OBJECTIVEThis study aims to do the following: construct a three-dimensional finite element model of an labial inverted impacted maxillary central incisor and its supporting tissues, analyze stress distribution in the periodontal tissue when various tractions are exerted, and provide references for treating impacted maxillary central incisor.

METHODSA three-dimensional finite element model oflabial inverted impacted maxillary central incisor and its periodontal tissues was established using Mimics 10.01 and Ansys 14.0 software based on original cone beam computed tomography (CBCT) data. Various traction values (20, 30, 40, 50, 60, and 70 g) were exerted on the incisal margin in the direction perpendicular to the impacted tooth. Different Von Mises stress values were determined.

RESULTSStress distribution on the periodontal ligament increased with traction size. When 30 g traction was exerted on the labial inverted impacted maxillary central incisor, the Von Mises stress was 24 919.0 Pa, which was within the range of the optimum force and close to its maximum value.

CONCLUSIONThe optimum traction for early orthodontic treatment of labial inverted impacted maxillary central incisor is nearly 30 g.

Finite Element Analysis ; Incisor ; Lip ; Maxilla ; Periodontal Ligament ; Tooth, Impacted

OBJECTIVE To determine the feasibility of clindamycin-loaded calcium phosphate cement(CLCPC) as a local antibiotic delivery system.METHODS The initial setting time(tI) and the final setting time(tF) were measured for 0%,2% and 5% CLCPC according to ASTM C266-89 method.Clindamycin concentrations eluting from the samples of 2% and 5% CLCPC in PBS were analyzed by HPLC at different times.The bacteriostasis tests were done by plate diffusion method for 2% and 5% CLCPC and 2% Palacos R-40 bone cement(PMMP) samples,and the diameters of the bacteriostasis ring and bacteriostasis duration were observed.The setting product and crystal size of 0%,2% and 5% CLCPC were analyzed and observed by X-ray diffraction(XRD) and scanning electron microscopy(SEM).RESULTS The setting time could be shortened by adding clindamycin(tI,tF) of 2% and 5% CLCPC.Clindamycin was with burst-release from CLCPC within the intial 6-hour period and the release rate slowed down on 4th day.Clindamycin could still release until to the 42th day.The ring of 2% Palacos R-40 bone cement(PMMP) bacteriostasis was smaller than that of 2% CLCPC,and the ring of 2% CLCPC bacteriostasis was smaller than that of 5%CLCPC.The bacteriostasis still existed to the 42th day of test for 2% and 5%CLCPC and 2% Clindamycin-loaded Palacos R-40 bone cement(CLPMMP).From the 30th day,many bacterial colonies were seen in the culture media laying 2%CLPMMP sample.On the contrary,bacterial colony was not found in the media putting 2% and 5%CLCPC.XRD and SEM showed that clindamycin did′t have an influence on setting product,crystal size and structure of CPC.CONCLUSIONS Clindamycin-loaded calcium phosphate cement can be used as a local antibiotic delivery system.

OBJECTIVE To establish the implanted biofilm model of rabbit implant infection.METHODS SEP was cultured,purified,identified,and tested for the drug sensitivity and the biofilm production.Healthy adult rabbits were randomly divided into 4 groups,8 in each group.The stainless steel screws and washer UHMWPEs were implanted into the femoral condyle of the non-articular surface of the rabbit right stifle knee.The knee joints were inoculated with 1ml sterile saline,102,103 and 104 CFU SEP,respectively.Wounds were observed postoperatively.After the 14th days postoperation,the knee synovium of 32 rabbits sacrificed were taken out by aseptic technique and were cultured to determine whether the knees were infected and which concentration of SEP was the appropriate for causing knee joint infection.UHMWPEs from the appropriate ID group were observed to find whether there were biofilms on the surface by SEM and LCSM.RESULTS The bacterial strain was identified as SEP and could produce biofilm.Among the knee joints inoculated with 1ml saline,102,103 and 104 CFU SEP,the infective rate was 0,37.5%,100.0% and 100.0% and poor wound healing was in 0,1,2 and 4 rabbits,respectively.It showed 103 CFU of SEP was the appropriate ID.Biofilms were found on all UHMWPE surfaces from 103 CFU SEP group by SEM and LCSM.SEM showed SEP in the biofilms on the surface of UHMWPE was agglomerated and wrapped in the matrix.The structure of biofilms in which SEP radiated red fluorescence was inlaid in mucopolysaccharide stained green fluorescence was observed by LCSM.CONCLUSIONS The model provides an effective method to investigate the biofilm.

Experimental teaching plays an important role in pathological teaching.We have taken effective measures to renovate the methods for experimental teaching,establishing open teaching mode.As a result,teaching quality increases and students become more active in pathological learning.

Objective To study the effect of Zhimaikang Granules (Granules for lipid abnormality) on atherosclerosis of hyperlipidemia patients of phlegm turbidity retention type.Methods Totally 120 hyperlipidemia patients were randomized into treatment group and control group, 60 cases in each. The treatment group was administered Zhimaikang Granules, each time 1 bag, twice a day. The control group was given Simvastatin Tablets, oral taking before sleeping. Both groups were treated for 45 days. Changes of superoxide dismutase (SOD), malondialdehyde (MDA), and nitric oxide (NO) were observed.Results After treatment, activity of NO and SOD were significantly higher than before in both groups (P0.05).Conclusion Zhimaikang Granules was proved to enhance the activity of antioxidase, promote anti-free radical reactions, inhibit lipid peroxidation and protect endothelial cells in atherosclerosis patients.

Objective This study aims to do the following: construct a three-dimensional finite element model of an labial inverted impacted maxillary central incisor and its supporting tissues, analyze stress distribution in the periodontal tissue when various tractions are exerted, and provide references for treating impacted maxillary central incisor. Methods A three-dimensional finite element model of labial inverted impacted maxillary central incisor and its periodontal tissues was established using Mimics 10.01 and Ansys 14.0 software based on original cone beam computed tomography (CBCT) data. Various traction values (20, 30, 40, 50, 60, and 70 g) were exerted on the incisal margin in the direction perpendicular to the impacted tooth. Different Von Mises stress values were determined. Results Stress distribution on the periodontal ligament increased with traction size. When 30 g traction was exerted on the labial inverted impacted maxillary central incisor, the Von Mises stress was 24 919.0 Pa, which was within the range of the optimum force and close to its maximum value. Conclusion The optimum traction for early orthodontic treatment of labial inverted impacted maxillary central incisor is nearly 30 g.