Adhesion between prefabricated fiber-reinforced posts and different composite resin cores: a microtensile bond strength evaluation

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: For core buildup on a fiber post, dual-cure composites appear to be preferable to light-curing composites.     

The adhesion between prefabricated FRC posts and composite resin cores: microtensile bond strength with and without post-silanization.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. SIGNIFICANCE: For improved adhesion at the interface between prefabricated FRC posts and composite resin cores, post-silanization is advisable.     

Fracture resistance of endodontically treated teeth restored with three different prefabricated esthetic posts

Purpose: This study was undertaken to evaluate the role of composition of prefabricated esthetic posts in fracture resistance of endodontically treated teeth in vitro. Materials and Methods: Thirty human, single‐rooted teeth (maxillary central incisors and canines) with similar root dimensions, extracted for therapeutic reasons, were used in this study. The crowns were removed below the cementoenamel junction to obtain a standard root length of 17 mm. The roots were endodontically treated following the conventional manual technique and randomly assigned to three groups (n = 10) according to the post used: Aestheti‐Post, Bisco, Schaumberg, Illinois; FibreKor Post, Jeneric/Pentron, Wallingford, Connecticut; and CosmoPost, Ivoclar Vivadent, Schaan, Liechtenstein. The root canals were rendered patent, and the root preparations were standardized through flaring with the manufacturers' drills included in the respective kits. The posts were cemented with an adhesive system and a resin cement (All‐Bond 2 and C & B, Bisco, respectively), according to the manufacturers' directions. Composite resin (Tetric Ceram, Ivoclar Vivadent) crowns were built up using a preformed polyester matrix, and the specimens were mounted in metallic rings with cold‐cure acrylic resin and kept in saline solution at 4°C for 24 hours. Fracture resistance was then determined using an EMIC DL‐2000 universal testing machine. The crosshead speed was 0.5 mm/min with the 45‐degree compressing load at the middle third of the crown. Data were analyzed using one‐way analysis of variance and Tukey'stest (p<.001). Results: Mean fracture resistance was as follows: Aestheti‐Post, 83.5 kgf; FibreKor Post, 85.7 kgf; and CosmoPost, 36.5 kgf. The fracture strength of CosmoPost was significantly lower than that of the other posts. Teeth restored with CosmoPost had post fractures, and in three specimens, those were associated with root fractures. Teeth restored with the other two posts presented fractures on the composite crowns. CLINICAL SIGNIFICANCE Compared with ceramic posts, carbon‐fiber and glass‐fiber prefabricated esthetic posts provide endodontically treated teeth higher fracture resistance.     

Fracture resistance and failure patterns of endodontically treated mandibular molars restored using resin composite with or without translucent glass fiber posts

The elastic modulus of the restorative material is important in restoring endodontically treated teeth. This study aimed to compare the fracture resistance and failure patterns of 90 mandibular molars restored using resin composites with or without fiber posts, with respect to the number of residual cavity walls. Five restoration types were performed corresponding to different wall defects (groups 1-5). Groups were divided in two subgroups corresponding to the use or absence of fiber posts. Teeth were loaded and resistance of specimens was measured as the axial compressive load to cause fracture and macroscopic fracture patterns were observed. One way ANOVA revealed a significant difference in fracture resistance (p < 0.001). Tukey post hoc test also revealed significant differences between groups as samples restored with fiber posts exhibited mostly restorable fractures. It was concluded that the resistance of endodontically treated mandibular molars restored with composite resins is mainly affected by the number of residual walls. Using fiber-reinforced posts optimized fracture patterns.     

Restoring teeth with prefabricated fiber-reinforced resin posts.

The use of fiber-reinforced resin (FRR) posts to restore endodontically treated teeth has gained popularity as an alternative to cast or prefabricated metal posts. This may be due to the two important characteristics of fiber posts: I) their modulus of elasticity, which is similar to that of dentin, and 2) their ability to be adhesively cemented. The following article will discuss these characteristics, clinical indications for FRR posts, as well as increased fracture resistance, adhesion to root dentin, and guidelines for placement. LEARNING OBJECTIVES: This article reviews recent research on prefabricated fiber-reinforced resin (FRR) endodontic posts. Upon completing this article, the reader should: Understand clinical guidelines for the selection and cementation of FRR posts. Realize the importance of fracture resistance to the long-term performance of an endodontically treated tooth.     

