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Table of Content
20 June 2002, Volume 20 Issue 03
  • Effects of Epidermal Growth Factors on the Proliferation and Metabolism of A/J Mouse Embryonic Palatal Cells
    West China Journal of Stomatology. 2002, 20(03):  161-163. 
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    Objective:The purpose of this study was to investigate the effects of epidermal growth factors (EGFs) with different concen- tration on the OD, DNA, protein, and PGE2of A/J mouse embryonic palatal shelves cells (A/J MEPC) isolated from embryonic palatal shelves.Methods:The mouse embryonic palatal shelves cellswere grown in different 39 pores (or bottles) with 9 gradient concentrations of EGF (01005, 01010, 01050,01100, 01500, 11000, 51000, 101000, 501000 ng/ml), and four pores were prepared for the same concentration, then the OD, DNA, protein and PGE2of A/JMEPCwere measured after1 day, 3 days and 5 days.Results:EGFs stimulated DNA and PGE2synthesis of A/JMEPC, and augmented proliferation index (PIX). Their effects were very obvious in promoting the proliferation of A/JMEPC, when the concentrationwas 101000 ng/ml.Conclusion:EGFmay be important in regulating proliferation and metabolism of embryonic palatal shelves cells.

    A Study of Alumina Powder Used in Fabrication of GI-ⅡInfiltrated Ceramic
    Wang Hang, Chao Yonglie, Liao Yunmao, et al
    West China Journal of Stomatology. 2002, 20(03):  164-165. 
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    Objective:This investigationwas to analyze the mechanism of formation of porous structure by studying some characteristics of the alumina powder used forGI-ⅡInfiltrate Ceramic.Methods:The alumina powder crystal type was analyzed with X-diffractome- ter, and its size distributionwas obtained by powder size analysis device, and fracture surface of alumina adobe was observed under scanning electronic microscope.Results:Alumina crystalswere purelyAtype, with firmest structure and best stability. Fine pow- derwhose size was smaller than 015Lm occupied 9 wt% (mass) and, coarse powder with sizes between 1 to 315Lm occupied 75wt% (mass). The SEM graphs of adobe showed that fine powders were attached to the surface of coarse powders, dispersed evenly, and alumina powders contacted each other firmly.Conclusion:The crystal type, size distribution and even dispersion of the studied alumina powder contributed to the formation of porous structure of alumina sintered body (preform), whichwas the ma- terial prerequisite in forming porous preform and one of the key factors to the rise of strength of GI-ⅡInfiltrated Ceramic.

    A Study on Expression of Basic Fibroblast Growth Factors in Periodontal Tissue Following Orthodontic Tooth Movement Associated with Low Power Laser Irradiation
    Zhu Xianchun, Chen Yuanping, Sun Xinhua
    West China Journal of Stomatology. 2002, 20(03):  166-168. 
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    Objective:The purpose of this study was to investigate the effects of low power laser on basic fibroblast growth factors (bFGF) expression in periodontal tissue during tooth movement.Methods:18 white rabbits were randomly divided into 6 groups with 3 rabbits in each group, including groups of l, 3, 5, 7, 14 and 21days. Under an anesthesia condition by 2% pentobarbital sodium, the stainless coil springswere fixed between the firstmaxillary molar and the incisorproducing the force of 80 g. The right side of maxilla was considered as the experimental group under the irradiation of low power laser with the left side as the control groups. The expression of bFGF was investigated half-quantitatively through immunohistochemical analysis.Results:The expres- sion of bFGF in periodontal tissue with irradiation of lowpower laserwas higherthan the control side. There were significantdiffer- ences among the 5, 7, and 14 day groups. In the tension area of the experimental side, the expression of bFGF in the osteoblastic surface of alveolarbone was characteristically greaterthan thatof the control side.Conclusion:The laserof lowpowerpromotes the expression of bFGF in the periodontal tissue and alveolar bone remodeling.

