Effect of ammonia catalyst on the morphological structures of sol–gel‐derived bioactive glass 58S for dental application

Aim To determine the effect of ammonia on the surface morphology and chemical properties of sol–gel‐derived bioactive glass 58S powders for dental application. Materials and Methods Bioactive glass (BG) 58S powder was synthesized using a sol–gel method. Hydrochloric acid solution was mixed with ethanol, distilled water, and tetraethyl orthosilicate for 30 min, followed by the addition of triethyl phosphate and calcium nitrate tetrahydrate. The mixture was stirred until the particles were completely dissolved. Three different groups were prepared: BG‐1 (no ammonia added), BG‐2 (3 ml of ammonia added), and BG‐3 (5 ml of ammonia added). The gel was then aged and calcined. The solidified gel was crushed until the powder passed through a 200‐μm sieve. Subsequently, the surface morphology was evaluated using a scanning electron microscopy, whereas the chemical composition was assessed using a Fourier transform infrared spectroscopy (FTIR). Results BG‐2 and BG‐3 exhibited small‐sized cluster grains and a more porous micro‐ or nano‐structures. The crystallinity of the BG powder and its surface porosity increased with increased ammonia. The average microparticle sizes of the BG‐1, BG‐2, and BG‐3 were 196 ± 31, 45 ± 21, and 20 ± 9 μm, respectively, with nano‐grains in BG‐2 and BG‐3 showed strong tendency of agglomeration. FTIR verified the existence of a silica network‐based glass, with the Si–O–Si functional group visible in the spectrum of all groups. Conclusion The addition of ammonia as catalyst during the hydrolysis process resulted in small glassy grains and more porous surfaces of BG 58S, which is anticipated to promote greater bioactivity.