Resin composite color change by spatula manipulation, effects on surface and color stability

To evaluate the influence of spatulas on resin composite color stability, and characterize the surface of both the spatulas and the resin composites before and after manipulation.

Discs (ø6 mm x 2 mm) of suprananofilled resin composite (Palfique LX5/Tokuyama) and nanohybrid resin (Empress Direct/Ivoclar Vivadent) were fabricated. They were divided into groups (n=10), and manipulated with different spatulas: non-manipulated (control), metal spatulas (Almore Millennium/ Golgran, Almore #3/ Quinelato, LM Arte Modella/ Quinelato), or plastic spatulas (Jon). Manipulation involved lightly pressing the spatula 50 times against the resin composite on waterproof paper. Color was analyzed at three time points: immediately, after finishing and polishing, and after 24-hour immersion in distilled water, with CIELab* parameters, ΔEab, ΔE00, and ΔWID. Spatulas and resins were submitted to micromorphological and energy-dispersive X-ray spectroscopic (EDS) analysis. Generalized linear models or Kruskal-Wallis and Dunn tests (α=5%) were applied.

Resin color changed after manipulation with a metal spatula, but there was no significant difference in ΔEab and ΔE00 for the resin composites according to the spatula (p>0.05). The suprananofilled resin varied more than the nanohybrid resin over time (p<0.05). Abrasive wear was observed on the spatulas after manipulating the resin composites, with greater wear for the spatulas used with suprananofilled resin. EDS showed different spatula and resin composite compositions.

Metal spatulas influenced resin composite color stability, with greater color change for suprananofilled resin. The spatulas exhibited abrasive wear, attributable to the difference in hardness between the spatulas and the resin composites.