The experimental study on nano-HA-ZrO2 ceramic as dental implant materials

Objectives: It is not found that any HAp compound ceramic product has been widely used as dental implant all over the world. A combination of materials properties is thus expected to give a bioactive hydroxyapatite-containing implant material with improved mechanical properties in this study. Methods: Applying a novel consolidation technique-SPS(Spark plasma sintering), we obtained nano-HAp-ZrO2 ceramic (with two constitutions 4:6 and 5:5). The cubage density, the ratio of pores was determined. To evaluate its mechanical properties, its flexural strength, fracture toughness and hardness was also measured . In order to evaluate the preliminary biological properties of nano-HAp-ZrO2 ceramic, two tests were taken up according to ISO standards including in vitro cytotoxicity test and acute hemolysis test . Animal implanting test has been done to put ceramics in the hole of the rabbit femur orderly. The Ti based with HAp coating implants was used as positive control group. During the 1 month, 3month, 6month the implant parts were taken X-ray photos separately, and were made hard tissue undecalcified sections in each group, by Von Gieson staining. The biological properties of two ceramics were compared and evaluated. Results: 1, The HAp-ZrO2 ceramic did not contain any phases other than hydroxyapatite and the tetragonal modification of zirconia. It is fully densified thus free of pores. 2,There were no obvious statistic differences between cubage density and theoretic density of each group . 3, The toxicity grades of all groups were 0 or 1. 4,Histomorphometric comparison were made the sequence of the extent of material-bone combination: Ti-HAp group>(5:5) group>(4:6) group. Conclusions: Dense nano-hydroxyapatite-zirconia ceramic showed better mechanical properties than pure hydroxyapatite, no cytotoxicity, and good combination with bone tissue around implant area. The larger amount of composition of HAP is contained, the better biocompatibility of compound ceramic is, but with the lower mechanical properties.