The Effects of Different Post Space Conditioning Procedures and Different Endodontic Sealers on the Push-Out Bond Strengths of Fiber Posts

Comparison of various irrigation activation procedures after post space preparation on push-out bond strength of fiber posts: an in vitro study

ObjectiveThis study aimed to evaluate the effect of ultrasonic cleaning of the intracanal post space on the bond strength of fiber posts in oval canals filled with a premixed bioceramic (Bio-C Sealer [BIOC]) root canal sealer.Materials and MethodsFifty premolars were endodontically prepared and divided into 5 groups (n = 10), based on the type of root canal filling material used and the post space cleaning protocol. A1: gutta-percha + AH Plus (AHP) and post space preparation with ultrasonic cleaning, A2: gutta-percha + BIOC and post space preparation with ultrasonic cleaning, B1: gutta-percha + AHP and post space preparation, B2: gutta-percha + BIOC and post space preparation, C: control group. Fiber posts were cemented with a self-adhesive luting material, and 1 mm thick slices were sectioned from the middle and cervical third to evaluate the remaining filling material microscopically. The samples were subjected to a push-out test to analyze the bond strength of the fiber post, and the results were analyzed with the Shapiro-Wilk, Bonferroni, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Failure modes were evaluated using optical microscopy.ResultsThe results showed that the fiber posts cemented in canals sealed with BIOC had lower bond strength than those sealed with AHP. The ultrasonic cleaning of the post space improved the bond strength of fiber posts in canals sealed with AHP, but not with BIOC.ConclusionsBIOC decreased the bond strength of fiber posts in oval canals, regardless of ultrasonic cleaning.

ObjectivesThe objective of this study was to assess the impact of immediate and delayed post- space preparation on the push-out bond strength (PBS) of fiber posts by employing two root canal obturation techniques: continuous wave of condensation (CWC) and single-cone (SC) obturation.Materials and methodsForty-eight human maxillary premolar teeth were instrumented, and the samples were divided into four groups according to the obturation technique and the time of post-space preparation. SC and CWC underwent immediate post-space preparation; and CWC and SC underwent delayed post-space preparation. The smear layer and dentine tubules from the apical, middle, and cervical regions of the samples were observed via scanning electron microscopy (SEM) and the %VoidsVol of the medium 4-mm fiber posts of each group was calculated via micro-computed tomography (CT). Each post space of the root was subsequently cut into slices, resulting in three 1-mm slices at 3 different depths (apical to the cervical region) and subjected to a push-out test. The failure mode was assessed. The data were analysed via the Shapiro-Wilk test, one-way analysis of variance and Bonferroni correction tests.ResultsIn terms of depth from the apical to the cervical region, SC following immediate post-space preparation exhibited greater bond strength than did CWC following delayed post-space preparation. SEM images revealed that the smear layer was completely visible. In the SC with immediate post-space preparation group, the smear layer could be partially removed from the apical, middle and cervical regions of the samples and the outlines of the dentine tubules were visible. The percentage volume of the voids of the medium 4-mm fiber posts of the four groups and the samples in the three directions were not significantly different. No significant differences were observed in the CWC or SC obturation technique regardless of the time of post-space preparation or in immediate or delayed post-space preparation with different obturation techniques.ConclusionsSC followed by immediate post-space preparation provided better bond strength of fiber posts to intraradicular dentine than did CWC followed by delayed post-space preparation.

Introduction:The aim of this in vitro study was to evaluate the effect of MTA-based sealer (MTA Fillapex), eugenol-based sealer (Dorifill) and an epoxy resin sealer (AH Plus) on the bond strength of fiber posts cemented with a self-etch adhesive. Materials and Methods:The root canals of 72 maxillary incisors were prepared using the step-back technique after removing/cutting off the crowns. The samples were randomly divided to 4 groups (n=18). In group 1 (the controls) gutta-percha was used without sealer. In groups 2, 3 and 4, the canals were filled with gutta-percha using AH Plus, Dorifill and MTA Fillapex sealers, respectively, by cold lateral compaction technique. After post space preparation, the fiber posts were cemented in the root canals using self-etch adhesive. Then 1-mm-thick disks were prepared from the coronal thirds of all the root canals and subjected to a push-out test. Data were analyzed using the one-way ANOVA and post hoc Tukey’s tests. Results:The maximum (4.45±0.09 MPa) and minimum (1.02±0.03 MPa) bond strength values were recorded in the control and Dorifill groups, respectively. The mean push-out bond strength values were similar for MTA Fillapex and AH Plus sealers (P>0.05). However these values were significantly higher than that of the Dorifill sealer (P<0.05). Conclusion:Sealer type affected the bond strength of the fiber posts and MTA Fillapex decreased the dislodgment resistant of the fiber post.

