Assessment of the Push-Out Bond Strength for Glass Fiber Posts After Different Surface Treatments: An In Vitro Study

AIM

The goal of the study was to assess the push-out bond strength of the glass fibre post after different surface treatments.

MATERIALS AND METHODS

For the purpose of the investigation, 40 mandibular premolars were chosen. After gaining access, the biomechanical preparation was completed using the step-back approach up to a size 40K file, and the canals were sealed using gutta-percha cones and the lateral condensation procedure with AH Plus sealer (epoxide-amine resin pulp canal sealer). Peeso reamers were used to remove the canal fillings, leaving 5mm of gutta-percha apically. Drills included in the package were used to prepare the post spaces so that the posts would fit in their respective post slots. These were attached to self-curing acrylic resin blocks. Fibre posts were split into four groupings of n = 10 each for surface treatment, i.e., control, hydrogen fluoride, sandblasting, and hydrogen peroxide. The cementation of posts was done by utilising dual-cure resin cement. Two millimetres of the anatomical crown were removed from each sample. Each sample's 1-mm cervical segment was taken utilising the isotope from the remaining coronal area. To perform a push-out test, at the rate of 0.5mm/min of the crosshead, every sample was inserted into a universal testing device. Each post's dislodge force from the pre-set post spacing was measured. Statistics were utilised to analyse the data.

RESULTS

Strongest bonds were made by silanization, followed by sandblasting (p value=0.002). The weakest bonds were made by the control group.

CONCLUSION

The ultimate deduction was that when glass fibre posts underwent various types of surface treatments followed by silanization, it had a significant impact on increasing their strength.

Mechanical properties of glass-fibre-reinforced composite posts after laser irradiation with different energy densities

The aim of the present study was to evaluate the effect of the surface treatments on flexural strengths and flexural modulus of glass-fibre-reinforced composite (GFRC) posts. Sixty-three posts were randomly divided into 9 groups (n = 7), and various surface treatments were performed. The control group was left untreated. Other groups were treated with 9% hydrofluoric acid, sandblasting with 120 µm Al₂ O₃ particles and Er,Cr:YSGG laser irradiation with different powers (1 W, 2 W, 3 W, 4 W, 5 W and 6 W). The samples were subjected to 3-point bending test, and data were calculated. Statistical analysis was performed. The flexural strengths of fibre posts treated with sandblasting, hydrofluoric acid, 1 W and 2 W laser were statistically similar with control group (P > 0.01). However, the flexural strength of fibre posts treated with 3 W, 4 W, 5 W and 6 W laser was statistically lower than control group (P < 0.01). High laser irradiations cause melting on the post surface and breaks in fibrils.

Irrigación del conducto radicular y tratamiento de superficie de pernos de fibra, previo a la cementación: revisión de tema

Introducción: el tratamiento endodóntico es muy solicitado para preservar las piezas dentales, así como la utilización de pernos de fibra cuando el remanente coronario no es el adecuado para recibir una prótesis coronaria, permitiendo de esta manera reconstruir el muñón dental para la posterior colocación de la restauración definitiva. Objetivo: identificar tanto el tratamiento de superficie de pernos de fibra como el irrigante radicular idóneos para conseguir una cementación adecuada; así como conocer cuál es el tratamiento de superficie que produce menos desintegración de las fibras del perno de fibra. Materiales y métodos: se incluyeron 47 artículos publicados en inglés, durante los últimos 20 años, teniendo en cuenta que los mismos se obtuvieron hasta octubre del 2018. Conclusiones: previa la cementación de pernos sean estos de fibra o de cuarzo es indispensable realizar tratamiento de superficie para así mejorar la adhesión, estos pueden ser químicos o físicos, los que ofrecen mejor resultado sin alterar de manera significativa la estructura del mismo es el enarenado con partículas de diamante sintéticas de 1-3 µm seguido de silanización y dentro de los químicos H2O2 al 10% por 1 min seguido de silano. Para obtener mejores resultados se debe accionar el silano a una temperatura de 80°C. En cuanto a protocolos de irrigación depende del sistema de cementación que se vaya a emplear EDTA 18% + Hipoclorito de sodio al 5,25% o EDTA 18% + clorhexidina al 2% cuando se va emplear un cemento autoadhesivoy NaOCl al 11% cuando se utilice el acondicionamiento ácido de lavado y secado.

