Different molarities and dissolution-precipitation duration affect the formation of carbonate-apatite blocks for bone graft material

Objective: To determine diametral tensile strength and water absorption ability of Carbonate-apatite blocks fabricated from gypsum precursors (CaSO4) through a dissolution-precipitation method, with different solution molarities and immersion times. Material and Methods: Thirty-six CaSO4 gypsum specimens with 6 mm diameter; 3 mm height (Group A for diametral tensile strength) and 36 specimens of 6 mm diameter; 3 mm thickness (Group B for water absorption ability) were used. Each group was divided into 4 group treatments of: 1) dissolution-precipitation in solution of 0.5mol / L Na₂CO₃ + 0.5mol / L Na₃PO₄ for 48 hours and 72 hours; 1mol / L Na₂CO₃ + 1mol / L Na₃PO₄ for 48 hours and 72 hours. The C-Ap blocks were then tested using ATR-FTIR spectrometer to identify the formation of C-Ap functional groups. Furthermore, Group A specimens were tested for diametral tensile strength using Universal Testing Machine, and Group B specimens were tested for water adsorption ability using an analytical balance by measuring initial and final weight after immersion in saline solution at 37^oC for 24 hours. Results: The formation of carbonate-apatite (C-Ap) in groups with solution molarity of 1 mol/L for 48 hours and 72 hours resulted in a lower diametral tensile strength and water absorption ability than the groups with a 0.5 mol/L solution. Conclusion: Solution with different molarities and dissolution-precipitation duration affect the formation of carbonate-apatite blocks.