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Bond Strength of Composite Core Build-up Materials to Fiber-reinforced Posts: A Microtensile Comparison Between Conventional and Wet-ethanol Bonding Systems
Abstract
To evaluate the interfacial microtensile bond strength between a fiber-reinforced post (Rely X Post) and a core material (Multicore Flow) after placing different bonding agents.
After post surface treatment, 50 posts were divided into 5 groups. Group 1: Adper Prompt-L-Pop; group 2: SingleBond2; group 3: ScotchBond Multipurpose Plus; group 4: experimental bonding system (wet ethanol bonding technique); group 5: control group. After core reconstruction, the samples were tested with the microtensile test. Fracture type examination and SEM observation followed. Data were statistically analyzed with Kruskall-Wallis non-parametric ANOVA.
Microtensile testing revealed significant differences (p < 0.001). There were no differences between groups 1 to 4, but there was a statistically significant difference between groups 1 to 4 and the control. Fracture type observations revealed more adhesive failures than cohesive or mixed ones.
The experimental bonding technique did not improve bond strength compared to the different adhesive systems tested. However, placing a bonding agent between the post and the core seems to significantly increase microtensile bond strength.
... Although, the dentin/cement interface is a key factor for long-term clinical success of a luted post to root dentin, the glass fiber post/core interface also requires attention, as several studies pinpointed this interface as the weak link in the adhesion process. [11][12][13] Resin composites when used as a core material offer various advantages such as being most aesthetically acceptable restorations, they do not darken the teeth like conventional metal posts and have acceptable strength. These composites are also selected for colour contrast against tooth structure to facilitate tooth preparation for crowns. ...
... Studies have reported that, placing a bonding agent between the glass fiber post and dual cure resin core showed increase in bond strength both micromechanical and chemical bonding by enhancing post surface wetting. [11,14,23,24] Different theories have been proposed in order to elucidate the bonding mechanism through silane coupling agents. The chemical bonding theory states that the coupling action of the silane involves the formation of covalent bond from the reaction of organo-functional group (R) and the hydrolyzed alkoxy groups (R'O) 3 , respectively with the resin matrix and mineral substrate (glass or silica) of the composite material. ...
Aim: Toevaluate the retention of glass fiber dental post embedded in three different types of dual cure core materials namely, Luxacore Z, Compcore AF and Corecem. Materials and method:Ninety prefabricated fiber reinforced posts (D.T. light Posts) were taken and divided into three groups. The post surface was treated with silane coupling agent (Monobond-S, Ivoclar-VivadentSchaan, Liechtenstein) as per the manufacturer's instructions. Bonding agent (Prime and Bond-Dentsply, U.S.A.) was applied on post surface with brush and cured according to manufacturer's instructions.Each of the three core build-up materials were manipulated according to the respective manufacturer's instructions and a core of 4 mm core height was prepared by using prefabricated matrix. Thirty specimens for each core build up materials were made. The specimens were divided into the following groups each containing 30 samples (Group I-Luxacore Z, Group II-European Journal of Molecular & Clinical Medicine ISSN 2515-8260 Volume 08, Issue 03, 2021 2945 Compcore AF, Group III-Corecem). The data wasanalyzed using SPSS (version 20). One Way ANOVA and Tukey's post hoc multiple comparison testwere applied for statistical analysis. Result: In the present study, Luxacore Z showed greater retention value with glass fiber post (15.64 MPa) in comparison to Compcore AF (14.99 MPa) and Corecem (14.33 MPa) core resins. Conclusion: The retentive strength of dual cure resin Luxacore Z to the glass fiber post is significantly higher than dual cure resin Compcore AF and Corecem. Keyword: bond strength, composite, glass fibre post, post and core,
... Although, the dentin/cement interface is a key factor for long-term clinical success of a luted post to root dentin, the glass fiber post/core interface also requires attention, as several studies pinpointed this interface as the weak link in the adhesion process. [11][12][13] Resin composites when used as a core material offer various advantages such as being most aesthetically acceptable restorations, they do not darken the teeth like conventional metal posts and have acceptable strength. These composites are also selected for colour contrast against tooth structure to facilitate tooth preparation for crowns. ...
... Studies have reported that, placing a bonding agent between the glass fiber post and dual cure resin core showed increase in bond strength both micromechanical and chemical bonding by enhancing post surface wetting. [11,14,23,24] Different theories have been proposed in order to elucidate the bonding mechanism through silane coupling agents. The chemical bonding theory states that the coupling action of the silane involves the formation of covalent bond from the reaction of organo-functional group (R) and the hydrolyzed alkoxy groups (R'O) 3 , respectively with the resin matrix and mineral substrate (glass or silica) of the composite material. ...
... The inefficiency of this surface treatment is justified by the fiber post composition (epoxy resin matrix, inorganic particles and fiberglass particles), which prevents an intimate interaction between the constituents from primer/adhesive systems and fiber posts (BALBOSH; KERN, 2006). On the other hand, the surface treatment of fiber posts with adhesive systems was shown more efficient than when these components are not used (OUNSI et al., 2009). Although expressive positive results are not observed with this approach, the use of adhesive systems as chemical optimization for fiber post surface treatment is recommended because it allows a better adaptation to the post surface than conventional composite resins. ...
... C. et al. the principle of cleaning the surface, but it was used previously as a chemical optimization approach (NAUMANN et al., 2007;SIGNORE et al., 2009;SIGNORE et al., 2011). The application of sodium ascorbate is recommended after surface treatment with hydrogen peroxide (OUNSI et al., 2009), because it reduces the negative effect that excessive hydrogen peroxide etching may have on adhesion (LAI et al., 2001). ...
The surface treatment of fiber posts influence the bonding between composite resin cements and intraradicular retainers, being relevant to the prognostic of teeth without coronal structure. This study aimed to evaluate the different fiber post surface treatment protocols described on literature. The search strategy included a review of PubMed/MEDLINE database using fiber post associated with adhesion; bonding; surface treatment; as keywords. Papers not comprehending English language; assessment of post surface treatment; or testing of materials and their physicmechanical properties were excluded. Studies about glass and quartz fiber post surface treatment were considered for this literature review. Among the 190 articles included, silane agent was the material most used (60.52%) for the surface treatment of fiber posts, followed by application of alcoholic solutions (38.29%), and primer and/or adhesive systems (36.84%). Sandblasting of post surface was mentioned in (17.89%), but it affected the physical and mechanical properties. Hydrogen peroxide was mentioned only in 5.78% and it was shown to result on adequate exposure of the glass fibers without damaging them. It was concluded that a consensus for fiber post surface treatment still not exist in the current literature. Among the protocols described, the one using hydrogen peroxide followed by application of silane seems the most promising, since it allows increased bond strengths without fiber damage.
... Here, we have used a flowable resin core build-up material. The low viscous materials can easily fill porosities and irregularities formed by various pretreatment methods [20][21][22]. It has been reported that fibers and matrix properties and the bonding between these components could affect mechanical properties. ...
Statement of problem: The bonding of fiber post to resin core or root dentin is challenged by limited penetration of resin material to the polymeric matrix of fiber posts.
Objectives: The purpose of this study was to investigate the effect of Er,Cr:YSGG on micro push-out bond strength of glass fiber posts to resin core material.
Materials and Methods: We used 2 commercially available fiber posts, Exacto (Angelus) and White Post DC (FGM), which had similar coronal diameters. Specimens of each fiber post (n=36) were randomly divided into three subgroups (n=12 posts per group) according to different surface treatment methods: control (no surface treatment), irradiation by 1W Er,Cr:YSGG, and irradiation by 1.5W Er,Cr:YSGG. A cylindrical plastic tube was placed around the post. Resin core material was filled into the tube and cured. Coronal portions of the posts were sectioned into 1-mm-thick slices. Then, the specimens were subjected to a thermocyling device for 3000 cycles. The micro push-out test was carried out using a Universal Testing Machine. Data were analyzed using one-way ANOVA followed by Tukey’s HSD post hoc test to investigate the effect of different surface treatments on each type of fiber post.
