Objective To evaluate the effects of recombinant human bone morphogenetic-2-polylactide sustained release nanospheres (rhBMP-2-PLA-Ns) on cultured rabbit osteoblasts in vitro. Methods Rabbit osteoblasts were cultured in vitro, and rhBMP-2-PLA-Ns was added into the medium of the third generation of rabbit osteoblasts. The expression of the proliferating cell nuclear antigen (PCNA) was examined by immunofluoreacence staining, and the formation of tuberculums observed with alizarin red staining. Western blot was used to detect the effects of rhBMP-2-PLA-Ns on the expression of vascular endothelial growth factor (VEGF), which was compared with that in rhBMP-2 group and blank group. Results There was no significant difference in the number of osteoblasts with positive PCNA expression among three groups five days later. Ten days later, the number of osteoblasts with positive PCNA expression in rhBMP-2-PLA-Ns group was significantly higher than that in rhBMP-2 group and blank group, which indicated that rhBMP-2-PLA-Ns could enhance the expression of PCNA. Compared with rhBMP-2 group and blank group, rhBMP-2-PLA-Ns could significantly enhance the formation of tuberculums, with statistical difference (P<0.05). The expression of VEGF was detected in all three groups, and the level of the VEGF expression in rhBMP-2-PLA-Ns group was significantly higher than that in the other 2 groups (P<0.05). Conclusion The biological activity of rhBMP-2-PLA-Ns is superior than that of rhBMP2, and rhBMP-2-PLA-Ns can promote the proliferation, mineralization of osteoblasts and the secretion of VEGF, which has a better prospect in facilitating traumatic bone healing.

Objective:To investigate biomechanical changes of mandible in the impact injure simulated by finite element method (FEM).Methods:Mimics and Comsol software were used to build a FEM of human craniofacial bone based on CT scan data of a normal adult.LS-DYNA and Hypermesh software were used to simulate the impact with different quality,velocity and angulation pro-duced injures of human mandible,the biomechanical parameters of the mandible in the impact injury process were analysed.Results:A FEMof human maxillofacial bone was established,and the dynamic process of different impact force produced damage was simula-ted.Mandibular chin,angle and condylar neck was the stress concentrated area in the process of mandible injury.There was higher stress peak at the site which was closer to the impact position,the stress peak arrival time was also earlier.When the impactor with the same quality,the bigger the velocity,the greater the stress peak.When the impactor with the same velocity,the bigger the quali-ty,the greater the stress peak.When the impactor with the same velocity and quality,there was greater stress peak under the impact to mandible from angulation of 0 degree.Stress transfered to the surrounding bone from the impact position radially and gradually re-duced.The bone area with small cross-section was prone to high stress and more serious damage.Conclusion:The quality,the ve-locity,the impact angle and the impact site are the factors affecting the severity of impact injury.

Objective To compare the disinfectant effects of calcium hydroxide and traditional formaldehyde and cresol(FC) on the intracanal medicament in infected single rooted teeth. Methods A total of 84 single rooted teeth with chronic apical periodontits were randomly selected for the disinfection with calcium hydroxide or FC in root canal after the root canals were cleared routinely. Samples were taken before and after root canal disinfection a week later. The number and species of bacteria in the root canal and the change of clinic signs and symptoms were observed. All the patients were followed up for one year. Results The number and species of bacteria in the root canal decreased significantly and there was significant difference between the two groups ( P 0.05). Conclusion Calcium hydroxide is an effective disinfectant in root canal therapy.

Objective To develop a 3D finite element model for the human craniomaxillofacial region in an attempt to offer basis to the research of simulation of craniomaxillofacial injury.Methods A healthy adult male was submitted to head CT scan, and the data was imported into the Mimics 15.0 software for threshold segmentation and 3D reconstruction according to the classifications of bone tissue, skin tissue and subcutaneous tissue.The reconstruction data was imported into 3D reverse software Geomagic Studio 2012, and the images were optimized and the 3D model was generated.The three parts of the model were fitted according to the actual proportion using the 3D control software Solidworks 14.0, and then the boundary conditions were derived.Hypermesh 12.0 finite element processing software was used to build the volume mesh, and the model was established.Each layer of the model was given to the material parameters, and the simulation conditions were provided to test the model.Results This model was completely composed of volume meshes, including 214,250 hexahedral meshes and 411,920 nodes.This model can clearly show the stress distribution, the trend of fracture line, the displacement of fracture block of soft and hard tissue during the simulation, and the results are consistent with clinical practice.Conclusion A three-dimentional finite element model with good performance is established, which can be used for biomechamics simulation analysis of multiple sites on the head or the whole structure, and has a certain significance in clinical and scientific research.

