Effects of mechanical properties of adhesive resin cements on stress distribution in fiber-reinforced composite adhesive fixed partial dentures

Using finite element analysis (FEA), this study investigated the effects of the mechanical properties of adhesive resin cements on stress distributions in fiber-reinforced resin composite (FRC) adhesive fixed partial dentures (AFPDs). Two adhesive resin cements were compared: Super-Bond C&B and Panavia Fluoro Cement. The AFPD consisted of a pontic to replace a maxillary right lateral incisor and retainers on a maxillary central incisor and canine. FRC framework was made of isotropic, continuous, unidirectional E-glass fibers. Maximum principal stresses were calculated using finite element method (FEM). Test results revealed that differences in the mechanical properties of adhesive resin cements led to different stress distributions at the cement interfaces between AFPD and abutment teeth. Clinical implication of these findings suggested that the safety and longevity of an AFPD depended on choosing an adhesive resin cement with the appropriate mechanical properties.     

A Clinical Case Report on Indirect, Posterior Three-unit Resin-bonded FRC FPD

Purpose: This paper describes a clinical, conservative approach and the details of cavity preparation for the replacement of a maxillary first premolar using a minimally invasive preparation combined with the adhesive approach. Material and Methods: A patient with a missing first premolar was treated with a 3-unit indirect fiber-reinforced composite (FRC) fixed dental prosthesis (FDP). The preparation on the canine was a slot combined with modified wing to increase the amount of fiber in the restoration. Glass fiber (Vectris; Ivoclar Vivadent) was used in an anatomical shape for the framework and incrementally veneered with resin composite (Adoro; Ivoclar Vivadent). The cavities were prepared by etching enamel and dentin with orthophosphoric acid, priming the dentin, and applying a three-step adhesive system and dual-cured luting resin (Variolink II, Ivoclar Vivadent). Finally, the indirect FRC FDP was finished and polished with 15-μm diamond burs (Composhape, Intensiv) and a polishing kit. Results: The patient was satisfied with the esthetics and function of the restoration, which has served without repair for 5 years. At the 5-year clinical follow-up, the restoration was found to be clinically successful. Conclusion: The correct cavity-preparation technique in combination with the FRC system could enhance the long-term survival of an inlay FDP.     

Metal free,full arch,fixed prosthesis for edentulous mandible rehabilitation on four implants

Purpose

The goal of this work is to describe an implant-prosthetic protocol for rehabilitation of edentulous mandible, by using a fixed prosthesis made of fiber-reinforced composite material (FRC). The protocol contemplates a minimal invasive surgery and ensures predictable and safe results, with good aesthetic and performance combined to cost savings.

高强度玻璃纤维/树脂复合材料桩钉的临床应用

目的 :探讨自行研制的高强度玻璃纤维 /树脂复合材料桩钉的临床应用效果。方法 :观察 13例 19件修复体的使用情况 ,并对临床应用的有关问题进行分析。结果 :经过 0 .5 -3年的临床观察 ,无一例桩钉折断或脱落 ,修复效果满意。结论 :高强度玻璃纤维树脂桩钉具有较好的美观效果和强度 ,有较好临床应用价值。     

Pilot study of unidirectional E-glass fibre-reinforced composite resin splints: up to 4.5-year clinical follow-up

Objectives

This prospective clinical pilot study evaluated the performance of fibre-reinforced-composite resin (FRC) splints on mandibular anterior teeth.

Methods

Between June-2003 and January-2008, 19 patients (7 females, 12 males, 45-72 years old) from a group of consecutive patients who completed periodontal therapy received E-glass FRC splints (everStick Perio, StickTech) in combination with two types of flowable and restorative resin-composites (Filtek Flow, Filtek Supreme, n = 11; Tetric Flow, Tetric-Ceram, n = 8). Only patients with vital teeth, presenting mobility of grade 3, having at least one canine with no mobility on both sides of the dental arch were assigned for a splint therapy. The patients were recalled for periodical follow-up controls first at 6 months and thereafter annually. The evaluation protocol involved technical failures [chipping, debonding or fracture (tooth/restoration)] and biological failures (caries)]. Periodontal pocket depth (PPD) and clinical attachment level (CAL) were measured 6 months after splinting and annually. Six sites were measured for each natural tooth at the mesiobuccal, buccal, distobuccal, distolingual, lingual and mesiolingual sites.

