A Microleakage Study of Various Dental Fillers (Nanohydroxyapatite, Bioactive Glass and Nanohydroxyapatite/Bioactive Glass) for Dental Restoration

Microleakage has been considered a common issue in dental restorations, leading to secondary or recurrent caries. One approach to addressing microleakage in dental cements focuses on enhancing the material's mechanical properties and chemical adhesion to the tooth, thereby sealing microscopic gaps. This study aims to evaluate the mechanical properties and microleakage of various dental fillers comprising nanohydroxyapatite (HA), bioactive glass (BG), and HA/BG composite. Before microleakage evaluation, all dental cement samples were mixed with Fuji FX resin and applied to the cavity of premolar teeth. The results showed that all teeth restored with specific dental fillers had higher compressive strength than those restored with the commercial product (GIC Fuji IX), with the HA/BG composite exhibiting the highest compressive strength at 16.47 kPa. Moreover, all teeth restored with specific dental fillers demonstrated lower microleakage than those restored with commercial fillers, suggesting better sealing. However, there was a shrinkage of the HA cement, leading to microleakage as demonstrated by methylene blue penetration into dentin. Similar microleakage into dentin was obtained in the HA/BG composite, but there was no shrinkage as occurred in HA cement. Overall, bioactive glass cement exhibited superior sealing ability, with the least microleakage, as evidenced by methylene blue penetration limited to the surface (enamel layer). This microleakage evaluation indicates the potential of HA/BG composites as dental cements with superior mechanical performance, with further optimization to enhance chemical adhesion to teeth and minimize microleakage.