My first Magazine | Page 56

HIGH VISCOSITY BULK-FILL GIOMER AND ORMOCER-BASED RESIN COMPOSITES: AN IN-VITRO COMPARISON OF THEIR MECHANICAL BEHAVIOUR

Table 1. Materials, Manufacturer, chemical composition of matrix and filler as well as filler content by weight( wt.) and volume( vol.) %

Bulk Fill RBCs

Manufacturer, Color, Batch

Resin Matrix Filler Filler wt %/ vol %

Tetric EvoCeram ® Bulk Fill Nano-hybrid RBC

Admira Fusion x-tra Nano-hybrid RBC

X-tra Fil Hybrid RBC

SonicFill™ Nano-hybrid RBC

Beautifil Bulk restorative GIOMER

QuixFil Hybrid RBC

Ivoclar Vivadent IVA, P84129

Voco Universal, 1527519

Voco Universal, 1230323

Kerr A3, 3851737

Shofu Dental Corporation, Universal, 11402 Dentsply DeTrey Universal, 1209000241

Bis-GMA, UDMA

Organically modified silicic acid

Ba-Al-Si-glass, prepolymer filler( monomer, glass filler and ytterbium fluoride), spherical mixed oxide

79-81( including 17 % prepolymers)/ 60-61

n. s. 84 /-

Bis-GMA, UDMA, TEGDMA n. s. 86 / 70.1

Bis-GMA, TEGDMA, EBPDMA

Bis-GMA, UDMA, Bis-MPEPP, TEGDMA

Bis-EMA, UDMA, TEGDMA, TMPTMA, TCB-Resin

SiO2, Glass, oxide 83.5 /

S-PRG filler based on F-B-Al-Si-glass, prepolymer filler

87.0 / 74.5

Sr-Al-Na-F-P-Si-glass 86 / 66

Abbreviations: Bis-GMA, bisphenol-A diglycidyl ether dimethacrylate; EBPDM / Bis-EMA, ethoxylated Bisphenol-Adimethacrylate; TEGDMA, Triethyleneglycol dimethacrylate; UDMA, Urethane dimethacrylate; TMPTMA, Trimethylolpropan- Trimethacrylat; TCB resin, butane-1,2,3,4-tetracarboxylic acid, bis-2-hydroxyethyl methacrylate; Bis-MPEPP, Bisphenol A Polyethoxy-Dimethacrylat n. s., not specified Data are provided by manufacturers

Table 2. Influence of the parameters. Filler weight on the mechanical properties. Table contains the partial eta-square values. The higher the partial eta-square, the higher the influence of the selected factor on the measured property( p < 0.001)

2. Materials and Methods

One giomer, one ormocer as well as the first launched high-viscosity bulk-fill RBC were compared with three established high-viscosity bulk-fill resin composites( Table 1) by assessing their mechanical properties at macroscopic( σ and E flexural

) and microscopic scale( HM, HV, Y HU and

Creep).

2.1 Macro-mechanical Characteristics The flexural strength( σ) and flexural modulus( E flexural

) were determined in a three-point-bending test( n = 20). Therefore, specimens were made by compressing the composite material between two glass plates with intermediate Polyacetate sheets, separated by a steel mold having an internal dimension of( 2 x 2 x 16) mm. Irradiation occurred on the top and bottom of the specimens, as specified in ISO 4049:2009 standards; 20 the duration of the light exposures was 20s, with three light exposures, overlapping one irradiated section no more than 1 mm of the diameter of the light guide( Elipar tm Freelight 2, 3M ESPE, Seefeld, Germany, 1,241 mW / cm ²) to prevent multiple polymerizations. After removal from the mold, the specimens were ground with silicon carbide sand paper( grit size P 1200 / 4000( Leco)) to remove protruding edges or bulges, and then stored for 24 h in distilled water at 37 ° C. The specimens were loaded until failure in a universal testing machine( Z 2.5, Zwick / Roell, Ulm, Germany) in a threepoint-bending test device, which was constructed according to the guidelines of NIST No. 4877 with a 12 mm distance between the supports. 21 During testing, the specimens were immersed in distilled water at room temperature. The crosshead speed was 0.5 mm / min. The universal testing machine measured the force during bending as a function of the deflection of the beam. The bending modulus was calculated from the slope of the linear part of the force-deflection diagram.

2.2 Micro-mechanical Characteristics Fragments( n = 10) of the three-point-bending test specimens of each group were used to determine the micro-mechanical properties( Martens Hardness( HM), Vickers hardness( HV), indentation modulus( Y HU

) and creep) according to DIN 50359-1:1997-10 22 by means of a universalhardness device( Fischerscope H100C, Fischer, Sindelfingen, Germany). Prior to testing, the