My first Magazine | Page 40

IN VITRO WEAR OF 4 DIFFERENT UNIVERSAL COMPOSITES

F

H

T

Filtek Z350XT A2 body

Herculite Precis A2

Tetric N-Ceram A2

Germany 3M ESPE

82229 Seefeld Germany

Kavo Kerr Charlotte NC 28273 USA

Ivoclar Vivadent 9494-Schaan Liechtenstein

Agglomerated / non-aggregated 20 nm silica N321220 filler, non-agglomerated / non-aggregated 4 to 11 nm zirconia filler, and aggregated zirconia / silica cluster filler( comprised of 20 nm silica and 4 to 11 nm zirconia particles). Ba glass 0.4 μm, PPF,

3649560

20-50 nm SiO 2

Ba-Al glass, 0.5 and 0.7 μm, PPF, mixed oxide spheres 160 nm, Ytterbium trifluoride 180 nm, SiO 2

40 nm

P72199 years for Adaptic was 224 ± 151 µ m. Using better equipment, it became possible to distinguish between wear in the occlusal contact area( OCA) and the contact free area( CFA). It was found that the OCA: CFA ratio equals an average of 2.5. 4 Different equipment was used to accomplish this: Profilometer, 5, 6 3 coordinated table using a long lens to determine the vertical dimension, 7 and a computer controlled 3-coordinated table with a mechanical switch for the vertical dimension. 8 Today, laser scanners measure fast and efficient occlusal anatomy and wear. 9 Current composite wear resistance has vastly improved mainly due to refinement of filler technology. 10 Clinical studies document the excellent longevity of posterior composite restorations if applied correctly; 11-15 therefore, it seems that wear is no longer the primary concern. Wear behavior of restorative materials will remain important and in focus, since today more and more occlusal bearing restorations are placed clinically due to the recent expansion of the indication for composites, including cusp replacements. Palaniappan et al. 16 reported that hybrid composites had a vertical substance loss within the same magnitude as enamel. However, comparing the volumetric wear, enamel was worn significantly less than the 3 tested composites. Frankenberger et al. 17 observed significant wear of nanohybrid and fine hybrid composite restorations in extended class II cavities after 8 years of service. With more nanoparticle-based composite materials being introduced, there is a need of investigating wear resistance of those materials. Therefore, the objective of this investigation was to measure in vitro wear of 4 nano particle based, commercial universal composites. The null hypotheses are( 1) there is no difference in volumetric wear among composites tested, and( 2) there is no difference in wear rates calculated from the linear relationship of wear increase over cycling.

2. Materials and Methods

The four universal composites were received and the samples prepared according to standard procedures being equal for each brand. The manufacturer, filler composition and lot numbers are displayed in Table 1. Eight samples were prepared for each brand( n = 8), which resulted in total 32 samples. Thirty-two aluminum sample holders( inner Ø 7.9 mm depth 1.5 mm) were grit blasted with 27 µ m aluminum oxide( EtchMaster Tips Small, Groman, USA) then one coat of universal bond( Monobond Plus, Ivoclar Vivadent, Liechtenstein) was added and left for 60 seconds, followed by air blasting to evaporate the solvent. Then one coat of adhesive( Optibond FL 2, Kerr, USA) was applied and light cured for 10 s using the BluephaseG2( Ivoclar Vivadent, Liechtenstein) at“ HIGH Power” mode delivering 1383 mW / cm 2 at a distance of 1.5 mm( verified with MARC Resin calibrator, BlueLight Analytics Inc., Halifax, NS, USA). The composites were filled into the sample holders in two increments, and each was light cured for a total of 40 s that delivered 55 J / cm 2( 1383 mW / cm 2 x40). The composite surfaces were finished and polished by using( Sof-Lex Discs, 3M, USA), light orange disc for finishing and yellow disc for polishing for 10- 15 s. All samples were stored in distilled water for 3 weeks at 37 0 C. Steatite balls( Ø 6 mm) mounted into aluminum holders with composite were used as antagonists. One antagonist per sample( n = 32) was used and discarded after finishing all cycles. The samples were randomly distributed to the chewing simulator chambers( CS-4, Mechatronik, Germany) using random numbers. The chewing simulator was run according to the parameters listed in Table 2. The composite samples were scanned after 100, 500, 1,000, 2,000, 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, and 120,000 mastication cycles.