Effect of Additional Light Curing on Color Stability and Degree of Conversion of Mono-Shade Resin Composites

This study aims to examine the effect of additional light curing on the color stability and degree of conversion (DoC) of mono-shade resin composites cured using different light curing units and irradiation levels. Sixty-six disk-shaped samples were prepared for each of the mono-shade (Omnichroma/OC, Vittra APS Unique/VU) and multi-shade resin (Clearfil Majesty ES-2/CME) composites. The samples were randomly divided into three groups and cured for 20 s according to: (1) QTH at 800 mW/cm2 (16 J/cm2), (2) LED at 1000 mW/cm2 (20 J/cm2), and (3) 1400 mW/cm2 (28 J/cm2). After polishing, half of the samples in each group were exposed to additional light curing. Color parameters were measured at baseline and after 28 days of immersion in a coffee solution. CIEDE2000 color (triangle E00) and Whiteness Index (Delta WID) changes were used to assess color stability. triangle E00 and Delta WID were compared with the perceptibility and acceptability threshold. Mono-shade composites exhibited lower DoC with higher Delta E00 and Delta WID changes compared to the multi-shade composite. Mono-shade composites showed clinically unacceptable color and whiteness changes. Additional light curing performed using the same protocol both before and after polishing did not contribute to the color/whiteness stability and DoC of either mono-shade or multi-shade resin composites.

Journal

POLYMERS

Year

2026

Volume

18

Issue

3

eISSN

2073-4360

DOI

10.3390/polym18030403

WoS UID

WOS:001687708700001