EFFECT OF ENERGY DENSITY ON COLOR STABILITY IN DENTAL RESIN COMPOSITES UNDER ACCELERATED AGING

Abstract

The effects of the energy density that is used for polymerizationon properties of dental resin composites are well known.However, few studies relate color stability to this factor. Theaim of this study was to assess color changes (?E*), in vitro,in terms of accelerated aging under UV exposure of specimensprepared with different energy densities. Fourcommercial dental resin composites were included in thestudy. Thirty six specimens were prepared for each one ofthem, following the procedure established by ISO 4049 Standard,and assigned to three groups: A (3.75 J/cm²), B (9J/cm²), C (24 J/cm²). Each group was further subdivided intofour subgroups: 1 (no aging), 2 (500 hours aging), 3 (1000hours aging) and 4 (1500 hours aging). The results were analyzedby means of ANOVA and Tukeys test (? = 0.05) todetermine the effect of the factors. Correlation was performedin order to determine the possible relationship amongvariables.Energy density is not a significant factor in color stability.However, aging is directly proportional to color changes. ?E*depends on filler size; hybrid material presented ?E* of2.1(0.5), 2.4(0.6) and 3.3(0.3) at 500, 1000 and 1500 hours ofaccelerated aging respectively, and nanofilled material showed?E* of 3.0(0.6), 4.5(1.2) and 5.9(0.6) at the same times respectively.It can be concluded that ?E* does not depend on energydensity; however other factors are involved in color change.Further studies in this area are warranted.