    A Study on the Morphological Characters of Immortalized Mandibular Condylar Chondrocyte
    Duan Xiaohong, Wu Junzheng, Dong Shaozhong, et al
    West China Journal of Stomatology. 2002, 20(03):  169-171. 
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    Objective:The purpose of this study was to compare the morphological character between immortalized mandibular condylar chondrocyte (IMCC) and primarily cultured mandibular condylar chondrocyte (MCC).Methods:The phase contrast microscope, photomicroscope and transmission electron microscope were used to observe the morphological character of IMCC and MCC. The highresolution pathological image and word report system-1000 (HPIAS-1000) was used to compare the size of IMCC and MCC. Results:The phase contrast micrography showed thatMCCs in primary culture underwent distinct morphological changes with re- spect to shape, size, and density of the cells. The majority of MCCs were in polygonal shape earlier in culture, while more fusiform and spindle-shaped cellswere found after 4-5 passages. While IMCCswere polygonal-shaped, similar toMCCs. Subcul- ture, freezing and recovering had no effect on cellular shape of IMCC. Transmission electron microscopy indicated thatMCC had chondrocyte-like phenotype, while IMCC looked like prechondroblast or immature chondrocyte. Some of IMCCs had irregular nu- cleus, and the proportion of nucleus/cytoplasm changed. By analysis of HPIAS-1000, the diameter and area of IMCCwere obvi- ous smaller than those of MCC (P<0.01).Conclusion:IMCC retain the main morphological character of MCC, and also keep a stable phenotype, which belong to immature chondrocytes, similar to cells in the proliferative zone.

    A Fundamental Study on Bioreactions of Sr-HA
    Liao Dapeng, Zhou Zhengyan, Gu Yunfeng, et al
    West China Journal of Stomatology. 2002, 20(03):  172-174. 
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    Objective:Sr-HA, a newtype of hydroxyapatite biomaterial, was implanted into animals to study the bioreaction and charac- ter, which would be helpful for the further clinical applications in the future.Methods:Totally 24 rabbits were divided into 3 groups. The bone defectof 6 mm@12 mm@4 mmwasmade atbothmandibular angles of rabbits and Sr-HAof differentproportion (10%, 5%, 0) was applied to reform the defects. One group of animalswere killed randomly at 1, 3 and 6 months after opera- tion to evaluate the material biological compatibility using anatomic, X-ray examination, histological and ECTmethods.Results: The histological photographs showed that Sr-HA caused little infection around implanted area and, almost was not repulsed by hosts. With the degradation of biomaterial, there was more apparent new bone growth in the area around Sr-HA than that around HA and some ossification can be found in soft tissue nearby. Also a tight osteointegrity was gradually got after the operation, ac- cording to the results of X-ray and, the border between Sr-HA and bone was hardly discovered at the 6th month after the opera- tion. Amore obvious nuclide assembling was observed at the side of Sr-HA by ECTimages. With the biodegradation of Sr-HA, more new bone was intruded into the spare space of the biomaterial.Conclusion:Sr-HA has better biocompatibility and higher biodegradation than thatof pure HA. Itholds an excellentosteoinductivity and fairosteoconductivity to some degree too. So a more satisfying effect of bone defect rehabilitation was gained with the increasing new bone depositing in the free space of the material, when it degraded gradually.

    Effect of Angiogenesis Inhibitor (TNP-470) on the Morphology of GNM Cell Line in vitro
    Peng Liwei, Li Jinrong
    West China Journal of Stomatology. 2002, 20(03):  175-177. 
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    Objective:The purpose of this study was to investigate the effect of an angiogenesis inhibitor (TNP-470) on the ultra micro- structural morphological changes of GNM cell line, which was derived from human oral squamous cell carcinomas in vitro.Meth- ods:The GNM cells were cultured and, the effect of TNP-470 on ultra micro-structural morphological changes of GNM cells was observed under the inverted microscope, the scanning electron microscope (SEM) and the transmission electron microscope (TEM).Results:Numerous round cells, shrinkage of cellular membrane and dead cells were observed 48 hours after 2Lg/ml of TNP-470 was added into the GNMcellular suspension. After72 hours, GNMcells became shortened and, the numberofmicrovilli of the cellular surface was observed under the SEM and TEM. A large number of GNM cells turned into necrosis, accompanying with the destruction of mitochondria and endoplasmic reticula.Conclusion:TNP-470 has a strong tumor cytotoxic effect on GNM cells, which may be due to its destructibility on mitochondria and endoplasmic reticula of GNM cells. TNP-470 can alter the sur- face structure of GNM cell membrane, which suggests that TNP-470 may interrupt the metastasis of GNM cells.

