Development and analysis of a novel bovine hydroxyapatite calcium silicate cement for conservative pulp therapy
Aim: To develop an experimental endodontic cement using bovine bone-derived hydroxyapatite (BHA), Portland cement (PC), and a radiopacifier and to characterize its physicochemical and biological properties for use in endodontic treatment. Methods: BHA was manufactured from waste bovine bone and milled to form a powder. Four BHA supplemented PCs (BHA 10%/20%/30%/40%), a 10% nanohydroxyapatite (NHA) supplemented PC and an unsupplemented PC (PC65) were manufactured. A radiopacifier, either zirconia (ZrO) or tantalum (TaO) and a plasticizing agent were also included. The raw materials and synthesized cements were chemically characterized and cements were tested to evaluate their radiopacity, compressive strength, setting time, solubility, pH, and biocompatibility (using Saos-2 osteosarcoma cells). The radiopacity and biocompatibility of these cements were also compared with ProRoot MTA (PR-MTA). Compressive strength, solubility and pH were evaluated over a 4-week curing period. Results: The compressive strength of all cements increased with the extended curing times, with a significant increase in all groups from day 1 to day 28. The BHA10% group exhibited significantly higher compressive strength than: PC65, NHA & BHA30/40% at day 1; NHA, BHA30/40% at day 7; and PC65, NHA & BHA30/40% at day 28. The BHA10/20% groups exhibited significantly longer setting times than BHA 30/40% and PC65. NHA exhibited a longer setting time than any other material. No significant difference was observed between cements in terms of solubility and pH during 4-weeks of observation. ZrO was a more effective radiopacifier by weight than TaO. BHA did not alter radiopacity of cements. BHA 10/20% demonstrated significantly higher cell counts compared with BHA 30/40% and MTA at 72 h exposure. Conclusions: The addition of 10% and 20% BHA to an experimental PC-based cement containing 35% ZrO improved the material’s mechanical strength while enabling similar radiopacity and biocompatibility to PR-MTA. BHA is a cost effective additive which has the potential to improve the properties of calcium silicate endodontic cements.
Advisor: Cathro, Peter; Ratnayake, Jithendra; Choi, Joanne; Paul, Cooper; Dias, George
Degree Name: Doctor of Clinical Dentistry
Degree Discipline: Oral Rehabilitation
Publisher: University of Otago
Keywords: Calcium silicate cement; Endodontic; Vital pulp therapy; Conservative pulp therapy; Dental biomaterials
Research Type: Thesis