Fracture resistance of endodontically treated teeth restored with composite posts

STATEMENT OF PROBLEM: The most recent application of fiber-reinforced composites involves their use as post and core systems to restore endodontically treated teeth. Even though this last application has been advertised and used clinically by many dentists, there is very little information regarding the physical properties of these post systems. PURPOSE: The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth. MATERIAL AND METHODS: Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel (ParaPost) control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called "narrow" and "flared" canals. For the narrow canal group, post spaces were prepared with the corresponding reamer to restore the teeth with FibreKor, Luscent anchors, and Ribbond posts of 1.5 mm, 1.6 mm, and 2.0 mm in diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same posts but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Prefabricated posts (FibreKor and Luscent anchors) for narrow and flared canals were cemented with an autopolymerized resin cement and a flowable composite, respectively, whereas customized Ribbond posts were luted with a light-polymerized flowable composite for both canal types. An additional set of 20 Ribbond posts with coronal portions of variable size and shape referred to as "Ribbond nonstandardized" were also prepared and evaluated. Specimens were loaded to failure (kg) with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. Data were analyzed with analysis of variance and Student t tests (P<.05). RESULTS: Statistical analysis revealed no significant difference between flared and narrow canals in mean load to failure between the post systems except for the Ribbond posts (P<.01). For the narrow canal, the mean load ranged from a low of 4.55 (+/-1.49) kg for the Ribbond standard to a high of 12.9 (+/-1.64) kg for the Luscent anchors. For the flared canal the low mean was 9.04 (+/-1.76) kg for FibreKor and the high was equal for both Luscent anchors and Ribbond standard, 12.87 (+/-2.69) and 12.87 (+/-3.54), respectively. Overall, the ParaPost control group had the highest load value (18.33 +/- 3.27 kg) (P<.05). Ribbond nonstandardized had a mean load to failure of 24.91 (+/-11.53) Kg for the narrow canal group and 31.95 (+/-11.98) kg for the flared canal. Results from these groups were excluded from the statistical analysis because of the uncontrolled core sizes and high standard deviations. No root fractures occurred in any of the experimental groups. CONCLUSION: Results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite posts studied. However, the mode of failure or deflection of the fiber-reinforced composite posts is protective to the remaining tooth structure.     

Influence of the flexural modulus of prefabricated and experimental posts on the fracture strength and failure mode of composite resin cores

The purpose of this study was to evaluate the influence of flexural modulus of non-metal posts on the fracture strength and failure mode of composite resin cores. Thirty-two human premolars were divided into four groups: prefabricated glass fiber post with 1.0 mm diameter and composite resin core (Group PE1.0), that with 1.5 mm diameter and composite resin core (Group PE1.5), experimental post (flexural modulus; 4.25GPa) and composite resin core (Group EX), and preparation for abutment teeth only (Group NT). After a static loading test, the fracture strength and failure mode were recorded. Group NT (1670.81 N) showed higher fracture strength than Groups PE1.0 (866.44 N), PE1.5 (825.19 N) and EX (1075.63 N) (p<0.05). This study showed that the fracture strength of endodontically treated teeth restored with composite resin cores is not influenced by the flexural modulus of non-metal posts.     

Ex vivo fracture resistance of direct resin composite complete crowns with and without posts on maxillary premolars

