Comportamento óptico, estabilidade cromática e rugosidade superficial de resinas compostas convencionais e com correspondência simplificada de cor: estudo in vitro

Abstract

Introduction. The blending effect of composite resins with the dental substrate represents a central clinical challenge in contemporary restorative dentistry. Despite the growing interest in simplified shade-matching systems, such as cloud-shade composite resins, there is still limited evidence evaluating the chromatic blending ability, color stability, and surface roughness of this type of material. Objective. This study aimed to compare the color matching, post-staining color stability, and surface roughness of a nanofilled simplified shade-matching composite resin (Filtek™ Easy Match – EM) with two conventional composite resins: a microhybrid composite resin (3M ESPE Filtek® Z250 XT – Z250) and a conventional nanofilled layering composite resin (3M ESPE Filtek® Z350 XT – Z350). Methods. Direct restorations were performed on 36 bovine crowns (n = 12), and 36 disc-shaped specimens (n = 12) were fabricated using the same materials. Color matching was quantified by spectrophotometry using the CIEDE2000 color-difference formula (ΔE00) based on the CIELAB color system, and by visual assessment comparing the following conditions: dental substrate, after restoration, and after staining in a coffee solution for seven consecutive days. The translucency parameter (TP00) and translucency variation (ΔTP00) were calculated for the disc-shaped specimens. Mean surface roughness (Ra) was measured using a profilometer on the dental substrate, after restoration polishing, and after repolishing following staining. Data were analyzed using repeated-measures ANOVA, one-way ANOVA, two-way ANOVA (all followed by Tukey's post hoc test), Student’s t-test, and qualitative analysis (α = 0.05). Results. After restoration, Z350 exhibited the lowest ΔE00 values (1.51 ± 0.35), remaining below the clinical acceptability threshold (ΔE00 < 1.8), with visual color matching approaching perfection. In contrast, Z250 and EM exceeded these thresholds. After staining, Z350 exhibited the highest color-change values (ΔE00 = 2.80 ± 0.70), exceeding the acceptability limits, as did EM, whereas Z250 demonstrated greater color stability. Visual assessment revealed improved color matching after staining. All groups exhibited reduced translucency after staining, with no significant differences among materials (ΔTP00, p = 0.983). Surface roughness remained below 0.2 µm even after staining, with no significant differences among materials (p = 0.227). Conclusion. The composition of composite resins appears to influence the relationship between initial chromatic blending and color stability. In the present study, the conventional nanofilled resin composite exhibited superior immediate color matching but greater susceptibility to staining, whereas the microhybrid composite demonstrated lower initial optical accuracy and greater resistance to pigmentation. The simplified shade-matching resin composite showed intermediate performance among the materials. The partial divergence between instrumental and visual methods highlights the importance of multimodal assessment in studies evaluating the optical behavior of restorative materials.