Results: The 1.5W Er,Cr:YSGG laser statistically reduced micro push-out bond strength values in the Exacto groups (P0.05). Mode of failure analysis showed that mixed failure was the predominant failure type for all surface treatment groups.
Conclusions: The beneficial effect of Er,Cr:YSGG laser application could not be confirmed based on the results of this in vitro study. Er,Cr:YSGG laser could not significantly enhance the bond strength values. However, the 1.5W laser statistically decreased micro push-out bond strength in the Exacto fiber posts.
... However, the results indicated there was no significant difference between the groups studied, in spite of their different solvent component. Studies reported that application of different bonding agents had no effect on bond strength of composite core to post which was in agreement with this study results [24,35] but could influence the microtensile bond strength FRC post to den-tin [36]. ...
Statement of Problem: A strong bond of fiber post to resin core, as well as to dentin would critically ensure the durability of restorations in endodontically treated teeth.
Purpose: The purpose of this study was to evaluate the effect of etch-and-rinse dentin bonding systems on the bond strength between resin core and fiber post after application of 24% hydrogen peroxide.
Materials and Method: 24 fiber posts (RTD; St. Egèven, France) were treated with 24% hydrogen peroxide for 10 minutes. They were randomly divided into 4 groups (n=6) based on the bonding agent used: Group P: Prime&Bond, Group O: One Step, Group S: Single Bond and Group E: Excite. Each group was prepared according to the manufacturer’s instructions. For all posts, a flowable composite core (ÆliteFlo; Bisco, USA) was built-up over the bonded area. Each specimen was sectioned to produce 2 sticks, 1mm in thickness and underwent microtensile bond strength (µTBS). Data were analyzed using one-way ANOVA at the 0.05 level. The fractured surfaces of all sticks were evaluated by stereomicroscope (× 20). Scanning electron microscopy(SEM) assessment of two sticks from each group was performed to evaluate the surface morphology.
Results: The means and SDs of µTBS were: Group P: 10.95±1.74; Group S: 10.25±2.39; Group E: 9.52±2.07; and Group O: 9.12±1.34. There was no statistically significant difference in bond strength means between the groups tested (p> 0.05).
Conclusion: The results of this study indicated the bonding agents used had no significant influence on the bond strength of fiber post to composite core.
... This finding is similar to the other studies. [4,10,12,36] Carvalho et al., reported that the application of ethanol-wet bonding in threesteps bonding system (All bond 2) increased the bond strength of fiber post and root dentine. [13] Controversy, Sauro et al., [20] and Castangalo et al. [14] confirmed that ethanol-wet bonding significantly improved the bond strength of fiber post to root dentine. ...
Before the resin bond endodontic post-cementation, various solutions are used to improve bond strength of these posts to root dentine. The purpose of this study was to evaluate the effect of the different pre-treatments (ethanol, ethylene de amine tetra acetic acid [EDTA] and EDTA + ethanol) on the bond strength of adhesively lutted tooth colored fiber post.
Forty-eight human anterior teeth (incisor and canine) were selected in this experimental study. The species were endodontically treated, and the post-space was prepared. The species were randomly divided into four groups of 12 teeth in each and were treated as follows: (i) 0.1 M EDTA, (ii) 99.6% ethanol, (iii) 0.1 M EDTA followed by 99.6% ethanol and (iv) without any treatment (control). A push-out test was carried out after 24 h. Each tooth was cut into three 1 mm-thick sections. Fracture type was assessed using stereomicroscope. The data were analyzed by one way-ANOVA followed by Scheffe post-hoc test at P = 0.05.
Almost, in EDTA and (EDTA + ethanol) every sample failed at the interface between post and lutting cement. Predominant failure mode in ethanol and control group was mixed failure. The surface treatment methods did not have any significant effect (P > 0.05) on any group but EDTA group had the highest bond strength.
Surface treatment with (ethanol, EDTA, and EDTA + ethanol) does not significantly appear to be effective in improving the bond strength of fiber posts into root dentine. The highest bond strength was observed in EDTA group and the lowest in the control group.
... In this study, a silane was applied to all specimens before the strength testing since most studies seem to favor its use as a coupling agent and it is also recommended by the manufacturer [14,16,18]. In addition, bonding material and a flowable core build-up material were chosen since it has been shown that low viscous materials are more efficient in filling the irregularities formed by different pretreatment modalities [43,44]. The micro push-out test was chosen for our study since the micro push-out and the microtensile method demonstrated comparable results with fewer premature failures and lower variability using the micro push-out test [45]. ...
The study evaluated the micro push-out bond strength of resin material (Multicore Flow) to two types of fiber posts (FP), namely fiber-reinforced composite (FRC) Postec and Radix Fiber posts using Er:YAG laser pretreatment. FP were divided into four groups, two being control groups. Before the core build-up procedure, representative specimens from each group were chosen to determine the surface roughness (Ra) at three different areas using a contact profilometer, while after the procedure, 1.5-mm-thick discs were sectioned and the micro push-out method was used to assess the bond strength of the core build-up material to the fiber post in each group. Two-way analysis of variance was used for statistical analysis with the level of significance set at p < 0.05. Scanning electron microscopy was used to analyze the post surfaces after Er:YAG laser pretreatment and to classify the failure mode after loading. The type of pretreatment (p < 0.001) and an interaction between the pretreatment and type of post (p < 0.001) had a significant effect on the bond strength, while the type of post did not (p = 0.965). The mean bond strength in the Er:YAG laser pretreatment group was significantly lower compared to the FRC Postec posts control group (p < 0.001), while there was no significant difference between the Radix Fiber posts groups (p = 0.680). Mean Ra values from the Er:YAG laser pretreatment groups were significantly higher compared to control groups (p < 0.001). Er:YAG laser pretreatment at tested parameters negatively affected the bond strength of Multicore to FP and cannot be recommended as a standard procedure.
... As hydrophobic resin blends showed higher stiffness, improved stability over time, and
reduced water uptake11,15,16 when compared
to more hydrophilic ones10,
hydrophobic monomers should be preferred to produce a stable bond over time. However, if
the adhesive blend is too hydrophobic, suboptimal impregnation occurs since the solvents
cannot replace all the residual water within the demineralized dentin collagen fibrils. ...
Objective:
This study evaluated the performance of different adhesive systems in fiber post placement aiming to clarify the influence of different hydrophobic experimental blend adhesives, and of one commercially available adhesive on the frictional retention during a luting procedure.
Material and methods:
One luting agent (70 Wt% BisGMA, 28.5% TEGDMA; 1.5% p-tolyldiethanolamine) to cement fiber posts into root canals was applied with 4 different adhesive combinations: group 1: The etched roots were rinsed with water for 30 s to remove the phosphoric acid, then rinsed with 99.6% ethanol for 30 s, and blotdried. A trial adhesive (base to catalyst on a 1:1 ratio) was used with an experimental luting agent (35% Bis-GMA, 14.37% TeGDMA, 0.5% eDMAB, 0.13% CQ); group 2: A trial adhesive (base to catalyst on a 1:2 ratio) was luted as in group 1; group 3: One-Step Plus (OSP, Bisco Inc.) following the ethanol bonding technique in combination with the luting agent as in group 1; group 4: OSP strictly following the manufacturer's instructions using the luting agent as in group 1. The groups were challenged with push-out tests. Posted root slices were loaded until post segment extrusion in the apical-coronal direction. Failure modes were analyzed under scanning electron microscopy.
Results:
Push-out strength was not significantly influenced by the luting agent (p>0.05). No statistically significant differences among the tested groups were found as group 1 (exp 1--ethanol-wet bonding technique)=group 2 (exp 2--ethanol-wet bonding technique)=Group 3 (OSP--ethanol-wet bonding technique)=group 4 (control, OSP--water-wet bonding technique) (p>0.05). The dominating failure modes in all the groups were cohesive/adhesive failures, which were predominantly observed on the post/luting agent interface.
