Date of Award
Fall 2016
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Berzins, David
Second Advisor
Stafford, Stafford
Third Advisor
Toth, Jeffrey
Fourth Advisor
Roberts, Howard
Abstract
Camphorquinone (CQ) is the most commonly used photoinitiator in light-cured dental resin composites. However CQ is associated with a yellowing effect, which has led manufacturers to add alternative initiators into resin composites to reduce the amount of CQ used. The color change upon polymerization by light and aging in artificial saliva and room air of 8 commercial traditional or bulk-fill resin composites with or without additional photoinitiator(s) beside CQ was studied. The three traditional resin composites with CQ and additional photoinitiator(s) tested were Tetric EvoCeram (Ivoclar Vivadent), AELITE LS Posterior (Bisco), and Vit-l-escence (Ultradent). The two bulk-fill resin composites with CQ and additional photoinitiator(s) tested were Tetric EvoCeram Bulk Fill (Ivoclar Vivadent) and HyperFIL (Parkell, dual cure). The control resin composites with CQ only were Heliomolar (Ivoclar Vivadent, traditional), BEAUTIFIL-Bulk (Shofu, bulk-fill) and SonicFill 2 (Kerr, bulk-fill). Sixteen specimens for each material were prepared with Teflon disc molds (7 mm diameter x 2 mm thickness) and light cured for 40 seconds with a quartz-tungsten-halogen light-curing unit. Samples were aged at 37°C in room air or artificial saliva (n=8). Color measurements were obtained with a spectrophotometer before and after polymerization and after aging for up to three months. Color change was calculated using CIELab and CIEDE2000 formulae. One way and two way ANOVA and a post-hoc SNK test was conducted for statistical analysis. Commercial light-cured resin composites with additional photoinitiators beside CQ had greater color change upon polymerization than those with CQ only. Color changes with aging tended to be greatest within the first hour after light curing, but was not considered clinically perceptible on any resin composites tested except HyperFIL. Tetric EvoCeram Bulk Fill showed good color stability that was comparable to the traditional resin composites upon aging.