Evaluation of physical properties of fiber-reinforced composite resin

doi:10.1016/j.dental.2020.04.012

Dental Materials

Volume 36, Issue 8, August 2020, Pages 987-996

https://doi.org/10.1016/j.dental.2020.04.012 Get rights and content

Highlights

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Physical properties of a fiber-reinforced CAD/CAM resin disc (TRINIA) were examined.
•
TRINIA demonstrated distinct anisotropy.
•
TRINIA can be superior restorative material when specifying direction of mesh layers.

Abstract

Objectives

This study aimed to investigate physical properties of a fiber-reinforced CAD/CAM resin disc, which included woven layers of multi-directional glass fibers.

Methods

Fiber orientations of CAD/CAM specimens (TRINIA, SHOFU) were specified as longitudinal (L), longitudinal-rotated (LR), and anti-longitudinal (AL). A fiber-reinforced composite (everX posterior, GC (E)) and a conventional composite (Beauti core flow paste, SHOFU (B)) were also tested.

A three-point bending test and a tensile test with notchless prism-shaped specimens were conducted using a universal testing machine (AUTOGRAPH AG-IS, Shimadzu). A water absorption test was also carried out after the specimens were stored in water for 24 h or 1 week. Flexural strength and fracture toughness were obtained by conducting a three-point bending test.

Results

TRINIA L and LR groups showed significantly high flexural strength (254.2 ± 22.3 and 248.8 ± 16.7 MPa, respectively). Those were approximately 2.5 times higher than those in AL, E, and B groups (96.8–98.0 MPa) (p < 0.05, ANOVA and Tukey HSD test). No significant difference was shown in flexural modulus among the experimental groups. The fracture toughness in L group (9.1 ± 0.4 MPa/m^1/2) was found to be significantly higher than those in other groups (1.9–3.0 MPa/m^1/2; p < 0.05). TRINIA group demonstrated significantly lower water absorption (4.7 ± 1.9 μg/mm³) than did E (16.1 ± 3.1 μg/mm³) and B (17.3 ± 3.7 μg/mm³) groups (p < 0.05).

Significance

TRINIA demonstrated distinct anisotropy. TRINIA can be used as a superior restorative material when specifying directions of its fiber mesh layers.

Graphical abstract

Introduction

In recent years, restorative treatments for preserving sound tooth structures with minimal intervention to the dentin have become important, based on the concept of minimal intervention dentistry (MID) [1]. Composite resin have been widely used to achieve the MID concept. Hybrid resin developed for restoring molars has been clinically successful. These positive results have expanded the indications of composite resin in a wide range of restorations, such as fixed partial dentures and full-mouth rehabilitation [2], [3]. Subsequently, various attempts have been made to improve the mechanical properties of composite resin to meet this clinical demand.

In the industry, fibers have been used as reinforcement of resin, called as the fiber-reinforced plastic (FRP) [4]. FRP is also used in dentistry. The representative examples of FRP in dentistry are hybrid resin for crown restoration, fiber post, high strength composite resin bridge, and CAD/CAM glass fiber reinforced resin. In all these materials, the fiber contained in FRP should be able to bear the tensile and bending stress and need to firmly adhere to resin matrix [5].

There are three patterns of fiber forms in FRP; random short fiber reinforced type (RSFRT), unidirectional continuous fiber reinforced type (UCFRT), and textile laminate reinforced type (TLRT). RSFRT is reinforced by short fibers randomly arranged in the matrix resin. UCFRT is reinforced by continuous fibers arranged unidirectionally in the matrix resin. TLRT is reinforced by tailoring fiber bundles into mesh fabrics. However, contributions of these fibers in improving the mechanical properties of FRP have not been clearly demonstrated. In particular, the effects of forms and directions of the fibers on reinforcing restoratives need to be comprehensively investigated.

Recent developments in digital technologies have significantly progressed the production of a restorative crown, especially CAD/CAM systems. A CAD/CAM crown can be made now by a simple process of milling a hybrid composite or a ceramic block without using complex technical procedures.

In this study, a glass fiber reinforced resin disc, TRINIA (SHOFU, Kyoto, Japan), was used, which was composed of 55 wt% glass fibers and 45 wt% epoxy resin matrix. A TRINIA disc, with fibers aligned as meshes and layers in a disc, seems to have good potential to produce various kinds of restorations by CAD/CAM system [6].

The purpose of this study was to evaluate flexural strength (FS), fracture toughness (FT), and water absorption of CAD/CAM glass fiber reinforced resin – TRINIA – by regulating the directions of fiber layers.

