DENTAL MATERIALS
HIGH VISCOSITY BULK-FILL GIOMER AND ORMOCER-BASED RESIN COMPOSITES: AN IN-VITRO COMPARISON OF THEIR MECHANICAL BEHAVIOUR
Nicoleta Ilie 1a *
1
Department of Operative / Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians University of Munich, Goethestr. 70, 80336 Munich, Germany a
Dipl. Eng, PhD, Professor
Cite this article: Ilie N. High viscosity bulk-fill giomer and ormocer-based resin composites: an in-vitro comparison of their mechanical behaviour. Stoma Edu J. 2016; 3( 1): 54-62.
ABSTRACT
Received: February 23, 2016 Received in revised form: February 5, 2016
Accepted: April 22, 2016 Published online: February 25, 2016
Introduction: The paper aims to assess the mechanical properties of novel high-viscosity bulk-fill composites based on the giomer and ormocer technology, and to compare their performance with materials of the same category previously launched. Methodology: One Giomer( Beautifil Bulk restorative / Shofu), one ormocer-based( Admira Fusion x-tra / Voco) and the first launched bulk-fill composite( QuixFil / Dentsply) were compared to three established materials of the same category. The last( Tetric EvoCeram Bulk Fill / Ivoclar Vivadent; X-tra Fil / Voco; SonicFill / Kerr) were analysed under identical conditions and were partially presented in a previous study. The mechanical properties were assessed at macroscopic( flexural strength σ and flexural modulus
E flexural
) and microscopic scale( Martens HM and Vickers Hardness HV, indentation modulus Y HU
, Creep). Results: The effect of the parameter filler amount was significant on all measured properties( p < 0.001; partial eta squared varied among η P
²= 0.212( Creep) and 0.891( Y HU)), while being higher on the modulus of elasticity Y HU( η P
²= 0.891) and E flexural( η P
²= 0.805). Lower σ values were determined for the ormocer( 99.9 ± 10.7 MPa) and giomer-based composite( 106.0 ± 12.7 MPa), while the highest values were recorded for QuixFil, X-tra Fil and SonicFill. Significant lowest E flexural was measured for the group Tetric EvoCeram Bulk Fill( 4.5 ± 0.8 GPa) and Admira Fusion x-tra( 5.3 ± 0.5 GPa), while QuixFil( 9.4 ± 1.8 GPa) and X-tra Fil( 9.5 ± 0.6 GPa) showed statistical similar values and the highest values in the range of the analyzed materials. Conclusions: Owing to a lower inorganic filler amount, innovative modifications such as giomers or ormocers were related to materials with moderate mechanical properties, yet comparable to values measured in regular composites. Keywords: bulk-fill resin-based composites, strength, modulus of elasticity, hardness.
1. Introduction
In an effort to simplify and improve placement of direct resin-based composite( RBC) posterior restorations, manufacturers develop materials able to be cured in one 4 or even 5 mm thick increment. This allows to skip the time-consuming layering process and to reduce the risk of introducing failures or contaminants in-between increments. The material category is termed bulk-fill resin based composites and is classified on the basis of differences in viscosity and application technique, in low- and high-viscosity bulk-fill RBCs. The low mechanical properties of the former 1 require to finish a restoration by adding a capping layer made of regular RBCs, while high-viscosity bulk-fill RBCs are intended to restore the entire preparation. Several in-vitro studies confirmed that bulk-fill RBCs may be applied in increments up to 4 mm thickness, 2-5 when adequately cured. Besides, an acceptable marginal adaptation is reported, which is similar to that of standard RBCs. 6 In a similar vein, Furness et al. 7 attested a comparable proportion of gap-free tooth-restoration interfaces in either bulk-fill or conventional RBCs restorations. Yet, the proportion of gap-free interfaces tended to decrease with increasing depth in the preparation, but was largely unaffected by RBC type( one low-viscosity and three high-viscosity bulk-fill RBCs versus one nano-hybrid RBC) or placement technique( 4-mm bulk versus 2 x 2-mm increments). In contrast to these findings, Benetti et al. 8
* Corresponding author: Prof. Dr. Dipl. Eng. Nicoleta Ilie, Department of Operative / Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians University of Münich Goethestr. 70, D-80336 Münich, Germany Phone: + 49-89-44005-9412, Fax: + 49-89-44005-9302, e-mail: nilie @ dent. med. uni-muenchen. de
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