• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.104-109
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• 2013

PURPOSE. Among the surface treatment methods suggested to enhance the adhesion of resin cement to fiberreinforced 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 $38^{\circ}C$). Every specimen were bonded with dual-curing resin cement (Variolink N) and stored in distilled water for 24 hours at $37^{\circ}C$. 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 (${\alpha}$=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 fiberreinforced 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.

• The Journal of Advanced Prosthodontics
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• v.4 no.1
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• pp.37-42
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• 2012

PURPOSE. The influence of the modified process in the fiber-reinforced post and resin core foundation treatment on the fracture resistance and failure pattern of premolar was tested in this study. MATERIALS AND METHODS. Thirty-six human mandibular premolars were divided into 4 groups (n = 9). In group DCT, the quartz fibre post (D.T. Light-post) was cemented with resin cement (DUO-LINK) and a core foundation was formed with composite resin (LIGHT-CORE). In group DMO and DMT, resin cement (DUO-LINK) was used for post (D.T. Lightpost) cementation and core foundation; in group DMO, these procedures were performed simultaneously in one step, while DMT group was accomplished in separated two steps. In group LCT, the glass fiber post (LuxaPost) cementation and core foundation was accomplished with composite resin (LuxaCore-Dual) in separated procedures. Tooth were prepared with 2 mm ferrule and restored with nickel-chromium crowns. A static loading test was carried out and loads were applied to the buccal surface of the buccal cusp at a 45 degree inclination to the long axis of the tooth until failure occurred. The data were analyzed with MANOVA (${\alpha}$= .05). The failure pattern was observed and classified as either favorable (allowing repair) or unfavorable (not allowing repair). RESULTS. The mean fracture strength was highest in group DCT followed in descending order by groups DMO, DMT, and LCT. However, there were no significant differences in fracture strength between the groups. A higher prevalence of favorable fractures was detected in group DMT but there were no significant differences between the groups. CONCLUSION. The change of post or core foundation method does not appear to influence the fracture strength and failure patterns.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.103-108
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• 2012

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% $H_2O_2$, 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 $5^{\circ}C$ and $55^{\circ}C$. 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 (${\alpha}$=.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.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.126-132
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• 2013

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% $H_2O_2$, 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 (${\alpha}$=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 $H_2O_2$ + 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.

• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.257-266
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• 2010

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various post-and-core restorations, canals were restored with gutta-percha and resin core, or reinforced dentin wall with dual-cured resin composite, followed by placement of D.T. LIGHT-POST, ParaPost XT, and various sizes of EverStick Post individually. All of specimens were stored in the distilled water for 72 hours and underwent 6,000 thermal cycles. After simulation of periodontal ligament structure with polyether impression material, compressive load was applied at 45 degrees to the long axis of the specimen until fracture was occurred. Experimental groups reinforced with post and composite resin were shown significantly higher fracture strength than gutta-percha group without post placement (p < 0.05). Most specimens fractured limited to cervical third of roots. Post types did not influence on fracture resistance and fracture level significantly when cement space was filled with dual-cured resin composite. In addition, no statistically significant differences were seen between customized and standardized glass fiber posts, which cement spaces were filled with resin cement or composite resin individually. Therefore, root reinforcement procedures as above in immature teeth improved fracture resistance regardless of post types and sizes.

• The Journal of Advanced Prosthodontics
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• v.8 no.2
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• pp.94-100
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• 2016

PURPOSE. To evaluate the effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement. MATERIALS AND METHODS. The specimens were prepared to evaluate the bond strength of epoxy resin-based fiber posts (D.T. Light-Post) to dual-curing resin cement (RelyX U200). The specimens were divided into four groups (n=18) according to different surface treatments: group 1, no treatment; group 2, silanization; group 3, silanization after hydrogen peroxide etching; group 4, silanization with warm drying at $80^{\circ}C$ after hydrogen peroxide etching. After storage of the specimens in distilled water at $37^{\circ}C$ for 24 hours, the shear bond strength (in MPa) between the fiber post and resin cement was measured using a universal testing machine. The fractured surface of the fiber post was examined using scanning electron microscopy. Data were analyzed using one-way ANOVA and post-hoc analysis with Tukey's HSD test (${\alpha}=0.05$). RESULTS. Silanization of the fiber post (Group 2) significantly increased the bond strength in comparison with the non treated control (Group 1) (P<.05). Heat drying after silanization also significantly increased the bond strength (Group 3 and 4) (P<.05). However, no effect was determined for hydrogen peroxide etching before applying silane agent (Group 2 and 3) (P>.05). CONCLUSION. Fiber post silanization and subsequent heat treatment ($80^{\circ}C$) with warm air blower can be beneficial in clinical post cementation. However, hydrogen peroxide etching prior to silanization was not effective in this study.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.278-286
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• 2013