Conclusions:
The results of this study support the hypothesis that the proposal to replace water with ethanol to bond fiber posts to the root canal using highly hydrophobic resin is plausible, but this seems to be more the proof of a concept than a clinically applicable procedure.
... In the present study, Clearfil S3 bond was preferred as a self-etch adhesive in accordance with the previous study.[22] On the other hand, ASB total etch bond has previously been used in many comparative studies.[2324] Self-etch adhesives and composites may offer some advantages over the use of total etch adhesives. ...
The aim of this study was to evaluate the influence of different concentrations of Ethylenediaminetetraacetic acid (EDTA) solution on adhesion, that is, the bond strength of the different adhesive systems, to the pulp chamber dentin.
Recently extracted, sound, human, third molars were cut horizontally to expose the pulp horn. The roof of the pulp chamber and pulp tissue was removed. The teeth were then divided into five main groups. The teeth in each group were treated as follows: group 1, irrigated with saline; group 2, with 5% EDTA for 5 minutes; group 3, with 15% EDTA for 5 minutes; group 4, with 17% EDTA for 5 minutes and group 5, with 19% EDTA for 5 minutes. Treated specimens were dried and divided into 2 subgroups for adhesives; bonded with a total-etching adhesive (Adper Scotchbond Multi-purpose - ASB) or a one bottle of self-etch adhesive system (Clearfil S3 Bond - CS3). After the bonding procedure and composite restoration, teeth were sectioned and dentin sticks were obtained from each group for micro tensile testing (n = 10). Micro tensile testing was performed and scanning electron microscope (SEM) photographs were taken for each irrigated group.
In the ASB group, saline showed statistically higher bond strength values at the different concentrations of EDTA, while the micro-tensile bond strengths of the different concentrations of EDTA were not statistically different. In the CS3 group, saline and 5% EDTA showed statistically higher bond strength values than 17% and 19% EDTA, while the micro-tensile bond strengths of 15% EDTA compared to saline and 5% EDTA and 15% EDTA compared to 17% EDTA and 19% EDTA, were not statistically different.
This study showed that EDTA irrigation can affect the bond strength of adhesive systems on pulp chamber lateral walls. Clinically, low EDTA concentrations can be recommended if self-etch adhesives have been selected.
Purpose:
While it has been shown that no method produces specimens with exactly the same cross-sectional bonded area (BA), BA variations within and between studies are a well-known covariate in microtensile test results. However, no method has yet been described to accurately account for its influence. A procedure is presented that allows controlling for variations of BA effects on results. Further, a proposal for reporting is presented which enables results of different studies to be compared.
Materials and methods:
Partially using the results of the report in which the microtensile test was originally described, 144 both general (caused by differences in BA) and specific (due to a material's performance differences and intrinsic biological variability of specimens) variabilities were separated through linear regression of microtensile (MPa) to BA (mm2) pooled results. Comparing the specific variability of specimens - the residuals to the regression line - of groups allowed assessing differences between groups.
Results:
A means comparison of residuals showed that specific differences were significant (t-test, p = 0.0004). The null hypothesis could be rejected: materials' performances were different. This could not be determined in the original report, since BA variability was very high. A proposal for reporting of results to facilitate their clinical interpretation and comparison between studies is presented.
Conclusion:
Controlling for general variability caused by differences in BA size allows precise comparison of microtensile tests results.
Purpose: The aim of this study was to compare the bond strength obtained on root canal walls when using two different adhesive systems to bond a fiber reinforced composite (FRC) post inside a root canal and to evaluate the type of failure at the resin-dentine interface. Methodology : Thirty-eight central incisors were root canal treated, divided in 2 groups, and restored using FRC posts luted using resin cement (Multilink). Excite DSC was used as bonding agent in group 1 and an experimental ethanol-wet bonding system was used in group 2. The specimens were cut into 1mm-thick sections and a push-out test was carried out after 24h. Fracture type was assessed using optical and scanning electron microscopy.Results: Mean and standard deviation for the excite DSC and ethanol-wet groups were respectively 7.6±5.5 and 7.4±5.6 MPa. The Mann-Whitney rank sum test showed no statistical difference between the 2 groups (P=0.708). With regards to failure type, adhesive failure prevailed in the 2 groups. SEM evaluation revealed that adhesive failures occurred mainly at the resin- dentin interface. Conclusions: The 2 bonding systems exhibited similar short-term behavior. A baseline is established to test potential improvement of long-term behavior when using ethanol-wet bonding systems.
Objective:
To evaluate the morphologies of D.T. Light-Post (LP), JFP-II quartz (JQ), and JFP-II glass (JG) fiber posts and their microtensile bond strengths to light- or dual-cured resin core materials.
Method and materials:
The resin core materials that were used for the core buildup included three dual-cure core materials (Clearfil DC, Rebilda DC, and Luxacore Z) and a light-cured core material (Z100). The microtensile bond strength of each group was tested, and the morphology of each post and fractured surface was evaluated using scanning electron microscopy. Two-way ANOVA and Tukey or Dunnett T3 tests were used for statistical analyses.
Results:
LP exhibited wider fibers and less matrix than the JFP-II posts, and JQ exhibited a similar surface texture to JG. The bond strength of the JQ group was significantly less than that of the other groups, but for each of the resin core materials that were used in this study, there were no statistical differences between JQ and JG. The results also showed that the microtensile bond strengths of the Luxacore Z/LP and Z100/JG groups were significantly higher than those of the other groups. Cohesive failure was the exclusive mode of failure in the Z100 group, and the other fractured surfaces exhibited adhesive failure.
Conclusion:
The bonding between fiber posts and resin core materials is affected by the fiber type, but the type of dual-cure resin has no effect on the post and core bonds for any of the three posts used in this study.
In dentistry the restoration of decayed teeth is challenging and makes great demands on both the dentist and the materials. Hence, fiber-reinforced posts have been introduced. The effects of different variables on the ultimate load on teeth restored using fiber-reinforced posts is controversial, maybe because the results are mostly based on non-standardized in vitro tests and, therefore, give inhomogeneous results. This study combines the advantages of in vitro tests and finite element analysis (FEA) to clarify the effects of ferrule height, post length and cementation technique used for restoration. Sixty-four single rooted premolars were decoronated (ferrule height 1 or 2 mm), endodontically treated and restored using fiber posts (length 2 or 7 mm), composite fillings and metal crowns (resin bonded or cemented). After thermocycling and chewing simulation the samples were loaded until fracture, recording first damage events. Using UNIANOVA to analyze recorded fracture loads, ferrule height and cementation technique were found to be significant, i.e. increased ferrule height and resin bonding of the crown resulted in higher fracture loads. Post length had no significant effect. All conventionally cemented crowns with a 1-mm ferrule height failed during artificial ageing, in contrast to resin-bonded crowns (75% survival rate). FEA confirmed these results and provided information about stress and force distribution within the restoration. Based on the findings of in vitro tests and computations we concluded that crowns, especially those with a small ferrule height, should be resin bonded. Finally, centrally positioned fiber-reinforced posts did not contribute to load transfer as long as the bond between the tooth and composite core was intact.
