Comparison of mechanical properties of a new fiber reinforced composite and bulk filling composites

Research article ISSN 2234-7658 (print) / ISSN 2234-7666 (online) http://dx.doi.org/10.5395/rde.2015.40.4.262 Comparison of mechanical properties of a new fiber reinforced composite and bulk filling composites Hazem Abouelleil1*, Nelly Pradelle1,2, Cyril Villat1,3, Nina Attik1, Pierre Colon1,2, Brigitte Grosgogeat1,3 1 Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Université Lyon1, Villeurbanne, France 2 UFR D’odontologie, Université Paris Diderot, APHP, Hôpital Rothschild, Service d’Odontologie, Paris, France 3 UFR Odontologie, Université Lyon1, Service de Consultations et de Traitements Dentaires, Hospices Civils de Lyon, Lyon, France Received April 2, 2015; Accepted June 30, 2015. Objectives: The aim of this study was to evaluate the mechanical and physical properties of a newly developed fiber reinforced dental composite. Materials and Methods: Fiber reinforced composite EverX Posterior (EXP, GC EUROPE), and other commercially available bulk fill composites, including Filtek Bulk Fill (FB, 3M ESPE), SonicFill (SF, Kerr Corp.), SureFil (SDR, Dentsply), Venus Bulk Fill (VB, HerausKultzer), Tetric evoceram bulk fill (TECB, Ivoclar Vivadent), and Xtra Base (XB, Voco) were characterized. Composite samples light-cured with a LED device were evaluated in terms of flexural strength, flexural modulus (ISO 4049, n = 6), fracture toughness (n = 6), and Vickers hardness (0, 2, and 4 mm in depth at 24 hr, n = 5). The EXP samples and the fracture surface were observed under a scanning electron microscopy. Data were statistically analyzed using one-way ANOVA and unpaired t-test. Results: EXP, FB, and VB had significantly higher fracture toughness value compared to all the other bulk composite types. SF, EXP, and XB were not statistically different, and had significantly higher flexural strength values compared to other tested composite materials. EXP had the highest flexural modulus, VB had the lowest values. Vickers hardness values revealed SF, EXP, TECB, and XB were not statistically different, and had significantly higher values compared to other tested composite materials. SEM observations show well dispersed fibers working as a reinforcing phase. Conclusions: The addition of fibers to methacrylate-based matrix results in composites with either comparable or superior mechanical properties compared to the other bulk fill materials tested. (Restor Dent Endod 2015;40(4):262-270) Key words: Bulk composite; Fiber composite; Mechanical properties 1 Abouelleil H; Pradelle N; Villat C; Attik N; Colon P; Grosgogeat B, Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Université Lyon1, Villeurbanne, France 2 Pradelle N; Colon P, UFR D’odontologie, Université Paris Diderot, APHP, Hôpital Rothschild, Service d’Odontologie, Paris, France 3 Villat C; Grosgogeat B, UFR Odontologie, Université Lyon1, Service de Consultations et de Traitements Dentaires, Hospices Civils de Lyon, Lyon, France *Correspondence to Hazem Abouelleil, DDS, MD. Dental practitioner and Lecturer, Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Université Lyon1, Villeurbanne, France TEL, +33(0)478778689; FAX, +33(0)478 778712; E-mail, Introduction Dental composite resin recently became the material of choice for most patients and dental practitioners.1 However, volumetric shrinkage and fracture are still considered as major concerns with dental composites.2,3 In order to overcome these weaknesses, attempts have been made toward increasing both their physical and mechanical properties.4 This necessitates the comprehensive appraisal of each of its components such as the resin matrix, the filler or the filler-resin interface, and their role in affecting the material properties. Different studies have investigated this in order to improve composite properties, either by varying the particle size, percentage, or by development of the polymer matrix chemistry.4,5 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 262 ©Copyrights 2015. The Korean Academy of Conservative Dentistry. Mechanical properties of a fiber reinforced composite Evolution in both filler and polymer technology in dental composite resins led to a wide selection of materials that provide the adequate properties required for each clinical situation.4 Yet, the use of dental composites in high stress bearing areas remains to be a challenge for the dental practitioner, since bulk fracture is still considered one of the primary reasons for failure.2,6 Bulk fill composites were introduced in an effort to improve the performance of composite resin restorations, which was inserted in 4 mm increments mainly in the posterior areas and considered to have higher physical and mechanical properties to endure the higher masticatory stresses. Moreover, the reduced treatment time decrease the risk of air entrapment or moisture contamination.7 They are also claimed to reduce cuspal deflection and promote light transmittance. 7,8 Currently, various studies reveal the difficulty in comparing between the available materials due to variation in composition and viscosity.9-11 Bulk filling composites usually have higher filler volume percentage, and sometimes a modified initiator system to ensure better curing in depth, as compared to conventional composites. While no long term clinical studies are available regarding their intraoral performance, Ilie et al. found bulk filling composites to have lower mechanical properties, except for flexural strength as compared to nanohybrid and microhybrid resin based composites.9 However, other studies found them equally successful compared to conventional composites.7,12 Many bulk fill composite resins have been investigated regarding different parameters like degree of conversion, polymerization stress or microleakage. Such studies have shown that bulk fill composites resins have similar properties as conventional dental composite resins.12-16 Finan et al. studied the degree of conversion, biaxial flexural strength and Vickers hardness of two flowable bulk composites (SDR and XB), and despite the differences between the two materials, found that the properties justify their use in 4 mm increments.17 The variation in material composition and viscosity, whether flowable or non flowable bulk composites, leads to differences in physical and mechanical properties among the bulk fill composites available in the market.7 Fiber reinforcement of conventional dental composites were also introduced with the aim of enhancing their physical and mechanical properties, and increasing their resistance to fracture. The enhancement of the material properties was due to the stress transfer from the matrix to the fibers depending on the fibers length and diam (...truncated)