Effect of a 12‐methacryloyloxy‐dodecyl‐pyridinium‐bromide–containing adhesive with different post types on the long‐term bond strength to dentin

The use of matrix metalloproteinase (MMPs) inhibitors, such as 12‐methacryloyloxy‐dodecyl‐pyridinium‐bromide (MDPB), might improve the adhesion of glass‐fiber (GF) and polyfiber (PF) posts to root dentine. This study assessed the effect of an MDPB‐containing adhesive on the long‐term bond strength of GF or PF posts to bovine dentine. Bovine endodontically treated roots were randomly divided into six groups, according to the post type and adhesive system used, as follows: GF serrated post + MDBP‐free adhesive; GF serrated post + MDPB‐containing adhesive; GF smooth post + MDBP‐free adhesive; GF smooth post + MDPB‐containing adhesive; PF post + MDBP‐free adhesive; PF post + MDPB‐containing adhesive. Specimens were stored in water for 6 months, thermocycled (500 cycles wk^?1), and submitted to the pull‐out test and failure pattern analysis. The cement–dentin interface was evaluated using scanning electron microscopy. The pull‐out data were analyzed using anova and Tukey's test (α = 0.05). No significant interaction between the type of post and the adhesive system was found. Polyfiber posts showed lower bond strength than GF posts, whether serrated or smooth, and the bond strength of the serrated and smooth GF posts was not significantly different. Adhesive failures were predominant in all groups. The type of retainer influenced the bond strength, and MDPB‐containing adhesive did not improve the long‐term bond strength of posts to dentine.     

The interference of the cleaning procedure of root walls with two different solvents on the adhesion of fiberglass intraradicular posts

Aim: This study was undertaken to examine the effect of root canal (RT) sealers content and the cleaning procedure of RT walls on bond strength (BS) of a fiber reinforced composite (FRC) post cemented with resin-based or zinc phosphate cement. Materials and methods: Forty bovine roots were divided into 2 groups (n = 20) and obturated with gutta-percha points plus Sealer 26 sealer or gutta-percha points plus N-Rickert sealer. In each group, half (n = 10) of intracanal walls was cleaned with ethanol and the other half with sulfuric ether. In each of these subgroups, half of intracanal posts (n = 5) were cemented with Bistite resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test and tensile force until post dislodgement. The maximum forces required for post removal was expressed in MPa, means were submitted to statistical analysis (Analysis of Variance Test, a = 0.05). Results: Fiber reinforced composite cemented with zinc phosphate were significantly more retentive than those cemented with Bistite (p < 0.05). Regarding the influence of eugenol-based sealer on post retention, there was a statistically significant difference (p < 0.05) only between groups cemented with Bistite, in which canals filled with N-Rickert + gutta-percha showed lower BS than canals filled with Sealer 26 + gutta-percha. Conclusion: Despite endodontic cement used, higher pull-out bond strength were obtained when posts were cemented with zinc phosphate. Clinical significance: The importance of ethanol or sulphuric ether application to properly replace water from intraradicular dentine still requires further investigations, especially to clarify if this technique may reduce the effect of aging and improve the stability of the bond, when used to cement fiber posts into the root canal. Keywords: Laboratory research, Dentin, Eugenol, Resin cements, Root canal filling material, Pull-out test, Cleaning procedure. How to cite this article: Gomes MF, Botta SB, Matos AB, Garone- Netto N. The Interference of the Cleaning Procedure of Root Walls with Two Different Solvents on the Adhesion of Fiberglass Intraradicular Posts. J Contemp Dent Pract 2012;13(3):275-279. Source of support: Nil Conflict of interest: None declared.     

Bond strength of Resilon/Epiphany compared with Gutta‐percha and sealers Sealer 26 and Endo Fill

This study evaluated the bond strength of Epiphany^®/Resilon^® to radicular dentine and compared this with that of Gutta‐percha sealed with Sealer 26 and also Endo Fill^®. Fifteen human single‐rooted extracted teeth had their root canals enlarged to a standardised internal root diameter of 1.5 mm. The teeth were filled with: Group I – Epiphany^®/Resilon^® cones, Group II – Sealer 26^®/Gutta‐percha cones and Group III – Endo Fill^®/Gutta‐percha cones. Three 2 mm‐thick cross‐sections were obtained from each tooth (n = 15) and subjected to a push‐out test (1 mm min^?1). The means (MPa) were compared using anova /Newman–Keuls tests. There were no statistically significant differences between Group I and Group II (P > 0.01). Both bond strengths were significantly higher than that of Group III (P < 0.01). The root canal filling system Epiphany^®/Resilon^® showed bond strength similar to that of Sealer 26^®/Gutta‐percha. Both were higher than that of Endo Fill^®/Gutta‐percha.     

