The Effect of Light Curing Source on the Residual Yellowing of Resin Composites

Abstract

Laboratory Research SUMMARYPurpose. This study evaluated the amount of residual yellow in cured resin composites when polymerizing with either a quartz-tungsten-halogen (QTH) or blue light-emitting diode (LED). Material and Methods: Twelve shades (bleaching to conventional shades) of microfill, hybrid and microhybrid resin composite specimens (n=10) were polymerized with both light types. All the materials contained only camphorquinone as the photoinitiator. After exposure, the specimens were stored in the dark for 24 hours. Then, the specimen color parameters were recorded (L*, a*, b* and C* ab ) and color differences (ΔE* ab ) were determined by examining for changes among the test combinations. Group comparisons were examined using ANOVA and the Tukey-Kramer post-hoc test, and pairwise comparisons were made using Student's t-tests at a pre-set alpha of 0.05. Results: When a significant difference in residual yellow was noted, the QTH light produced a greater yellow tinge than most comparisons using the LED. The potential for producing more residual yellowing could not be anticipated with respect to composite filler classification or shade, as this effect may be more dependent on individual product composition. The extent to which residual yellowing differences were noted between light curing unit types fell within levels considered detectable by the human eye (ΔE>2.0). Clinical RelevanceThe selection of light curing unit (quartz-tungsten-halogen or blue light-emitting diode), composite classification and shade have an influence on the amount of residual yellow after photocuring and, in some combinations, the color difference may be visually detectable.

Effect of dual-peak LED unit on the polymerization of coinitiator-containing composite resins

“…CQ is a yellow compound with unbleachable chromophore group, so if a large concentration of CQ is contained in resin formulation, undesirable yellowing effect will take place. Furthermore, if CQ is not fully activated, some portion of CQ remains as unreacted molecules, and then it causes color mismatch and unpleasing aesthetic appearance [1][2][3] . Tertiary amines are basically added to accelerate the reaction process because the photopolymerization process through CQ occurs at a low rate 4) .…”

Influence of Curing Light Type and Staining Medium on the Discoloring Stability of Dental Restorative Composite

“…QTH cured composites have been described to exhibited more yellowing of upon curing (Brackett et al, 2007). In our accelerated aging tests, QTH curing showed more intrinsic colour changes attitude than LED curing for all tested composites materials.…”

“…Although no significant mechanical differences have been reported in the curing performance of QTH and LED systems (Campregher et al, 2007), the QTH light curing system tends to exhibit more yellowing of the resin composites upon curing (Brackett et al, 2007). Moreover, LED systems are often considered similar or comparatively better than QTH system in terms of the degree of polymerization (Hasler et al, 2006), polymerization shrinkage (Uhl et al, 2005), microleakage (Attar and Korkmaz, 2007), wear rate (Ramp et al, 2006), flexural properties (Keogh et al, 2004) and hardness (de Araújo et al, 2008).…”

A Review Of The Color Stability Of Resin Composites: The Etiology, Classification And The Treatment Of Composite Staining

“…18,19 Monomer polimer dönüşümünün ve boyutsal stabilitenin artması ile çözünebilirliğin azalması renk değişikliğinde düşüşe neden olur; [20][21][22] ilave polimerizasyonun ise bütün kompozitler üzerinde etkili olmadığı bildirilmiştir. 23,24 Falkensammer ve arkadaşlarının 25 farklı kompozit rezinleri (dualpolimerize self-adeziv rezin siman, otopolimerize rezin esaslı kompozit, dual-polimerize rezin esaslı kompozit, nanohibrit kompozit ve mikrohibrit kompozit) farklı solüsyonlarda bekleterek renk stabilitelerini karşılaştırdıkları bir araştırmada, en fazla renklenme dual olarak polimerize rezin simanda gözlenmiştir.…”

“…Jain ve arkadaşlarının 26 yaptıkları bir çalışmada, Belleglass-NG'nin (Kerr) gösterdiği yüksek renk stabilitesi materyalin sertleşme mekanizmasıyla (140°C' de 20 dakika süreyle nitrojen basıncı altında polimerize edilmesi) ilişkilendirilmiştir. Brackett ve arkadaşlarının 22 farklı bir çalışmalarında ise, kamforokinon içeren kompozitlerdeki arda kalan sarı renk miktarı, QTH (kuartz-tungsten-halojen) ve LED (light-emitting diode) ile polimerize edildikten sonra karşılaştırılmış; QTH kullanımı sonrası daha fazla miktarda sarımsı izler kaldığı bildirilmiş ve bu farklılıkların gözle farkedilebilir oranda olduğu da belirtilmiştir. 27 Samra ve arkadaşları 28 ise postpolimerizasyon sistemi ve artmış renk stabilitesi arasında direkt bir ilişki bulamamışlardır.…”