A comparative evaluation of the effect of phototherapy of fiber post on its bond strength to dental composite

The aim of the study was to evaluate the effect of diode laser as a phototherapy on surface treatment of fiber post and its bond strength to resin core build-up material. In this in-vitro study fifty fiber post of 1 mm tip-diameter and 20 mm length were used. The posts were mounted and randomly divided into 5 groups (n = 10) according to different surface treatment methods i.e. Group 1: Control, Group 2: Application of 37% Phosphoric Acid, Group 3: Treated with 40% H₂O₂, Group 4: Sandblasted with 50 μm aluminium oxide particles and Group 5: treated with diode laser. In all specimens including control, a cylinder of resin composite around the fiber post was made. All Specimens were mounted in a universal testing machine. Push-out test was performed and bond strengths were calculated. Using analysis of variance (ANOVA) and post hoc Tukey multiple comparisons test, means of push out bond strength were compared among the study groups. The highest bond strength was shown among Sandblasted [50 μm, Aluminium Oxide (Al₂O₃)] group [139.86] and the lowest push-out bond strength was observed in Control specimens [75.73]. The bond strength values of fiber post treated with Diode laser [100.81] and 40% H₂O₂ [105.64] were comparable.

Effect of different fiber post surface treatments on microtensile bond strength to composite resin

STATEMENT OF PROBLEM

The interface of fiber post and composite resin is a site of potential failure of adhesion. Improving this interface adhesion through different pretreatments of the fiber post surface has been suggested, but the results are controversial.

PURPOSE

The purpose of this in vitro study was to evaluate the effect on the bond strength to composite resin of pretreating glass fiber post surfaces with hydrogen peroxide, phosphoric acid, and a silane coupling agent.

MATERIAL AND METHODS

Glass fiber posts were treated for 1 or 5 minutes with 30% hydrogen peroxide or 35% phosphoric acid. Treated posts were divided into silanization and no silanization groups. Control groups included no treatment or treatment with silanization alone (total of 10 groups; n=14). Composite resin was bonded to the fiber posts, and the specimens were cut into beams with the fiber post in the middle and the composite resin at both sides. The beams were attached to a mechanical testing device, and microtensile bond strength was evaluated. Fracture modes were assessed using stereomicroscopy. Statistical analysis was done with 3- and 2-way ANOVA (α=.05). Additional specimens were evaluated with a scanning electron microscope (SEM) to evaluate the effect of treatments on the characteristics of fiber post surfaces.

RESULTS

The highest bond strength values were found in the group treated with phosphoric acid for 5 minutes with silanization, followed by the group treated with silanization alone. ANOVA showed a statistically significant effect for silanization (P<.05), but no statistically significant effect for surface treatment. SEM evaluation revealed cracked and dislodged superficial fibers in all groups, with no obvious difference in fiber exposure among the groups.

CONCLUSIONS

The silane coupling agent had a significant effect on the bond strength of the tested glass fiber posts to composite resin, whereas 30% hydrogen peroxide or 35% phosphoric acid did not.

Comparison of the effect of shear bond strength with silane and other three chemical presurface treatments of a glass fiber-reinforced post on adhesion with a resin-based luting agent: An in vitro study

Background:

Loss of retention has been cited to be the most common cause of the failure of postretained restoration with irreversible consequences when materials with different compositions are in intimate contact at the post/adhesive interface. With this background, a study was conducted to improve the adhesion at the resin phase of fiber posts using silane and other chemical pretreatments.

Materials and Methods:

Hundred glass fiber-reinforced posts were tested with 4 different protocols (n = 25) using silane as a control (Group A) and other three experimental groups, namely, Group B-20% potassium permanganate, Group C-4% hydrofluoric acid, and Group D-10% hydrogen peroxide were pretreated on the postsurface followed by silanization. These specimens were bonded with dual-polymerizing resin-based luting agent, which were then loaded at the crosshead speed of 1 mm/min to record the shear bond strength at the post/adhesive interface. The data were analyzed using one-way ANOVA test for multiple group comparisons and the post hoc Bonferroni test for pairwise comparisons (P < 0.05).

Results:

Group B showed more influence on the shear bond strength when compared to other protocols, respectively (P < 0.001).

Conclusion:

Alone silanization as a surface treatment did not improve the bond strength. Combination of chemical presurface treatments followed by silanization significantly enhanced the bond strength at the post/adhesive interface.

Hydrogen bonds of a novel resin cement contribute to high adhesion strength to human dentin

OBJECTIVE

The detachment of fiber posts from root canals is primarily caused by the loss of adhesion between dentin and cement; therefore, the purpose of this study was to formulate a novel resin cement that improves the bond strength of fiber posts to the dentin-cement interface.