Thin and thick layers of resin‐based sealer cement bonded to root dentine compared: Adhesive behaviour

This study aims to evaluate tensile and shear bond strengths of one epoxy (AH) and two methacrylate resin‐based sealers (EZ and RS) in thin and thick layers bonded to root dentine. An alignment device was prepared for accurate positioning of 20 root dentine cylinders in a predefined gap of 0.1 or 1 mm. Sealer was placed in the interface. Bond strength tests were conducted. Mode of failures and representative surfaces were evaluated. Data were analysed using anova and post‐hoc tests, with P < 0.05. The thick layer of sealer produced higher bond strength, except for the shear bond strength of EZ. Significant differences between thin and thick layers were found only in tensile bond strengths of AH and RS. Mixed type of failure was constantly found with all sealers. Bond strengths of thick layers of resin‐based sealers to root dentine tended to be higher than with thin layers.     

Effect of three radicular dentine treatments and two luting cements on the regional bond strength of quartz fibre posts

The purpose was to investigate by push-out tests and scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) the effect, after first acid etching the post space walls, of three radicular dentine treatments on the regional bond strength of quartz fibre posts placed using two heavily filled resin luting cements. The crowns of 39 extracted maxillary central incisors were sectioned transversely 2 mm coronal to the labial cement-enamel junction and the roots endodontically treated. After standardized post space preparations and etching 15 s with 32% phosphoric acid, 36 roots were randomly divided into six equal groups. Quartz fibre posts (D.T. LIGHT-POST) were placed using three radicular dentine treatments (0.9% sodium chloride (NaCl) for 60 s, 10% sodium hypochlorite (NaOCl) for 60 s, 17% ethylenediaminetetraacetic acid (EDTA) for 60 s followed by 5.25% NaOCl for 60 s) and two resin composite luting cements (ONE-STEP PLUS/DUO-LINK; ONE-STEP PLUS/LuxaCore Dual). Transverse segments (S1–S7), 1.00 mm (SD = 0.05 mm) thick, were sectioned from the coronal 8 mm of each root. Push-out bond strength tests were performed on coronal, middle and apical post space segments (S2, S4, S6) at a crosshead speed of 0.5 mm/min. Data were recorded and analyzed using a two-way mixed ANOVA design (a = 0.05). Three segments (S1, S5, S7) from roots in each group were examined using SEM/EDS. After post space preparation, acid etching and using each of the three radicular dentine treatments, the three remaining roots were sectioned longitudinally for SEM observation of the post space walls. At all root segment sites, the mean bond strengths from using 0.9% NaCl were significantly lower than for the other two radicular dentine treatments (P ≤ 0.02), and DUO-LINK cement had significantly higher mean bond strengths than LuxaCore Dual cement (P ≤ 0.01). There was a significant linear trend for reduced bond strengths from coronal to apical post space segments (P < 0.001), which was supported by the SEM/EDS observations of dentine tubule appearance and resin tag formation. Acid etching followed by either 10% NaOCl or 17% EDTA and 5.25% NaOCl dentine treatments of the post spaces provided good adhesion and resin luting cement tag infiltration of dentinal tubules in the coronal and middle segments in particular.     

The effect of calcium silicate-based sealer on the push-out bond strength of fibre posts

Background: The aim of this study was to assess the effect of the iRoot SP root canal sealer on the push‐out bond strength of fibre posts cemented with self‐adhesive resin cement. Methods:  Forty‐eight extracted maxillary incisors were randomly divided into four groups according to the tested sealer (n = 12): group 1 – control (only gutta‐percha points, no sealer); group 2 – AH Plus Jet (resin‐based sealer); group 3 – Endofill (zinc oxide‐eugenol‐based sealer); and group 4 – iRoot SP (calcium silicate‐based sealer). All root canals were filled with gutta‐percha, and groups 2–4 additionally received one of the sealers. Fibre posts were cemented with the self‐adhesive resin cement Clearfil SA Cement. The specimens were sectioned in the coronal, middle and apical regions, producing three slices of 1 mm thickness. The push‐out test was performed. All data were submitted to ANOVA and Tukey tests (α = 0.05). Results:  No statistically significant differences were found between the control group, AH Plus Jet and iRoot SP (p > 0.05). The Endofill sealer showed significantly lower bond strength compared to the other sealers and the control group (p < 0.05). Conclusions:  The calcium silicate‐based sealer did not adversely affect the bond strength of the fibre posts cemented with self‐adhesive resin cement.     

