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 express nonstructural protein 2 transactivated protein (NS2TP) of hepatitis C virus (HCV) in the prokaryotic expression system and prepare polyclonal antibody,and to study the expressions in different liver tissues.Methods NS2TP gene was amplified by polymerase chain reaction (PCR) technique and cloned into the prokaryotic expression vector pET-32a(+),which was transformed into E.coli BL21.The protein was induced by isopropyl thiogalactose (IPTG) and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and confirmed by Western blotting assay.The recombinant protein were expressed and purified in a large amount.The rabbit was immunized with the purified protein to prepare polyelonal antibody.The liver tissues of patients with chronic HCV infection and healthy controls were detected by immunohistochemistry method.Results The recombinant NS2TP protein (relative molecular mass:33×103 ) and polyclonal antibody with high titer and specificity were successfully prepared.NS2TP expressions in the liver of patients with chronic HCV infection were higher than those of healthy controls,and were mainly distributed in the nucleus of hepatocytes.Conclusions The NS2TP expression level and intracellular location in liver tissue of patients with chronic HCV infection are understanded,which could bring new clues for further study of the biological function of NS2TP and the pathogenesis of HCV infection.

Objective: Strategy for wound repair of skin and soft tissue defect and systematic rehabilitation treatment for functional reconstruction of patients with severe burn or trauma on knees. Methods: From January 2015 to October 2016, 26 patients with skin and soft tissue defect on knees after severe burn or trauma were hospitalized in our unit. Among these patients, 14 patients had patellar ligament defect, and 16 patients had knee joint capsule defect. Wound debridement was operated on 1 to 3 days after admission. After debridement, the area of skin and soft tissue defect ranged from 10 cm×7 cm to 42 cm×18 cm. Vacuum sealing drainage (VSD) treatment was performed after debridement, and flap transplantation operation was performed after VSD treatment for 5 to 7 days. Defects of nine patients were treated with local rotation flaps. Seven patients with skin and soft tissue defects on knees and knee joint capsule defects of 5 cm×3 cm to 9 cm×7 cm were treated with free anterolateral femoral flaps combined with fascia lata. Ten patients with skin and soft tissue defects on knees and patellar ligament defects of 6 cm×3 cm to 12 cm×4 cm were treated with free anterolateral femoral flaps combined with iliotibial tract. The area of flaps ranged from 11 cm×9 cm to 22 cm×15 cm. After flap transplantation operation, functional reconstruction of knee joint was carried out according to early, continuous, and sequential systematic rehabilitation treatment strategy. The pain degree and function of knee joint of patients were scored by the International Knee Documentation Committee (IKDC) Knee Evaluation Form before operation and 12 months after operation. The knee joint flexion and extension degrees of patients were measured by joint protractor in 2 weeks and 12 months after operation. The color Doppler ultrasound was used to evaluate integrity of knee joint capsule and continuity of patellar ligament of patients in 6 and 12 months after operation. Results: All flaps of 26 patients survived well, and wounds healed completely after the operation. Distal parts of flaps of 2 patients treated with free anterolateral femoral flaps had local necrosis after the operation, and their wounds healed after debridement and transplantation of autologous intermediate split-thickness skin graft of thigh. The IKDC Knee Evaluation Form score of patients was (79±8) points in 12 months after operation, which was significantly higher than (64±7) points before operation (t=7.20, P<0.05). The flexion degree of knee joint of patients was (117±10)° in 12 months after operation, which was significantly larger than (35±8)° in 2 weeks after operation (t=32.65, P<0.05). The extension degree of knee joint of patients was (12±9)° in 12 months after operation, which was significantly smaller than (61±9)° in 2 weeks after operation (t=19.63, P<0.05). In 6 and 12 months after operation, 9 patients treated with local rotation flaps had good integrity of knee joint capsule and continuity of patellar ligament; 7 patients treated with free anterolateral femoral flaps and fascia lata had good integrity of knee joint capsule; 10 patients treated with free anterolateral femoral flaps and iliotibial tract had good continuity of patellar ligament. During follow-up of 12 months, all flaps survived well; knees of all patients had good appearance; knee joints functioned normally. Conclusions Good appearance and function of knees can be achieved by repairing wound of skin and soft tissue defect on knees after severe burn or trauma with local rotation flaps or free anterolateral femoral flaps with fascia lata or iliotibial tract plus systematic rehabilitation treatment of knee joint in early stage after flap transplantation operation.

Objective:To evaluate the effect of goal-oriented online and offline mixed teaching method on the trainees of burn operating room.Methods:From June 2019 to June 2020, 42 trainees of burn operating room in our hospital were selected for the randomized parallel trial, and they were randomly divided into two groups, routine group and research group. The routine group adopted the conventional online and offline mixed teaching method, while the research group adopted the goal-oriented online and offline mixed teaching method. The internship time of both group lasted for 1 month. Results and excellent rates, self-confidence and burn surgery skills evaluation before and after the internship, and satisfaction with the internship mode were compared between the two groups. SPSS 19.0 was used for t test and chi-square test. Results:The results and excellent and good rates of theoretical examination and practical examination in the research group were higher than those of the routine group. The scores of self-confidence, choice of operation mode, innovation and optimization of operation, control of operation complications and treatment of intraoperative emergencies in the two groups after internship were higher than those before internship, and the above scores of research group were higher than those of the routine group after internship. The satisfaction scores of the students on enhancing self-confidence, and improving operational ability, learning initiative and learning efficiency in the research group were significantly higher than those in the routine group ( P < 0.05). Conclusion:Goal-oriented online and offline mixed teaching method on trainees in burn operating room can not only improve the examination results, enhance their confidence and burn surgery skills, but also achieve their satisfaction.