| Objective: To study the effects of ultrasonic bone welding technology and screwing technology assisted PDLLA materials on the biomechanical properties of rabbit mandible,and to provide the relevant basis for the clinical application of ultrasonic bone welding technology.Method: Thirty-six male healthy adult rabbits were randomly sorted according to the Excel random number table method and divided into four groups of 9 animals in each group.The groups were as follows that Group A: ultrasonic bone welding technology-assisted PDLLA material group,Group B: screw-in technology-assisted PDLLA material group,Group C: negative control group,Group D : blank control group.Animals sacrificed 4,8 and 12 weeks postoperatively for general observation of samples(successful modelling,postoperative infection,rejection),X-ray inspection(RUST score),three-point bending inspection(maximum load)and 3D finite element analysis(stress concentration and displacement)were used to compare the biomechanical properties of bioresorbable materials after fixation by ultrasonic bone welding technology and screwing technology.Results: There were no swelling and infection in the operation area in the experimental animals at 4,8 and 12 weeks after surgery,and there were significant differences in RUST scores between groups in 4 weeks and 8 weeks after surgery(P<0.05),and there was no significant difference in RUST scores 12 weeks after surgery(P>0.05).After comparing the pairs,it was found that 4 weeks after surgery,There were significant differences between the 8-week ultrasonic bone welding technology-assisted PDLLA material group and the negative control group(P<0.05),the difference between the screwin technology-assisted PDLLA material group and the negative control group(P<0.05),and the difference between the ultrasonic bone welding technologyassisted PDLLA material group and the screw-in technology-assisted PDLLA material group was not statistically significant(P>0.05).Under the vertical stress loading above the bone defect,the stress of the fixed nail of the PDLLA material group assisted by ultrasonic bone welding technology was evenly distributed along the force direction,and the stress concentration occurred near the neck,and the equivalent force difference was very small compared with the screw-in technologyassisted PDLLA material group,and the displacement was small,and the stability was good.Under the three working conditions of simulated occlusion,the stress and displacement caused by the resistance of the near-middle fixed nail to the loading force of the PDLLA material group assisted by ultrasonic bone welding technology are large.In the three-point bending test,the maximum load results of different groups showed significance(P<0.05),and there was no significant difference between the maximum load results of the ultrasonic bone weldingassisted PDLLA material group and the screw-in technology-assisted PDLLA material group at 4 weeks,8 weeks,and 12 weeks after surgery(P<0.05).Conclusion: Compared with the screw-in technology-assisted PDLLA material,the initial stability and mechanical strength of ultrasonic bone welding technology can meet the requirements of jaw healing in rabbit mandible internal fixation experiment. |
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