ABSTRACT
Objective@#To analyze the quantitative relationship between the number of layers of laser pulses and the amount of step in ultra-short pulse laser cutting of cortical bone, optimize the robot's vertical single stepping parameters, and to explore the feasibility of automatic preparation of dental implant cavity using robot controlling ultra-short pulse laser, in order to lay the foundation for automated dental implant surgery.@*Methods@#Eight pig ribs were segmented into to make 16 specimens. Using the robotic surgical system and path planning software independently developed by our group, circular holes with a diameter of 4 mm were cut two-dimensionally in the rib segments to obtain the quantification relationship of the number of laser pulse layers (n) and the depth of two-dimensional (2D) cutting (d). When conducting the three-dimensional (3D) cutting procedure, the number of pulse layers were set to 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 layers, the vertical single step amount was an integer value corresponding to the results of 2D cutting depth, and the number of pulses (n') corresponding to the minimum difference between the theoretical depth of cut and the actual depth of cut was obtained. The n' was taken as the most suitable single step pulse layer, the rib segment was cut, and the depth of single cut was measured while the integer value was taken as the most appropriate vertical single step amount (d'). The vertical parameters of laser single stepping were set as n' layer pulse and d′ μm step size. The 3D cutting produces a cylindrical cavity with a diameter of 4 mm and a height of 2 mm to evaluate the 3D cutting accuracy (the difference between the measured value and the theoretical value of cutting diameter or depth). Ten 4 mm×3 mm implant holes were automatically prepared on the bilateral femurs of 5 Japanese big white rabbits, and ten 4 mm×3 mm implants made by 3D printer were artificially implanted, and the preparation effect of the implant cavities was evaluated.@*Results@#The quantitative relationship curve between the number of laser pulses (n) and 2D depth of cut (d) showed a linear upward trend. The linear fitting obtained the quantitative relation function formula d=9.278 4 n±26.763 0, R2=0.988 9. The optimum number of single step pulse layers was 5 layers, and the vertical single step amount was 50 μm, so as to set the vertical parameters of a single step of a 3D cutting, and the 3D cutting diameter accuracy was (3.98±2.87) μm, with a depth accuracy of (15.42±5.44) μm. Automated preparation of 10 implant cavities on the femur of the rabbit were completed. When the implants were placed into the implant cavities, there was resistance, but they were fully seated and primary stability has been achieved after seating implant placement.@*Conclusions@#The method of non-contact automatic preparation of dental implant cavities using robot controlling ultra-short pulse laser is feasible. By optimizing the single cutting process parameters, precise control of laser cutting cortical bone can be realized.
ABSTRACT
Objective To explore the effect of a new organ preservation solution with HOE642 on the apoptosis of the donor lung from a modified lung transplantation model of rabbits.Methods 24 male rabbits were divided into two groups [low potassium dextran (LPD) group and HOE group],established rabbit models for next 2-h reperfusion using LPD solution or new organ preservation solution.Detected the levles of apoptosis index and caspase-3,the expression of Fas/Fas-L and Bcl-2/Bax.Results Compared with LPD group,HOE group revealed significant lower level of apoptosis index and caspase-3 (P＜0.05),lower expression of Fas/Fas-L and Bax,and higher expression of Bcl-2 (P＜0.05).Conclusion The potential donor lung protective mechanism offered by the new organ preservation solution with HOE642 might be the inhibition of apoptosis via both intrinsic and extrinsic pathways.
ABSTRACT
Objective To investigate the expression of Na+/H + exchanger isoform-1 (NHE-1) during ischemia-reperfusion (IR)in rat lung tissue and determine whether cariporide preconditioning protects lung from inflammatory injury via inhibiting NHE-1 protein expression.Methods Twenty i-solated perfused lungs were randomly divided into 4 groups:the lungs in control group (group C) were continuously perfused for 120 min;the lungs in group IR were subjected to 30 min perfusion, followed by 60 min ischemia and 30 min reperfusion;in group LiCl preconditioning,the lungs were preconditioned with LiCl for 30 min,then continuously perfused for 90 min;in cariporide precondi-tioning+IR (CIR)group,the lungs were preconditioned with cariporide for 30 min,following 60 min ischemia and 30 min reperfusion.After reperfusion,the NHE-1 protein expression was determined by immunohistochemistry and the histopathologic change and pathology scores were ascertained from HE sections.Results The NHE-1 protein expression in lung tissue in groups IR and LiCl were signifi-cantly increased compared with groups C and CIR (P <0.05),and there was no difference between groups C and CIR.Histological examination revealed marked inflammatory changes in groups IR and LiCl,whereas no significant changes in lungs of groups C and CIR.The pathology score of lung in groups IR and LiCl were higher than that in groups C and CIR (P <0.05),and there was no differ-ence between the last two groups.Conclusion IR results in an increased NHE-1 protein expression in rat isolated perfused lung,and the selective NHE-1 inhibitor cariporide could repress the NHE-1 pro-tein expression,thereby decrease the lung inflammatory injury after IR.