Evaluation of fixation of expandable implants in the mandibles of ovariectomized sheep.

PURPOSE: This study aimed to investigate the effects of an expandable implant (EI) in ovariectomized sheep. METHODS: The EI and taper implant (control group) were produced and placed in mandibles of ovariectomized sheep. Twelve weeks after implantation, resonance frequency analysis, biomechanical tests, histomorphometry, and micro-computed tomography were applied to detect the osseointegration in the 2 groups. RESULTS: The implant stability quotient values, maximal pullout forces, and bone-implant contact (BIC) were 60.3 ± 7.9, 511.0 ± 18.7 N, and 53.14% ± 4.56%, respectively, in the EI group and 58.3 ± 8.9, 394.5 ± 54.5 N, and 46.85% ± 5.04%, respectively, in the control group. There was no significant difference between the 2 groups in implant stability quotient values (P > .05); however, in the EI group the maximal pullout force and BIC were increased significantly (P < .05 and P < .01, respectively). Micro-computed tomography analysis showed that the bone volume/total volume ratio and trabecular number increased significantly (P < .01) and trabecular separation decreased significantly (P < .05) in the EI group. CONCLUSIONS: EI could improve osseointegration in osteoporosis after 12 weeks of implantation by increasing BIC around the implant and by supplying an extra osseointegration surface.

[Transforming the sintered ostrich cancellous bone to multiphasic calcium phosphate ceramic].

OBJECTIVE: To transform the sintered ostrich cancellous bone(ostrich true bone ceramic, OTBC) to multiphasic calcium phosphate ceramic and study its components and characterization. METHODS: The OTBC blocks were soaked in different concentration of sodium pyrophosphate (Na(4)P(2)O(7).H(2)O,NP) solution and heated to 1100 degrees C to transform its constitution from HAP into multiphasic calcium phosphate ceramics. Then the surface configuration of the material was observed by SEM and the following properties of the material:porosity,bending strength,mineral composition and element ratio were analyzed. RESULTS: The prepared material was a kind of porous calcium phosphate ceramic composed of beta-TCP, HAP and NaCaPO(4). With increase of the NP concentration,the content of HAP decreased while beta-TCP and NaCaPO(4) increased. The average bending strength of the material was (1.95+/-0.46)Mpa,the Ca/P element ratio was 1.511 and the average porosity was(60.71+/-6.9)%. The pore size was uneven. CONCLUSION: The OTBC could be transformed into beta-TCP /HAP /NaCaPO(4) multiphasic calcium phosphate ceramic by heating with NP. With characteristic porous structure, the prepared OTBC could become a new type of bone graft.