The resin-dentin interdiffusion zone produced by a dentin-adhesive system that removes the smear layer and concurrently decalcifies superficial dentin was morphologically examined by both scanning and transmission electron microscopy. Cross-sectioned resin-bonded dentin discs were etched with an argon-ion beam to make the resin-dentin interface observable by SEM. For the TEM examination, the sections were partly decalcified by an aqueous EDTA solution to facilitate ultramicrotomy and to disclose the ultrastructure of the interdiffusion zone. Both SEM and TEM confirmed the presence of the resin-dentin interdiffusion zone as the junction between the deep unaltered dentin structure and the restorative resin. Within the interdiffusion zone, three sublayers with characteristic ultrastructure and staining were identified by TEM. An upper diffuse black layer contained few structural features. Underneath, partially-altered collagen fibrils were closely packed, mostly running parallel with the interface and perpendicular to the dentinal tubules. Their outline was electron-dense, forming tunnel-like structures. At the base of the upper layer, several stained projections were found to bulge out into the underlying collagen network and appeared to be confined by obstructive, parallel-running collagen fibrils. Finally, the third dense layer, containing hydroxyapatite crystals, demarcated the superficially demineralized dentin layer from the deeper unaltered dentin. Resin diffusion into the decalcified dentin surface layer was evident, but diminished with depth, presumably reducing deeper resin impregnation into the interfibrillar spaces. The citric acid dentin-pretreatment probably caused denaturation of the superficial collagen fibrils. Its decalcifying effect gradually weakened with depth, leaving behind hydroxyapatite crystals at the base of the interdiffusion zone.(ABSTRACT TRUNCATED AT 250 WORDS)
The mechanism responsible for hydrogen-peroxide- or sodium-hypochlorite-induced reductions in dentin bond strength is unknown. This in vitro study tested the hypothesis that these oxidizing agents were responsible by attempting to reverse the effect with sodium ascorbate, a reducing agent. Human dentin was treated with these oxidants before or after being acid-etched and with or without post-treatment with sodium ascorbate. They were bonded with either Single Bond or Excite. Hydrogen peroxide reduced the bond strengths of both adhesives, while sodium hypochlorite produced reduction in adhesion of only Single Bond (p < 0.05). Following treatment with sodium ascorbate, reductions in bond strength were reversed. Transmission and scanning electron microscopy showed partial removal of the demineralized collagen matrix only by sodium hypochlorite. The observed compromised bond strengths cannot be attributed to incomplete deproteinization and may be related to changes in the redox potential of the bonding substrates.
There is concern that the use of sodium hypochlorite (NaOCl) and RC-Prep may lower the bond strength of resin cements. The objective of this study was to evaluate the effect of 5% NaOCl and RC-Prep treatment on the bond strength of a resin cement, C&B Metabond. Control roots (group 1) were biomechanically prepared using 0.9% NaCl as an irrigant; group 2, roots with 5% NaOCl; group 3, roots with RC-Prep; group 4, roots with 0.9% NaCl followed by 10% ascorbic acid; group 5, roots with 5% NaOCl followed by 10% ascorbic acid (pH 4); group 6, roots with 5% NaOCl followed by 10% neutral sodium ascorbate; and group 7, roots with RC-Prep followed by 10% ascorbic acid. All roots were then filled with C&B Metabond, incubated in water for 24 h, and then cross-sectioned into six 1-mm thick slabs representing cervical and middle root dentin. The slabs were trimmed and tested for tensile bond strength. The results demonstrated that both 5% NaOCl and RC-Prep produced significantly (p < 0.05) large reductions in resin-dentin bond strengths, and the reductions could be completely reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate.
The aim of this study was to evaluate the efficacy of a new bonding-luting system in resin tag, adhesive lateral branch, and hybrid layer formation when used in combination with an experimental fiber post.
Thirty anterior teeth extracted for periodontal reasons were selected for this study. They were endodontically treated and randomly divided into three groups of 10 samples each: group 1 = Excite light-cured bonding agent in combination with Variolink II resin cement; group 2 = Excite dual-cured bonding agent self-activated by an experimental microbrush in combination with MultiLink resin cement; and group 3 = one-step bonding system in combination with Dual Link resin cement. In groups 1 and 3, the primer-adhesive solution was light cured before placing the resin cement and the post, whereas in group 2 the adhesive/luting materials were not light cured. Twenty FRC Postec translucent posts (groups 1 and 2) and 10 EndoAesthetic translucent fiber posts (group 3) were used. One week later, the root samples were processed for scanning electron microscopic (SEM) observations.
Microscopic examinations of restored interfaces from group 2 revealed a resin-dentin interdiffusion zone higher than that seen in samples from groups 1 and 3 (P < .05). At the apical and middle thirds, the samples from group 2 showed significantly more resin tags than the other two groups.
The dual-cure self-activating system showed a more uniform resin tag and resin-dentin interdiffusion zone formation along root canal walls than light-curing systems.
This overview presents a description of organofunctional trialkoxysilane coupling agents (silanes), their chemistry, properties, use, and some of the main clinical experiences in dentistry.
The main emphasis was on major dental journals that have been reviewed from 1958 up to the latest research news from 2002. A MEDLINE search with the key words "dental silanes" was used. Special silane literature and journals outside dentistry were also cited.
The main emphasis is on the use of silanes in prosthetic and restorative dentistry. Clinical relevance was based mainly on either short- or long-term tests. The interpretation of various results is not given, mainly because of controversial observations that may be very difficult to explain. Nevertheless, the majority of the clinical results pointed to silanes playing a significant role in the adhesion process. Silane reaction mechanisms were not entirely understood, and there exist several theories for bonding mechanisms for silanes and substrates.
Dental materials offer a continuously challenging forum for silanes, and silanes will play an essential role in material development.
Restoration of root-treated teeth is routinely performed in clinical practice with a choice of therapeutic options, considering many factors to provide optimal mechanical properties, esthetics, and longevity. The aim of the present work was to present a preliminary clinical report on the use of fiber posts and direct resin composites for restoring root-treated teeth.
Thirty-eight anterior and 62 posterior endodontically treated teeth were selected from 3 private prosthodontic offices. The protocol used included endodontic treatment, with translucent fiber posts (DT post) bonded to the post-space using a '1-bottle' adhesive (One-Step, Bisco) and a dual-cure resin cement (DuoLink, Bisco). Direct resin restorations were performed using a micro-hybrid resin composite (Gradia Direct, GC) and a layering technique. Both opaque dentin and enamel and translucent enamel shades were used.
Patients were recalled after 6, 12, 24, and 30 months, and the restorations assessed according to predetermined clinical and radiographic criteria. These clinician-mediated evaluation methods confirmed the good clinical performance of the restorations.
Restoration of endodontically treated teeth with fiber posts and direct resin composites is a treatment option, that in the short term conserves remaining tooth structure and results in good patient compliance.
The aim of this study was to evaluate the bond strengths between various resin composites used as core materials (Multicore Flow, Ivoclar-Vivadent; Tetric Flow, Ivoclar-Vivadent; Filtek Flow, 3M-ESPE; Tetric Ceram, Ivoclar-Vivadent; Filtek Z250, 3M-ESPE), and an FRC post (FRC Postec Plus, Ivoclar-Vivadent) by means of the microtensile nontrimming technique.
Five experimental groups were used. For the microtensile nontrimming technique, 45 to 50 beam-shaped specimens per group were obtained from cylinders of core material, which had been built up around the post by progressively adding small increments of composite resin. Each specimen was loaded in tension until failure at either one of the two post/core interfaces present in each stick. The differences in interfacial bond strength amongthe groups were tested for statistical significance with the one-way ANOVA test, followed by the Dunnett test for post-hoc comparisons.
The measured bond strengths in MPa were 17.29 +/- 6.02 for FRC+MultiCore Flow, 16.37 +/- 6.92 for FRC+Tetric Flow, 13.14 +/- 5.35 for FRC + Filtek Flow, 12.38 +/- 4.34 for FRC + Tetric Ceram, and 10.75 +/- 5.43 for FRC + Filtek Z250. The statistical analysis revealed that MultiCore Flow achieved significantly higher bond strengths than Filtek Flow (p = 0.03), Tetric Ceram (p < 0.001), and Filtek Z250 (p < 0.001). The bond strength of Tetric Flow was significantly higher than that of Filtek Z250 (p = 0.003).
For core buildup on a fiber post, dual-cure composites appear to be preferable to light-curing composites.
