This paper is aimed to develop a computerized three dimensional system for displaying and analyzing mandibular helical axis pathways. Mandibular movements were recorded using a six-degrees-of-freedom ultrasonic jaw movement recording device. The three-dimensional digital models of the midface and the mandible were reconstructed and segmented from CT skull images. The digital models were then transformed to the coordinate system of mandibular motion data by using an optical measuring system. The system was programmed on the base of the Visualization ToolKit and Open Scene Graphics Library. According to the motion data, transformation matrices were calculated to simulate mandibular movements. Meanwhile, mandibular helical axis pathways were calculated and displayed three dimensionally by means of an eigenvalues method. The following parameters of mandibular helical axis were calculated: the rotation around instantaneous helical axis, the translation along it, its spatial orientation, its position and distance relative to any special reference point. These parameters could be exported to describe comprehensively the whole mandiblular movements. It could be concluded that our system would contribute to the study of mandiblular helical axis pathways.
Humans ; Imaging, Three-Dimensional ; Mandible ; Models, Anatomic ; Movement ; Rotation

Objective:To analyze occlusal contact areas on the working and nonworking sides during unilateral mastication.Methods: Eighteen subjects without any temporomandibular disorder(TMD) symptoms participated in the present study.The subjects were presented with 3 g gum for right masticating.Chewing movement was simulated using virtual craniofacial movement simulation system.Then occlusal contact areas were calculated at four selected moments during the closing phase in the third chewing cycle: the occurrence of occlusal contact,one third time,two thirds time,the intercuspal occlusion.Results: During the closing phase in the third chewing cycle,the total occlusal contact areas on working side increased from(9.3?0.4) mm2 to(39.2?1.2) mm2,and that on nonworking side increased from(2.3?0.5) mm2 to(40.3?1.2) mm2.At the occurrence of occlusal contacts,occlusal contact areas of the first and second mandibular molars were on average(3.7?0.2) mm2 and(3.5?0.2) mm2 on working side,and(0.5?0.2) mm2 and(1.2?0.3) mm2 on nonworking side,respectively.However,when the mandible moved to the intercuspal position,their areas were sharply increased to(14.8?0.7) mm2 and(13.9?0.4) mm2 on working side,and(13.6?0.5) mm2 and(12.1?0.5) mm2 on nonworking side,respectively.In addition,nonworking-side contacts were observed for 12 subjects at the occurrence of occlusal contacts,and for all subjects at two thirds time.Conclusion: This paper provides a new method useful for analyzing occlusal contacts during functional movements.This study revealed the pattern of occlusal contacts during the closing phase in the chewing cycle.Moreover,it was confirmed that nonworking-side contacts occurred during unilateral mastication.

Objective To establish an HPLC method for the content determination of sodium Danshensu inBawei Qidan Capsule.Methods HPLC was applied and the determination was performed on Shim-pack CLC-ODS C18 column (250 mm×4.6 mm, 5μm) with methanol-water- acetic acid (7∶92∶1, V/V/V) solution at a flow rate of 1.0 mL/min and detection wavelength at 281 nm. The column temperature was 30℃, and injection volume was 10μL.Results Through methodological study, the linear range of sodium Danshensu was 0.494 4-4.944μg (r=0.9996), the average recovery was 97.20%, RSD=1.13%.Conclusion The HPLC method for the content determination of sodium Danshensu inBawei QidanCapsule was user-friendly, accurate and reliable, with good repeatability and stability, which can be used for quality control ofBawei Qidan Capsule.

Objective:To explore a method for setting up three dimensional finite element model of posterior glass fiber reinforced composite resin-bonded-fixed-partial dentures (GFRC-RBFPD) including restoration, periodontal tissue and alveolar bone. Methods:A stone model was fabricated including abutments and pontic of restoration, then it was scanned with laser scanner. Acquired data were integrated in Geomagic 5.0. Basic 3D geometric model was established. Different parts of abutement and prosthesis were designed in I-DEAS 10 NX Series and Geomagic, then periodontal tissue and alveolar bone were set up in Geomagic 5.0. Completed 3D geometric model was input into MSC.Marc Mentat 2003 for mesh generation. Boundary conditions were defined. Model was calculated in Mentat 2003. Results:3D geometric model and finite element model including GFRC-RBFPD, abutments, periodontal membrane and bone (bone lamina dura,cortical bone and cancellous bone) were established.Little contour information was lost, comparability between models was improved.Conclusion:The 3-dimensional laser scanning technique, CAD and mesh generation technique are effective in the establishment of 3-dimensional finite element model of GFRC-RBFPD.

