BACKGROUND:Finite element contact analysis was performed in premolars of lower mandible with enamelo-dentinal junction defects, which provided biomechanical evidence for the prevention of wedge-shaped defect and occlusion treatment.
OBJECTIVE:To analyze the effects of undermining damage of the enamelo-dentinal junction on the stress distribution of sclerous tissues of dental cervix.
METHODS:Triangle defects were established and models of wedge-shaped defect were designed in mandibular premolar along the enamelo-dentinal junction. The stresses during tightly biting and masticatory movement were simulated. Nonlinear contact analysis was conducted in sclerous tissues of mandibular premolar in the buccal cervical region.
RESULTS AND CONCLUSION:By simulating the stresses during tightly biting and masticatory movement, the stresses were concentrated in the defected regions of mandibular premolar at the enamelo-dentinal junction. With the defect length increased in size, the stress value and the magnitude of the stress field both increased. These indicated that the destruction of enamelo-dentinal junction altered stress distribution in the buccal cervical region. In the clinic, wedge-shaped defect should be fil ed promptly.

Objective To study the differences of esophageal manometry (M),pH set-up method (P) and X-ray (X) on positioning of the 24-hour esophageal pH catheter and relative factors. Methods Fifty subjects underwent M, then pH catheter was located by P and X. The difference between methods and the relative factors such as body height,lower esophageal sphincter (LES) length etc were analyzed. The difference of less than 2 cm between two methods was accepted. Results The length between the location determined by M,Pand X and nose were (37.9 ±2.9),(40.8 ±4.4) and (40.7 ±5.3) cm, respectively.There was significant difference between P and M as well as between X and M (P＜ 0.01 ). The coincidence rate was 62.0%(31/50) between P and M;84.0%(42/50) between P and X;and 58.0%(29/50) between X and M. Compared with P,M was (2.9 ±3.9) cm nearer to the stomach. Age, body height and LES length were main factors which affect the difference between P and M (P＜ 0.01 or ＜ 0.05),body height and LES length were main factors which affect the difference between X and M (P＜0.05 or ＜0.01). Conclusions Compared with M, the location determined by P is nearer to stomach. The location of X is varied. Body height and LES length are main relative factors.

OBJECTIVETo study the distribution of stress of simulating teeth with wedge shaped defects in the cervical region.

METHODSThe models of anisotropic enamel of the mandibular first premolar and the opposite maxillary first premolar crown were created. A defect was introduced into the model of mandibular premolar in the buccal cervical region along the enamelo-dentinal junction (DEJ). The stress distribution in the cervical region of the mandibular premolar was investigated considering lateral condition simulating working micromotions. In this case, the stroke was applied to the maxillary first mandibular in a stepping procedure using nonlinear contact analysis.

RESULTSThe stresses were concentrated in the defect of the enamel and dentin at the DEJ in the condition of lateral loading. As the defect length increased in size, the peak maximum principal stress (MPS) value and the magnitude of the stress field along the DEJ both increased.

CONCLUSIONUndermined cervical DEJ had a significant effect on the stress distribution in the buccal cervical region.

Bicuspid ; Dental Enamel ; Dental Stress Analysis ; Dentin ; Finite Element Analysis ; Humans ; Mandible ; Maxilla

BACKGROUND:Among many transplanted cells,adult autologous bone barrow-derived mononuclear cells have beenused in clinical practice because they are easy to be obtained,without immunological rejection and ethical disputationand other advantages.How to distinguish donor cells from receptors and observe the survival of donor cells following stem cell transplantation still trouble people.OBJECTIVE: superparamagnetic iron oxide (SPIO)particles-labeled bone marrow-derived mononuclear cells from minipigs were used to observe the feasibility of in vivo tracking with magnetic resonance imaging(MRI).DESIGN:A controlled observation experiment.SETTING:Institute of Cardiovascular Disease,Zhongda Hospital Affiliated to Southeast University.MATERIALS:This experiment was carried out in the Institute of Cardiovascular Disease,Zhongda Hospital Affiliated to Southeast University between April 2006 and August 2006.Healthy Chinese minipigs,aged 3 to 4 months,weighing from 20 to 30 kg,were provided by the Experimental Animal Center of Southeast University[SYXK(Su)2002-0012].METHODS: Autologous bone marrow-derived mononuclear cells of minipigs were isolated and cultured. Bone marrow-derived mononuclear cells in the suspension were traced with SPIO particles.Ferrum in the cells were shown by Prussian blue staining, and cell viability was evaluated by trypan blue exclusion method. Eleven minipigs used for preparation of model of myocardial infarction were divided into experimental group(n=9)and control group(n=2).By means of percutaneous left or right cervical artery or femoral artery puncturation, 1.5 to 2.0 mm balloon was used to occlude 1/3 left anterior descending branch,304 to 405 kPa,60 minutes later,ischemic preconditioning was conducted 3 tO 4 times before operation. When pig models of myocardial infarction were successful that was proved by surface electrocardiogram,bone marrow-derived mononuclear cells were percutaneously injected into coronary artery.Coronary arteriography was performed through femoral artery acupuncture at 24 hours after establishing infarction models.Suspension of bone marrow-derived mononuclear cells was perfused into coronary artery with OTW catheter.Then,the injector and OTW catheter for containing cells were rinsed with normal saline containing heparin and infused with the residual cells within 10 minutes.Non-labeled cells were perfused in 2 minipigs of control group by the same method.Postoperatively, bone marrow-derived mononuclear cells were traced by magnetic resonance and compared with Prussian blue-stained myocardial tissue sections.RESULTS: Seven minipigs of experimental group and one minipig of control group were Involved in the final analysis.One of each group was used for preparation of model of myocardial Infarction.One minipig of experimental group died from anesthetic accident before magnetic resonance.①Bone marrow-derived mononuclear cells all were nearly labeled by SPIO particles. Bone marrow-derived mononuclear cells could further proliferate in culture medium containing Fe2O3-PLL without obvious changes of cellular shape. ②T2+WI showed that 5 of 8 models of myocardial infarction presented fuzzy low-echo signal region in peripheral myocardial infarction after transplantation of labeled cells and the low-echo signal disappeared 4 weeks Iater. Ex vivo T2+WI sequence showed there was a dot-distributed low-echo signal region in the peripheral infarction region.③It was found in histological examination that 5 models(cell number over 106) had Prussian blue-positive cells,which distributed the same as those in magnetic resonance signal reducing region.CONCLUSION:SPIO particles-labeled bone marrow-derived mononuclear cells are safe and effective;T2+ WI is sensitive to tracing SPIO particles-labeled bone marrow-derived mononuclear cells;Magnetic resonance can in vivo trace SPIO particles-labeled stem cells transplanted through coronary artery,magnetic resonance signal change is related with the number of stem cells and division growth.