The purpose of this study was to determine if hydrophobic resins can be coaxed into dentin wet with ethanol instead of water. The test hypothesis was that dentin wet with ethanol would produce higher bond strengths for hydrophobic resins than would dentin wet with water. This study examined the microtensile bond strength of 5 experimental adhesives (50 wt% ethanol/50% comonomers) of various degrees of hydrophilicity to acid-etched dentin that was left moist with water, moist with ethanol, or air-dried. Following composite buildups, hourglass-shaped slabs were prepared from the bonded teeth for microtensile testing. For all 3 types of dentin surfaces, higher bond strengths were achieved with increased resin hydrophilicity. The lowest bond strengths were obtained on dried dentin, while the highest bond strengths were achieved when dentin was bonded moist with ethanol. Wet-bonding with ethanol achieved higher bond strengths with hydrophobic resins than were possible with water-saturated matrices.
A model is presented of the single-fiber push-out test with the objective of studying the interface failure process in metallic and intermetallic-matrix composites (MMCs and IMCs) and extracting the shear properties of fiber/matrix interface from the experimental data. The process of cooling from the composite consolidation temperature, specimen preparation for the push-out test, and the actual testing are simulated by using the finite element method. The mechanics of interface failure are analyzed and an attempt is made to capture the debonding sequence during a thin-slice push-out test. A stress-based criterion for debonding and a criterion for interfacial sliding based on frictional resistance are used to predict the interfacial behavior during the push-out test. The influence of processing-induced residual stresses on interface behavior during the push-out test is examined in detail. Load versus displacement behavior during the push-out test is numerically generated as a function of different interfacial strengths: these results are then used as a calibration curve to predict the interfacial shear strength for a given experimentally measured peak push-out load. The effect of the variation in the reported material data on processing-induced residual stress, and eventually on the push-out test results is studied. SiC/Ti-15-3 MMC is used as the model material for the prediction of interfacial shear strength.
An analysis of the stress distributions along the fiber-matrix interface in a 'thin-slice' fiber push-out test is presented for selected test geometries. For the small specimen thicknesses often required to displace large-diameter fibers with high interfacial shear strengths, finite element analysis indicates that large bending stresses may be present. The magnitude of these stresses and their spatial distribution can be very sensitive to the test configuration. For certain test geometries, the specimen configuration itself may alter the interfacial failure process from one which initiates due to a maximum in shear stress near the top surface adjacent to the indentor, to one which involves mixed mode crack growth up from the bottom surface and/or yielding within the matrix near the interface.
This study evaluated the fracture resistance of pulpless teeth with various ferrule designs and amounts of coronal tooth structure. One millimeter of coronal tooth structure above the crown margin substantially increased the fracture resistance of endodontically treated teeth, whereas a contrabevel at either the tooth-core junction or the crown margin was ineffective. The thickness of axial tooth structure at the crown margin did not appreciably improve resistance to fracture.
This in vitro study compared physical properties of root canal posts made of carbon fiber-reinforced epoxy resin with those of stainless steel posts. Three-point bending tests were used to derive the transverse modulus of elasticity of the posts. Resin composite cores on the posts were subjected to tensile forces to test the bonds between the cores and posts. Carbon fiber posts appeared to have adequate rigidity for their designed purpose. The bond strength of the resin composite cores to the carbon fiber posts was significantly less than that to the stainless steel posts.
The purpose of this study was to compare the regional bond strengths of C&B Metabond resin to root canal dentin, with or without treatment using a eugenol-containing endodontic sealer liquid. Eighteen extracted human canines were decoronated at the cementoenamel junction with a slow speed saw. The apical third of the root was removed leaving the cervical and middle dentin. The canal space was then enlarged with files, Gates-Glidden burs, and parapost drills. The teeth were ground on either the mesial or distal sides, permitting direct access to the entire canal. The cervical or middle third dentin was treated with Kerr Root Canal Sealer liquid, alternating between the middle and cervical thirds. Each tooth served as its own control. The adhesive resin was then luted directly to the prepared canal. Specimens, 1 x 1 x 8 mm, were prepared and mounted to a Vitrodyne testing machine enabling microtensile bond strengths to be measured. Data were analyzed using a two-way ANOVA and the least squares means test. The mean microtensile bond strengths for the cervical and middle third dentin treated with eugenol were 13.6 +/- 6.1 MPa (n = 33) and 14.8 +/- 3.9 MPa (n = 29), respectively. Without the eugenol, the mean bond strengths were 18.1 +/- 6.0 MPa (n = 31) and 17.3 +/- 4.6 MPa (n = 31) for the cervical and middle sections. The specimens treated with the eugenol liquid had significantly lower bond strengths than those without eugenol (p < 0.05) only in the cervical third. The region of the tooth tested had no effect on bond strength. That is, bond strength of the cervical third was not significantly different from bond strength on the middle third in either of the two groups (with or without eugenol) tested.
The hypotheses tested were that the bond strength of adhesive cements to root canal dentin (1) would be reduced as a function of configuration factor, polymerization process and type of luting material and (2) would be lowered near the apex of the tooth.
Human canines and premolars were prepared for post cementation using Single Bond/Rely X ARC, ED Primer/Panavia F, C and B Metabond, and Fuji Plus. The specimens were divided into two groups. For intact roots, the posts were luted using standard clinical procedures. For flat roots, the posts were applied directly into flat ground canals. All roots were sectioned into 0.6 mm thick slices, trimmed mesio-distally and stressed to failure at 1 mm/min. The muTBS of each slab was calculated as the force at failure divided by the bonded cross-sectional surface area. The results were compared using a one-way ANOVA and Tukey multiple comparison intervals (alpha=0.05). Least squares linear regression analysis was used to assess the effect of dentin location on bond strength.
All cements showed significantly (p</=0.05) lower bond strengths in intact vs. flat roots. The muTBS of posts to intact roots were not significantly different for Single Bond/Rely X ARC and Panavia F, but both were significantly lower (p</=0.05) than the bonds produced by C and B Metabond and Fuji Plus cements. For Single Bond/Rely X ARC and Fuji Plus a significant decrease in bond strength was observed in dentin closer to the apex of the root.
Stresses from polymerization shrinkage and problems with adequate access to the root canal complicate the formation of high-strength bonds when cementing endodontic posts with resin cements.
[corrected] To microscopically evaluate the structural characteristics of post-and-core units made with a fiber post and different types of composite resins used as build-up materials.
Forty endodontically treated human maxillary incisors were prepared for receiving a fiber post (Aesthetic Post Plus, RTD). One-Step (Bisco) was used as a bonding material, and C&B resin cement (Bisco) for luting the post. The posted roots were randomly divided into eight groups. In each group a different material or technique was applied to build up the abutment. The materials on trial were Z100 (3M-ESPE), Lumiglass (RTD), Gradia (GC), Build-it! (Jeneric Pentron). On the specimens of Groups 5-8, the same materials were used for build-ups, with the addition of a preshaped plastic shell (Composipost, Core Form, RTD). All the post-and-core specimens were cut perpendicular to their long axis and processed for SEM observation. The objective was to detect the presence of voids/bubbles within the resin abutment, and of gaps at the interface between the post surface and the core material. These aspects were quantified with reference to indexes. The differences among the scores were tested for statistical significance (p<0.05).
In the absence of any matrix, cores built up with Gradia showed the highest integrity, and those made with Z100 the best adaptation onto the post. In the presence of shells, Build-it! provided the most satisfactory result. Build-it! was the only material to perform better when used in combination with a shell.
When hybrid composites are used to build up a core onto a fiber post, a higher homogeneity of the abutment and a better post-core integration are achieved if the build up is done in the absence of any matrix.
This study prospectively evaluated the clinical performance of three types of translucent posts over a follow-up period of between 2 and 3 years.
