[The effect of sintering temperature on the physical and mechanical properties of dental zirconia toughened ceramic].

OBJECTIVE: To investigate the effects of sintering temperature on the physical and mechanical properties of dental zirconia toughened ceramic (ZTC). METHODS: 3 mol% yttria-stabilized zirconia compacts were prepared by dry press method and then sintered at 1,490 degrees C, 1,530 degrees C, 1,570 degrees C and 1,610 degrees C respectively. The physical properties and bending strength were then measured. RESULTS: The result of the study indicated along with the rise of sintering temperature density and shrinkage of ZTC increased, but the pore structure decreased. It also showed the peak of bending strength was in 1,570 degrees C. CONCLUSIONS: In terms of sintering temperature and bending strength among the selected temperature, the best sintering temperature of 3 mol% yttria-stabilized zirconia should be about 1,570 degrees C.

[The complications of nerve injury after the Le Fort I osteotomy].

OBJECTIVE: To investigate the incidence of the temporary and permanent sensory disturbance of the inferorbital nerve (ION) after Le Fort I osteotomy. METHODS: Thirty patients with 60 inferorbital nerves were examined preoperatively, 1 week, 1 month, 3 months and 6-months after the operation of the Le Fort I osteotomy by using sharp-blunt testing, 2-point discrimination, electric pain response test (ZGK-1 electrometer). RESULTS: The incidence of the temporary nerve impairment was 75% (45 of 60) and the obvious recovery was found after 1 to 3 months after the operation. No permanent sensory disturbance was found in the patients. CONCLUSIONS: The inferorbital nerve injury after Le Fort I osteotomy is usually temporary and the sensory recovery was in 1 to 3 months after the operation.