance was set at 0.05. RESULTS: In NaOCl-treated groups, PMTA showed a significantly higher push-out bond strength than the other three materials (p = 0.00). In the control groups, the bond strength of BD was significantly higher than that of PMTA, ERRMF, and NMTA (p < 0.05). Compared with the control group, NaOCl treatment significantly increased the push-out bond strength of PMTA (p = 0.00) and ERRMF (p = 0.00) and significantly reduced the bond strength of BD (p = 0.00) and NMTA (p = 0.03). None of the specimens showed an adhesive type of failure. The majority of the samples exhibited a cohesive failure type. Morphological observations revealed that the surfaces exhibited cubic crystals. In ERRMF, the crystals were few in number. Sodium hypochlorite enhanced the crystallization of NMTA. CONCLUSION: The push-out bond strengths of PMTA and ERRMF were significantly increased after exposure to 2.5% NaOCl in the early setting phase, and those of BD and NMTA were significantly decreased. CLINICAL SIGNIFICANCE: The results of the present study suggest that early exposure of NaOCl increase the push-out bond strength of PMTA and ERRMF. PMTA had the highest push-out values. Therefore, it would be a potentially useful perforation repair material for single visit endodontic treatment.

Pull-out retentive strength of fiber posts cemented at different times in canals obturated with a eugenol-based sealer.

STATEMENT OF PROBLEM: Currently, no standard luting protocol exists for fiber posts. In addition, no agreement has been reached on the time interval between canal obturation and post space preparation and cementation. PURPOSE: The purpose of this in vitro study was to evaluate the retention of fiber posts cemented with 3 different types of cement: Paracore, Variolink II, and RelyX Unicem cement after 24 hours or 2 weeks in root canals obturated with gutta percha and a eugenol-based sealer. MATERIAL AND METHODS: Seventy-two caries-free, freshly extracted, single-rooted human mandibular first premolar teeth with straight root canals were prepared and obturated with gutta percha and Endofil sealer. Specimens were divided into 2 groups (n=36): post spaces prepared 24 hours after obturation and post spaces prepared 2 weeks after obturation. Posts in both groups were luted with 1 of 3 different luting agents (n=12), ParaCore, Variolink II, or RelyX Unicem cement. Each tooth specimen was vertically secured in a universal testing machine, and a constant pull-out loading rate of 0.5 mm/min was applied until cement failure occurred. Data were statistically analyzed with 2-way and 1-way ANOVAs and t tests. RESULTS: Two-way ANOVA indicated statistically significant differences in mean post retention among the 3 cement types (P<.001) and among the means of the different time intervals investigated (P<.001). Significant differences were noted among all cement types tested between the 24-hour and 2-week time intervals (P<.05). CONCLUSIONS: Time elapsed between canal obturation and post cementation significantly influenced fiber post retention, regardless of the type of resin cement. Fiber posts showed significantly higher retention if cemented after 24 hours of obturation than if cementation occurred after 2 weeks.

Comparative evaluation of push-out bond strength of ProRoot MTA, bioaggregate and biodentine.

OBJECTIVE: To evaluate the push-out bond strength of Biodentine (BD) in comparison with two available calcium silicate based materials, bioaggregate (BA) and ProRoot MTA (WMTA). MATERIALS AND METHODS: One hundred and twenty-three Root dentin slices of freshly extracted single Rooted human teeth were randomly divided into three groups (n = 41) according to the used test material: WMTA, BA, BD. After canal space preparation, the filling materials were placed inside the lumen of the slices. After 72 hours, the maximum force applied to materials at the time of dislodgement was recorded and slices were then examined under a stereomicroscope at ×40 magnification to determine the nature of bond failure. Analysis of variance (ANOVA) test was used to compare means of push-out bond strength. Post-hoc test was then accomplished for multiple comparisons. Chi-square test was used to determine if there is significant association between the type of material and type of failure. RESULTS: The mean push-out bond strength ± standard deviation in MPa values of WMTA, BA and BD were 23.26 ± 5.49, 9.57 ± 3.45, 21.86 ± 6.9, respectively. There was no significant difference between the means of WMTA and BD (p = 0.566), but the mean of BA was significantly lower than those of WMTA and BD (p = 0.000). Under stereomicroscope, WMTA and BA showed a majority of mixed type of failure than cohesive failure, while BD showed the opposite. No adhesive failure was observed in any specimen. CONCLUSION: The findings of the present study imply that the force needed for BD displacement is similar to WMTA and significantly higher than the force required to displace BA.