METHODS

Three concentrations (30, 35, and 40wt.%) of bis[2-(methacryloyloxy)-ethyl] phosphate (2MP) were prepared as dentin bonding agent components. Isobornyl acrylate (IBOA) and ethylhexylacrylate (EHA) were used as key components to fabricate the resin cement (named IE cement). The adhesive strengths of IE cement to coronal and root canal dentin were tested after placement of specimens in a water bath at 100% humidity and 37°C for either 24h or 5 months. The microtensile bond test, the push-out bond test, and the fracture toughness test were performed. Four commercially available resin cements (Nexus(®) third generation (NX3), Variolink II, RelyX Unicem, and Panavia F 2.0) were used for comparisons. X-ray photoelectron spectroscopy (XPS) was used to analyze the interaction of collagen extracted from human dentin and 2MP as well as the fracture surfaces of the specimens submitted to the microtensile bond test.

RESULTS

The 35% concentration of 2MP, in combination with IBOA and EHA, was the most effective for improving the IE cement's bond strength to dentin. The XPS results revealed that the phosphate groups of 2MP formed hydrogen bonds with the collagen and that such bonds prominently decreased in number in the specimens that were stored for 5 months.

SIGNIFICANCE

The combination of 2MP, IBOA, and EHA can effectively increase the adhesive strength of IE cement to dentin via hydrogen bond formation.

Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future.

Effect of antioxidants on push-out bond strength of hydrogen peroxide treated glass fiber posts bonded with two types of resin cement

Objectives

Hydrogen peroxide (H₂O₂) surface treatment of fiber posts has been reported to increase bond strength of fiber posts to resin cements. However, residual oxygen radicals might jeopardize the bonding procedure. This study examined the effect of three antioxidant agents on the bond strength of fiber posts to conventional and self-adhesive resin cements.

Materials and Methods

Post spaces were prepared in forty human maxillary second premolars. Posts were divided into five groups of 8 each: G1 (control), no pre-treatment; G2, 10% H₂O₂ pre-treatment; G3, G4 and G5. After H₂O₂ application, Hesperidin (HES), Sodium Ascorbate (SA) or Rosmarinic acid (RA) was applied on each group respectively. In each group four posts were cemented with Duo-Link conventional resin cement and the others with self-adhesive BisCem cement. Push-out test was performed and data were analyzed using 2-way ANOVA and tukey's post-hoc test (α = 0.05).

Results

There was a statistically significant interaction between the cement type and post surface treatment on push-out bond strength of fiber posts (p < 0.001, F = 16). Also it was shown that different posts' surface treatments significantly affect the push-out bond strength of fiber posts (p = 0.001). H₂O₂ treated posts (G2) and control posts (G1) cemented with Duo-link showed the highest (15.96 ± 5.07MPa) and lowest bond strengths (6.79 ± 3.94) respectively.

Conclusions

It was concluded that H₂O₂ surface treatment might enhance the bond strength of fiber posts cemented with conventional resin cements. The effect of antioxidants as post's surface treatment agents depends on the characteristics of resin cements used for bonding procedure.

A simplified etching technique to improve the adhesion of fiber post

PURPOSE

Numerous methods were used to etch the fiber posts to improve its bonding to root canal dentin. Our aim was to evaluate the efficacy of 37% phosphoric acid in etching fiber posts in comparison with 24% hydrogen peroxide.

MATERIALS AND METHODS

Ninety human maxillary central incisors were taken and post space preparation was done. Ninety fiber posts were taken and divided into three groups (n=30) based on the surface treatment they received (H₃PO₄, H₂O₂, distilled water) and each group was further divided (n=10) based on the time period of application (15 seconds, 30 seconds, 60 seconds). All the posts were luted into canals using Rely X UniCem-2. Each tooth was then sectioned into six slices and subjected to push out test. Data obtained was subjected to statistical analysis at P<.05. The surface topography was evaluated using scanning electron microscopy.

RESULTS

Highest bond strength values were noted in 15 seconds etched phosphoric acid group and 60 seconds etched hydrogen peroxide group with no significant difference between two groups. Surface topography revealed complete epoxy layer removal with no damage to its structural integrity in those groups.

CONCLUSION

H₃PO₄ etching for a period of 15 seconds is an effective alternative in improving the adhesion of fiber post to root dentin.