Objective To investigate the relationship between nucleotide excision repair cross-complementing (ERCC) gene polymorphisms [single nucleotide polymorphism (SNP) sites: rs11615, rs13181, rs238406, rs6498486, rs17655] and susceptibility to endemic arsenic poisoning. Methods The study recruited 848 subjects, including 348 cases and 500 controls, from populations exposed to high arsenic levels through drinking water in northwest China, and 3 - 5 ml venous blood was collected. The genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism techniques(PCR-RFLP). Logistic regression analysis was used to assess the association of genotypes with endemic arsenic poisoning. Results The polymorphisms of rs11615 (ERCC1), rs238406 (ERCC2), rs6498486 (ERCC4) and rs17655 (ERCC5) and endemic arsenic poisoning were not related(P > 0.05). Participants who carried the CC genotype or at least one C allele for the ERCC2 rs13181 had an increased risk of endemic arsenic poisoning[OR(95%CI)=1.63(1.13,2.34),1.64(1.14,2.34)]compared with wild type homozygous individuals. Conculsions There is no positive correlation between the polymorphisms of ERCC1 rs11615, ERCC2 rs238406, ERCC4 rs6498486, ERCC5 rs17655 and endemic arsenic poisoning. ERCC2 rs13181 polymorphism increases the risk of endemic arsenic poisoning.

The traditional view is that breast reconstruction is not an option for day surgery center. As a result, few hospitals in the world conduct this operation in day surgery center. Endoscopic breast reconstruction with liposuction and robot-assisted breast reconstruction are minimally invasive surgeries for breast cancer patients, but they cannot be carried out in the day surgery center due to long operation time. The novel endoscopic-assisted immediate implant-based breast reconstruction after nipple sparing mastectomy through a single axillary incision for breast cancer patients has been successfully conducted in the day surgery center in our hospital due to short operation time and small trauma. Standardized management of the complete process from the patient selection to follow-up after discharge brings rapid recovery and few complications. At the same time, the development of endoscopic surgery makes the breast almost scarless and improves aesthetic results. Therefore, the mode of endoscopic-assisted reconstruction in the day surgery center of our hospital is expected to be popularized in the whole country.

Objective    To explore the surgical technique and preliminary results of endoscopic nipple-sparing mastectomy (E-NSM) and immediate pre-pectoral implant-based breast reconstruction (BR) with titanium-coated polypropylene mesh (TiLoop Bra) via single axillary incision for breast cancer patients. Methods    The clinical data of 9 consecutive female patients who underwent E-NSM and immediate pre-pectoral implant-based BR with TiLoop Bra from  March to May 2021 were retrospectively analyzed. The mean age of patients was 40.6 (22-60) years. The operation time, early complications were collected, and the patients' social and mental health, breast satisfaction and chest function before and after the operation were assessed with the BREAST-Q questionnaire. Results    All the patients had unicentric tumor with a mean diameter of 2.4 (0.6-4.7) cm. The mean distance from the tumor to the nipple was 2.5 (2-4) cm. There were 2 patients with tumor stage 0 and 7 patients with stageⅠ. The mean operation time was 161.1 (125-201) min, the mean blood loss was 41.1 mL and the hospital stay time was 1.5 d. There were 5 patients in the day-care unit. All the patients were successfully followed up with a median follow-up time of 1 (1-2) month. One (11.1%) patient with depigmentation of the nipple-areola complex caused by mild ischemia. None of the patients had incision complications, subcutaneous emphysema, hematoma, infection, nipple-areola or skin flaps necrosis, implant loss. During the follow-up period, no local/regional recurrence or distant metastasis was found. Chest well-being was decreased in the first month after the surgery compared with preoperative status, and the difference was statistically significant (P=0.001). There was no statistical difference in the breast satisfaction or psychosocial function scores between pre- and post-operation (P>0.05). Conclusion    E-NSM and immediate pre-pectoral implant-based BR with TiLoop Bra via single axillary incision has minimal trauma, rapid postoperative recovery, short operation time, few early complications and good early cosmetic effect, and the short-term result is satisfactory.