Results

All splints were applied from canine to canine in the mandible. In total, 5 recalls were performed and no drop-out was experienced. One partial debonding of the FRC splint with Tetric Flow/Tetric-Ceram combination was observed after 40 months. No caries was found around any of the splints and no teeth had to be extracted until the final follow up. The splinted teeth were found to be vital in the vitality tests. Overall survival rate was 94.8% (Kaplan-Meier). The survival rate was not significantly affected by the composite type (Filtek-Flow/Filtek Supreme: 100%, Tetric Flow/Tetric Ceram: 96% (p = 0.92) [Kaplan-Meier, Log Rank (Mantel-Cox) (CI = 95%)]. Hazard ratio for Tetric Flow/Tetric Ceram group was 0.05 (95% CI) and for Filtek Flow/Filtek Supreme group 0.00 (95% CI). Whilst overall PPD measurements of the dentition ranged between 6 and 12 mm, the CAL measurements ranged between 4.9 and 10 mm at baseline. The mean PPD for the splinted teeth decreased from 8.9 ± 1.8 mm to 5.2 ± 1.2 mm, and CAL decreased from 7.2 ± 1.6 mm to 4.6 ± 1 mm at the end point.

Conclusion

Direct tooth splinting with E-glass FRC material performed successfully up to 4.5 years. Periodontal status of the splinted teeth showed decreased PPD and CAL.     

Bone tissue responses to glass fiber-reinforced composite implants – a histomorphometric study

Objectives: The aims of this study were to evaluate bone-to-implant contact (BIC) and the osteoconductive capacity of bioactive fiber-reinforced composite implant (FRC) in vivo .
Material and methods: Threaded sand-blasted FRC implants and threaded FRC implants with bioactive glass (BAG) were fabricated for the study. Titanium implants were used as a reference. Eighteen implants (diameter 4.1 mm, length 10 mm) were implanted in the tibia of six pigs using the press-fit technique. The animals were sacrificed after 4 and 12 weeks. Histomorphometric and scanning electron microscopic (SEM) analyses were performed to characterize BIC.
Results: In general, the highest values of BIC were measured in FRC-BAG implants, followed by FRC and Ti implants. At 4 weeks, the BIC was 33% for threaded FRC-BAG, 27% for FRC and 19% for Ti. At 12 weeks, BIC was 47% for threaded FRC-BAG, 40% for FRC and 42% for Ti. Four weeks after implantation, all the implants appeared biologically fixed by a newly formed woven bone arranged in the thin bone trabeculae filling the gap between the implant and the bone of the recipient site. Twelve weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the FRC-BAG implants.
Conclusion: Our results suggest that the FRC implant is biocompatible in bone. The biological behavior of FRC was comparable to that of Ti after 4 and 12 weeks of implantation. Furthermore, the addition of BAG to the FRC implant increased peri-implant osteogenesis and bone maturation.     

玻璃纤维预拉伸对增韧光固化树脂基桩力学性能的影响

目的 研究玻璃纤维预拉伸对自行研制的高强玻璃纤维增韧光固化树脂复合材料（FRC）桩力学性能的影响。方法 利用加载装置将高强玻璃纤维分别拉伸0%、0.5%、1.0%后,按60%体积比浸入自行配置的光固化树脂基质,采用压膜法制成玻璃纤维增韧树脂基齿科桩,三点弯曲测试各试样的弯曲模量、弯曲强度和弯曲载荷,测试结果进行统计学分析。使用扫描电子显微镜观察FRC桩横截面和断裂面的形态。结果 玻璃纤维拉伸率对FRC桩的力学性能影响有显著差异,其中拉伸率为1.0%的玻璃纤维制成的FRC桩综合性能最佳,弯曲模量(20.40±1.40) GPa,弯曲强度(573.38±29.45) MPa,弯曲载荷(180.42±5.88) N,与未预拉伸的玻璃纤维增韧的FRC桩有显著差异(P<0.05)。结论 玻璃纤维预拉伸对FRC桩有增韧效果。     

Reinforcement effect of adhesively luted fiber reinforced composite versus titanium posts.