Surface roughening of PET films through blend phase coarsening

In this study, a novel method to increase the surface roughness of polyethylene terephthalate (PET) films is proposed. The mechanism of phase coarsening at the surface in extruded thin films of PET blended with low concentrations of polystyrene (PS) was investigated. A small amount of poly(hyroxyl ether) of bisphenol A (phenoxy resin, PKHH) was found to significantly increase the surface roughness due to its effect on the PS-PET interfacial tension. X-ray photoelectron spectroscopy (XPS) results indicated that in the presence of PKHH, PS droplets migrated spontaneously towards the surface of the polymer film. An increased local concentration of PS near the surface took the form of encapsulated droplets. Above the flow temperature of the blend, the local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in the instabilities on the surface of the film. The adhesion properties of films with various roughnesses were determined using a pull-off test and found to be significantly increased, which suggested that co-continuous morphology and the coarsening process increased the adhesive properties of the film.

Effects of post surface conditioning before silanization on bond strength between fiber post and resin cement

PURPOSE

Post surface conditioning is necessary to expose the glass fibers to enable bonding between fiber post and resin cement. The purpose of the present study was to evaluate the effect of different surface conditioning on tensile bond strength (TBS) of a glass fiber reinforced post to resin cement.

MATERIALS AND METHODS

In this in vitro study, 40 extracted single canal central incisors were endodontically treated and post spaces were prepared. The teeth were divided into four groups according to the methods of post surface treatment (n=10): 1) Silanization after etching with 20% H₂O₂, 2) Silanization after airborne-particle abrasion, 3) Silanization, and 4) No conditioning (Control). Adhesive resin cement (Panavia F 2.0) was used for cementation of the fiber posts to the root canal dentin. Three slices of 3 mm thick were obtained from each root. A universal testing machine was used with a cross-head speed of 1 mm/minute for performing the push-out tests. Two-way ANOVA and Tukey post hoc tests were used for analyzing data (α=0.05).

RESULTS

It is revealed that different surface treatments and root dentin regions had significant effects on TBS, but the interaction between surface treatments and root canal regions had no significant effect on TBS. There was significant difference among H₂O₂ + Silane Group and other three groups.

CONCLUSION

There were significant differences among the mean TBS values of different surface treatments. Application of hydrogen peroxide before silanization increased the bond strength between resin cements and fiber posts. The mean TBS mean values was significantly greater in the coronal region of root canal than the middle and apical thirds.

Effect of silane activation on shear bond strength of fiber-reinforced composite post to resin cement

PURPOSE

Among the surface treatment methods suggested to enhance the adhesion of resin cement to fiber-reinforced composite posts, conflicting results have been obtained with silanization. In this study, the effects of silanization, heat activation after silanization, on the bond strength between fiber-reinforced composite post and resin cement were determined.

MATERIALS AND METHODS

Six groups (n=7) were established to evaluate two types of fiber post (FRC Postec Plus, D.T. Light Post) and three surface treatments (no treatment; air drying; drying at 38℃). Every specimen were bonded with dual-curing resin cement (Variolink N) and stored in distilled water for 24 hours at 37℃. Shear-bond strength (MPa) between the fiber post and the resin cement were measured using universal testing device. The data were analyzed with 1-way ANOVA and by multiple comparisons according to Tukey's HSD (α=0.05). The effect of surface treatment, fiber post type, and the interactions between these two factors were analyzed using 2-way ANOVA and independent sample T-tests.

RESULTS

Silanization of the FRC Postec Plus significantly increased bond strength compared with the respective non-treated control, whereas no effect was determined for the D.T. Light Post. Heat drying the silane coupling agent on to the fiber-reinforced post did not significantly improve bond strength compared to air-syringe drying.

CONCLUSION

The bond strength between the fiber-reinforced post and the resin cement was significantly increased with silanization in regards to the FRC Postec Plus post. Bond strength was not significantly improved by heat activation of the silane coupling agent.

Comparative evaluation of effects of different surface treatment methods on bond strength between fiber post and composite core

PURPOSE

Debonding of a composite resin core of the fiber post often occurs at the interface between these two materials. The aim of this study was to evaluate the effects of different surface treatment methods on bond strength between fiber posts and composite core.

MATERIALS AND METHODS

Sixty-four fiber posts were picked in two groups (Hetco and Exacto). Each group was further divided into four subgroups using different surface treatments: 1) silanization; 2) sandblasting; 3) Treatment with 24% H₂O₂, and 4) no treatment (control group). A cylindrical plexiglass matrix was placed around the post and filled with the core resin composite. Specimens were stored in 5000 thermal cycles between 5℃ and 55℃. Tensile bond strength (TBS) test and evaluation using stereomicroscope were performed on the specimen and the data were analyzed using two-way ANOVA, Post Hoc Scheffe tests and Fisher's Exact Test (α=.05).