Selected were 225 patients with one premolar in need of endodontic treatment, followed by restoration with a fiber post and porcelain crown. The sample was randomly divided into three groups of 75 patients each. The same type of post was used in all patients within a group: group 1 = Aesthetic Plus; group 2 = DT; and group 3 = FRC Postec. For bonding the post, a light-curing adhesive (One-Step) and a dual-curing resin cement (Duo-Link) were applied in group 1 and 2 roots, whereas self-curing materials (Excite DSC as adhesive and MultiLink as resin cement) were used in group 3. After 6, 12, and 24 months, patients were recalled, and a clinical and radiographic examination was performed. For some patients, 30-month follow-up data were also collected.
Debonding of the post occurrred in eight cases (3.5%); in another six cases, a recurrence of the periapical lesion was reported.
The statistical analysis did not reveal any significant difference in the survival rate of the tested posts, suggesting that all are equally and sufficiently reliable for clinical use.
This in vitro study evaluated the effect of various surface treatments of prefabricated posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White) and zirconia (Cerapost) on the bonding of two resin cements: ParaPost Cement and Panavia F by a diametral tensile strength (DTS) test. The posts received surface treatments in three categories: 1) roughening by sandblasting and hydrofluoric acid etching; 2) application of primer by coating with Alloy Primer, Metalprimer II and Silane and 3) a combination treatment in the form of roughening (sandblasting or etching) supplemented by the application of a primer or in the form of the Cojet system. After surface treatment, the post was embedded in a cylinder of resin cement (diameter = 4.0 mm, height = 4.0 mm). The surface-treated post was centered in the resin cement-filled mold with the aid of fixation apparatus. Fifteen minutes from the start of mixing the resin cement, the specimen was freed from the mold and stored in water at 37 degrees C for seven days. Following water storage, the specimen was wet-ground to a final length of approximately 3 mm. The DTS of specimens was determined in a Universal Testing Machine. The bonding of resin cement to titanium alloy posts was increased by several surface treatments of the post. However, coating with primers as sole treatment had no effect on bonding. With the DTS method applied, none of the surface treatments had an effect on the bonding to glass fiber posts. The bonding of both resin cements to zirconia posts was improved by Cojet treatment, while sandblasting, followed by silane application, improved bonding of Panavia F.
To determine the effect of surface treatments on bond strength of two resin cements (ParaPost Cement and Panavia F) to posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White), and zirconia (Cerapost), and to dentin.
After embedding, planar surfaces of posts (n = 9 to 14) and human dentin (n = 10) were obtained by grinding. The posts received one of three surface treatments: 1. roughening (sandblasting, hydrofluoric acid etching), 2. application of primer (Alloy Primer, Metalprimer II, silane), or 3. roughening followed by application of primer (sandblasting or etching followed by primer, Cojet treatment). ParaPost Cement and Panavia F were bonded to the post and dentin specimens, and the bonded specimens were placed in water at 37 degrees C for 7 days. The specimens were debonded in shear.
Panavia F had significantly higher bond strength to ground ParaPost XH, Cerapost, and dentin than did ParaPost Cement. Most surface treatments resulted in an improved bond strength of resin cements to the posts. Compared to the ground control, Cojet treatment and sandblasting were the most effective treatments. Etching of Cerapost with hydrofluoric acid with and without silane treatment significantly decreased the bond strength of Panavia F to the post.
The bond strength of resin cements to the posts was affected by the material of the post, the surface treatment of the post, and by the type of resin cement. The bond strength of resin cement to dentin was influenced by the type of resin cement.
The restoration of endodontically treated teeth is a topic that is extensively studied and yet remains controversial from many perspectives. This article reviews the major pertinent literature on this topic, with an emphasis on major decision-making elements in post placement and restoration of endodontically treated teeth. Recommendations are made for treatment planning, materials, and clinical practices from restorative and endodontic perspectives.
Endodontically treated teeth restored with posts are susceptible to coronal leakage after long-term function. We hypothesize that demineralized collagen matrices (DCMs) created in dentin by acidic zinc phosphate cement within the dowel spaces degrade with time. Forty-two post-restored teeth were extracted after three periods of clinical service and were examined, by means of scanning and transmission electron microscopy, for the status of the DCMs. SEM revealed a progressive degradation of the DCMs, becoming less dense after 3 to 5 years, losing structural integrity after 6 to 9 years, and partially disappearing after 10 to 12 years. TEM revealed evidence of collagenolytic activity within the DCMs, with loss of cross-banding and unraveling into microfibrils, and gelatinolytic activity that resulted in disintegration of the microfibrils. Bacterial colonization and the release of bacterial enzymes and of host-derived matrix metalloproteinases may contribute to the degradation of collagen fibrils in root dentin after clinical function.
To verify whether substrate, shape, or thickness of microtensile specimens have a significant influence on their measured bond strength.
Sixty-four extracted molars provided microtensile specimens, which were prepared on enamel and dentin, in different shapes and thicknesses. The teeth were randomly divided into 16 groups (n = 4). Groups 1-8 included hourglass-shaped specimens. In Groups 1-4 specimens were prepared from enamel and in a thickness at the bonding interface of 0.5 mm x 0.5 mm, 1 mm x 1 mm, 1.5 mm x 1.5 mm, and 2 mm x 2 mm, respectively. In these same thicknesses, hourglasses were trimmed in Groups 5-8, but the specimens were prepared from dentin. Groups 9-16 included specimens obtained following the non-trimming technique. Groups 9-12 provided enamel sticks in the four evaluated thicknesses. In these same thicknesses and shape but from dentin were cut the specimens of Groups 13-16. Two specimens from each group were viewed using a scanning electron microscope. On the other ones, microtensile bond strength was measured and the values were statistically analyzed.
Substrate, shape, and thickness of the specimens had a significant effect on their recorded bond strength (p < 0.05). Higher bond strength values were recorded by dentin versus enamel specimens and by sticks versus hourglasses. Also, bond strength decreased as specimen thickness increased. SEM analysis revealed that the trimmed specimens, especially if from enamel, often exhibited lines of fracture in the area of action of the bur.
It seems advisable to avoid the trimming action particularly on enamel specimens. If the hourglass shape is preferred, the cross-sectional area should not exceed 1 mm x 1 mm.
The objective of this clinical report was to evaluate the effectiveness of a microbrush as a carrier of priming-adhesive solution in formation of resin tags, adhesive lateral branches, and resin-dentin interdiffusion zone (RDIZ) when the brush was used to bond fiber posts under clinical conditions.
Twenty endodontically treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed, and their written consent was obtained. The samples were randomly divided into 2 groups of 10 samples each. In group 1, One-Step (Bisco, Schaumburg, Ill) was applied with a brush with Duo-Link resin cement (Bisco). In group 2, One-Step was applied with a microbrush with Duo-Link resin cement (Bisco). Use of the adhesive systems and resin cements was strictly according to manufacturers' instructions. The priming-adhesive solution was light-cured before the dual resin cement and the post were placed. Twenty Aestheti-Plus posts (white quartz fiber posts; RTD, St. Egreve, France) were used. A week after application, the root samples were extracted and processed for SEM observations.
Both adhesive systems showed RDIZ and resin tag and adhesive lateral branch formation. In Group 2 samples, RDIZ morphology was easily detectable and uniform along root canals. Also, resin tag formation was well represented in all thirds. In group 1 samples, resin tag formation at the apical third and RDIZ formation was less evident. Statistically significant differences were found among the two groups at the apical third.
The microbrush permitted a more uniform RDIZ and resin tag formation along the entire length of the canal than did the standard brush. The microbrush can be routinely used for bonding fiber posts into root canal preparations.
Aim of the study was to measure the adhesion between two types of translucent prefabricated FRC posts (FRC Postec, Ivoclar-Vivadent, FRC; Light-Post, RTD, LP), and two types of flowable composites used as core materials (UnifilFlow, GC, UF; Tetric Flow, Ivoclar-Vivadent, TF), with or without the application of a silane (Monobond-S, Ivoclar-Vivadent, S) on the post surface.
