Surface Micromorphology of Experimental Composites Doped with Bioactive Glass After Different Storage Times.

Objective: To evaluate the surface micromorphology of bioactive glass-modified resin composite materials after storage in simulated body fluid for different periods of time and ultrasonic cleaning.

Materials and methods: A resin composite material (Heliomolar Flow, Ivoclar Vivadent) was modified by incorporating 10 or 20 wt% of bioactive glass 45S5. The unmodified conventional composite (0 wt% bioactive glass) served as the control. Surface morphology of light-cured composite specimens was examined by profilometry both before and after storage in simulated body fluid (SBF; pH = 7.4, t = 37 °C) for 0, 3, 7, or 30 days, and surface roughness (Ra) was recorded. After storage, ultrasonic cleaning (UC) of the specimens was performed for 10 min in an ultrasonic bath filled with deionized water, and the profilometric measurements were subsequently repeated. In addition, the surfaces of specimens were examined by scanning electron microscopy (SEM).

Results: Directly after specimen preparation, the Ra values of the composites modified with bioactive glass were similar to those of the conventional composite (0 wt% bioactive glass). A longer immersion in SBF and higher added concentrations of bioactive glass led to an increase in surface roughness. SEM examination revealed that precipitates were formed on the surfaces of specimens containing bioactive glass after exposure to SBF for at least 7 days. The density of these precipitates increased with exposure time and added bioactive glass content. After subsequent ultrasonic cleaning, a significant Ra reduction was observed for specimens containing 10 and 20 wt% bioactive glass and stored for 30 days (p < 0.001). For the resin composite material doped with 20 wt% bioactive glass particles, UC revealed a significant Ra reduction at all time points.

Conclusion: The increase in the surface roughness of bioactive glass-modified composites after storage in SBF might be partly attributed to precipitate formation on their surfaces. After ultrasonic cleaning, surface roughness was still increased, indicating poorer surface quality compared to conventional composite.