Bond strengths of three types of fibre-reinforced post systems in various regions of root canals

Aim To evaluate the bond strengths of three adhesive/resin cement/fibre post systems to coronal, middle and apical thirds of post space dentine. Methodology Three types of glass‐fibre post systems were selected for the study. Saremco Post Non‐stop Fibre (Saremco), FRC Postec Plus (Ivoclar Vivadent) and Anatomical Post (Dentalica) were luted in prepared root canals using adhesive system and resin cement provided by the respective manufacturer. The luting agent was placed into the root canal using a specific syringe with needle. A push‐out test was performed on sections from the apical, middle and coronal parts of each specimen to measure bond strength. All fractured specimens were observed using a stereomicroscope to identify the modes of failure. Results Bond strength values were significantly affected both by the post–adhesive–cement system used and by root region (P < 0.05). Additionally, there was no significant interaction between the post system and region of canal factors (P > 0.05). The highest bond strength values were found in the coronal third for all experimental groups. The middle and apical thirds exhibited similar bond strengths with no statistically significant differences amongst them. Saremco and Precision post systems had the highest retentive strengths, whilst the Ivoclar post system had the lowest values. Microscopic analysis of the specimens revealed a prevalence of post–cement and mixed failures. Conclusions Type of post–adhesive–cement system and root position had a significant effect on fibre post retention. The coronal region of the canals was characterized by significantly higher bond strengths.     

Bond strength and fracture analysis between resin cements and root canal dentin

The aim of this research is to evaluate bond strength between translucent fibre posts (White Post DC, FGM or FRC Postec Plus, Ivoclar/Vivadent) and intraradicular dentin at three different levels (cervical, middle and apical) using a dual‐cure (AllCem, FGM) or self‐curing (Multilink, Ivoclar/Vivadent) resin cement. Also, the fracture type after push‐out test was analysed under SEM. Thirty‐two extracted single‐root teeth were selected. After undergoing endodontic therapy, they were randomly divided into four groups according to their post type and resin cement. Root canals were etched using 37% phosphoric acid, and Excite DSC adhesive (Ivoclar/Vivadent) was applied in all groups. The root was sectioned to obtain nine 1‐mm‐thick slices (three per third: coronal, middle, apical). All slices were subjected to push‐out tests. Data were analysed using two‐way anova . The mean bond strengths vary from 6.6 (4.6) MPa [apical] to 11.9 (5.9) MPa [cervical]. There were no significant differences between groups. Pearson χ²‐test revealed significant differences in fracture types for all groups (P < 0.0001). The apical third had the lowest bond strengths and it was also shown to be the most critical region for luting fibre posts.     

Effect of post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts

The aim of this study was to evaluate the effect of different post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push‐out test. Data were statistically analysed with anova (P = 0.05). After push‐out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.     

Push‐out bond strength of an experimental self‐adhesive resin cement

The adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest over the past years. The aim of this study was to assess the post retentive potential of experimental self‐adhesive resin cement (EXP) when used alone and in combination with a self‐etch adhesive. Fiber posts were placed in endodontically treated teeth and divided into four groups (n = 6) according the luting material, as follows: group 1 (EXP alone); group 2 (EXP used with self‐etch adhesive); group 3 (marketed dual‐cured cement used with self‐etch adhesive); and group 4 (marketed self‐adhesive cement). The push‐out test was used to assess the retentive strength of fiber posts (expressed in MPa), and specimens were analyzed under a stereomicroscope to determine failure mode. The adhesive interface between the cement and root canal dentin for each group was evaluated using scanning electron microscopy. The post retentive potential of group 1 (EXP) (7.48 ± 4.35 MPa) was comparable with that of marketed cements from group 4 (6.79 ± 3.68 MPa) and group 3 (8.77 ± 4.58 MPa). When EXP was used in combination with self‐etch adhesive (group 2), significantly higher push‐out bond‐strength values were measured (15.87 ± 4.68 MPa) compared with the other groups.     

