Mechanical Stability of Self-Adhesive/Ion-Releasing Resin Composites

The purpose of this study was to assess the effects of water storage on the surface microhardness (VHN) and fracture toughness (K-1C) of two self-adhesive restorative materials compared to traditional resin composite and resin-modified glass ionomer cement (RMGIC) restorative materials. Methods: Two self-adhesive materials (Activa and Vertise Flow), a nonflowable composite (Filtek Z250), and an RMGIC (Fuji II) were evaluated. Hardness measurements (n = 12) were recorded at three time intervals: (i) one-hour post-irradiation; (ii) after one day of storage in water at 37 degrees C; and (iii) after 90 days of storage in water at 37 degrees C. Fracture toughness (K-1C) measurements (n = 12) were conducted after one day of storage in water at 37 degrees C and 90 days of storage in water at 37 degrees C. ANOVA and Tukey post hoc tests were used for statistical analysis. Results: Baseline VHN data were 38.2-58.3, decreasing significantly to 28.8-55.6 following 90 days of water storage. The Filtek Z250 had the highest VHN before and after storage, while the Activa had the lowest. K-IC values varied between 0.98-1.32 MPa center dot m(0.5). The highest value was for the Filtek Z250 while the Fuji II showed the lowest value (after both 1 and 90 days of storage in water). However, K-IC values decreased significantly after storage, except for the Fuji II. Conclusion: Self-adhesive/ion-releasing resin composites were negatively affected by water storage. Material reinforcements are possible future areas to explore.