Objective To observe the effect of comfort levels in patients during long-term video electroencephalographic(VEEG) monitoring on the monitoring effect. Methods A total of 168 patients with consecutive epilepsy were observed about the Bruggrmann comfort scale(BCS) and artifacts of VEEG during VEEG monitoring. Pearson′s correlation coefficient was used to evaluate a possible correlation between BCS and artifacts. Results The average single score before VEEG, including psychological comfort, social comfort, comfortable environment and overall comfort was (2.87±1.04), (2.63±0.98), (2.40± 1.25), (2.84 ± 0.90), (2.69 ± 1.07) points, which was (2.06 ± 1.38), (1.66 ± 1.40), (1.89 ± 0.57), (1.83 ± 1.24), (1.86 ± 1.19) points after VEEG. There was significant difference between 2 groups (t=4.011-6.353, P<0.05). The overall comfort score and the average single project blinks or eye movement artifacts, physical artifacts, chewing or swallowing artifacts and electrocardiogram artifacts were negatively correlated (r=-0.843--0.585, all P < 0.05), which would reduce the number of these artifacts when increased; there was no correlation (r=-0.204,-0.158, P>0.05) between the average single score of comfort and sweating, skin artifacts, and electrocardiogram artifact. Conclusions There is a significant negative correlation between patient's BCS and the occurrence of artifacts during VEEG monitoring. Comfort evaluation and comfort care before monitoring has great significance in raising the long-term VEEG monitoring accuracy.

Objective To compare the concordance among RECIST, EASL and modified RECIST criteria for the evaluation of tumor response after transarterial chemoembolization of primary liver cancer.Methods Fifty patients with primary liver cancer underwent 2 TACE cycles separated by 30-40 days.Triphasic helical CT or MRI scans were performed at baseline, at 4 weeks after TACE procedure, and 2 independent radiologists evaluated tumor response according to above-mentioned three different criteria. Chisquare test was used to compare the response rate, and kappa coefficients were used to evaluate the coherence. Results When tumor responses were evaluated using the RECIST-EASL and modified RECIST criteria, the numbers of the patients achieved complete response, partial response, stable disease,progressive disease were 0, 10, 30, 10; 6,21,14,9; 6,21,13,10 respectively. The objective response rates for three different criteria were 20%, 54%, 54% respectively ( P ＜ 0. 01 ). Kappa coefficients between RECIST and EASL, between RECIST and modified RECIST, between EASL and modified RECIST were 0. 382, 0. 170, and 0. 857 (P = 0. 000). Conclusions RECIST criteria underestimates the extent of tumor response after TACE in primary liver cancer. Both EASL and modified RECIST criteria appear to agree with each other in determining treatment response. Furthermore, the modified RECIST is more convenient in clinical practice compared with EASL criteria.

Objective Pneumoperitoneum is usually the result of hollow visceral perforation and requires emergent laparotomy.However,about 10％ of patients lack a pathologic cause requiring surgical intervention and can be resolved with conservative management.The aim of this study is to discuss the indications for conservative management of pneumoperitoneum in children.Methods We retrospectively reviewed the data of 5 children with pneumoperitoneum without peritonitis treated in our pediatric surgery department between January 2009 and December 2010.Results There were 5 children with an average age 5.4 years.Radiologic examinations demonstrated pneumoperitoneum and visceral perforations were suspected in the local hospitals.The abdominal examination revealed no peritoneal signs in all patients.Among them,peritoneal aspirations were implemented in 4 patients and the results were negative.One of five patients underwent laparotomy that demonstrated no visceral perforation.The remaining four were successfully managed conservatively and the pneumoperitoneum was completely resolved between 3 and 9 days.All children were without abdominal symptoms and signs throughout at least 2 years follow-up.Conclusion The presence of free intraperitoneal air does not always indicate hollow visceral perforation and the need for emergent laparotomy.It appears that therapeutic effectiveness can be readily achieved with conservative management in children with pneumoperitoneum without peritonitis.

Objective To investigate the efficacy of prophylactic pancreatic stent placement and nonsteroidal antiinflammatory drugs( NSAIDs) for the prevention of post?endoscopic retrograde cholangiopan?creatography(ERCP) pancreatitis(PEP). Methods A total of 623 patients with high risk factors for PEP were treated with prophylactic pancreatic stent placement ( 145 patients, group A) or rectal NSAIDs( 478 pa?tients, group B) for PEP prevention by using the propensity score matching( PSM) analysis. Incidence of PEP, moderate and severe PEP were investigated. According to risk factors of PEP, indications of prophy?lactic pancreatic stent placement were analysed. Results Of 623 patients with high risk factors, 145 pairs were generated after PSM.Pancreatitis occurred in 32 patients,10 (6?9%) in group A and 22 (15?2%) in group B( P<0?05 ) . Moderate?to?severe pancreatitis developed in 5 ( 3?4%) patients in group A and 14 (9?7%) patients in group B(P<0?05).Risk factors of post?ERCP PEP were cannulation attempts duration longer than 10 minutes, precut sphincterotomy, more than one pancreatic guidewire passages and history of ampullectomy. Conclusion Although the NSAIDs represent an easy, inexpensive treatment, prophylactic pancreatic stent placement is still a better prevention strategy for PEP.Prophylactic pancreatic stents should be recommended to those with risk factors including cannulation attempts duration longer than 10 minutes, precut sphincterotomy, more than one pancreatic guidewire passages and ampullectomy.

