How Do the Surface Coating and One‑Year Water Aging Affect the Properties of Fluoride‑Releasing Restorative Materials?

Abstract

Objective: To evaluate the effects of surface coating and 1‑year water aging on flexural strength, compressive strength (CS) and surface roughness of fluoride‑releasing restorative materials.

Materials and Methods: The specimens were prepared from seven materials: GCP Glass Fill (GCP), Amalgomer CR (AHL), Zirconomer (Shofu), Fuji IX GP Capsule (GC), Beautifil II (Shofu), Estelite Σ Quick (Tokuyama), and reliaFIL LC (AHL). The specimens were randomly divided into two groups for each test: surface coated with G‑Coat Plus (GC) and uncoated. Each group was subdivided into two groups stored in distilled water at 37°C for 24 h and 1 year before testing (n = 10). The flexural and CS were evaluated according to ISO standards on a universal testing machine. The surface roughness was assessed with AFM. After flexural strength test, a cross‑section of the coated specimens was evaluated with SEM. Data were analyzed with one‑way analysis of variance, Duncan and independent t‑tests (P = 0.05).

Results: After 24 h, a significant increase was observed on the flexural and CS of Amalgomer CR, Zirconomer, and Fuji IX GP by coating (P < 0.05). After 1 year, the coating increased the flexural strength of Amalgomer CR and Zirconomer, and CS of GCP Glass Fill (P < 0.05). The coating decreased the surface roughness of GCP Glass Fill, Amalgomer CR, and Zirconomer after 1 year (P < 0.05). The water aging decreased the mechanical  properties of glass ionomer‑based materials and increased their surface roughness (P < 0.05).

Conclusion: The mechanical properties and surface roughness of glass ionomer‑based materials were affected by coating and water aging.

Keywords: Compressive strength, flexural strength, glass ionomer cement, surface coating, surface roughness