ABSTRACT
Objective@#The study presents a new method to prefabricate the nasoalveolar molding appliances for preoperative cleft lip and palate by using three-dimensional technology.@*Methods@#A long term retrospective study of 40 cases of infants with unilateral cleft lip and palate who underwent the preoperative 3D models of alveolar bone acquisition, computer aided design for the rapid prototyping process, gypsum powder printing maxillary three-dimensional entity model and install the appliance for 3-4 months (or alveolar cleft<2 mm). Simultaneously, primary rhinoplasty can be done during cleft lip repair. All patients had clinic visits three times each month.@*Results@#Deformities of infants who underwent this treatment, were significantly improved. The alveolar cleft was significantly reduced (P<0.01), while bilateral alveolar tissue volume was significantly increased (P<0.01). Alveolar bone morphology was more symmetrical than before.@*Conclusions@#The digital design and manufacture system of appliances for preoperative cleft lip and palate can be successfully applied to the preoperative orthodontic treatment. The sequence treatment of cleft lip and palate becomes better improved. It can shorten the time duration and the numbers of clinic visit on the basis of ensuring the accuracy of preoperative orthodontic effect.
ABSTRACT
Objective To reconstruct a vehicle-bicycle-cyclist crash accident and analyse the injuries us-ing 3D laser scanning technology, multi-rigid-body dynamics and optimized genetic algorithm, and to provide biomechanical basis for the forensic identification of death cause. Methods The vehicle was measured by 3D laser scanning technology. The multi-rigid-body models of cyclist, bicycle and vehicle were developed based on the measurements. The value range of optimal variables was set. A multi-ob-jective genetic algorithm and the nondominated sorting genetic algorithm were used to find the optimal solutions, which were compared to the record of the surveillance video around the accident scene. Re-sults The reconstruction result of laser scanning on vehicle was satisfactory. In the optimal solutions found by optimization method of genetic algorithm, the dynamical behaviours of dummy, bicycle and ve-hicle corresponded to that recorded by the surveillance video. The injury parameters of dummy were consistent with the situation and position of the real injuries on the cyclist in accident. Conclusion The motion status before accident, damage process by crash and mechanical analysis on the injury of the victim can be reconstructed using 3D laser scanning technology, multi-rigid-body dynamics and opti-mized genetic algorithm, which have application value in the identification of injury manner and analysis of death cause in traffic accidents.