The experimental groups were: 1.1 FRC+UF; 1.2 FRC+S+UF; 1.3 FRC+TF; 1.4 FRC+S+TF: 2.1 LP+UF; 2.2 LP+S+UF; 2.3 LP+TF; 1.4 LP+S+TF. The bond strength at the interface between post and core was measured with the microtensile non-trimming technique. Thirty to thirty-five beam-shaped specimens per group were obtained from cylinders of core material, which had been built up around the post by progressively adding small increments of composite resin. Each specimen was loaded in tension until failure at either one of the two post-core interfaces present in each stick. The differences in interfacial bond strength among the groups were tested for statistical significance with the two-way ANOVA.
The measured bond strengths in MPa were: [table: see text]. The statistical analysis revealed that post-silanization had a significant effect on adhesion (p<0.05). With any combination of post and core materials tested, the application of a silane onto the post surface prior to building up the core significantly increased the post-core bond strength.
For improved adhesion at the interface between prefabricated FRC posts and composite resin cores, post-silanization is advisable.
This study tested the null hypothesis that the use of dentin adhesives produces no improvement on the fixation of fiber posts with resin cements in endodontically treated teeth. Post spaces were prepared in 36 single-rooted root-filled teeth. Silanized glass fiber posts were cemented to the post spaces using a self-etch (ED primer/Panavia 21) and a total etch resin cement (Excite DSC/Variolink II), with or without the accompanying dentin adhesives. Fixation strengths and interfacial ultrastructure were evaluated using a "thin slice" push-out test and transmission electron microscopy. For both resin cements, the fixation strengths obtained from specimens luted with resin cement only did not differ significantly from those in which the intraradicular dentin was first bonded with a dentin adhesive. In the presence of incomplete smear layer removal and interfacial gaps, the dislocation resistance of bonded fiber posts was contributed largely by sliding friction.
To verify the influence of different etching procedures of the post-surface on microtensile bond strength values between fiber posts and composite core materials.
60 DT Light Posts were divided into 10 subgroups using five different chemical surface treatments and two composite materials to build-up the abutment. Chemical surface treatments including etching with potassium permanganate; treatment with 10% hydrogen peroxide; treatment with 21% sodium ethoxide; etching with potassium permanganate and 10 vol.% HCl; silanization (control group) were performed on the post's surface. The build-up was performed using (A) Core Paste XP (Dent Mat) and (B) Unifil Flow (GC). Two samples of each group were randomly selected to investigate the morphologic aspect of the post/core interface with a scanning electron microscope (SEM). The remaining specimens were cut so as to obtain microtensile sticks that were loaded in tension at a cross-head speed of 1mm/min until failure. The statistical analysis was performed using two-way ANOVA and the Tukey's test for post-hoc comparisons (alpha=0.05).
SEM examination showed an interpenetrating adhesion network between the treated fiber post-surface and the composite material in all the groups tested. The results achieved with potassium permanganate had a significant influence on microtensile interfacial bond strength values with both the tested materials. Post-superficial treatments enhanced the bond strength particularly of Core Paste XP.
Etching procedures showed a similar effect on the post-surface and enhanced the adhesion of composite core build-ups as a result of micromechanical and chemical retention.
Coupling of fiber posts to composites is hampered by absence of chemical union between epoxy resins and methacrylate-based resins. This study examined a clinically feasible protocol for creating micromechanical retention on the surface of fiber posts, using hydrogen peroxide etching to remove the surface layer of epoxy resin. This was followed by silanization of the exposed quartz fibers to enhance their chemical bonding to composites. Etching with 24% H2O2 for 10 min or 10% H2O2 for 20 min produced a 50 microm thick surface zone that is depleted of epoxy resin, leaving intact, undamaged quartz fibers for silanization. Low viscosity flowable composites were employed to infiltrate this zone, to simulate the creation of hybrid layers in acid-etched dentin by dentin adhesives. Interfacial strengths were enhanced with the adjunctive use of H2O2 etching and silanization, and were probably dependent on the ability of the flowable composites to completely infiltrate this interdiffusion zone.
Esthetic posts have been developed to maximize the foundation of esthetic restorations. The purpose of this study was to evaluate the effect of silane on the bond strength of three fiber-reinforced resin posts (fiber posts).
Fifty-four extracted human maxillary central incisors and canines were endodontically treated. D.T. Light Post (DT, Bisco), FRC Postec (FR, Ivoclar Vivadent), and ParaPost Fiber White (PP, Coltène/Whaledent) were inserted using the resin adhesive system provided by the respective manufacturer. For half of the specimens in each group, the fiber posts were treated with a silane solution (Monobond S, Ivoclar Vivadent). A push-out test was performed on three different sections of each root to measure bond strengths. Data were analyzed with ANOVA and Bonferroni's post hoc test at P<0.05.
The use of silane did not result in any statistically significant difference at any level of the root. Silane did not result in any significant different bond strengths (MPa) for each of the posts. When the data were pooled, the use of silane did not result in statistically significant different bond strengths at P>0.403: No silane=12.7+/-8.4; Silane=14.1+/-7.0. The coronal third of the root (17.5+/-6.7) resulted in statistically greater bond strengths than the medium third (12.9+/-6.8) and than the apical third (9.8+/-7.3) at P<0.002 and P<0.0001, respectively. The medium third and the apical third resulted in no statistically significant different bond strengths from each other at P>0.07. The type of post did not result in statistically significant different bond strengths at P>0.417: DT=14.7+/-6.8 MPa; FR=13.3+/-6.6 MPa; PP=12.2+/-6.6 MPa.
The use of a silane coupling agent did not increase the push-out bond strengths of the three fiber posts used in this study. All posts bonded to root dentin at the same magnitude. Bonding is more predictable at the most coronal level of the root.
To evaluate the microtensile bond strengths of different resin composites used as core materials around fiber posts.
Forty DT Light-Posts (RTD) were randomly divided into eight groups, according to the resin composite used. They included two core materials specifically developed for core build-up--Group 1: Core-Flo (Bisco Inc.) and Group 2: UniFil Core (GC Corp.); three hybrid composites--Group 3: Tetric Ceram (Ivoclar-Vivadent), Group 4: Gradia Direct (GC Corp.), Group 5: Bisfil 2B (Bisco, Inc.); and three flowable composites--Group 6: AEliteflo (Bisco, Inc.), Group 7: Filtek Flow (3M ESPE) and Group 8: UniFil Flow (GC Corp). A cylindrical plastic matrix was placed around the silanized post and filled with the respective resin composite. Each bonded post provided five to eight sticks for microtensile testing. Each stick was loaded to failure under tension at a cross-head speed of 0.5mm/min. One-way ANOVA and Tukey's test were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks.
Resin composites exhibited a significant influence on microtensile bond strength (p<0.05). Core-Flo showed the highest bond strength (11.00+/-0.69 MPa) although it was not statistically significantly different from all groups, except from the flowable composites. Under SEM, all the composites adapted well to the fiber post, with a variable extent of voids observed along the fractured composite interfaces.
Although good adaptation to the post surface was achieved, bond strength to fiber post remains relatively weak. Core build-up and hybrid composites are better alternatives to flowable composites as core build-up materials.
Endodontically treated teeth often have little coronal tooth tissue remaining and as such require a post to retain the core and the restoration. Therefore, tooth coloured adhesive inserted fiber posts in combination with resin based core material can be used. In this study, the tensile bond strength of core materials to fiber posts was investigated. Three different core materials, Clearfil Core, CoreRestore 2 and MultiCore Flow in combination with two different fiber posts systems, ER DentinPost and DT Light Post, were tested. The posts were shortened to the lengths of 15 mm. The specimens were obtained while the upper part (3 mm) of the posts was covered with standardized cylinders of the core materials. Clearfil Core in combination with the DT Light Post (230.5 N +/- 42.2 N) and ER DentinPost (154. N +/- 33.6 N) had the highest tensile bond strengths of all groups. The tensile bond strength of CoreRestore 2 to DT Light Post (149.9 N +/- 29.5 N) was higher than the tensile bond strengths of the combinations MultiCore Flow/DT Light Post (140.9 N +/- 31.4 N) and Multi- Core Flow/ER DentinPost (122,. N +/-19,. N). The group Core-Restore 2TER DentinPost had the lowest tensile bond strengths (80,1 N ++/-19,4 N). The adhesion of the resin based core materials to the fiber posts is influenced by the post design and core materials. The combination of core materials with the type of fiber post has a great influence on the tensile bond strength.
