Calcium Hydroxide Combined with Bioactive Glasses: Physicochemical, Antimicrobial and Bond Strength Evaluation

This study evaluated the pH, solubility, antimicrobial activity, and bond strength of a calcium hydroxide intracanal medication (80% calcium hydroxide and 20% zirconium oxide in polyethylene glycol 400 vehicle), evaluated alone or combined with 20% F18 bioactive glass or copper-doped F18 bioactive glass. Polyethylene tubes containing the medications were immersed in distilled water. pH (n=10) was measured after 1, 3, 7, 14, and 21 days, and solubility (n=7) was determined after 7 and 14 days. Antimicrobial activity (n=6) was assessed using a modified direct contact test against Enterococcus faecalis and/or Candida albicans. For bond strength analysis (n=12), bovine roots were filled with the medications for 14 days and subsequently obturated with Bio-C Sealer or AH Plus. Specimens were subjected to a push-out test, and data were analyzed by ANOVA and Tukey's test (α=0.05). All formulations exhibited an alkaline pH (p>0.05). The formulation without bioactive glass showed higher solubility (p<0.05). The copper-doped bioactive glass formulation was the most effective against E. faecalis in single- and dual-species biofilms (p<0.05), whereas the formulation without bioactive glass completely eradicated C. albicans (p<0.05). Regarding bond strength, no differences were observed among groups obturated with AH Plus (p>0.05). When Bio-C Sealer was used, the F18 bioactive glass formulation exhibited the highest bond strength to dentin (p<0.05). Calcium hydroxide combined with F18 bioactive glass reduced solubility and improved the bond strength of Bio-C Sealer, whereas copper-doped bioactive glass enhanced antimicrobial performance, supporting their potential clinical applicability.