Effects of modeling liquid/resin and polishing on the color change of resin composite

Abstract

Modeling liquids/resins have been used to build up resin composite (RC) restorations, although there is a lack of information regarding their effects on the color stability of the latter. Therefore, the purpose of the present study was to evaluate the effects of the presence of modeling liquid between layers of RC and the finishing/polishing state of the material on color change in specimens exposed to red wine staining over time. Specimens were prepared by placing four increments (±0.5 mm thick) of RC (Filtek™ Z350 XT, 3M ESPE) into molds; half of which were prepared by applying modeling liquid (Scotchbond™ Multi-Purpose™ Adhesive, SBMP, 3M ESPE) between the layers of RC, whereas the other half were prepared without SBMP (control). Light-activation was performed after application of the final RC layer using a light-emitting diode (Radii, SDI) curing unit with an irradiance of 900 mW/cm 2 for 20 s. Each group was divided according to the surface finishing protocol (n = 7): nothing (non-polished) or polishing with Sof-Lex™/diamond paste (polished). Initial colors of the specimens were evaluated with a digital spectrophotometer and the CIEL * a * b * color system. The specimens were stored in wine (37°C) for 12 months, and the color measurements were reassessed after 4, 6, and 12 months of storage. Scanning electron microscopy (SEM) analysis was performed at the end. Data were analyzed using ANOVA and Tukey's test (α = 5%). The presence of SBMP resulted in lower overall color change of the RC as compared with the control. The non-polished specimens exhibited a significantly higher color change than the polished specimens. SEM images corroborated the previous findings. In summary, the use of modeling liquid between layers of RC shows potential for application to reduce or delay the staining process of RC over time. Moreover, polishing is essential to provide increased color stability of the RC restoration.

Translucency and color stability of resin composite and dental adhesives as modeling liquids – A one-year evaluation

“…This finding is corroborated by recent studies. 3,5 Specimens prepared with SBMP appeared to be stronger and more cohesively packed than those prepared without, and these features could positively influence the chemophysical stability of the composite. 2,3 The absence of translucency changes for specimens stored in wine, with the only exception occurring in the SB group after 12 months of storage, is notable.…”

“…Here, we used the CIE L * a * b * system to evaluate ΔE * . Although some recent studies have demonstrated that another measurement system, i.e., CIEDE2000, may provide a better fit than the former in the evaluation of color difference thresholds, 10,18,19,20 many other studies use the CIE L*a*b* color system to analyze color outcomes in dentistry 3,5,21,22,23 because this system features predictability and clinical importance. ΔE * did not increase after 12 months of storage in specimens prepared with the modeling liquids.…”

“…However, when present between layers of RC, modeling liquids are able to reduce or delay staining in the material. 3,5 The optical properties of RCs are not expected to remain stable over time, especially considering the degradation phenomena that composites may undergo after placement in the oral environment. 6,7,8 Among these properties, color shade and translucency are the main characteristics susceptible to modification, and special attention must be given to restorations prepared using modeling liquids because these liquids may influence the color and translucency of the composites after aging.…”

Effects of adhesive used as modeling liquid on the stability of the color and opacity of composites

“…However, obtaining satisfactory esthetic restorations depends on both clinicians’ skill and the physical properties of the composite, including its handling characteristics. As the stickiness of several composites can hinder the insertion and sculpting procedures, some clinicians have used low viscosity materials as modeler liquids to facilitate the building up of the restoration by reducing the surface tension of the composite . Moreover, the low viscosity resin might penetrate through any porosity created during the incremental insertion of the composite, helping to reduce the defects on the restoration's body and ultimately improving the mechanical properties and color stability …”

The Effect of Color Selection on the Color Stability of the Resin Cement

“…The surface morphology including roughness can be more exposed to color changes. Sedrez-Porto et al (26) reported that polishing is essential for color stability of resin composites. Only thermal cycling was used in this study.…”