The influence of different silane/dentin adhesives on the microtensile bond strengths of a hybrid composite to sodium ethoxide-etched quartz fiber posts was investigated. A prehydrolyzed silane was applied without an adhesive and compared to two-component systems in which hydrolysis of the silane occurred after mixing with the acidic monomer present in the dentin adhesives. Nanoleakage along post/core interfaces was examined after silver nitrate tracer penetration using scanning electron microscopy. Higher interfacial strengths and more uniform adaptation between the etched fiber post surface and the composite core were recorded after post treatment with silane/adhesive couplings. The combination of silane with two-step self-etch adhesives improves the chemical retention of composites around etched fiber posts with minimal nanoleakage. Although the one-step self-etching adhesive/silane combination enhances post adhesion, the extensive nanoleakage provides channels for rapid water sorption that may expedite hydrolytic degradation of the post/core interface.
To test the bond strength between a quartz-fiber-reinforced composite post (FRC) and a resin cement. The null hypothesis was that the bond strength can be increased by using a chairside tribochemical silica-coating system.
Thirty quartz-FRCs (Light-Post) were divided into 3 groups according to the post surface treatment: G1) Conditioning with 32% phosphoric acid (1 min), applying a silane coupling agent; G2) etching with 10% hydrofluoric acid (1 min), silane application; G3) chairside tribochemical silica coating method (CoJet System): air abrasion with 30-microm SiOx-modified Al2O3 particles, silane application. Thereafter, the posts were cemented into a cylinder (5 mm diameter, 15 mm height) with a resin cement (Duo-Link). After cementation, the specimens were stored in distilled water (37 degrees C/24 h) and sectioned along the x and y axes with a diamond wheel under cooling (Lab-cut 1010) to create nontrimmed bar specimens. Each specimen was attached with cyanoacrylate to an apparatus adapted for the microtensile test. Microtensile testing was conducted on a universal testing machine (1 mm/min). The data obtained were submitted to the one-way ANOVA and Tukey test (alpha = 0.05).
A significant influence of the conditioning methods was observed (p < 0.0001). The bond strength of G3 (15.14 +/- 3.3) was significantly higher than the bond strengths of G1 (6.9 +/- 2.3) and G2 (12.60 +/- 2.8) (p = 0.000106 and p = 0.002631, respectively). Notwithstanding the groups, all the tested specimens showed adhesive failure between the resin cement and FRC.
The chairside tribochemical system yielded the highest bond strength between resin cement and quartz-fiber post. The null hypothesis was accepted (p < 0.0001).
To evaluate the bond strengths of six different luting cements to fiber-reinforced composite (FRC) posts after various pre-treatment procedures.
180 FRC posts were divided into three groups (n=60) and received the following surface treatments. Group 1: untreated control; Group 2: silane treatment; Group 3: CoJet treatment. The posts of each group were fixed with six different luting cements. Push-out tests were performed to determine the bond strengths between the cements and the fiber posts.
The observed bond strengths (MPa) of the different resin cements to the posts were significantly affected by the type of cement (P< 0.001), but not by the pre-treatment chosen (P> 0.05; 2-way-ANOVA). Without consideration of the pre-treatment procedures, Clearfil showed the highest bond strengths, followed by Panavia F and RelyX, whereas Multilink, Variolink and PermaFlo showed significantly lower bond strength values (P< 0.05; Tukey's B).
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.
To assess the microtensile bond strengths of a core composite with two different viscosities, MultiCore Flow (F) and Heavy Body (HB) (Ivoclar-Vivadent), on dentin and glass-fiber posts with methacrylate resin matrices, in combination with three dentin adhesives: Syntac Classic (S), Excite DSC (E), and AdheSE (A) (Ivoclar-Vivadent). The omission of an intermediate adhesive coating on silanized posts was also examined to see if this resulted in post-core bond strength reduction.
Six experimental dentin and 6 experimental post groups were formed with different core material viscosity/adhesive combinations. In two control post groups, no adhesive was applied on the silanized posts. The core material was stratified on deep dentin or on the posts. From the built-up teeth and the post-core units, microtensile sticks were obtained.
The bond strengths measured on dentin were (MPa): S-F 12.7 +/- 6.4; S-HB 18.3 +/- 7.6; E-F 33.1 +/- 13.7; E-HB 34.1 +/- 10.2; A-F 33.5 +/- 14.8; A-HB 35.5 +/- 14.4. The post-core strengths were: S-F 9.4 +/- 2.5; S-HB 7.1 +/- 3.8; E-F 8.6 +/- 3.8; E-HB 8.1 +/- 4.4; A-F 8.1 +/- 2.7; A-HB 8.3 +/- 2.4; no adhesive-F 10.4 +/- 3.6; no adhesive-HB 6.3 +/- 2.7. Significantly higher interfacial strengths were achieved on dentin than on posts (p < 0.05). Adhesive type significantly affected core-dentin adhesion, with Excite DSC and AdheSE outperforming Syntac Classic (p < 0.05). Neither core material viscosity nor adhesive type significantly influenced post-core adhesion (p > 0.05). Omission of an intermediate adhesive layer had no effect on post-core adhesion (p > 0.05).
Even after post surface silanization, the bond established by the composite core material with the post remains weaker than that created with coronal dentin.
To evaluate the tensile bond strength between two different composite resin cores and (Clearfil Core, MultiCore Flow) and fibre posts (DT Light Post), with and without silanization of the post surface.
Forty fibre posts were shortened to a length of 15 mm. Specimens were then produced by covering the upper 3 mm of the posts with standardized composite core build-ups. The bonding surfaces of twenty posts were treated with silane coupling agent (Monobond-S). Four experimental groups were formed: G1: Clearfil Core; G2: Monobond-S + Clearfil Core; G3: MultiCore Flow; G4: Monobond-S + MultiCore Flow. Each post was positioned upright in a post centric device with moulds to ensure standardized shapes of the abutments. After tensile bond strength testing, the type of failure at the interface was determined. The results obtained were compared using an unpaired sample t-test.
The mean tensile bond strengths and standard deviations were [MPa] 10.08 +/- 0.92 for Clearfil Core, 10.47 +/- 1.05 for Clearfil Core + silane; 6.65 +/- 0.79 for MultiCore Flow and 6.91 +/- 0.83 for MultiCore Flow + silane. Statistical analysis revealed that Clearfil Core achieved significantly higher bond strengths than MultiCore Flow (P < 0.0001). Post silanization had no significant effect. All tested specimens had an adhesive failure mode.
Type of composite had a significant effect on tensile bond strength. Silanization of fibre post surfaces had no effect on core retention.
To retrospectively evaluate the long-term clinical performance of three types of fiber posts after a service period of 7-11 years.
985 posts were included in the study: 615 Composiposts, 160 AEstethic Posts and 210 AEsthetic Plus Posts were placed into endodontically treated teeth. Four combinations of dentin adhesives/luting materials were used. Endodontic and prosthodontic results were recorded.
A 7-11% failure rate was recorded for the three types of posts. A total of 79 failures were recorded: 39 due to endodontic reasons, one root fracture, one fiber post fracture, 17 crown dislodgements and 21 due to post debonding. The mechanical failures were always related to the lack of coronal tooth structure. The results indicated that fiber posts in combination with bonding/luting materials may be used routinely for restoring endodontically treated teeth. Mechanical failure of restored teeth with fiber posts can be related to the amount of residual coronal structure.