OBJECTIVE: The aim of the present study was to investigate the influence of the rigidity of different post materials (titanium versus glass fiber reinforced composite [FRC]) on the fracture resistance of endodontically treated teeth (ETT). METHOD: Forty-eight caries-free maxillary central incisors were randomly assigned to six groups (n=8). After endodontic treatment, teeth of four groups were flattened 2mm above and two groups at the cemento-enamel junction (CEJ). As control, specimens of one group received neither composite build-up nor post, and teeth were left empty (E). In another group only a resin composite build-up was placed (C). In two groups, both titanium and FRC posts were inserted. One group with titanium (2/T) and FRC (2/FRC) post received a 2mm deep ferrule preparation. For one group with titanium (0/T) and FRC (0/FRC) post no ferrule design was provided. All-ceramic crowns were adhesively luted on all specimens. Specimens were exposed to thermomechanical loading and finally statically loaded until failure. RESULTS: The median fracture load values (min-max) were: E=317 (242-404); C=387 (335-475); 0/FRC=352 (0-440); 2/FRC=502 (326-561); 0/T=420 (0-548), 2/T=517 (416-653). Statistically significant differences were computed between E, C, 2/FRC, 0/T and 2/T; between C, 2/FRC and 2/T; between 0/FRC, 2/FRC and 2/T; between 0/T and 2/T regarding maximum fracture load. SIGNIFICANCE: Fracture resistance of ETT is not influenced by the rigidity of the post material. The combination of ferrule preparation and endodontic post results in higher load resistance after TML than any other build-up design.     

Bond strength of Gradia veneering composite to fibre-reinforced composite

This study investigated the shear bond strength of light-curing veneering composite resin to glass fibre-reinforced composite (FRC). Polymer pre-impregnated FRC reinforcement was further impregnated with dimethacrylate monomer resin. The light polymerized FRC substrate was ground and dimethacrylate intermediate resin was applied on the surface before the light-curing veneering composite. Adhesional behaviour of veneering composite to the initially light polymerized FRC substrate was compared with well-polymerized FRC substrate. The treatment time of FRC substrate by the intermediate resin for 5 s and 5 min were also compared. Shear bond strength of veneering composite to FRC was determined for dry and thermocycled specimens (n = 6). The analysis of variance (anova) revealed significant differences (P = 0.042) between the shear bond strengths when 5 s and 5 min intermediate resin treatment times were compared. The highest shear bond strength (21.0 MPa) for FRC substrates was achieved when the well-polymerized FRC substrate was treated for 5 min with the intermediate resin and stored dry before tests. Thermocycling reduced the shear bond strengths. The results of this study suggest that applying the intermediate resin increased the shear bond strength values of veneering composite to FRC with multiphase polymer matrix. It was also concluded, that the use of multiphase polymer matrix FRC can be polymerized to high degree of conversion without deferiorating the shear bond strength of veneering composite to the FRC.     

Fiber-reinforced composites in dentistry – An insight into adhesion aspects of the material and the restored tooth construct

ObjectiveThis review aimed to highlight the insight into adhesion aspects within the components of the glass FRC (i.e., fiber and matrix) and between resin luting material and the glass FRC construction.MethodsThe fundamentals of semi-interpenetrating polymer network (semi-IPN) based FRCs and their advantages in forming a solid adhesive interface with indirect FRC restoration, dental adhesive, and luting cement are elaborated. The important resin matrix systems and glass fibers used in FRCs are discussed. This is principally based on a survey of the literature over Medline/PubMed, Web of Science, and Scopus databases and a review of the relevant studies and publications in scientific papers in international peer-reviewed journals for the specific topic of biomaterials science. The keywords used for the search approach were: adhesion, fiber-reinforced composite, glass fiber, and semi-interpenetrating polymer network.ResultsThe polymer matrix systems of semi-IPN-based FRCs and formation of secondary-IPN layer are pivotal for bonding of multiphasic indirect dental constructs and repair. Additionally, describing areas of indication for FRCs in dentistry, explaining the adhesion aspects of FRC for the cohesion of the material itself, and for obtaining durable adhesion when the FRC construct is luted to tooth and remaining dentition. Current progress in the field of FRC research and future directions are summarized and presented.SignificanceBy understanding the isotropic-anisotropic nature of fibers and the interfacial adhesion within the components of the FRC; between resin cement and the FRC construction, the clinically successful FRC-based multiphasic indirect tooth construct can be achieved. The interfacial adhesion within the components of the FRC and between resin luting material and the FRC construction play a key role in adhesion-based unibody dental restorations.     

