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

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).

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.

(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.

The novel root-end filling material (NRFM) is a promising root-end filling material with good physicochemical properties and low cytotoxicity.