Effect of EDTA conditioning upon the retention of fibre posts luted with resin cements

Aim To determine if a final rinse with EDTA improves the short‐term in‐tooth retentive strength of adhesively luted fibre‐reinforced composite posts. Methodology Six different commercial fibre post systems were tested. Post spaces in extracted human anterior teeth were irrigated with either 6% NaOCl or 6% NaOCl followed by 17% EDTA. Posts were luted using the manufacturer’s recommended bonding agent and luting cement. Two different sizes of post were tested for each post system. After 24 h of storage, the retentive strength of the post to the tooth (14 per group, 336 total) was tested using a pull‐out technique. Three‐way anova and the Student–Newman–Kuels test were used to test the effects of irrigation regimen, post size and post brand on the retentive strength of the fibre post. Results Almost every sample failed at the interface between dentine and luting cement. Irrigation method did not have any significant effect (P > 0.14) for any group other than ParaPost Fibre White (P < 0.001). The overall retention of a post appeared to be correlated to the amount of surface texture on the post; the smooth ICEPost was the least retentive brand, the textured FibreKor and the ParaPost Fibre White posts were moderately retained, and the threaded Flexi‐Post Fibre and the Flexi‐Flange Fibre posts were the most retentive brands tested. For all brands, larger diameter posts were more retentive than smaller diameter posts (P < 0.008). Conclusions A final rinse of EDTA did not improve the short‐term retention of fibre posts except for ParaPost Fibre White.     

The effect of the application of gaseous ozone and ND:YAG laser on glass‐fibre post bond strength

The aim of this study was to investigate the effects of the application of gaseous ozone and Nd:YAG laser on glass‐fibre post bond strength. Forty‐two madibular premolar roots were cut, endodontically instrumented and irrigated with 2.5% NaOCl. Post spaces were prepared and roots were divided into three groups (n = 14). The antimicrobial pretreatment was conducted as follows: gaseous ozone, Nd:YAG laser and control (no additional disinfection methods). Scanning electron microscope analysis was made for each group (n = 2). A resin cement was used for luting the posts. For push‐out test, each root was cut horizontally (two cervical, two middle and two apical). Statistical analyses were performed with one‐way anova (α = 0.05). Fracture types were observed. There was no statistically significant difference between the groups (P > 0.05). There were statistically significant differences in cervical and apical segments of laser and control groups (P < 0.05). The disinfection of the post spaces with Nd:YAG laser and ozone had no adverse effects on bond strength of glass‐fibre post.     

The effect of luting cement thicknesses on the push-out bond strength of the fiber posts

Abstract

Objective. The aim of this study was to evaluate the effect of luting cement thicknesses on the push-out bond strength of the fiber posts. Materials and methods. Sixty human maxillary canine teeth were endodontically treated. Post spaces were prepared and root specimens randomly divided into three groups: Group 1: etch-and-rinse (Variolink II/Exite DSC), Group 2: self-etch (Panavia F2.0/ED primer) and Group 3: self-adhesive (Clearfil SA Cement). Then each group was divided into four sub-groups according to the cement thickness, as follows: Sub-group 1: 0.35 mm, Sub-group 2: 0.25 mm, Sub-group 3: 0.15 mm, and Sub-group 4: 0.05 mm. Three slices of 1 mm thickness were obtained from each root specimen (n = 15). Push-out tests were performed and data was analyzed with two-way ANOVA and Tukey tests. Results. The etch-and-rinse system (Variolink II) had a significantly higher bond strength compared with the other systems (?p < 0.05). The thickest cement group (0.35 mm) had a significantly lower bond strength compared with the 0.15 and 0.05 mm groups in the etch-and-rinse and self-adhesive groups (p < 0.05). In the self-etch group, the cement thicknesses did not significantly affect the bond strength (p > 0.05). Conclusions. The etch-and-rinse system offered better bonding to root dentine than the self-adhesive and self-etch systems. The increases in cement thickness significantly reduced the bond strength of fiber posts to root dentine for both the etch-and-rinse and self-adhesive systems.     

