In vitro Study of Root Fracture Treated by CO2 Laser and DP-bioactive Glass Paste

Background/Purpose: An ideal material has yet to be discovered that can successfully treat vertical root fracture. Therefore, the purpose of this study was to use a continuous-wave CO2 laser of medium-energy density to fuse DP-bioactive glass paste (DPGP) to vertical root fracture. Methods: The DP-bioglass powder was based on a Na2O-CaO-SiO2 -P2O5 system and it was mixed with phosphoric acid (65% concentration) with a powder/liquid ratio of 2 g/4 mL to form DPGP. The interaction of DPGP and dentin was analyzed by means of X-ray diffractometer (XRD) and differential thermal analysis/thermogravimetric analysis (DTA/TGA). Root fracture line was filled with DPGP followed by CO2 laser irradiation and the result was examined by scanning electron microscopy (SEM). Results: The main crystal phase of DPGP was monocalcium phosphate monohydrate (Ca(H2PO4)(2) center dot H2O) and the phase transformed to dicalcium phosphate dihydrate (CaHPO 4 center dot 2H(2)O) after mixing DPGP with dentin powder (DPG-D). Additionally, gamma-Ca2P2O7 and beta- Ca2P2O7 were identified when DPG-D was lased by CO2 laser. The reaction temperature was between 500 degrees C and 1100 degrees C. SEM results demonstrated that the fracture line was effectively sealed by DPGP. Conclusion: The chemical reaction of DPGP and dentin indicated that DPGP combined with CO2 laser is a potential regimen for the treatment of vertical root fracture