[Reconstruction of the mandibular model using a three-dimensional laser scanner].

OBJECTIVE: To construct a three-dimensional (3D) mandibular model using a 3D laser scanner, and explore a new method for reconstructing the finite element geometry model. METHODS: A mandible specimen was scanned with the 3D laser scanner to form the point clouds of the mandibular surface, which were subsequently aligned for reconstruction of the mandibular model. RESULT: A 3D model of the mandible surface was reconstructed, which could be used for finite element simulation. CONCLUSION: The 3D laser scanning system can be used to reconstruct the 3D model with irregular geometry for finite element simulation.

[Applied anatomic study on blood supply for extracranial segment of facial nerve].

OBJECTIVE: To explore the arterial origin and the distribution of the extracranial branches of the facial nerve. METHODS: Red latex or red chlorinated polyvinyl chloride was injected into the arteries of 15 fresh adult head specimens by both common carotid artery catheterization. The arterial origin and distribution of the extracranial branches of the facial nerve were observed. RESULTS: The nutrient arteries of the extracranial branches of the facial nerve originated from stylomastoid artery of the posterior auricular artery, the facial nervous branch of superficial temporal artery, transverse facial artery, superior and inferior facial nervous branches of external carotid artery and the posterior and anterior facial nervous branches of external carotid artery. The outer diameters of them were (0.8 +/- 0.2) mm, (0.9 +/- 0.4) mm, (1.9 +/- 0.3) mm, (1.0 +/- 0.2) mm, (1.1 +/- 0.4) mm, (1.0 +/- 0.2) mm and (1.1 +/- 0.6) mm respectively. The sub-branches of the attendant artery of the facial nerve anastomosed each other in addition to supplying their own nerve, and a rich vascular network was formed between the facial nerve and adjacent tissue. CONCLUSION: The study on blood supply of the extracranial segment of the facial nerve can provide anatomic basis for avoiding injury of the nutrient arteries of the facial nerve during operation of the parotidean and masseteric region clinically.

Effects of stanozolol on bone mineral density and bone biomechanical properties of osteoporotic rats.

OBJECTIVE: To evaluate the effects of stanozolol on the bone mineral density (BMD) and bone biomechanical properties of rats with glucocorticoid (GC)-induced osteoporosis (OP). METHODS: Twenty-eight male Sprague-Dawley rats of 3-month old were randomly divided into Group A (the basal control group), Group B (the age-matched control group), Group C (GC-induced OP group) and Group D (stanozolol-administrated group), 7 in each group. The rats in Group A were killed when experiment commenced, and those in Group B were given normal saline ig., while those in Groups C and D received the prednisone acetate (4.5 mg/kg, twice a week) alone and in combination with stanozolol (0.5 mg/kg, 6 times a week), respectively. Ninety days later, the bilateral femur and the 5th lumbar vertebra of the rats were isolated for BMD test using dual-energy X-ray absorptiometry scanner, and the torsion test, three-point bending test and compression test using electronic testing device. RESULTS: Compared with Group B, the mean BMD of the femur and the 5th lumbar vertebra in Group C decreased by 14.64% (P<0.01), the BMD of the bilateral distal femoral segment and the 5th lumbar vertebra decreased by 21.42% (P<0.01), 19.62% (P<0.05) and 23.48% (P<0.01) respectively. The load that the femur withstood in three-point bending test decreased by 17.1% (P<0.05), and the other biomechanical parameters also declined. When compared with Group C, the BMD in Group D increased, the torsional angle of the femur increased by 72.5% (P<0.05) and the other biomechanical parameters also tended to increase. CONCLUSIONS: BMD and biomechanical properties of the rat femur and the 5th lumbar vertebra decrease in response to a long-term GC administration, which can be prevented by stanozolol.

Effects of prednisone on bone mineral density and biomechanical characteristics of the femora and lumbar vertebras in rats.

OBJECTIVE: To explore effects of prednisone on the bone mineral density (BMD) and biomechanics of the femora and lumbar vertebras in rats. METHODS: Twenty one 3-month-old male Sprague-Dawley rats weighing 226+/-12 g were randomly divided into basal control, age-matched and hormone groups. The rats in basal control group were killed at the beginning of the experiment without any treatment, and those in age-matched group were given oral normal saline (5 ml x kg(-1) x d(-1)) while the rats in hormone group received oral prednisone acetate (4.5 ml x kg(-1) x d(-1) twice a week) to establish osteoporotic models. The treatment for the latter 2 groups of rats lasted for 90 days, after which the BMD and mechanical measurements of the femurs and L5 vertebra were carried out by way of torsion, three-point bending and compression tests. The measurements were also conducted in the basal control group at the time indicated above. RESULTS: In hormone group, the total BMD of the femora and L5 vertebra was decreased by 14.64%(P<0.01), and the BMD in the right and left distal femoral segments and the vertebra decreased by 21.42% (P<0.01), 19.62% (P<0.05) and 23.48%(P<0.01), respectively, in comparison with the control group. In the meantime, the loads of three-point bending test in hormone group was decreased by 17.1%(P<0.05), whereas the rest parameters tended to decrease as compared with the control group. CONCLUSIONS: Chronic use of corticosteroid is more liable to cause bone mass loss in rat cancellous bone than in the cortical bone, and mechanical properties of the cortical and cancellous bone, especially those of the latter, will also decline, to give rise to easy bone fracture at the trabecular bone in osteoporotic conditions.