偶联剂和不同粘接剂对纤维桩粘接强度的影响

目的:利用薄片推出实验比较硅烷偶联剂和三种树脂粘接剂对纤维桩剪切粘接强度的影响.方法:60颗因牙周病等原因拔除的上颌单根前牙,根管治疗后行纤维桩修复的桩道预备.随机分为5组,每组12颗牙.分别采用下列粘接剂粘接Matchpost纤维桩:A组:Paracore粘接剂+偶联剂;B组:Paracore粘接剂;C组:Panavia F粘接剂+偶联剂;D组:Panavia F粘接剂;E组:Multilink N粘接剂+偶联剂.纤维桩粘接后,在牙根中部横向切割1.0mm层厚切片2个,在Zwick Z100材料试验机上行薄片推出试验(Push-Out Bond Test),记录失败载荷,计算剪切粘接强度,体视显微镜观察粘接失败类型.结果采用SPSS 11.5进行方差分析和χ2检验.结果:五组样本的剪切粘接强度(MPa)分别为A组:14.69±2.76;B组:9.46±3.11;C组:13.12±3.10;D组:10.40±3.30;E组:13.86±3.81,方差分析提示五组间差异有统计学意义(P <0.01).采用偶联剂处理时,Paracore粘接剂和Panavia F粘接剂与纤维桩间的剪切粘接强度均高于未用偶联剂处理者(P <0.05).采用偶联剂处理时,三种树脂粘接剂与纤维桩的剪切粘接强度间差异无统计学意义(P >0.05).五组粘接失败类型间差异有统计学意义(P <0.05),未采用硅烷偶联剂处理纤维桩表面者,出现纤维桩-粘接剂界面失败者增多.结论:在树脂粘接前,玻璃纤维桩表面氢氟酸酸蚀后,采用硅烷偶联剂处理可显著提高纤维桩与树脂粘接剂间的剪切粘接强度.     

Effect of remaining dentine structure and thermal‐mechanical aging on the fracture resistance of bovine roots with different post and core systems

Aim To evaluate the influence of remaining dentine thickness around post and core systems and the thermo‐mechanical stresses on fracture resistance of bovine roots. Methodology This study involved 288 bovine incisor roots with standardized dimensions. Roots were randomly distributed into 24 groups (n = 12) according to root conditions [intact, semi‐weakened, or weakened] and post and core systems [custom cast core, composite resin core, prefabricated metallic post, or prefabricated carbon fibre post], submitted or not to thermomechanical aging [5000 thermal cycles and 100 000 mechanical cycles at a 135‐degree angle to the long axis of the root]. Specimens were submitted to a tangential compressive load (135° angle) at a crosshead speed of 0.5 mm min^?1 until failure. Fracture resistance data were analyzed using 3‐way anova and Tukey test: α = 5%. Results Roots restored with composite resin cores demonstrated no resistance to mechanical aging. No statistically significant difference was observed between aged and nonaged specimens involving all post‐systems. Roots restored with custom cast cores had the highest fracture strength, followed by prefabricated metallic posts and carbon fibre posts, regardless of root conditions and thermomechanical aging. The remaining dentine thickness affected significantly roots restored with custom cast cores; weakened roots had a lower fracture resistance. Conclusions Although custom cast cores had a higher fracture resistance when compared to the other techniques, the results were highly dependent on remaining dentine thickness. Prefabricated posts performed in a similar manner in intact, semi‐weakened and weakened roots reinforced with composite resin.     

Various irrigation protocols for final rinse to improve bond strengths of fiber posts inside the root canal

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.     

Influence of dentin pretreatment with synthetic hydroxyapatite application on the bond strength of fiber posts luted with 10‐methacryloyloxydecyl dihydrogen phosphate‐containing luting systems