PURPOSE. The aim of this study was to determine whether the push-out bond strengths between the radicular dentin and fiber reinforced-composite (FRC) posts with various resin cements decreased or not, according to the coronal, middle or apical level of the root. MATERIALS AND METHODS. FRC posts were cemented with one of five resin cement groups (RelyX Unicem: Uni, Contax with activator & LuxaCore-Dual: LuA, Contax & LuxaCore-Dual: Lu, Panavia F 2.0: PA, Super-Bond C&B: SB) into extracted human mandibular premolars. The roots were sliced into discs at the coronal, middle and apical levels. Push-out bond strength tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and the failure aspect was analyzed. RESULTS. There were no significant differences (P>.05) in the bond strengths of the different resin cements at the coronal level, but there were significant differences in the bond strengths at the middle and apical levels (P<.05). Only the Uni and LuA cements did not show any significant decrease in their bond strengths at all the root levels (P>.05); all other groups had a significant decrease in bond strength at the middle or apical level (P<.05). The failure aspect was dominantly cohesive at the coronal level of all resin cements (P<.05), whereas it was dominantly adhesive at the apical level. CONCLUSION. All resin cement groups showed decreases in bond strengths at the middle or apical level except LuA and Uni.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.229-235
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• 2015

Objectives: To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores. Materials and Methods: Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at $135^{\circ}$ vertical angle, subjected to thermo-mechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data. Results: Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable. Conclusions: Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.

• Composites Research
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• v.34 no.1
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• pp.57-62
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• 2021

As interest in the eco-friendly ships and lightweight equipment is increasing in the shipbuilding and marine industry, composite materials are applied to equipment such as pipes. In this study, a basalt fiber reinforced furan composite (BFC), an eco-friendly material, was manufactured to apply the pipe insulation cover that requires environment-friendly and heat/flame retardant performance. An optimization study of post-curing conditions of BFC was conducted, and experiments and analysis were performed on mechanical strength, heat/flame retardant properties, and affinity properties. Finally, as a result of the study BFC material is proved to be a good candidate to apply pipe insulation cover.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.24-31
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• 2016

Purpose: Many studies have shown that airborne-particle abrasion of fiber post can improve the bonding strength to resin cement. But, airborne-particle abrasion may influence the property of fiber post. The purpose of this study is to evaluate the influence of airborne-particle abrasion on flexural strength of fiber post. Materials and Methods: Two fiber-reinforced posts; DT Light Post Size 2 (1.8 mm diameter, Bisco Inc) and RelyX Fiber Post Size 3 (1.9 mm diameter, 3M ESPE); were used in this study. Each group was divided into 3 subgroups according to different surface treatments; without pretreatment: $50{\mu}m$ aluminum oxide (Cobra$^{(R)}$, Renfert): and $30{\mu}m$ aluminum oxide modified with silica (Rocatec Soft$^{(R)}$, 3M ESPE). After airborne-particle abrasion procedure, three-point bending test was done to determine the flexural strength and flexural modulus. The diameter of each posts was measured to an accuracy of 0.01 mm using a digital micrometer. There was no diameter change before and after airborneparticle abrasion. The mean flexural moduli and flexural strengths calculated using the appropriate equations. The results were statistically analyzed using One-way ANOVA and Scheffe's post-hoc test at 95% confidencial level. Results: There was no significant difference on flexural strength between groups. Conclusion: In the limitation of this study, flexural strength and flexural modulus of fiber post are not affected by airborne-particle abrasion.