AIM: To investigate ex vivo the fracture resistance and failure mode of direct resin composite complete crowns with and without various root canal posts made on maxillary premolars. METHODOLOGY: The clinical crowns of 40 human extracted single-rooted maxillary premolars were sectioned at the cemento-enamel junction. The canals were prepared with Gates Glidden drills up to size 4. Thirty samples were provided with standardized post spaces in the palatal canal and all roots were embedded in acrylic. Minimal standardized preparations in the canal entrances were made. Groups of 10 samples were treated with (i) prefabricated metal posts, (ii) prefabricated glass fibre posts, (iii) custom-made glass fibre posts, and (iv) no posts (control). Posts were cemented with resin cement and resin composite complete crowns were made. All specimens were thermocycled (6000x, 5-55 degrees C). Static load until fracture was applied using a universal loading device (crosshead speed 5 mm min(-1)) at a loading angle of 30 degrees . Failure modes were categorized as favourable and unfavourable failures. RESULTS: No significant difference was observed between the mean failure loads (group 1: 1386 N, group 2: 1276 N, group 3: 1281 N, and group 4: 1717 N, P > 0.05), nor between frequencies of failure modes (P > 0.05). All failures were fractures of the resin composite crown in combination with tooth material (cohesive failures). CONCLUSIONS: Within the limits of this laboratory investigation it is concluded that severely damaged and root filled maxillary premolars, restored with direct resin composite complete crowns without posts have similar fracture resistances and failure modes compared to those with various posts, which suggest that posts are not necessarily required.     

Retention of prefabricated posts with dental adhesive and composite

Sixty-three No. 4 Dentatus threaded posts were cemented in extracted teeth and tested for tensile strength. The cementing medium was Silar composite alone or in combination with a conventional bonding agent or Scotchbond dental adhesive, or both. Results indicate that: Retention was greater when the posts were cemented with the Silar composite preceded with the application of Scotchbond. Retention was less with Silar composite alone or combined with a conventional bonding agent. Scotchbond is suggested for use as a bonding agent when cementing Dentatus posts with composites.     

Microtensile bond strength of quartz fiber posts to different composite cores

The aim of this in vitro study was to assess the microtensile bond strength of quartz fiber posts to different composites, and to composite combinations used as core materials. Thirty fiber posts were treated with a 24% hydrogen peroxide solution and silanized. The posts were divided into 5 groups according to the resin composite used as follows (n = 6): G1 - ?lite Flow (Bisco, Inc), G2 - Filtek Z250 (3M ESPE), G3 - Biscore (Bisco, Inc), G4 - ?lite Flow + Filtek Z250, G5 - ?lite Flow + Biscore. The resin composites were placed around the posts to produce cylindrical specimens. Two 1-mm2 thick sticks containing the post in the center and composite cores on both ends were provided from each cylinder and tested for microtensile strength with a crosshead speed of 0.5 mm/min. One-way ANOVA and Tukey HSD tests were used for statistical analysis. Fractured surfaces were observed using a stereomicroscope with 20× magnification. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks. The results showed that G2 had the highest bond strength values, and the lowest values were seen with G3. There were significant differences between groups 1, 2, 4 and groups 3, 5 (p < 0.05). Under the stereomicroscope, most of the failures were adhesive between the post and core material. Under SEM, ?lite and Z250 had smoother surfaces than Biscore, containing less porosities and voids.     

Fracture resistance of endodontically treated teeth with different heights of crown ferrule restored with prefabricated carbon fiber post and composite resin core by intermittent loading

This study evaluated the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber posts and varying quantities of coronal dentin. Sixty freshly extracted upper canines were randomly divided into groups of 10 teeth each. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis. Data were analyzed by 1-way analysis of variance and Tukey test (alpha = .05). Significant differences (P < .001) were found among the mean fracture forces of the test groups (positive control, 0 mm,1 mm, 2 mm, 3 mm, and negative control groups: 1022.82 N, 1008.22 N, 1292.52 N, 1289.19 N, 1255.38 N, and 1582.11, respectively). These results suggested that the amount of coronal dentin did not significantly increase the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber post and composite resin core.     