Section snippets

Materials

Materials used in this study are presented in Table 1. A glass fiber-reinforced resin disc (TRINIA, SHOFU, Kyoto, Japan) was composed of 45 wt% epoxy resin matrix and 55 wt% multi-directionally interlaced glass fibers, which aligned woven layers parallel to the top surface of the disc. Exposed fiber size was not disclosed. By SEM observation, the width and thickness of E-glass fibers were 1.2–1.5 mm and 0.1–0.4 mm, respectively. A fiber-reinforced composite resin (everX Posterior, GC, Tokyo, Japan)

Results

FS and flexural modulus (FM) of the materials tested are presented in Fig. 3. TRINIA longitudinal and longitudinal-rotated groups, which had the multi-directional glass fibers layered longitudinally parallel to the specimens, demonstrated significantly high FS (254.2 ± 22.3 and 248.8 ± 16.7 MPa, respectively). Those were approximately 2.5 times higher than those of TRINIA anti-longitudinal (96.9 ± 2.9 MPa), everX posterior (98.0 ± 15.9 MPa), and Beauti core flow paste (96.8 ± 3.3 MPa) groups. TRINIA

Discussion

Fiber reinforced materials have become popular in dental restorations, especially in post-core for restoring pulpless teeth [9], [10], [11] and in constituting the framework for bridge restoration [12], [13], [14]. Superior mechanical properties of fiber-reinforced composite resin have been reported [15]. Fiber-reinforced composite resin, containing randomly distributed short glass fiber (0.2–0.3 mm), have been demonstrated to have higher FS, elastic modulus, and FT compared to conventional

Conclusion

TRINIA demonstrated distinct anisotropy. TRINIA can be used as a superior restorative material when specifying directions of its fiber mesh layers.

Funding sources

This study was supported by the Grants-in-Aid for Scientific Research (17H04382, 17K19907 and 16K20454) from JSPS and SECOM science Technology Foundation Grant (2019).

Conflict of interest

None declared.

Acknowledgements

The authors are grateful to SHOFU for kindly providing some of the materials used.

