Effect of oral environment on new fiber-reinforced composites system

This journal suppl. entitled: Abstracts of the Academy of Dental Materials Annual Meeting, 9-12 October 2013 - Vancouver, BC, CanadaPURPOSE: Fiber-reinforced composite (FRC) consists of matrix that is reinforced with thin fibers, which have high tensile strength and flexural modulus (Zhang and Matinlinna, Silicon 4 (2012) 73). The bis-GMA-MMA combination is widely used as resin matrix, whereas bis-GMA is reported to be the most cytotoxic monomer among dental resin composite monomers (Moharamzadeh et al., Material 2 (2009) 514). Resin matrix 1,6-hexanediol dimethacrylate (HDMA) has similar reactive groups than bis-GMA, and is not listed among carcinogens (Vallittu and Sevelius, J Prosthet Dent 84 (2000) 13). The purpose of this study was to investigate the water sorption of a new resin matrix system of FRC based on HDMA. METHODS AND MATERIALS: Materials used were: E-glass fiber bundles (Stick Tech, Finland), HDMA (Esstech, USA), bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), CQ (Esstech, USA) and CEMA (Esstech, USA). Fifteen specimens (2mm×2mm×25mm) were prepared and divided into 3 groups. Composition of group 1: 78.4%HDMA +19.6%MMA+ 1.0%CQ + 1.0%CEMA; group 2: 49.0%HDMA +49.0%MMA+ 1.0%CQ + 1.0%CEMA; and group 3: 78.4%bis-GMA +19.6%MMA+ 1.0%CQ + 1.0%CEMA. Specimens with two fiber rovings of 25mm long were placed in a mould and monomers were added and light-cured with halogen light-curing unit on both sides for 3×40 s. Specimens were immersed in 15 ml distilled water of 37 ◦C for 21 days. The difference in weights, before and after immersion were recorded. Data obtained were analyzed by one-way ANOVA and LSD. RESULTS: As for the difference in weights (before and after immersion), group 1 showed the lowest average (0.004%), followed by group 3 (0.003%) and group 2 (0.01%). Statistical analysis (ANOVA) proved a significant difference among the three groups (p 0.05). CONCLUSION: It can be concluded that FRC based on HDMA matrix system (group-1) is comparable to bis-GMA (group-3) on its water sorption.postprin

Cytotoxicity evaluation of new resin matrix system on fiber-reinforced composites

This journal suppl. entitled: Abstracts of the Academy of Dental Materials Annual Meeting, 9-12 October 2013 - Vancouver, BC, CanadaPURPOSE: Recent commercial resin matrix systems use bis-GMA as the basic matrix. A previous studies showed that bis-GMA affected the vitality of dental pulp and induced pulpal inflammation (Engelmann J, et al. Biomaterials 2004;25:4573), was able to disturb normal differentiation procedures of pulp fibroblasts (Imazato S, et al. J Biomed Mater Res Part B: Appl Biomater 2009;88B:378), and induced allergic contact stomatitis (Stoeva et al. J IMAB-Ann Proc 2008;book 2:45). A monomer alternative to bis-GMA, such as 1,6-hexanediol dimethacrylate (HDMA), is under current research. The purpose of this study was to determine the cytotoxicity property of HDMA on fibroblast cells by MTT method. METHODS AND MATERIALS: The materials used were bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), HDMA (Esstech, USA), CQ (Esstech, USA), CEMA (Esstech, USA), Eglass fibers (Stick Tech, Finland), Vero fibroblast cell line (UGM, Indonesia). Fifteen specimens of FRCs (2×2×25)mm were prepared and divided into 3 groups. The experiment groups were 78.4%HDMA +19.6%MMA+ 1.0%CQ + 1.0%CEMA (Exp-1 group) and 49.0%HDMA +49.0%MMA+ 1.0%CQ + 1.0%CEMA Exp-2 group), whilst the control group was 78.4%bis-GMA+19.6%MMA+ 1.0%CQ + 1.0%CEMA. Specimens were milled and diluted in culture medium (0.1mg powder/1mL medium). Specimen solution of 100µL was added into 96-well plate containing fibroblast cells of 2×104 cells/100µL and incubated for 24 h. MTT of 10µL was added to the well, incubated for 4h, then 100µL stop solution was added. The OD of the cells viability was determined by a ELISA reader with a wavelength of 550 nm. Cells viability was calculated in percentage and analyzed by ANOVA and LSD. RESULTS: Analysis by one way ANOVA revealed significant differences of cells viability among the groups (p 0.05). CONCLUSION: A resin matrix system based on HDMA–MMA (exp-1 group and exp-2 group) revealed a significant difference of fibroblast cells viability compared to a bis-GMA–MMA matrix system. The HDMA–MMA matrix systemwas less cytotoxic than bis-GMA–MMA matrix system.postprin

Effect of a New Resin Matrix System on fiber-reinforced composites

Oral Session: Scientific Groups - 36. Dental Materials: New Restorative Material Technology: no. 289OBJECTIVES: There are concerns that dental materials based on bis-phenol-A-diglycidylmethacrylate (bis-GMA) may be hazardous. Alternative monomers for bis-GMA, such as 1,6-Hexanediol dimethacrylate (HDMA), is under our current research. The aim of this research was to determine the effect of resin matrix compositions on the biomechanical properties of E-glass FRCs. METHODS: Three monomer compositions based on bis-GMA (Sigma-Aldrich, USA), methylmethacrylate (MMA) (ProSciTech, Australia), HDMA (Esstech, USA), and camphorquinone (CQ) (Esstech, USA), N,N-cyanoethyl methylaniline (CEMA) (Esstech, USA), unidirectional E-glass fibers (Stick Tech, Finland) were used. The ratio of the ...postprin

