DENTAL MATERIALS
Original Articles
IN VITRO WEAR OF THREE BULK FILL COMPOSITES AND ENAMEL
Jean-François Roulet 1 *, Nader Abdulhameed 2, Chiayi Shen 3
Department of Restorative Dental Sciences, Center for Dental Biomaterials, College of Dentistry, University of Florida, 1395 Center Drive, Gainesville, Fl 32608 USA
1
Dr. med. dent, Dr. hc., Professor, Director of Center for Dental Biomaterials
2
BDS, MS, PhD Student, Clinical Assistant Professor
3
PhD, Associate Professor
Received: November 11, 2017
Revised: November 25, 2017 Acccepted: December 12, 2017 Published: December 13, 2017
Academic Editor: David C. Watts, BSc, PhD, DSc, FInstP, FRSC, FRSB, FADM, Professor of Biomaterials Science, School of Dentistry, The University of Manchester, Manchester, M13 9PL United Kindom
Cite this article: Roulet J-F, Abdulhameed N, Shen C. In vitro Wear of Three Bulk Fill Composites and Enamel. Stoma Edu J. 2017; 4( 4): 248-253
ABSTRACT DOI: 10.25241 / stomaeduj. 2017.4( 4). art. 1
Introduction: This in vitro study aimed at testing the hypotheses that( 1) there is no difference in wear in vitro among 3 bulk-fill composites investigated and their respective antagonists, and( 2) the tested bulk-fill wear is not different from enamel. Methodology: X-tra fil( Voco; [ X ]), Tetric-N-Ceram Bulkfill( Ivoclar Vivadent; [ T ]), QuiXX( Dentsply; [ Q ]), and enamel [ E ] specimens( Ø = 8 mm, depth = 1.5 mm, n = 8 / material) were subjected to wear in a chewing simulator( CS 4.8, SD Mechatronik) with steatite antagonists( Ø = 6mm). 1.2x10 5 cycles( 0- 49 N, 0.7 mm lateral movement, 1 Hz) were performed while simultaneously thermocycling( 5 / 55 ° C) every 90 s. The volumetric wear of the materials was measured with a 3D laser scanner. Results: The total wear of bulk-fills was: [ X ]: 0.64 ± 0.07 mm 3; [ T ]: 0.66 ± 0.08 mm 3; [ Q ]: 1.58 ± 0.14 mm 3. The total wear of enamel( 0.24 ± 0.03 mm 3) was significantly lower than that of the bulk-fills( p < 0.0001). The total wear of the antagonists was: [ X ]: 0.32 ± 0.02 mm 3; [ T ]: 0.24 ± 0.04 mm 3; [ Q ]: 0.27 ± 0.02 mm 3; [ E ]: 0.12 ± 0.01 mm 3. The wear of the antagonists by [ X ] was significantly higher than by [ T ] and [ Q ]( p < 0.001). Enamel produced the lowest wear of the antagonists( p < 0.0001). The wear was linear between 5x10 3 and 1.2x10 5 wear-cycles. A negative correlation between the wear of the composite materials and that of the antagonists was found. Conclusion: In vitro wear of Tetric-N-Ceram Bulkfill was in the expected range and equal to X-tra fil. QuiXX wear was 2.7 times higher. The antagonist wear was significantly lower, less than 50 % of the wear of the composites and the enamel. Both hypotheses were rejected. Keywords: chewing simulator, wear, bulk-fill composite, thermocycling, enamel.
1. Introduction Approximately 5 years ago a new category of resin composites was introduced for bulk-filling deep and wide dental cavities. These new materials, called bulk-fill composites, are claimed to provide a faster and easier procedure than the traditional incremental restoration technique. 1-7 This innovation was introduced following the general marketing trend for faster, easier and more convenience in restorative dentistry. Bulk-fill resin composites are claimed to be placed up to 4 or 5 mm thick increments( bulks) skipping the time-consuming layering process, and cured with light exposure time of up to 20 s. 8 To accomplish this, the well-known and clinically proven resin chemistry and filler technology had to be modified in several aspects. The translucency of the material had to be increased to allow the blue light-curing wavelength to penetrate to the required depth of the material. 9 It was accomplished by either using less pigments and / or by matching the refractive index of the resin as closely as possible to those of the fillers in order to minimize the light scattering at the resin-filler interface. 8 Another possibility was to use more effective photo initiator systems( e. g. germanium-based light-initiators, such as Ivocerin, Ivoclar Vivadent AG, Schaan, Liechtenstein), which allow the composite to be cured with less light energy per cm 2. 10 Furthermore, for bulk-fill composites it is beneficial to reduce the polymerization shrinkage stress, to reduce the stress challenge to the toothrestoration interface, thus allowing a good seal of the restauration by the adhesive system. One way to accomplish this is to minimize the resin content of the composite by using rather coarse fillers( particle sizes much higher than 5-10 µ m). Since the surface area of such particles is smaller, less resin is needed to wet it. 11 However, if this is done with conventional glass fillers, the surface characteristics and thus the polishability deteriorate. 12 A way around this is to use composite fillers having almost the same composition as the cured composite. They polish
* Corresponding author: Professor Jean-François Roulet, Dr. med. dent, Dr. hc., Professor, Director of Center for Dental Biomaterials, Department of Restorative Dental Sciences, Center for Dental Biomaterials, College of Dentistry, University of Florida, 1395 Center Drive, Gainesville, Fl 32608 USA; Phone + 1 352 273 5850; Fax: + 1 352 846 1643, e-mail: jroulet @ dental. ufl. edu
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Stoma Edu J. 2017; 4( 4): 248-253 http:// www. stomaeduj. com