To compare calcium silicate-based endodontic sealer and epoxy resin-based sealer remnants on root canal walls after post space preparation and their influence on the bond strength of fibre posts fixed with a dual-cured resin cement. Thirty-six extracted single-root mandibular premolars were instrumented and divided randomly into two equal groups with different endodontic sealers. iRoot SP (Innovative BioCeramix, Vancouver, Canada) was employed in the experimental group and AH Plus (Dentsply Sirona, Charlotte, NC, USA) was used in the control group. Sealer remnants were observed under an endodontic microscope after root canal therapy and post space preparation. Fibre posts were fixed with dual-cured resin cement. Specimens were taken at each third of the post space. The push-out bond strength was measured using a universal testing machine and fracture modes were assessed. Statistical analysis was performed using an independent samples t test and one-way analysis of variance. There was no statistically significant difference in bond strength of fibre posts between the control and experimental group (P > 0.05); however, sealer remnants were observed in 38.9% of the samples treated with iRoot SP and none of the samples treated with AH Plus. The major fracture mode in samples treated with iRoot SP was adhesive failure between the resin cement and the post, and no adhesive failure between the resin cement and dentine occurred at the site of the sealer remnant. The presence of iRoot SP remnants on the root canal walls after post space preparation did not interfere with bonding. iRoot SP is a viable option for root canal obturation before fibre post cementation.

Irrigation after post space preparation and its effects on the bond strength of different adhesive strategies are still an issue of interest. The aim of the present study was to investigate the effects of various irrigation protocols (IPs) on the push-out bond strengths of fiber posts. One-hundred and fifty extracted human anterior teeth were divided into three groups (n = 50 each) and endodontically treated. The post space was irrigated before post placement using the following five IPs in each group: IP1 (control): 5 ml of distilled water; IP2: 5.25% sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation (PUI); IP3: 1% NaOCl applied with PUI; IP4: 18% ethylenediaminetetracetic acid (EDTA) followed by 5.25% NaOCl; and IP5: 2% chlorhexidine (CHX). Fiber posts placement in each group was performed using three different adhesive strategies. A self-etch adhesive system revealed higher bond strength (16.2 ± 6.9 MPa) compared with an etch-and-rinse adhesive (8.5 ± 4.2 MPa) and a self-adhesive resin cement (9.2 ± 4.7 MPa). The use of 18% EDTA/5.25% NaOCl increased the bond strength of the self-adhesive resin cement. Conversely, this IP decreased the bond strength for the etch-and-rinse adhesive system, whilst 1% NaOCl enhanced the bond strength for the same system. Consequently, each adhesive strategy may need to be adapted to a specific IP.

(1) Background: The main aim of this study was to investigate the effects of different cements (Panavia V5, RelyX U200) and placement techniques (indirect ultrasonic vibration and manual method) on the bond strength of glass fiber posts in teeth with different post space preparation methods and to evaluate the failure types. (2) Methods: A total of 120 human upper central teeth were collected for the study. One week after root canal treatment, 10 mm long post space preparation was performed using post drills. Post spaces were irrigated in three different ways, namely NaOCl, NaOCl + EDTA solutions, and passive ultrasonic irrigation of NaOCl and EDTA solutions. Glass fiber posts were divided into two groups for resin cement systems, namely RelyX U200 (3M ESPE) or Panavia V5 (Kuraray Medical). Two different methods, namely the indirect ultrasonic vibration and the manual method, were applied for post placement. Then, 1.2 mm sections were taken from the middle and coronal regions of the inserted fiber posts for a push-out test. (3) Results: the Irrigation × Cement (p = 0.002), Cement × Section (p = 0.043) and Placement × Section (p = 0.049) pairwise interactions were statistically significant. (4) Conclusions: in our study, the effects of different post cavity preparations, different cement types, and different placement techniques on the bond strength of the fiber post were observed.