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Effect of nanofibers as reinforcement on resin-based dental materials: A systematic review of in vitro studies
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This systematic review provides an update on the effect of nanofibers as reinforcement on resin-based dental materials. A bibliographic search was conducted in MEDLINEPubMed, Embase, Web of Science, Scopus, BVS (LILACS, BBO e IBECS), Cochrane, LIVIVO, and gray literature (BDTD) to identify relevant articles up to May 2021. In vitro studies that evaluated and compared the mechanical properties of nanofibers resin-based composite materials, were eligible. No publication year or language restriction was applied, and methodological quality was assessed using two methods. In a total of 6100 potentially eligible studies, 81 were selected for full-text analysis and 35 were included for qualitative analysis. Of the 35 included studies, a total of 29 studies evaluated the flexural strength (FS) of the materials. These groups were distinguished according to the resin-based materials tested and nanofiber types. Most of the studies evaluated materials composed of glass fibers and demonstrated higher values of FS when compared to resin-based materials without nanofibers. The incorporation of nanofibers into resin-based dental materials improved the mechanical properties compared to resin-based materials without nanofibers, suggesting better performance of these materials in high-stressbearing application areas. Further clinical studies are required to confirm the efficacy of resin-based materials with nanofibers.
Fibre-reinforced Cad/CAM post and cores: The new “gold standard” for anterior teeth with extensive coronal destruction?–A fully digital chairside workflow
2023, Heliyon
Since one-third of persons suffer a dental trauma, treatment of anterior teeth using post and core (PC) is becoming important. In teeth with extensive destruction, cast PC (CPC) remain the “gold standard”, even though they lead to aesthetic impairment and have a mismatching elastic modulus to that of dentin. Prefabricated fibre-reinforced posts have elastic modulus similar to that of dentin but the accuracy of fit and mechanical stability are worse. This study was aimed to evaluate the deviation and mechanical performance of fibre-reinforced CAD/CAM PC (FRPC) fabricated in a fully digital chairside workflow, compared to those of CPC.
On 30 teeth, a PC preparation was conducted, and a conventional and digital post impression were taken with an intraoral scanner. Fifteen teeth each were treated with CPC and FRPC, respectively. The deviation was evaluated by superimposing the datasets of the digitalised stone models and digital post impressions. Decementation and root fracture during chewing simulation were analysed by microscopy and X-ray. Statistical analysis was performed by pairwise comparison and Kaplan-Meier analysis.
The median deviation for the “coronal”, “middle” and “apical” were 14.5, 18.0 and 113.7 μm, respectively. The pairwise comparison for “coronal”/“middle” showed no significance (p = 0.465), whereas that for “coronal”/“apical” and “middle”/“apical” showed highly significant differences (p < 0.001). After chewing simulation, five decementations and two root fractures were detected for CPC. For FRPC, neither decementation nor root fracture were documented.
Within the limitations of this study, FRPC performed significantly better than CPC.
Finite element analysis of maxillary first molar with mesial-occlusal-distal-palatal defect restored with different post-and-core strategies
2023, Heliyon
To explore which restoration strategy generates the most favorable stress distribution in an endodontically-treated maxillary first molar with mesial-occlusal-distal-palatal defect.
Models with one post in palatal canal (PP), each post in palatal and distobuccal canals (PDP), each post in palatal and mesiobuccal canals (PMP), and each post in all canals (PDMP) were established for an endodontically-treated maxillary first molar with mesial-occlusal-distal-palatal defect either with fiber-reinforced composite (FRC) post or gold alloy cast (GAC) post. A 400-N vertical force and a 225-N lateral force were respectively applied. The Mohr-Coulomb stress ratio (σ_{MC ratio}) in the residual tooth structure (RTS), the resin cement, and the crowns, the tensile stress (σ_t) and compressive stress (σ_c) in the FRC posts, the von-Mises stress ratio (σ_{vM ratio}) in the GAC post-and-cores, and the σ_t and shear stress (σ_s) at the adhesive interfaces were calculated using finite element analysis.
FRC posts generated lower σ_{MC ratio} than GAC posts in the RTS (0.3274–0.3643 vs. 0.3399–0.4118). Among the FRC post groups, the PDMP group got the lowest σ_s at the dentin-post interface (14.92 MPa) and the abutment-crown interface (8.242 MPa) under vertical loading, as well as the lowest σ_{MC ratio} in the RTS (0.3381) and the lowest σ_s at the dentin-post interface (38.00 MPa) under lateral loading.
From the point of stress distribution, placing FRC posts in the palatal, distobuccal, and mesiobuccal canals is the optimal strategy in restoring a severely damaged maxillary first molar, provided that lateral occlusal force is reduced.
Mechanical comparison of milled fiber-reinforced resin composite and Co–Cr frameworks with different connector cross-sectional geometries: An in vitro study
2023, Journal of the Mechanical Behavior of Biomedical Materials
This study compared the effect of using milled fiber-reinforced resin composite and Co–Cr (milled wax and lost-wax technique) frameworks for 4-unit implant-supported partial fixed dental prostheses; and also, evaluated the influence of the connector's cross-sectional geometries on the mechanical behavior. Three groups of milled fiber-reinforced resin composite (TRINIA) for 4-unit implant-supported frameworks (n = 10) with three connectors geometries (round, square, or trapezoid), and three groups of Co–Cr alloy frameworks manufactured by milled wax/lost wax and casting technique, were analyzed. The marginal adaptation was measured before cementation using an optical microscope. Then, the samples were cemented, thermomechanical cycled (load of 100 N/2 Hz, 10⁶ cycles; 5, 37, and 55 ᵒC, a total of 926 cycles at each one), and cementation and flexure strength (maximum force) analyzed. Analysis of stress distribution in framework veneered considering resin and ceramic properties for fiber-reinforced and Co–Cr frameworks, respectively, implant, and bone was by finite element analysis under three contact points (100 N) on the central region. ANOVA and Multiple paired test-t with Bonferroni adjustment (α = 0.05) were used for data analysis. Fiber-reinforced frameworks showed better vertical adaptation (mean ranged from 26.24 to 81.48 μm) compared