Effect of angulation in different curing-light devices on color variation in composite resins

Objective – The present study aimed to evaluate the influence of the tip angulation of two curing-light devices on the total color variation (ΔE) of conventional and flowable composite resins. Materials and Methods – A total of 120 disc-shaped specimens were prepared using three types of composite resins: Vittra APS®, Opallis Conventional®, and Opallis Flow®. The specimens were divided into 12 experimental groups, considering two tip angulations of the curing-light devices (0º and 45º) and two different devices: Valo Cordless® (third-generation LED with a broad spectral range) and Radii-cal® (second-generation LED with a narrow spectral range). The resins were photoactivated according to the manufacturers' instructions, and colorimetric analysis was performed using the CIELab* system at baseline and after 15 days, with a reflection spectrophotometer. Data were analyzed using Levene’s and Shapiro-Wilk tests, followed by three-way ANOVA and Tukey’s test, with a significance level of 5%. Results – Statistically significant differences were observed (p < 0.05): the Valo Cordless® resulted in lower color variation; the Opallis Flow® resin showed greater color stability; and increasing the tip angulation to 45º led to higher color variation in Vittra APS® and Opallis Conventional® resins when using the Radii-cal® unit. Conclusion – Both the type of composite resin and the curing-light devices, as well as its angulation, influence the color stability of restorations. Clinical Relevance – Clinically, these findings highlight the importance of proper light-curing technique and appropriate material selection to ensure the aesthetic quality and longevity of restorations.