Different methods were used to treat the fiber posts and root canals, and evaluated their influence on the bond strength of fiber posts. After thirty extracted human, single-rooted premolars were endodontically treated and post space was prepared in each tooth with post drills, they were randomly assigned into nine groups with 33 fiber glass posts. Different treatment methods for fiber posts and root canals were applied. Following post cementation, slice specimens were prepared. The push-out test was performed using a universal testing machine, and the failure modes were examined with a stereomicroscope. Bond strengths (mean ± SD) were: CC group (7.07 ± 1.51 MPa); CE group (10.57 ± 2.90 MPa); CM group (10.06 ± 3.00 MPa); SiC group (7.23 ± 2.06 MPa); SiE group (10.51 ± 2.26 MPa); SiM group (10.50 ± 2.70 MPa); PC group (9.79 ± 2.79 MPa); PE group (11.70 ± 1.76 MPa); PM group (11.06 ± 3.17 MPa). The bond strength of polydopamine group was significantly higher than silane group and control group (p < 0.05). NaClO/EDTA group had higher bond strength than the MTAD group, and both were higher than the control group (p < 0.05). Combined treatment of fiber post and root canal was more advantageous to improve the bond strength between fiber post and root canal. Surface polydopamine functionalization was confirmed to be a reliable method for improving the bond strength of fiber posts. The effect of 5.25% NaClO + 17% EDTA solution on the bond strength is more significant than MTAD solution. When the fiber posts were treated with PDA and the root canals were treated with NaClO/EDTA, the best bond strength can be obtained. In this experiment, fiber posts and root canals were treated separately. The aim of this paper is to explore the influence of different treatment methods on the bond strength of fiber posts, in order to screen out the most effective processing methods and provide theoretical guidance for the clinical application.

Background: Changes in barometric pressure conditions that occur during flying and diving under hyperbaric oxygen conditions were found to influence the retention of dental restorations. Aim: This experimental laboratory study aimed to evaluate the bond strength of glass fiber posts after being cemented with self-adhesive resin cement (RelyX™ Unicem, 3M ESPE) and self-etch adhesive resin cement (RelyX™ Ultimate, 3M ESPE) under normal atmospheric pressure and hyperbaric pressure cycles that simulate diving conditions. Methods: A total of 40 extracted, single-rooted mandibular premolars were treated endodontically and randomly divided into two groups according to the cements used for fiber post cementation. Each group was further randomly divided into two equal subgroups that were subjected to normal atmospheric pressure conditions and a simulated hyperbaric condition in a hyperbaric chamber. The pull-out bond strength of fiber posts was tested using a universal testing machine. Data were analyzed using one-way analysis of variance with the Tukey post-hoc test (p&lt;0.05). Results: At normal atmospheric pressure the mean value of the pull-out bond strength of RelyX Ultimate cement was significantly higher than that of RelyX Unicem cement. At hyperbaric pressure condition no significant difference was found between the mean values of the pull-out bond strength of RelyX Ultimate and RelyX Unicem cement. Conclusion: Hyperbaric pressure cycles demonstrated improved pull-out bond strength of glass fiber posts in RelyX Unicem cement but did not have significant effect on pull-out bond strength in RelyX Ultimate cement. Both resin cements have similar pull-out bond strength of glass fibers post after simulated dives.