Effect of water immersion on monomer and strength of FRC

This journal suppl. entitled: Abstracts of the Academy of Dental Materials Annual Meeting, 8-11 October 2014 - Bologna, ItalyPURPOSE: There is an interest in the use of fiber-reinforced composite (FRC) to support the concept of minimal invasive dentistry. The exposure of FRC to the oral environment causes detrimental effect of water sorption (Takashi et al. Dent Mat 2006 22:291). With time water molecules will act as plasticizers and decrease the mechanical properties (Mese and Guzel. J Prosthet Dent 2008 99:153). Monomer system is the backbone of the dental composite (Garcia et al. Clinical Dentistry 2005: 215) and residual monomer may dissolve in water (Tanaka et al. J Oral Rehab 1991 18:353). Some released monomers are knownto elicit cytotoxic effects (Sakaguchi and Powers. Craig’s Restorative Dental Materials 2012:343), and methyl methacrylate (MMA) is mentioned as cytotoxic (Pradeep and Sreekumar. J Contemp Dent Pract 2012 6:838). This study investigated the effect of water immersion duration on monomer release and the compressive strength of fiber-reinforced composite. METHODS AND MATERIALS: Materials used were: E-glass fibre (Stick Tech, Finland), bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), CQ (Esstech, USA) and CEMA (Esstech, USA). Fifteen specimens (2mm×2mm×25mm) with the composition of: 78.4% bis-GMA+19.6%MMA+ 1.0%CQ + 1.0%CEMA were prepared and divided into 2 groups: compressive strength (CS-12specimens) and residual monomer (RM-3specimens). Each specimen had two fiber rovings of 25mm and placed in a mould, and light-cured with halogen light-curing unit on both sides for 3×40 s. Specimens from each group were divided into three groups based on the water immersion durations (1, 14 and 21 days) and immersed into 10 ml distilled water at 37 ◦C. The three RM-specimens were analyzed using HPLC to test the residual monomer concentration. All CS-specimens were tested using UTM (Torsee’s UTM, Tokyo Testing Machine Mfg., Co., Ltd., Japan) for the compressive strength. RESULTS: The data of MMA concentration was descriptively analyzed. It started on day 1 (2352.96µg/ml) followed by an increase on day14 (3567.15µg/ml) and decreased on day 21 (2427.19µg/ml). Compressive strength showed an average (MPa) for day 1 (93.84±8.30); day 14 (67.83±4.82) and day 21 (51.08±2.10), respectively. Data from the compressive strength was analyzed by ANOVA, and it proved a significant decrease as the water immersion duration increases (p < 0.05). CONCLUSION: The duration of water immersion of e-glass FRC showed different effect on the concentration of released monomer and the compressive strength. Highest concentration of MMA concentration occurred on day 14 and followed by a decrease. As for the compressive strength, it decreased as the water immersion duration increased.postprin

Biomechanical properties of a new fiber-reinforced composite

Oral Session: Scientific Groups - 36. Dental Materials: New Restorative Material Technology: no. 290OBJECTIVES: Nowadays the replacement of bis-GMA is gaining more and more interest because of its potential risks. A potential resin matrix component, 1,6-hexanediol dimethacrylate (HDMA) has lower viscoucity than bis-GMA.The present study evaluated the effect of water immersion and HDMA concentrations on the three-point bending and hardness of a new fiber-reinforced composite (FRC) material. METHODS: In addition to unidirectional E-glass fibre bundles (Stick Tech, Finland), monomers sed were HDMA (Esstech, USA), MMA (ProSciTech, Australia), CQ (Esstech, USA) and CEMA ...postprin

Biomechanical Effects of New Resin Matrix System on Dental Fiber-Reinforced Composites

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Immediate repair bond strengths of microhybrid, nanohybrid and nanofilled composites after different surface treatments

OBJECTIVES: To evaluate immediate repair bond strengths and failure types of resin composites with and without surface conditioning and characterize the interacting composite surfaces by their surface composition and roughness. METHODS: Microhybrid, nanohybrid and nanofilled resin composites were photo-polymerized and assigned to four groups: (1) no conditioning (Control), (2) no conditioning, polymerized against a Mylar strip (Control, with strip), (3) intermediate adhesive resin (IAR) application, and (4) chair-side silica coating, silanization and intermediate resin application (SC). Resin composites, similar as their substrates, were adhered onto the substrates. Shear force was applied to the interface in a universal testing machine and failure types were evaluated under light microscopy. Surface characterization was done by contact angle measurements, X-ray photoelectron spectroscopy, scanning electron and atomic force microscopy. RESULTS: Significant effects of the resin composite type and surface conditioning were observed. Conditioning the composites with their IARs does not result in significant improvements in bond strength compared to the control with strip (bond strengths between 14.5 and 20.0 MPa). SC increased the bond strength in all composites except TE by an average 8.9 MPa, while in all composites the surface roughness increased from 7 to 384 microm. Failure types in this group were exclusively cohesive. Physico-chemical modelling of the composite surfaces showed that the surfaces were dominated by the resin matrix, with a major increase in silica-coverage after SC for all composites. CONCLUSION: Intermediate adhesive resin conditioning did not improve the composite-to-composite immediate repair strength. Silica coating and silanization followed by its corresponding IAR, strongly increased repair bond strengths and provided exclusively cohesive failures in the substrate in all composites