ABSTRACT
Objective To quantitatively study the pressure of residual lateral displacement in distal radius AO C3.1 fracture after manual reduction corrected by dynamic airbag pad using finite element analysis and to verify its effectiveness for correcting the residual displacement of fractures. Methods Imageware 13.0, Mimics 15.0 and ANSYS Workbench were used to simulate 1 cm residual lateral displacement after manual reduction of distal radius fracture corrected by dynamic airbag pad. Then the correlation between the distance of residual lateral displacement and the adjustment of dynamic airbag pad pressure were quantitatively analyzed. Results In the case of constant load restrained by airbag ribbon, during the process of pressure adjustment by splint pad, the stress was mainly distributed in the fracture end where the airbag pad was located. About 2.4 kPa pressure was needed to correct 1 mm displacement on radial side, while about 1.3 kPa pressure was needed to correct 1 mm displacement on dorsal side. The dynamic airbag pad was depressurized after the restoration of residual shift. At this time, displacement could be effectively prevented due to the constant load of airbag ribbon and the frictional load at the fracture end. Conclusions In the case of constant load constrained by airbag ribbon, intelligent airbag splint can effectively correct the residual lateral displacement after the manual reduction of the distal radius AO C3.1 fracture and prevent it from being displaced by adjusting pressure of the dynamic airbag pad.
ABSTRACT
Objective To elucidate the relationship between mandibular lateral displacement and mandible asymmetry by observing the morphological changes of condylar head and mandible during mandibular lateral displacement in growing rats.Methods Forty-eight male Wistar rats at the age of four weeks were divided at random into experimental and control groups,with 24 rats in each group.A super-hard resin plate was cemented to upper incisors to displace rat mandibles 2 mm to the left during closure(Ipsilateral side).A metal crown was fitted to lower incisors.The rats were killed 2,4,8 or 12 weeks after appliance attachment.The mandible was dissected out and halved.The length and width of condylar head were measured with a caliper.Radiographic films of the mandibles were exposed,and selected measurements were made.Results The length of condylar cartilage on the ipsilateral side was significantly larger than contralateral side in experimental group(P
ABSTRACT
Objective:To analyse the anatomical change of the human temporomandibular joint(TMJ) in the position of mandibular lateral displacement and to provide the anatomical data for temporomandibular disorder.Methods:3 of the 8 samples of selected fresh cadavers were adjusted to mandibular lateral displacement position, and 5 to edge-to-edge occlusion position,then samples were fixed and sectioned according to coronal and sagittal planes by using plastination technique. The feature of the thin plastination sections of the TMJ in the mandibular lateral displacement position and were compared with that in edge-to-edge occlusion position.Results:On the working side in mandibular lateral displacement position, condylar moved backwords,upwards and outside in the articular fossa. Articular discs of TMJ did not move following condylar movement,but posterior band of the articular disc was suppressed by the condylar and articular fossa. On the non-working side in mandibular lateral displacement position, condylar moved ahead,downwards and inwards along posterior incline of articular tuberculum,then articular discs did not move,and middle band of articular discs was suppressed by the condyle and articular tuberculum.Conclusions:The TMJ disc does not shift as TMJ condylar process turns in articular fossa.When the condylar turns and slides at the same time,the articular discs shift.
ABSTRACT
The purpose of this study was to evaluate the effect of the lateral displacement on the mandibular condylar growth in the rabbit. The experimental animals were twenty White NewZealand rabbits of 4-week old. Ten of them was used as control group, and experimental animal was composed of remaining ten. Laterodeviation appliance was made of cast base metal and appliance was cemented with resin in permanent fashion. Experimental group were sacrificed at 1, 2, 4, 6, 8 weeks form beginning of the experiment. Both of temporomandihular joint were prepared for histologic study. The conclusions are: 1. In control group, there was slight increase of proliferative zone and hypertrophic zone at 2-week control animal and slight reduction at 4-week, 6-week and 8-week control animal were similar to 1-week control animal. 2. In right mandibular condyle of experimental group, 2-week experimental animal showed marked increase of proliferative zone and hypertrophic zone at posterior surface of condylar head. In 8-week experimental animal marked increase at anterior surface of anticular surface is observed. 3. In left mandibular condyle of experimental group, proliferative zone and hypertrophic zone were reduced at 1-week experimental animal and slight increase at 2-week. Proliferative zone and hypertrophic zone were reduced at 4-week experimental animal and were slightly increased at 6 week. 4. After 8 weeks, right and left condyle were not different in experimental group. The condylar cartilage was stabilized 8 weeks after the experiment. No marked traumatic change was seen, but minute focal bleeding was seen at articular cavity in 1-week, 2-week and 4-week experimental animal. 6-week and 8-week experimental animal did not show bleeding tendency in articular cavity.