Objectives: Calcium hypochlorite (CH) has been recently used as a root canal irrigant. The aim of the present study was to compare the effect of CH and sodium hypochlorite (SH), as root canal irrigants, on the push-out bond strength of fiber posts cemented with an etch-and-rinse resin cement.Materials and Methods: In this experimental in-vitro study, 40 human anterior teeth with similar root lengths were randomly divided into five groups (N=8) according to the protocol of root canal irrigation as follows: group 1: saline (control); group 2: 2.5% SH; group 3: 5.25% SH; group 4: 2.5% CH; group 5: 5% CH. Before post placement, the post space was irrigated using the same irrigation protocol, and after that, they were irrigated by distilled water. Fiber posts were cemented with All-Bond 3 bonding and Dou-Link Universal cement. After thermocycling (1000 cycles, 5-55°C), a push-out test was performed, and data were analyzed using one-way analysis of variance and Tukey's post-hoc test with SPSS version 23 (α=0.05).Results: The highest and lowest mean bond strengths were detected in groups 2 and 5, respectively. There was no significant difference between group 1 and the SH groups (P>0.05), but the difference between group 1 and the CH groups was significant (P<0.001). There was a significant difference between SH groups and CH groups (P<0.001).Conclusion: Compared to SH, as a root canal irrigant, CH decreased the push-out bond strength of fiber posts cemented with an etch-and-rinse resin cement.

To evaluate the modified micro-push-out bond strengths of prefabricated glass fiber posts with silaneafter 35% phosphoric acid to resin cements. In the study, 40 glass fiber posts were randomly divided into 2 groups (20 posts in each group) for different surface treatments. Group 1, treated with silaneafter 35% phosphoric acid; group 2, no surface treatment (Control group). Then each group was randomly divided into 2 minor groups (modified group and traditional group), with each group with 10. So the four groups were group 1M (phosphoric acid + silane-modified), group 1T (phosphoric acid + silane-traditional), group 2M (control-modified), and group 2T (control-traditional). A modified micro-push-out bond strength test method was used in modified groups. In traditional groups, the 20 extracted human, single-rooted teeth were endodontically treated. Gutta-percha was removed with #1-2 Peeso Reamers (Mani), and the post space of each specimen was enlarged with a standard drill system from the corresponding fiber post system to create a 9 mm post space with at least 4 mm of filling material in the root apex. Following post cementation according to the manufacturer's instructions, the traditional micro-push-out bond strengths were tested using a universal testing machine(0.5 mm/min). Both failure modes were examined with a stereomicroscope. The data of the four groups were statistically analyzed using the one-way ANOVA test(α= 0.05). The bond strengths were (18.85±1.42) MPa for group 1M, (19.39±1.35) MPa for group 1T, (11.26±1.57) MPa for group 2M, and (11.27±1.83) MPa for group 2T. The bond strength of Group 1 was significantly higher than that of group 2(P<0.05), no matter which method was used. The fracture mode 100% in group M was the destruction of the post/resin interface, compared with 65.7% in group T. In contrasted to the traditional micro-push-out test, the modified test can evaluate the bond strength of fiber post to resin cement more effectively, and 35% phosphate acid + silane treatment can improve the bonding strength.

Objectives:The main disadvantage of fiber posts is their low bond strength to root canal wall. The aim of the present study was to assess the effect of different root canal post space treatments on push-out bond strength of fiber posts to root canal dentin.Materials and Methods:After post space preparation in 40 endodontically treated human premolars, the teeth were randomly divided into four experimental groups: Group 1: control group, group 2: Endsolv R, group 3: ultrasonic cleaning, group 4: Clearfil Repair. Afterwards, the posts were bonded with Panavia F 2.0 bonding cement. The bond strength of fiber posts to root canal wall in the middle part of canal was evaluated following thermocycling using push-out test. Data were analyzed using one-way ANOVA and Tamhane’s multiple comparisons test. The failure mode of each group was determined under a stereomicroscope.Results:There was a significant difference in the mean push-out bond strength among the groups (P<0.05). The lowest bond strength was noted in the control group. The control group had significant differences with ultrasonic and Clearfil Repair groups (P<0.05). The bond strength of Endsolv R group increased; however, it was not significant (P>0.05).Conclusions:It seems that ultrasonic cleaning and Clearfil Repair can modify the root canal wall and significantly increase the bond strength of fiber posts.