Bond strength of fiber-reinforced composite bars for orthodontic attachment

Long fiber-reinforced composites (FRC) have been shown to have enhanced mechanical properties that allow their use in orthodontic appliances as bars that join teeth to form either anchorage or active units. This study was designed to determine if the bonding of an orthodontic attachment has sufficient strength to withstand loading during clinical use. The experimental model consisted of a hydroxyapatite stone that simulated enamel, FRC bars, and a bonded metal hook. Three specimen types were compared: (1) a metal hook-pad (the control), (2) a woven FRC with a hook-pad, and (3) a unidirectional FRC with a hook-pad. Loads were applied both parallel and at 90 degrees to the tooth surface. Under no condition was the FRC pad combination weaker than the control pad. Under some loading conditions, the loads before failure were as much as 3 times greater than those for the control. The lowest strength was found with loads at 90 degrees to the tooth surface for all 3 types. Failure normally occurred in the FRC and rarely at the bracket or tooth interface. The excellent bonding of the orthodontic attachment to the FRC and the high strengths of the FRC attachment combination demonstrate the ability to form connecting bars between teeth for either anchorage or active segmental movements. These bars offer advantages in simplicity in treatment by reducing the need for some bands, attachments, or wires.     

The effect of fiber orientation on the polymerization shrinkage strain of fiber-reinforced composites.

OBJECTIVE: The aim of this study was to characterize the linear polymerization shrinkage strain of glass fiber-reinforced composite (FRC) according to the fiber orientation. METHODS: Test specimens (n=5) (10.0 x 10.0 x 1.5mm) were prepared from different brands of photopolymerizable resin-preimpregnated FRC; unidirectional continuous FRC, experimental random-oriented FRC, and bidirectional continuous FRC. As control materials, particulate filler composite resin and unfilled dimethacrylate monomer resin were used. Two uniaxial strain gages (gage length 2mm) were used to measure shrinkage strains in two directions: longitudinally and transversally to the fiber direction. The uncured composite or resin was placed on top of the strain gages, covered with a separating sheet and a glass plate, and irradiated for 40s with a light-curing unit. The shrinkage strain was monitored for 300 s. ANOVA and Tukey's posthoc test were used at a significance level of 0.05. RESULTS: ANOVA revealed that orientation of fiber and brand of material had a significant effect (P<0.05) on shrinkage strain. The unidirectional FRC revealed no shrinkage longitudinally to the fiber direction, whereas the shrinkage occurred transversally to the fiber direction. Particulate filler composite resin and unfilled resin revealed equal shrinkage strain in both of the measured directions. SIGNIFICANCE: Anisotropic nature of FRC exists with regard to polymerization shrinkage strain. The variation of polymerization shrinkage strains of FRC compared to those of particulate filler composites and unfilled resin might be important for future clinical applications.     

Early plaque formation on fibre-reinforced composites in vivo

In the present study, two different fibre-reinforced composites (FRCs) (glass and polyethylene FRC), dental ceramic and restorative composite were compared with respect to early plaque formation in vivo. Disc-shaped specimens were randomly distributed among the upper first and second molars of 14 healthy adult volunteers. Plaque samples were collected 24 h after the attachment of the specimens. Mutans streptococci (MS), non-mutans streptococci and total facultative bacteria were cultured. The plaque recovered from polyethylene FRC harboured significantly more MS than the plaque of ceramic, restorative composite and glass FRC. For the counts of non-mutans streptococci and total facultative bacteria, polyethylene FRC showed the highest counts, and ceramic showed a trend towards lower counts. The amount of plaque accumulation showed an association to the earlier reported surface roughness values of the studied materials. It was concluded that in the oral environment, polyethylene FRC promotes plaque accumulation and adhesion of MS more than glass FRC, restorative composite and dental ceramic. Glass FRC resembles restorative composite with respect to plaque accumulation and the adherence of MS.     

Effect of water storage on the impact strength of three glass fiber-reinforced composites.

