Influence of modeling liquids and adhesive agents on the surface properties of resin composite.

objectiveThe aim of this study was to investigate the effects of modeling liquids and adhesive agents with different compositions on the color stability and surface roughness of resin composite surfaces under clinically relevant conditions, particularly in areas that may remain unpolished after anatomical modeling. The influence of different oxygen inhibition control protocols and the presence or absence of finishing and polishing procedures were also evaluated. MATERIALS AND

methodsA total of 160 disk-shaped specimens (6 mm diameter, 2 mm thickness) were prepared using a nanohybrid resin composite (Filtek Z550). Specimens were assigned to eight groups according to surface treatment: air exposure, Mylar strip, glycerin gel, or application of five different modeling agents or adhesive systems (Optibond FL, Scotchbond Universal, GC Modeling Liquid, Estenia C&B Liquid, and Composite Wetting Resin) using a sable brush, followed by polymerization under glycerin gel. Each group was subdivided into unpolished (A) and polished (B) subgroups (n = 10). Color measurements were performed using a spectrophotometer (Vita Easyshade Compact), and surface roughness (Ra) was measured with a contact profilometer (Surfest SJ-301) at baseline and after 7 days of coffee aging. Data were analyzed using non-parametric statistical tests (Kruskal–Wallis, Dunn test with Bonferroni correction, and Wilcoxon signed-rank tests; α = 0.05).

resultsSignificant differences in color change (ΔE₀₀) were observed among both A and B subgroups. In unpolished specimens, modeling agent application significantly improved color stability; AIR–A showed the highest discoloration, whereas SU–A exhibited the lowest ΔE₀₀ values, with no significant differences among the modeling agent–applied A groups. In the polished condition, MS–B demonstrated the lowest ΔE₀₀ values and ESTML–B the highest. Among the modeling agent applied B groups, ESTML–B showed significantly greater discoloration than SU–B, while SU–B did not differ from GCML–B, OFL–B, or CWR–B. Surface roughness (Ra) differed significantly among groups at baseline and after aging. AIR–A and GLY–A exhibited the highest roughness in unpolished specimens, whereas MS showed the lowest values. The modeling agent applied unpolished groups did not differ significantly. Polishing significantly reduced Ra in all groups except MS; after polishing, MS–B, GCML–B, and SU–B demonstrated the lowest roughness, whereas ESTML–B exhibited the highest.

conclusionsFinishing and polishing procedures are essential for achieving optimal surface quality and color stability of resin composite restorations. However, in anatomically complex areas where complete polishing may be limited, the controlled application of a modeling liquid or adhesive agent during the modeling phase may contribute to improved surface characteristics compared with no agent application.