Er,Cr:YSGG lasers are currently being investigated for disinfecting the root canal treatment. The aim of this study was to compare the effects of various irrigation protocols on push-out bond strength of fiber posts. Fifty maxillary anterior teeth were divided into five groups (n = 10) according to the protocol that applied into the post space. Group-1: distilled water, Group-2: 5% NaOCl, Group-3: 2% CHX, Group-4: Er,Cr:YSGG laser (1.5 W, 20 Hz, 85 air, 75 water, 26.7 J/cm2), Group-5: Er,Cr:YSGG laser (1.25 W, 50 Hz, 34 air, 24 water, 12.7 J/cm2). Fiber posts were cemented with resin cement. The remaining part of the root, three slices were obtained from each specimen and push-out test was performed. One-way ANOVA and Duncan’s test at a 5% level of significance were used for the statistical analysis. Post space irradiation with Er,Cr:YSGG laser (1.5 W 20 Hz, 85 air, 75 water, 26.7 J/cm2) increases push-out bond strength of fiber post to root canal dentin. Further investigations are needed to establish and optimize ER,Cr:YSGG laser parameters to increase the push-out bond strength of fiber posts.

Fiber posts are widely used in endodontically treated teeth with extensive loss of coronal structure. The purpose of this study was to investigate immediate and the long-term effects of chlorhexidine (CHX) and benzalkonium chloride (BAC) application, on the push-out bond strength of fiber posts. Sixty mandibular premolars were decoronated, and root canal treatment was performed. After post space preparation, the specimens were divided into three groups according to the post space-surface pretreatment (n = 20); no surface treatment (control group-Group 1), 2% CHX application (Group 2), and 1% BAC application (Group 3). A self-curing adhesive cement and an etch and rinse adhesive were used for the cementation of posts. Three sections (one cervical, one middle, and one apical) of 1 mm thickness were prepared from each specimen. A push-out test was performed immediately on the half of the specimen sections (n = 10). The other half of the specimen sections were subjected to 20.000 thermal cycles before applying the push-out test (n = 10). The failure mode of each specimen was observed under a stereomicroscope at ×40 magnification. The data were analyzed by one-way analysis of variance (ANOVA), Tukey Honestly significant difference (HSD), and Tamhane tests (P = 0.05). The cervical thirds displayed the highest, and the apical thirds showed the lowest values in all groups (P < 0.05), except the control-aged group (P = 0.554). The aged control groups' values were found to be significantly lower than the aged CHX and BAC groups (P < 0.001). Aging significantly reduced the bond strength values of specimens in control groups (P < 0.001). However, aging did not significantly affect the push-out bond strength values of CHX and BAC groups (P > 0.050). The failure types were adhesive between the post and cement (type 1) in all groups, except control-aged group (type 2). The application of 2% chlorhexidine or 1% BAC may be an essential step that can be taken to preserve the bond strength of fiber posts.

The aim of this study was to evaluate the effect of chlorhexidine and ethanol application on the push-out bond strength and bond durability of fiber posts cemented with an etch-and-rinse adhesive system/resin cement to intraradicular dentin. Fifty-four bovine roots were shaped for the cementation of a fiberglass post and received the application of 37% phosphoric acid. They were then randomly divided into three groups, according to the type of dentin treatment (n = 18) performed: no treatment (control group), 100% ethanol, or 2% chlorhexidine. Next, the adhesive system (Adper Scotch Bond Multipurpose Plus, 3M ESPE) was applied to the dentin, according to the manufacturer's instructions. Glass fiber posts were cemented with dual resin cement (Rely X ARC, 3M ESPE). After 48 hours, the specimens were serially sectioned for push-out test analysis, providing two slices from each root third (cervical, medium and apical), one of which was tested immediately and the other stored in distilled water for 180 days. The data were analyzed with three-way analysis of variance (ANOVA) for repeated measures and Tukey's test at a 5% significance level. Intraradicular treatment with chlorhexidine yielded the highest bond strength means, followed by ethanol treatment. The control group presented the lowest bond strength means. Water storage exerted no effect on bond strength values. Both chlorhexidine and ethanol improved push-out bond strength to intraradicular dentin, with the former providing the best results, regardless of the storage time. The application of 2% chlorhexidine or 100% ethanol may be an important step that can be taken to enhance bond strength of fiber posts to intraradicular dentin, when dual resin cements are used.