OBJECTIVES: The effect of water sorption on the impact strengths of two pre-impregnated fiber-reinforced composites (FRCs) and one impregnated FRC were studied. All FRCs were available clinically. METHODS: Eight 1.0 mm x 2.0 mm x 25.0mm bar-shaped specimens of each material were prepared according to manufacturers' instructions. The impact strength of each specimen was tested (adoption from ISO 179-1 Plastics-Determination of Charpy impact properties) after the specimens were immersed in 23.0+/-1 degrees C distilled water for seven, 60 and 180 days. The data were analyzed using the Weibull method. Scanning electron micrographs were taken to examine the mode of failure. RESULTS: Weibull analysis of the B10 strength of the FRCs showed that the difference in impact strength for each FRC due to the duration of water immersion was not significant (P>0.05). The impact strength of pre-impregnated E-glass FRC (Vectris) (75 kJ/m(2)) was not significantly different from the pre-impregnated S-glass FRC (FiberKor) (66 kJ/m(2)) (P>0.05). The impregnated FRC possessed impact strength (42 kJ/m(2)) that was not significantly different from the pre-impregnated S-glass FRC but was significantly lower than the pre-impregnated E-glass FRC. x100 SEMs of the three types of FRC specimens revealed fiber failure to be the predominant mode of failure. SIGNIFICANCE: Water immersion up to 180 days duration did not significantly affect the impact strength of three FRCs. The impact strength of the impregnated FRC was not significantly different from the pre-impregnated S-glass FRC but was significantly lower than the pre-impregnated E-glass FRC.     

Flexural properties of fiber reinforced root canal posts.

OBJECTIVES: Fiber-reinforced composite (FRC) root canal posts have been introduced to be used instead of metal alloys and ceramics. The aim of this study was to investigate the flexural properties of different types of FRC posts and compare those values with a novel FRC material for dental applications. METHODS: Seventeen different FRC posts of various brands (Snowpost, Carbopost, Parapost, C-post, Glassix, Carbonite) and diameters, (1.0-2.1 mm) and a continuous unidirectional E-glass FRC polymerized by light activation to a cylindrical form (everStick, diameter 1.5 mm) as a control material were tested. The posts (n=5) were stored at room's humidity or thermocycled (12.000 x, 5 degrees C/55 degrees C) and stored in water for 2 weeks before testing. A three-point bending test (span=10 mm) was used to measure the flexural strength and modulus of FRC post specimens. RESULTS: Analysis of ANOVA revealed that thermocycling, brand of material and diameter of specimen had a significant effect (p<0.001) on the fracture load and flexural strength. The highest flexural strength was obtained with the control material (everStick, 1144.9+/-99.9 MPa). There was a linear relationship between fracture load and diameter of posts for both glass fiber and carbon fiber posts. Thermocycling decreased the flexural modulus of the tested specimens by approximately 10%. Strength and fracture load decreased approximately 18% as a result of thermocycling. SIGNIFICANCE: Considerable variation can be found in the calculated strength values of the studied post brands. Commercial prefabricated FRC posts showed lower flexural properties than an individually polymerised FRC material.     

Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

PURPOSE: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or bisphenol glycidylmethacrylate monomers and 1 ultrahigh molecular weight polyethylene fiber. Failure types were also evaluated. MATERIALS AND METHODS: A total of 40 caries-free, human maxillary central incisors (n = 10 per group) received surface-retained direct cantilever restoration (1 pontic) after etching and application of bonding agent. Four FRC materials were used (FRC1 = EverStick; FRC2 = BR-100; FRC3 = Interling; FRC4 = Ribbond), and pontics were built up using 1 particulate filler composite (Clearfil Photo Posterior). After the fracture test, failure types were analyzed. RESULTS: No significant difference was found between the 4 FRC types veneered with particulate filler composite (893 +/- 459 N to 1326 +/- 391 N) (P = .1278). Complete pontic fracture at the connector area was most prominent for FRC4 (90%), followed by FRC3 (70%). Only FRC2 (10%) showed some fiber fractures, with half of the fiber remaining attached on the enamel surface of the abutment. CONCLUSION: The fracture strengths of cantilever FPDs made of 4 FRC materials with different monomer matrices and architectures, veneered with particulate filler composite, did not show significant differences. However, failure behavior varied between groups.     

