In vitro Wear of Composite with Varied Cure, Filler Level, and Filler Treatment

Abstract

For the clinical wear of composite filing materials to be reduced, compositional factors such as degree of cure, filler level, and silanation level should be optimized. An oral-wear-stimulating machine was used to explore the effects of these factors on abrasion and attrition wear as well as on opposing enamel wear. The composites were made from Sr glass (1-2 micron avg) and a 50/50 Bis-GMA/TEGDMA resin. Series I (A-D, E) were light-cured (Triad II) for 9, 12, 25, and 40 sec/side to produce degree of cure (DC) as measured by FTIR of 56, 60, 61, and 63%, respectively. E received an additional heat cure (120 degrees C for 10 min) to reach a DC of 66%. Series II (D, F-I) were filled to 62, 53, 48, 37, and 28 vol%, respectively. In series III (D, J-M), the portion of fillers treated with a silane coupler (MPS) was 100, 80, 60, 40, and 20%, respectively. Samples were cycled 50,000 times against an enamel antagonist in a poppy seed/PMMA slurry in the oral wear simulator to produce abrasion (load = 20 N) and attrition (load = 70 N) simultaneously. Wear depth (micron: n = 5) was measured by profilometry. Results for each series were analysed by ANOVA/Turkey's (p < or = 0.05). The wear depths did reflect cure values, though only the abrasion difference for E < A was significant. Greater wear was correlated with lower filler levels (r2 = 0.88; p < 0.05), significantly increasing below 48 vol% (G). Wear increased linearly as the percent of silane-treated fillers was reduced (r2 = 0.99; p < 0.05). Abrasion and attrition did not differ significantly for any composite. Wear of the opposing enamel was largely unchanged by these factors. Compositional factors including degree of cure, filler level, and silanation directly affected the wear resistance of dental composites evaluated in an oral wear simulator.

Morphological analysis of flowable resins after long-term storage or surface polishing with a mini-brush

“…At least to some extent, the coupling agent protects the filler against hydrolytic degradation 17,18) . However, the base resin in the resin polymer is imperfectly polymerized, and this is one of the factors adversely affecting the surface properties 6,19) .…”

A comparison of microhardness of indirect composite restorative materials

“…Therefore, the type of matrix and the degree to which conversion occurs during polymerization might also influence the mechanical properties, especially when aging occurs in the oral environment 3 .…”

Reciprocating wear test of dental composites: effect on the antagonist

“…This correlation is very complicated as there are no standards for some mechanical characterization of these composites, namely for abrasion tests [1]. There are a large number of variables involved in the in vitro studies, and the type of tests used in experimental approach varies greatly from investigating team [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. To understand the multiplicity of approaches about the subject, a summary of the most important variables was done.…”

“…Among the published studies, large differences can be observed on the contact conditions, counterface material and abrasive agent [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Concerning the antagonist material, steels [2,6,7,14,16,17] and enamel [1,[3][4][5]8] are the most tested ones.…”

“…Concerning the antagonist material, steels [2,6,7,14,16,17] and enamel [1,[3][4][5]8] are the most tested ones. However, some studies use polymers [9,18] or ceramics [10,13] and one of them uses titanium as antagonist [15].…”