Hydroxyapatite Formation of Dental Restorative Materials

Objective: This study aimed to analyze the formation of hydroxyapatite (HA) of dental restorative materials. Materials and Methods: The bioactivity of four materials were studied in vitro: Cention N (Ivoclar Vivadent) (Cention), ACTIVA™ BioACTIVE-RESTORATIVE™ (Pulpdent) (Activa), Filtek™ Bulk Fill Flowable Restorative (3M) (Filtek), and Fuji IX GP ® (Fuji). Disc-shaped specimens of each material (N=12), 4 mm thick and 5 mm in diameter, were created by placing the materials in a mold and cured following the manufacturers' instructions. The specimens were polished and stored in individual 20mL Falcon-tubes containing 10 mL phosphate buffered saline (PBS), five of each group for 2 weeks and other five of each group for 7 weeks. Two specimens of each material served as the control samples and stored in distilled water. The PBS solution was replaced every week. The specimens were then removed and washed thoroughly with distilled water and dried at room temperature. Amray 3300 FESEM (SEMTech) field scanning electron microscope (SEM) imaging and PulseTor SDD (Silicon Drift Detector) Energy-dispersive X-ray spectroscopy (EDS) analysis were used to determine the surface characteristics (morphology) and chemical composition of the surface precipitate. Weight percentage of calcium and phosphorous were compared between the control, 2- and 7-weeks groups for each material, and between materials for control, 2, and 7 weeks groups. Results: Cention displayed significantly higher weight percentage of surface precipitate calcium (19.6 % at 2 weeks and 20.9 % at 7 weeks) and phosphorous (15.8 % at 2 weeks and 14.5 % at 7 weeks) compared to controls and other materials. SEM images showed agglomerates of spherical particles on the surface of Cention. Conclusion: All results indicated that HA was formed on the surfaces of Cention specimens stored in PBS