Objective To study the efficacy of repairing bone defect with the composite of allogeneic morselized bone, bone morphogenetic protein(BMP)and collagen. Methods 1.5 cm long bone defect was created in each radius of 34 New Zealand rabbits. A composite of 200mg allogeneic minute morselized bone with 10 mg BMP and 0.2 ml collagen was placed into the bone defect of left radius in each rabbit (group A); the contralateral bone defect was filled with a composite of 200 mg allogeneic morselized bone and 0.2 ml collagen (group B). The bone mineral density(BMD)of the defects was evaluated at 8 and 12 weeks. The biomechanic tests were examined at 12 weeks. In group C, only 0.2 ml collagen was implanted as control. Results Radiological and histological examination revealed that the defects healed completely in both experimental groups, but there were more new bone formation, early bridging and rapid healing in group A compared with that of group B. The value of BMD in group A was higher than that in group B. The three-points bending test of group A showed that ultimate strength and bending stiffness were superior than that of group B, the anti- axial compressive stiffness as well; and the torsion rigidity and maximal torque of group A were also greater than that of group B. There were significantly statistic differences in all biomechanical tests between the two groups. Histological evaluations displayed that there were significant differences in matured level of new bone formation and remodeling process between two experimental groups. The new lamellar cortical bone formation was more matured, and the remodeling process was more perfect in group A comparing to that of group B, which might contribute to the better mechanical properties of group A. The defects did'nt achieve any osseous healing in control group. Conclusion The allogeneic morselized bone can be used effectively to repair segmental bone defects. The experiment suggests that the bone healing process can be promoted by the composite morselized bone graft with BMP and collagen.

Objective To study the expression of basic fibroblast growth factor (bFGF) in ectopic osteogenesis of autogenetic minimal morselized bone so as to discuss the bone formation of minimal morselized bone. Methods All 48 rabbits were divided into two groups randomly. Then autogenetic minimal morselized bone and bulk bone were implanted into the muscle bag models of gluteus maximus muscle respectively. Samples were harvested on day 1,3,5,7,11,14,21 and 28 postoperatively and tested by the methods of histology, immunohistochemistry (IHC) and in situ hybridization (ISH). Results (1) The morselized bone grew faster than the bulk bone and was replaced by neonatal bone on the 28th day. In the group of bulk bone, the ability of osteogenesis was weaker dominated by bone absorption. (2) In the morselized bone group, the expression peaks of bFGF and bFGFmRNA appeared at day 5-7 postoperatively, mainly appeared in the mesenchymal cells, fibroblast, chondrocyte and osteoblast by the method of IHC and ISH. While in the group of bulk bone, the expressions of bFGF and bFGFmRNA were similar to those in the morselized bone group. The difference between the two groups was significant ( P

BACKGROUND: Currently, acid etching and bonding technology have been widely used in clinical stomatology. Data have indicated that the main content of inorganic elements (calcium and phosphorus) has a certain difference between the dental enamel and dentin of the young and adult permanent teeth. OBJECTIVE:To measure the content of main inorganic elements, calcium and phosphorus, in the dental enamel and dentin from young and adult permanent teeth with spectrophotometry and ethylene diamine tetraacetie acid titration method. METHODS:Each 20 adult and young permanent teethin vitrowere selected. Plaster stone and water was mixed; when it was nearly dried, the teeth were verticaly cast in the mixture and the tooth surface was exposed. The models were cut into the slices using syj-200 precision cutting machine, and then the slices were put into nitric acid and dissolved through heater to prepare standard solution. At last, the concentrations of calcium and phosphorus in the hard tissue of both young and adult permanent teeth were measured with spectrophotometric method and titration method. RESULTS AND CONCLUSION:The content of calcium and phosphorus and calcium/phosphorus ratio in the hard tissue of young permanent teeth were less than those of adult permanent teeth (P < 0.05), reflecting that the organic matter content was more than that in adult permanent teeth, but their mineralized degree was inferior to that of adult permanent teeth (P < 0.05). These findings indicate that the young permanent teeth are more acid proof than the adult permanent teeth; therefore, the acid etching time can be properly prolonged for young permanent teeth in clinical treatment, in order to achieve better effects.

Objective To explore the volume size of mastoid pneumatization in normal adults and the relation‐ship with a history of recurrent otitis media in childhood .Methods A total of in 40 adults (80 ears) ,based on with or without otitis media in childhood ,were divided into the study group (n= 20) and the control group (n=20) . The volume sizes of mastoid pneumatization were measured by temporal bone CT scanning of three-dimensional re‐construction ,and the relationship with the history of childhood ear infections was studied .Results The average vol‐ume of pneumatization in all 80 temporal bones was 10 .4 ± 1 .8 ml .The average volume of pneumatization in sub‐jects without otitis media history (48 ears) and subjects with a history of otitis media (32 ears) were 9 .7 ± 2 .2 ml and 6 .3 ± 1 .7 ml ,respectively .The difference was statistically significant (P<0 .05) .For the subjects with single ear disease in the study group ,the average volume of pneumatization in subjects without otitis media history(8 ears) and subjects with a history of otitis media(8 ears) were 9 .2 ± 1 .3 ml and 5 .8 ± 3 .6 ml ,respectively ,and there were statistically significant differences(P<0 .05) .The average volume of pneumatization in the control group (40 ears) was 10 .1 ± 4 .4 ml .Comparing with the subjects with out otitis media history(8 ears) in the study group ,there was no statistically significant difference (P>0 .05) .Conclusion The volumes of mastoid pneumatization in normal ears have a wide range .The subjects with a history of recurrent otitis media in childhood may be the cause of the volume decrease of mastoid pneumatization in adulthood .

Objective To investigate the effects of prolonged low-dose neutron-γ radiation on peripheral blood lymphocytes of logging workers. Methods The health information of workers in a logging company was collected by on-site blood sample collection and questionnaire survey. Individual doses of γ and neutron radiation were recorded using LiF elements and CR-39, respectively. Lymphocyte count in peripheral blood was measured by blood cytometer. Cell cycle and cyclins were detected by flow cytometry. Results The annual dose of some logging workers exceeded 5 mSv. Lymphocyte counts showed a difference of 15% between the group exposed to the lowest annual dose of 0–1 mSv (mean: 2.45 × 10⁹/L) and the group exposed to the highest annual dose of 5–25 mSv (mean: 2.08 × 10⁹/L). In comparison to pre-shift workers, logging workers exhibited a G1-phase arrest in the lymphocyte cycle, along with increased expression of cyclins p21 and CDK2. Conclusion Prolonged exposure to low-dose neutron-γ radiation leads to reduced lymphocyte counts as well as changes in lymphocyte cycle and cyclin expression.