Objective To investigate the clinical efficiency of endoscopic pancreatic sphincterotomy ( EPS) combined with pancreatic duct stent for acute recurrent pancreatitis ( ARP ) caused by biliary microlithiasis. Methods A total of 71 patients were diagnosed as having ARP resulting from biliary microlithiasis from April 2005 to November 2016, and their clinical data were retrospectively analyzed. Patients were divided into two groups according to different endoscopic therapy, EPS ( n=34) and EST group (n=37), respectively. The rate of pancreatitis recurrence, post-ERCP pancreatitis (PEP) and biliary complications were compared by Chi-square test and the influencing factors of recurrence were evaluated by survival analysis. Results The follow-up time ranged from 2 to 108 months ( median 21. 5 months) in EPS group and ranged from 5 to 120 months ( median 39 months) in EST group. Twelve months after endoscopic therapy, 2 patients in EPS group and 5 in EST group suffered recurrent pancreatitis(χ2=0. 461, P=0. 497). Recurrence occurred in 13 patients in 60 months after endoscopic therapy, 4 patients in EPS group and 9 in EST group. Cox regression analysis indicated different endoscopic treatment ( RR=6. 808, 95%CI: 1. 389-33. 356, P=0. 018) and type 2 diabetes ( RR=0. 134, 95%CI:0. 029-0. 608, P=0. 009) were statistically significant factors. There were no significant difference in incidence of PEP (20. 6% in EPS group, 10. 8% in EST group,χ2=1. 294, P=0. 255) and biliary complications between two groups (11. 8% in EPS group, 24. 3% in EST group, χ2=1. 869, P=0. 172). Conclusion EPS combined with pancreatic stenting is effective for acute recurrent pancreatitis caused by microlithiasis. Type 2 diabetes may also lead to recurrence of acute pancreatitis.

Objective:To compare the changes of biliary microbiota after enteral extended biliary stents (EEBS) implantation with that of conventional plastic stents in animal experiment, and to preliminarily investigate its possible mechanism in preventing stents occlusion.Methods:A total of 12 healthy Bama minipigs were randomly assigned to the conventional plastic stent group ( n=6) and the EEBS group ( n=6) using simple random method. The bile samples of all pigs were collected before stents implantation and 4 weeks after stents placement. The biliary microbiota composition and diversity before and after different stents implantation were analyzed by 16S rRNA gene sequencing and compared. Results:No complications including acute cholangitis, perforation, bleeding, or death occurred in 12 pigs. Eight days after stents implantation, stents were out of bile duct in all pigs under endoscopy, while the bile samples were collected again for analysis. The main composition of biliary microbiota at the phylum level were Proteobacteria, Firmicutes and Bacteroidota. Alpha-diversities revealed the Shannon ( P=0.004) and Simpson index ( P=0.008) significantly decreased in the conventional stent group after stents placement, and Bata diversity analysis also showed a significant difference in microbial composition (Anosim: R=0.514 8, P=0.011). There was no significant difference in Observed species index ( P=0.095), Chao1 index ( P=0.136), Shannon index ( P=0.353), Simpson index ( P=0.227) or Bata diversity (Anosim: R=0.059 3, P=0.187) in the EEBS group before and after stents placement. LEfSe algorithm indicated Bacteroides_ fragilis and Proteobacteria- Gammaproteobacteria- Enterobacterales- Enterobacteriaceae- scherichia_ Shigella- Escherichia_ coli significantly increased in the conventional stent group, and Desulfobacterota- Desulfovibrionia- Desulfovibrionales- Desulfovibrionaceae- Bilophila significantly increased in the EEBS group after stents placement. Conclusion:The biliary microbiota change slightly after EEBS implantation in the short-term, and EEBS may prevent duodenobiliary reflux by prolonging the reflux path.