Hardness, roughness, and compressive strength of different filled resin composites after thermal aging and bleaching procedures.

Purpose: To evaluate the effect of aging and bleaching on the physico-mechanical properties of the different filled resin composites.

Methods: Samples of resin composites [Arabesk (A), G-aenial Anterior (G), i-LIGHT N (I) and Palfique Estelite Paste (P) \ were first divided into two subgroups. Thermal aging was applied to half of the samples. Then, fresh and aged samples were divided into three subgroups (n= 8): control (C) (no treatment), office bleaching (O), home bleaching (H), thermal aging (T), thermal aging +office bleaching (TO) and thermal aging +home bleaching (TH). The microhardness (kg/mm²), surface roughness (µm), and compressive strength (MPa) values were measured. The data were analyzed with 3‑way ANOVA and Bonferroni post hoc pairwise comparison tests (P< 0.05).

Results: T significantly decreased the hardness and increased the roughness of all the resin composites (P< 0.05). The compressive strength of all resin composites decreased after aging. O and H increased the roughness of the A, I and P (P< 0.001). H increased the microhardness of the G (P< 0.05).

Clinical Significance: Thermal aging and bleaching agents adversely affected the hardness, roughness, and compressive strength of the nonaged composites tested. Bleaching agents have less effect on the physico-mechanical properties of aged composites. Therefore, bleaching can be a safe and conservative esthetic treatment plan for patients who have long-standing composite restorations.