The aim of this in vitro study was evaluate the effect of application of synthetic hydroxyapatite on fiber post bond strength to radicular dentine. Forty, single‐root teeth were endodontically treated and an 8 mm post space was prepared. Specimens were randomly placed in four groups (n = 10 in each) and treated using the following fiber post luting procedures: group 1, 17% EDTA + Panavia SA; group 2, 17% EDTA + Teethmate Desensitizer + Panavia SA; group 3, All‐Bond Universal + Duo‐Link Universal; and group 4, All‐Bond Universal + Teethmate Desensitizer + Duo‐Link Universal. Fiber posts were luted in the post space and light‐cured for 120 s using a light‐emitting diode (LED) lamp. After 7 d of storage at 37°C, the teeth were cut into 1‐mm‐thick slices, which were subjected to a push‐out test until failure using a universal testing machine. Two specimens per group were prepared for scanning electron microscopy analysis. An energy‐dispersive X‐ray spectroscopy detector was used for elemental analysis of the specimen surface. The results were statistically analyzed using one‐way anova . The fiber post bond strength was statistically significantly increased after the application of Teethmate Desensitizer to post space walls, either with a 10‐MDP‐containing self‐adhesive cement or with a universal adhesive. Scanning electron microscopy and EDAX analysis showed that Teethmate Desensitizer created a calcium phosphate precipitate over post space dentinal tubules, which significantly improved the bond strength of the fiber post luted with 10‐methacryloyloxydecyl dihydrogen phosphate (10‐MDP)‐containing adhesive systems.     

Push‐out bond strength of gutta‐percha with a new bioceramic sealer in the presence or absence of smear layer

The purpose of this study was to compare the bond strength of a new bioceramic sealer (EndoSequence BC Sealer) and AH Plus in the presence or absence of smear layer. Extracted single‐rooted human teeth were prepared and randomly divided into four groups. In groups 1 and 3, the root canals were finally irrigated with 5.25% NaOCl and smear layer was not removed, but in groups 2 and 4, the root canals were finally irrigated with 17% EDTA followed by 5.25% NaOCl in order to remove the smear layer. In groups 1 and 2, the root canals were obturated with gutta‐percha/AH Plus, but in groups 3 and 4, obturation was performed with gutta‐percha/EndoSequence BC Sealer. Push‐out bond strength and failure modes were evaluated. The bond strength of gutta‐percha/AH Plus and gutta‐percha/EndoSequence BC Sealer was not significantly different (P = 0.89). The presence or absence of smear layer did not significantly affect the bond strength of filling materials (P = 0.69). The mode of bond failure was mainly cohesive for all groups. In conclusion, the bond strength of the new bioceramic sealer was equal to that of AH Plus with or without the smear layer.     

Effect of the timing of radiation therapy on the push-out strength of resin cement to root dentine

This study investigated the effect of radiation timing on the bond strength of resin cement to intraradicular dentine. Fifty human teeth were distributed into 5 groups (n = 10): Control (nonirradiated teeth), Before-RCT (teeth irradiated before root canal treatment), After-CH (teeth irradiated after canal preparation and placement of calcium hydroxide intracanal dressing), After-RCT (teeth irradiated after completion of root canal treatment) and After-FPL (teeth irradiated after luting of a glass fibre post). Each tooth received 70 Gy irradiation. The roots were sectioned for push-out strength testing. After-RCT and After-FPL groups had significantly lower push-out strength than the control at the middle third (p < 0.05). Control and After-CH groups had a higher percentage of cohesive dentine failure. Radiotherapy after root canal obturation and post luting adversely affected the adhesiveness of resin cement to intraradicular dentine. Teeth irradiated before root canal treatment and after placement of calcium hydroxide had the best performance.     

Effect of maleic acid on the bond strength of fibre posts to root dentine

The aim of this study was to evaluate the effect of maleic acid (MA) on both the bond strength of fibre post to root dentine and smear layer removal after post space preparation. Sixty, single‐canal premolars were endodontically treated and randomly assigned to four groups: group 1 [0.9% saline solution (control]); group 2 [2.5% sodium hypochlorite (NaOCl)]; group 3 [17% ethylenediaminetetraacetic acid (EDTA) followed by 2.5% NaOCl]; and group 4 (7% MA followed by 2.5% NaOCl). Self‐adhesive resin cement was used to test the adhesion of a glass‐fibre post to the root dentine through a micropush‐out test. Scanning electron microscopy was performed to examine and score the treated specimens for smear layer removal, and stereomicroscopy was applied to investigate the failure modes of fibre posts. Maleic acid exhibited the highest mean bond‐strength values in the apical regions among all the groups. Most failure modes (31.9%) were adhesive‐type failures between the dentine and luting materials. Maleic acid performed statistically significantly better than the other groups regarding smear layer removal, especially in the apical region. Maleic acid is an effective irrigant that can remove the smear layer, open dentinal tubules, and act as a high‐efficiency final irrigant in activation protocols.