engleski

Long-term reliability analysis of bond strength of experimental remineralizing composites based on bioactive glass 45S5

Aim: To apply the statistical approach of reliability analysis (Weibull) to the bond strength data of experimental remineralizing composites in order to evaluate the aging- related changes that would not be discernible by using conventional statistics. Materials and Methods: Experimental composites were prepared by blending a Bis-GMA/TEGDMA resin with bioactive glass (BG) and inert fillers (barium glass and silica) in a centrifugal mixer. Two remineralizing composites with 10 or 40 wt% of BG were denoted as bioactive-10 and bioactive-40. Inert fillers were added up to the total filler load of 70 wt%. Control composite contained only inert fillers (70 wt%). Dentin substrates were prepared from intact third molars, wet-polished using P600 silicon carbide paper and embedded in an acrylic resin. Composite cylinders (d=3mm, h=2mm) were bonded on dentin substrates using a two-step self-etch bonding agent (Clearfil SE Bond 2, Kuraray). Specimens were stored at 37 °C in distilled water and fractured in shear mode after 1 week and 1 year. The optimal sample size for reliability analysis was obtained by preparing n=20 per experimental group (total n=120 for the whole study). Results: Mean bond strengths measured after 1 week and 1 year were statistically similar for the control composite (21.9 vs. 24.0 MPa) and for bioactive-10 (19.6 vs. 19.1 MPa). However, Weibull statistics revealed a significant decline in bond reliability after aging: Weibull moduli decreased from 13.5 to 3.9 for the control composite and from 12.3 to 3.8 for bioactive-10%. For bioactive-40, mean bond strength declined significantly after 1 year (8.1 vs. 6.8 MPa) but its reliability remained unimpaired, as identified by statistically similar Weibull moduli. Conclusions: While conventional statistics were unable to discriminate changes in mean bond strength, the deterioration of bond strength after 1 year was identified using reliability analysis in both the control and experimental bioactive composite.

long-term reliability ; bioactive glass 45S5

nije evidentirano