A novel root-end filling material based on hydroxyapatite, tetracalcium phosphate and polyacrylic acid

Aim: To develop a novel root-end filling material (NRFM) based on hydroxyapatite, tetracalcium phosphate and polyacrylic acid, to determine its chemical composition and to compare its physical properties and cytotoxicity with those of glass-ionomer cement (GIC) and grey Portland cement (GPC). Methodology: The NRFM was prepared by blending distilled water with powders of hydroxyapatite, tetracalcium phosphate, solid polyacrylic acid, solid citric acid and sodium citrate. Chemical analysis was then performed by X-ray diffraction and Fourier transform infrared spectrophotometry. Physical properties were compared with GIC and GPC regarding setting time, compressive strength, pH value and washout resistance; cytotoxicity was assessed using a transwell cell culture system. Results: (i) The NRFM was primarily composed of HA, calcium polyacrylate and calcium citrate. (ii) The mean and standard deviation setting time of NRFM was 11.0 (0.8) min; its compressive strength was 25.6 (2.7) MPa and 38.2 (5.7) MPa at 1 and 7 days respectively. Its pH value ranged from 6.14 to 8.28 and it remained intact after the washout test, whereas GIC and GPC disintegrated. (iii) Dimethyl-thiazol-diphenyl tetrazolium bromide (MTT) and crystal violet (CV) assay revealed that cell-viability on the NRFM was not significantly different form that of the negative control group after treatment for 24, 48 and 72 h. Conclusion: The novel root-end filling material (NRFM) is a promising root-end filling material with good physicochemical properties and low cytotoxicity.