RESULTS

There was a significant difference between the effect of different surface treatments on TBS (P<.001) but different brands of post (P=.743) and interaction between the brand of post and surface treatment (P=.922) had no significant effect on TBS. Both silanization and sandblasting improved the bonding strength of fiber posts to composite resin core, but there were not any significant differences between these groups and control group.

CONCLUSION

There was not any significant difference between two brands of fiber posts that had been used in this study. Although silanization and sandblasting can improve the TBS, there was not any significant differences between surface treatments used.

Growth factor release from a chemically modified elastomeric poly(1,8-octanediol-co-citrate) thin film promotes angiogenesis in vivo

The ultimate success of in vivo organ formation utilizing ex vivo expanded "starter" tissues relies heavily upon the level of vascularization provided by either endogenous or artificial induction of angiogenic or vasculogenic events. To facilitate proangiogenic outcomes and promote tissue growth, an elastomeric scaffold previously shown to be instrumental in the urinary bladder regenerative process was modified to release proangiogenic growth factors. Carboxylic acid groups on poly(1,8-octanediol-co-citrate) films (POCfs) were modified with heparan sulfate creating a heparan binding POCf (HBPOCf). Release of proangiogenic growth factors vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), and insulin-like growth factor 1 (IGF-1) from HBPOCfs demonstrated an approximate threefold increase over controls during a 30-day time course in vitro. Atomic force microscopy demonstrated significant topological differences between films. Subcutaneous implantation of POCf alone, HBPOCf, POCf-VEGF, and HBPOCf-VEGF within the dorsa of nude rats yielded increased vascular growth in HBPOCf-VEGF constructs. Vessel quantification studies revealed that POCfs alone contained 41.1 ± 4.1 vessels/mm², while HBPOCf, POCf-VEGF, and HBPOCF-VEGF contained 41.7 ± 2.6, 76.3 ± 9.4, and 167.72 ± 15.3 vessels/mm², respectively. Presence of increased vessel growth was demonstrated by CD31 and vWF immunostaining in HBPOCf-VEGF implanted areas. Data demonstrate that elastomeric POCfs can be chemically modified and possess the ability to promote angiogenesis in vivo.

Does the surface treatment affect the bond strength of various fibre-post systems to resin-core materials?

OBJECTIVES

The aim of this study was to evaluate the effects of surface treatments on bond strength of resin-core materials to three different types of fibre posts.

METHODS

Prefabricated glass (FRC Postec, Ivoclar), quartz (DT light, Bisco) and individually formed glass (Everstick, Stick Tech) fibre posts with a coronal diameter of 1.5 mm were randomly divided into three groups according to the surface treatment performed. In Group 1 sandblasting with aluminium oxide particles (Rocatec Pre, 3M Espe) was followed by the application of a silane coupling agent. In Group 2, posts were immersed in 9.6% hydrofluoric acid gel for 60 s and silanized for 60 s. In Group 3, no surface treatment was performed and it served as control. The resin-core material (Biscore, Bisco) or resin composites (Admira, Voco) were applied to the tube in 2-mm thick increments and light-cured for 40 s using a halogen light curing unit. 1 mm thick discs (n=10/per group) were prepared for the micropush-out test. The discs were pushed out in a universal testing machine (Lloyd Instruments). Statistical significance was determined by a multifactorial analysis of variance followed by Tukey's post hoc test or independent t tests.

RESULTS

ANOVA revealed that fibre posts and core materials had a significant effect on micropush-out bond strength values (p<0.001). The surface treatment with hydrofluric acid gel and sandblasting with aluminium oxide particles significantly enhanced bond strength values of fibre posts except Everstick post (p<0.05).

CONCLUSION

Different surface treatments of fibre posts might affect the bonding capacity of resin-core systems to these posts.

Light-transmitting ability of marketed fiber posts

If proper polymerization of resin-based cements is to be achieved for fiber post luting, light activation is needed for photo-curing agents, recommended for self-curing materials. The study was aimed at verifying whether the light-transmitting ability of marketed fiber posts reflected the manufacturers' claims for translucency. Ten posts per type were light-irradiated with a curing unit. Spectrophotometric measurements of the amount of photons reaching different post levels were taken. Data were statistically analyzed (linear regression, two-way ANOVA; alpha = 0.05). No light transmission was recorded through FibreKleer and Tech21 X-OP. For the other posts, light intensity decreased from coronal to apical and rose again at the apical tip, where it peaked for GC Fiber Post, Macrolock Illusion Post, and Radix Fiber Post. Light transmission was significantly higher at the coronal level. A statistically significant difference in translucency was found for Dentin Post X and FRC Postec Plus in comparison with Reforpost, FibreKleer, Tech21 X-OP, and Composipost.