to the Co–Cr frameworks (mean ranged from 64.11 to 98.12 μm), contrary to horizontal adaptation (respectively, means ranged from 281.94 to 305.38 μm; and from 150.70 to 174.82 μm). There were no failures during the thermomechanical test. Cementation strength showed three times higher for Co–Cr compared to fiber-reinforced framework, as well as flexural strength (P < .001). Regarding stress distribution, fiber-reinforced had a pattern of concentration in the implant-abutment complex. There were no significant differences in stress values or changes observed among the different connector geometries or framework materials. Trapezoid connector geometry had a worse performance for marginal adaptation, cementation (fiber-reinforced 132.41 N; Co–Cr 255.68 N) and flexural strength (fiber-reinforced 222.57 N; Co–Cr 614.27 N). Although the fiber-reinforced framework showed lower cementation and flexural strength, considering the stress distribution values and absence of failures in the thermomechanical cycling test, it can be considered for use as a framework for 4-unit implant-supported partial fixed dental prostheses in the posterior mandible. Besides, results suggest that trapezoid connectors mechanical behavior did not perform well compared to round or square geometries.
Retentive force of conical crowns combining zirconia and fiber-reinforced composite
2022, Journal of Dentistry
Citation Excerpt :
Furthermore, elastic deformation of the secondary crown made of FRC may limit the relative movement between the primary and secondary crowns. The FRC used in this experiment consisted of 55 wt% glass fiber and 45 wt% epoxy resin matrix [34]. The horizontally oriented glass fiber sheets are multidirectionally interlaced and stacked in vertical direction.
This study investigated the retentive force of conical crowns combining zirconia primary and fiber-reinforced composite (FRC) secondary crowns and their changes due to aging.
Zirconia primary crowns were produced with a convergence angle of 3°. Thirty-two secondary crowns were milled from FRC and divided into two groups (n = 16/group) based on the polishing method of the secondary crown inner surfaces: diamond paste (Group 1) and silicone points (Group 2). After fitting the secondary crowns with different fitting forces (F), loosening forces (L) were determined. Tests were repeated after an occlusal stop (OS) was added to the secondary crown and artificial aging (10,000 insertion/removal cycles). Data were compared using the Wilcoxon and Mann–Whitney U tests.
Crowns without an OS showed L/F ratios of 0.4586 (Group 1) and 0.4104 (Group 2). With an OS, maximum retention was not significantly affected by the polishing method and could be limited to L_max = 19.31±7.77 N (Group 1) and L_max = 16.12±5.92 N (Group 2).
These findings suggest that the combination of conical zirconia primary and FRC secondary crowns can obtain acceptable retentive forces that are not affected by aging if the inner surfaces are polished with diamond paste. OS generation could limit maximum retention, but should be adjusted if the target value of 10 N is not to be exceeded. With a change of the convergence angle to 4°, L/F values for crowns without an OS would be close to 1/3, which is considered ideal for conical crowns.
The combination of zirconia primary crowns and FRC secondary crowns was found feasible to ensure the required retention for clinical use over a long time span. Furthermore, it offers an alternative to metal-based restorations while ensuring high levels of biocompatibility and esthetics.
Mechanical behaviour of prosthodontic CAD/CAM polymer composites aged in three food-simulating liquids
2022, Dental Materials
Citation Excerpt :
However, reinforced PEEK and carbon fibre reinforced composites were associated with significantly lower vertical bone loss as ISF (0.7 and 0.8 mm, respectively) than the titanium group (0.96–1.0 mm) [14]. A few in vitro studies have investigated HPP composites in terms of their load dissipating feature [15–18], biocompatibility [19–21] and mechanical properties in relation to fibre orientation [22,23] or filler content [24]. However, there is a need to monitor mechanical properties of new polymer composites under simulated challenges of the oral environment.
This study investigated the effect of ageing in three food-simulating liquids (FSLs) on mechanical properties of three prosthodontic CAD/CAM polymer composites intended for construction of implant-supported frameworks.
Materials investigated were: (i) a carbon fibre-reinforced composite (CarboCAD 3D dream frame; CC), (ii) a glass fibre-reinforced composite (TRINIA; TR), and (iii) a reinforced PEEK (DentoKeep; PK). Filler contents and microstructural arrangements were determined by thermo-gravimetry and tomography (µ-CT), respectively. Flexural properties (FS and E_f) were measured by 3-point bending (3PB) of 1 mm and 2 mm thick beam specimens. Fracture toughness (K_IC) was measured by single-edge-notched-bending (SENB). All measurements were made at baseline (dry) and after 1-day and 7-day storage at 37 ℃ in either water, 70 % ethanol/water (70 % E/W) or methyl ethyl ketone (MEK). Failed specimens were examined microscopically. Statistical analyses included four-way ANOVA, two-way ANOVA and multiple Tukey comparison tests (α = 0.05). Multiple independent t-tests were performed regarding thickness effects on FS and E_f (α = 0.05).
At baseline, the mechanical properties increased in the sequence: PK < TR < CC (p < 0.001). FS ranged from 192.9 to 501.5 MPa; E_f from 4.2 to 18.1 GPa; and K_{IC f}rom 4.9–12.4 MPa.m^0.5. Fibre-reinforced composites (CC and TR) were significantly stronger than PK. However, all properties of CC and TR reduced after 1 d storage in 70 % E/W and MEK with FS ranging from 58.6 to 408 MPa; E_f from 1 to 15.4 GPa; K_IC from 6.87 to 10.17 MPa.m^0.5. Greater reductions occurred after 7 d storage. MEK was more detrimental than 70 % E/W and water on fibre-reinforced composites.
Mechanical properties of each CAD/CAM composite were strongly dependent upon media and ageing. Although the mechanical properties of PK were initially inferior, it was relatively stable in all FSLs. All three materials exhibited sufficient mechanical properties at 1 mm thickness, but thicker specimens were more tolerant to ageing.

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Evaluation of physical properties of fiber-reinforced composite resin

Highlights

Abstract

Objectives

Methods

Results

Significance

Graphical abstract

Introduction

Section snippets

Materials

Results

Discussion

Conclusion

Funding sources

Conflict of interest

Acknowledgements

J Prosthet Dent

Dent Mater

J Prosthodont Res

J Dent

J Biomech

J Prosthodont Res

Dent Mater

Dent Mater

J Prosthet Dent

Dent Mater

J Mech Behav Biomed Mater

FDI, statement