Objective To evaluate the relationship between the incidence rate of hepatic encephalopathy in patients with cirrhosis and the model for end-stage liver disease (MELD).Methods The total of 120 patients with decompensated cirrhosis were enrolled and followed-up.MELD score was obtained to observe the incidence of hepatic encephalopathy.Results The incidence of hepatic encephalopathy was 44.17％(53/120).MELD score in hepatic encephalopathy patients was significantly higher than that in none hepatic encephalopathy patients[(21.69 ± 9.22) scores vs.(9.32 ± 4.63) scores],and there was significant difference (P ＜ 0.05).With the increase of MELD score,the incidence of hepatic encephalopathy increased (P ＜ 0.01).The best critical value of MELD score was 14.13 scores (the sensitivity of 86.05％ and the specificity of 88.37％),when MELD ≥14.13 scores,the incidence of hepatic encephalopathy within 3 months was significantly higher [63.16％(48/76) vs.11.36％(5/44)] (x2 =30.32,P＜ 0.01).Conclusion MELD can help predicting the incidence of hepatic encephalopathy in decompensated cirrhosis patients.

BACKGROUND: The strength and elasticity of general starch can be enhanced dramatically after plastic blends. The major characters of this material are magnitude molecular weight, many enwinded points, extreme containment of small molecules,and great gelation ability. It can be used as a biodegradable replacement of alginate. Furthermore, by adding osteoinductive factors, thermoplastics starch (TP) can be used as an organic engineering material, which can provide dual functions:anti-bleeding and bone formation. TP can also be used as intraoral tissue formation membrane and burn dressings.OBJECTIVE: To evaluate the bio-safety of TP through a cytotoxicity test.DESIGN: A controlled observation.SETTING: Beijing Research Institute of Traumatology and Orthopaedics; Beijing Jishuitan Hospital; Beijing University of Chemical Technology; Peking Univesity School of Stomatology.MATERIALS: The experiment was conducted at the laboratory of Beijing Research Institute of Traumatology and Orthopaedics from April to October in 2006. TP sample was obtained by plasticization of corn starch (12 wt % water content) with glycerol in a Haake Rhenmix at 110℃ and with 80 rounds per minute for 25 minutes, elongation at break from 115.3% to 245.3%. It was prepared by Beijing Key Laboratory for Preparation and Processing of Novel Polymeric Materials, Beijing University of Chemical Technology. Mouse fibroblast L-929 cell strain was provided by the cell bank of Peking University Health Science Center.METHODS: 1 × 107 L-1 cell aqueous suspension was cultured into leaching liquor ( 50% ), serving for TP group, and routine culture medium served for negative control group. Effect of TP on relative growth rate of L-929 cell strain was quantitatively measured by MTI" assay. The cytotoxicity of TP was evaluated according to GB/T16175-1996. Morphological changes and proliferation of cells were observed after2, 4, and 7 days of culture in the medium through an inverted phase contrast microscope.MAIN OUTCOME MEASURES: Cytotoxicity, morphological changes and proliferation of cells, and cell relative growth rate.RESULTS: Cytotoxicity: After 2 and 4 days of incubation, the absorbance (A) value was lower in the TP group than in the negative control group. After 7 days of incubation, the A value was significantly higher compared to negative control group (P＜0.01). It indicated that after 2 and 4 days of incubation, the cytotoxicity in the TP group was larger than in the negative control group, while after 7 days of incubation, it was on the opposite. All the test time, TP's cytotoxicity grade ranged from 0 to 1. Morphological change and proliferation of cells: After 2 days of incubation, both groups of cells were not extended to the outside of the scope, with a majority shape of being round, triangle, and quadrangle in the TP group or fusiform cells in the negative control respectively. Four days later, there were gaps among cells in the TP group, while in the negative control group, there were hardly any distance between cells and some cells piled up. Seven days later, cells in starch medium suddenly grew up to such a degree that all the cells lapped over and presented with more bloom than the negative control. Cell relative growth rate: After 2, 4, and 7 days of incubation, relative growth rate increased with time, being 85.63%,82.22%, and 113.05%, respectively.CONCLUSION: TP has no evidence of cytotoxicity and has good bio-safety.