Curing-dependent changes in color and translucency parameter of composite bleach shades.
OBJECTIVE
The goal of this study was to evaluate curing-dependent changes in color and translucency parameter (TP) values of composite bleach shades.


METHODS
Thirty bleach shades of microhybrid and microfill composites were analyzed. Specimens (n = 5) were made as disks, 10 mm in diameter and 2 mm thick, using cylindrical molds. Specimens were polymerized for 60 seconds using a light-curing unit. Data were collected before and after composite curing using a spectrophotometer and analyzed using the appropriate color-difference metric equations.


RESULTS
L*a*b* ranges (maximum minus minimum values) for microhybrids were 17.7, 2.91, and 7.97, respectively. Corresponding ranges for microfills were 14.4, 1.26, and 4.27, respectively. Curing-dependent color differences varied from 3.7 to 12.0 deltaE* units, whereas TP values of cured resin composites varied from 2.0 to 7.1. Light-curing caused increase of microhybrid TP values (+0.7) and decrease of microfill TP values (-0.7). Color differences were found to be acceptable for five of six composite pairs of the same shade designation (each of them made by the same manufacturer) in post-curing measurements against white background.


CONCLUSIONS
Curing-dependent color and TP changes indicate that dentists should use cured composite for matching of shade and translucency. Tested materials became less saturated, with microhybrids becoming darker and microfills becoming lighter after polymerization. Light-curing caused an increase in translucency of microhybrids and a reduced translucency in microfills.
Department of Restorative Dentistry and Biomaterials, The University of Texas Health Science Center at Houston, Dental Branch, USA. rparavina@uth.tmc.edu
Rade D
RD
Paravina
Joe C
JC
Ontiveros
John M
JM
Powers
D003116:Color; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D008027:Light; D011108:Polymers / Q000737:chemistry; D017797:Prosthesis Coloring
D003188:Composite Resins; D011108:Polymers