Additionally, higher curing light intensities may lead to superior physical and mechanical properties.8 Light-emitting diode (LED) curing lights are used to polymerize necessary resin-based restorative materials, and their effect on the physical properties of resin-based restorative materials has been investigated.9 Because contemporary LED lights yield superior irradiance (approximately 1,000 mW/cm2) to QTH light (approximately 800 mW/cm2), LED lights are expected to polymerize resin materials as or even more effective than QTH.9 Post-cure heating of resin composite materials is a extremely popular restorative technique. This method subjects a light-cured composite inlay to an immediate heat treatment for the purpose of increasing material cure and thus enhancing clinical properties.
10 In Rueggeberg��s study, the degree of color change was influenced more by the amount of resin content in the composite systems than by the particular resin composition. Microfill composite resins showed greater potential for color change than did the other types of materials. If clinicians are considering using conventional light-cured composite materials for inlays, the choice of material as well as the post-cure temperature will influence the ability to match the inlay with the initial shade of composite chosen.11 An important factor is the possibility of using post-polymerization mechanisms associated with heat, pressure, or high light intensity in indirect composite systems.12 With respect to materials, indirect and direct composites have similar compositions.
13 Currently, easy and inexpensive techniques have been enhanced for direct composites in indirect restorations. Coupled with the use of devices that are always found in dentists�� offices to apply these techniques, better performance can now be obtained and harnessed from material properties, resulting in improved dental health.14 Presently, electronic shade-matching instruments have been used for dental practice.15 In order to determine objectively the color changes on composite restorations, some methods have been experienced, among them the spectrophotometry, which makes the study of several parameters related to color stability of composite resins possible. In this method reflected wavelength by a body is changed in values expressed in ��E* units.
The ��E* values can be used so that present the color changes provided by the composite resin after treatment or period of time.16 Instrumental color analysis offers a potential advantage over visual Brefeldin_A color determination, as instrumental readings are objective, quantifiable, and more rapidly obtainable.17 The Comission Internationale de l��Eclairage Lab (CIE L*a*b) color system has been used for determination of color difference.18�C21 Chroma is calculated as C*ab= (a*2+ b*2) ?.