不同直径预成氧化锆桩和纤维桩修复的抗折性比较

目的观察不同直径预成氧化锆桩和纤维桩与核树脂桩核冠修复上颌中切牙的抗折力。方法 24颗完整上中切牙根管充填后随机分为4组,分别采用直径1.5mm、1.35mm预成氧化锆桩和直径1.5mm、1.375mm预成纤维桩与核树脂加Ni-Cr合金铸造冠修复。对所有样本进行抗折实验,并对其断裂模式进行观察和分析。结果直径1.5mm、1.35mm预成氧化锆桩组抗折力为508.5±143.3N和434.9±141.7N,大于直径1.5mm、1.375mm的预成纤维桩组抗折力(292.2±54.5N,238.5±79.1N),差异有统计学意义(P<0.05)。预成氧化锆桩组样本的损坏模式为桩的断裂或合并根颈部的损伤,根颈部的损伤中50%为破坏性牙折;预成纤维桩组样本的损坏模式为桩的弯曲,根颈部的损伤中83.3%为可修复性牙折。结论预成氧化锆桩与核树脂桩核冠修复上颌中切牙可承受较高的载荷,预成纤维桩对预防破坏性根折有利。     

Effect of eugenol-containing endodontic sealer on retention of prefabricated posts luted with adhesive composite resin cement.

Reported studies have implicated eugenol in the reduction in retention of restorations luted with chemically cured composite resin cement. This study investigated the effect of residual eugenol in the root canal on the retention of ParaPost dowels cemented with Panavia EX composite resin. An attempt was also made to identify and to determine the most effective cleansing procedure. Findings of this study demonstrated a substantial decrease in retention of posts luted with Panavia composite resin cement in the presence of eugenol. Irrigation with ethyl alcohol (ethanol) or etching with 37% phosphoric acid gel was found to be effective in restoring the resistance to dislodgment of the posts, but alcohol produced the most consistent and reliable results.     

Diametral tensile strength of a resin composite core with nonmetallic prefabricated posts: an in vitro study

STATEMENT OF PROBLEM: A number of prefabricated nonmetallic posts are currently available for use in conjunction with resin composite cores before fabrication of crowns for endodontically treated teeth. Information is needed regarding the strength of the composite and the nature of attachment between its components. PURPOSE: The aim of this study was to determine the influence of different types of posts on the fracture resistance of a resin composite core material using the diametral tensile strength (DTS) test. MATERIAL AND METHODS: Cylindrical specimens, 6 mm in diameter and 3 mm high, were prepared from resin composite (Tetric Ceram) and a group of prefabricated posts (n=10) as follows: resin composite only (control); Vectrispost (VTS); FiberKor (FKR); AEstheti-Plus post (ATP); Light-Post (LTP); Dentorama post (DRM), and Para-Post (PRP) as a second control. Specimens were stored for 7 days in water at 37 degrees C and then subjected to DTS test in a universal testing machine until failure occurred and load was recorded (N). Mean values and SD for DTS values (MPA) were calculated, and data were analyzed statistically with 1-way analysis of variance, followed by the Tukey test (alpha=.05). Representative specimens from each group were examined with SEM to determine nature of failure. RESULTS: Mean values (SD) in MPa for DTS were as follow: Control group: 49.64 (3.36); VTS: 29.77 (3.36); FKR: 31.9 (2.39); ATP: 28.92 (2.2); LTP: 34.26 (3.37); DRM: 33.45 (2.46), and PRP: 27.90 (2.40). Analysis of variance indicated significant differences among the groups (P<.05). SEM examination indicated that for PRP failure was adhesive in nature, whereas with all nonmetallic posts, cohesive failure was more predominant. CONCLUSION: The use of posts did not result in reinforcement of resin composite core when diametral tensile force was applied. When used with the core material, LTP, DRM, and FKR resulted in the highest DTS values, whereas PRP resulted in the lowest values.     

Three-dimensional finite element analysis of stress distribution in composite resin cores with fiber posts of varying diameters

Using three-dimensional finite element analysis (3D-FEA), stress distributions in the remaining radicular tooth structure were investigated under the condition of varying diameters of fiber post for fiber post-reinforced composite resin cores (fiber post and core) in maxillary central incisors. Four 3D-FEA models were constructed: (1) fiber post (?1.2, ?1.4, and ?1.6 mm) and composite resin core; and (2) gold-cast post and core. Maximum stresses in the tooth structure for fiber post and core were higher than that for gold-cast post and core. In the former models, stresses in the tooth structure as well as in the composite resin were slightly reduced with increase in fiber post diameter. These results thus suggested that to reduce stress in the remaining radicular tooth with a large coronal defect, it is recommended to accompany a composite resin core with a fiber post of a large diameter.