Post-endodontic restorations with adhesively luted fiber-reinforced composite post systems: a review

PURPOSE: To review the literature on adhesive luting of fiber-reinforced composite posts (FRC) to provide evidence for the clinical procedure of restoring endodontically treated teeth using FRC posts. METHODS: Data focusing on bonding behavior between root canal dentin, luting agent, and FRC post in vitro as well as in vivo performance of teeth restored with FRC posts were reported. These data were identified by searches of "PubMed", "Scopus", and "Cochrane Library" databases with the terms "post-endodontic restoration", "fiber post", "adhesive luting", "root canal dentin", "clinical study", and "pre-treatment fiber post". Papers published up to September 2007 were selected, and most relevant references were chosen. Cross-referencing of significant papers identified additional relevant articles. RESULTS: FRC posts seem to have become increasingly popular for the restoration of endodontically treated teeth. Compared to metal posts, FRC posts revealed reduced fracture resistance in vitro, along with a usually restorable failure mode. Bonding behavior among FRC post, luting agents, and root canal dentin demonstrated varying results. Bond strengths between FRC posts and resin cements can be enhanced by using various pre-treatment procedures; however, bonding to root canal dentin still seems to be challenging. Most clinical studies investigating survival rates of teeth restored with FRC posts revealed promising results, but risk factors (e.g., the loss of coronal tooth structure) have not been studied intensively. In addition, randomized controlled clinical long term trials are scarce.     

Reinforcing effect of glass-fiber-reinforced composite on flexural strength at the proportional limit of denture base resin

OBJECTIVE: To evaluate the reinforcing effect of fiber-reinforced composite (FRC) on flexural strengths at the proportional limit (FS-PL) of a denture base resin. MATERIAL AND METHODS: Bar-shaped acrylic resin specimens and maxillary acrylic resin complete denture specimens were fabricated. The FS-PL of the reinforced bar-shaped specimens was tested. Novel FRC, FibreKor, Remanium, Palatal Bar Wire, and Clasp-Wire were used as reinforcing materials. Likewise, the compressive strength at the proportional limit (CS-PL) of the reinforced maxillary denture specimens was tested. RESULTS: The FS-PL of the bar-shaped specimens reinforced with the FRCs was significantly higher than that of the unreinforced specimens. The FS-PL of the bar-shaped specimens reinforced with the 1.0-mm-thick FRC was similar to the FS-PL of specimens reinforced with Remanium or Palatal Bar Wire. The FS-PL of specimens reinforced with the 1.5-mm-thick FRC was significantly higher than with the metal-reinforcing materials. The reinforcing efficiency of the 1.0-mm-thick FRC was 1.78-1.79 and of the 1.5-mm-thick FRC 3.14-3.27. The reinforcing effect of the FRC on the CS-PL of the maxillary denture specimen was similar to the effect on the FS-PL of the bar-shaped specimens. The reinforcing efficiency was 1.40 for the 1.0-mm-thick FRC and 1.67 for the 1.5-mm-thick FRC. CONCLUSION: The unidirectional glass-fiber-reinforced composite had a reinforcing effect on the flexural strength at the proportional limit of the denture base resin.     

Load bearing capacity of fibre-reinforced and particulate filler composite resin combination

OBJECTIVES: Longevity of particulate filler resin (PFR) is controversial for large restorations with high occlusal-stresses. The aim of this study was to reinforce PFR with fiber reinforced composite (FRC) and to evaluate the effect of thickness of FRC substructure and thickness of overlaying PFR, on the static load-bearing capacity of the material combination. METHODS: A total of 336 test specimens having a FRC substructure (short random or continuous bidirectional fibre orientation) and layer of restorative PFR were prepared for this study. In Group A, the specimens contained short random oriented fibres (length: 2-3mm) and in Group B, there were continuous bidirectionally oriented fibres. The specimens (n = 12/group) were polymerized with a hand light-curing unit and were either dry-stored or thermocycled before they were statically loaded with a steel ball until fracture, using a universal testing machine. RESULTS: Increase the volume fraction of the short random FRC versus the fraction of PFR, the load-bearing capacity of the specimen increased (p < 0.001). Short random FRC revealed significantly different behavior than the bidirectionally oriented FRC (p < 0.001). By combining the FRC layer of 0.5mm in thickness with a layer of 2.5mm of PFR gave load values of 1462N and 1196N, which were considerably higher than values for plain PFR of 3mm in thickness (782N and 729N). CONCLUSION: The results suggest that by adding a FRC substructure under the PFR, the load-bearing capacity of the material combination was increased.     

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.