    The Character of Glial Line-cell Derived Neurotrophic Factor mRNA Expression in a Facial Nerve-striking Model
    Wang Chen, Zhou Shuxia, Zheng Chunmei et al
    West China Journal of Stomatology. 2002, 20(03):  178-180. 
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    Objective:It has been known thatglial line-cell derived neurotrophic factor (GDNF) has the nutritional and protective effect in motor neurons. In this experiment, we investigated the character of GDNF mRNA expression in a facial nerve-striking model; combinedwith other scholarscexperimental results; and analyzedwhat role GDNF plays in the regeneration process of injured motor nerves.Methods:We established a strikingmodel in rabbitfacial nerveswith a striking gunwith the striking velocity of 10m/s and the total striking energy of 715J. Thenwe detected the GDNFmRNAexpression in facial neurons and axonswithin situhybridiza- tion on days 3, 7, 14 and 21 after striking. We counted the expression numbers of facial neurons and, compared with normal fa- cial neurons and peripheral facial nerves.Results:We detected GDNF mRNA expression in the facial neurons from day 3 to day 21 after the facial nerve injured by striking. The peak of GDNF mRNA expression appeared on the 7th day, and then the expres- sion number of facial neurons decreased gradually. Ahigh level expressionwas also detected on day 21. GDNFmRNA expression was not detected neither in Schwann cells nor in normal facial neurons from the 3rd day to the 21st day.Conclusion:GDNF is a kind of neurotrophic growing factor (NGF) that could be activated by injury. The characterofGDNFmRNAexpressionwas accor- dant to the process of nerve regeneration. These results showed thatGDNF plays a very important role in the regeneration of injured motor nerves.

    Immunohistochemical Detection of Micrometastases in Cervical Lymph Nodes from Squamous Cell Carcinoma of Tongue in Neck Dissection Specimens
    Li Weizhong, Zhao Tong, Zhang Jinhua, et al
    West China Journal of Stomatology. 2002, 20(03):  181-183. 
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    Objective:The purpose of this study was to explore a feasible method to detect the micrometastases.Methods:Totally 152 cases of negative cervical lymph nodes (CLNs) from 30 patients with squamous cell carcinoma in tongue were included in this study. The HE-stained slices of the CLNwere reexamined by two experienced pathologists and, conformed that no carcinoma cells were found. Two slices were made from each paraffin specimen and, the sliceswere stained with the microwave immunohistoche- mical technique with monoclonal antibody CK (AE1/AE3) (DAKO Co. Denmark, 1B100).Results:Among these 152 cases 7 (416%) positive lymph nodes were found in 4(1313%) patients, and CLN metastases were found in all the patients before the surgical treatment. Mostof the micro-metastatic nodes appeared in the upperdeep cervical area, exceptthatone of themwasfound in the submandibular triangle.Conclusion:The results suggest thatmicrometastases frequently occurred in negative lymph nodes. The present method may be useful in detecting the micrometastases of lymph nodes and in evaluating clinical stages of patientswith oral cancers.

    A Study of Effects of Pingyangmycin Injection on Treatment of Lymphangiomas in Oral, Maxillofacial and Cervical Regions
    Gao Qinghong, Wang Changmei, Wen Yuming, et al
    West China Journal of Stomatology. 2002, 20(03):  184-186. 
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    Objective:The purpose of this study was to investigate the indication and therapeutic effects of Pingyangmycin injection as a primary therapy of lymphangiomas in oral, maxillofacial and cervical region.Methods:A total of 195 patients (106 males and 89 females) with lymphangiomas in oral and maxillofacial regions were treated in the affiliated dental hospital of Sichuan University fromMay 1990 to December 2000. The patients.ages ranged from 015 to 46 years. The tongue was the most commonly involved site, followed by the cheek and the neck. The 200 lymphangiomas (5 patients had 2 lymphangiomas in different sites) underwent the therapy of Pingyangmycin, which was injected as with 1 mg/ml in saline. The total dose of Pingyangmycin ranged from 5 mg to 70 mg and 5 to 58 times, 1 time per 2~4 weeks.Results:The curative rate of cystic-type lymphangiomaswas the highest. Of the 51 cystic lymphangiomas, 110 capillary lymphangiomas, 18 cavernous lymphangiomas and 21 combinations of capillary and cavernous lymphangiomas, the curative rates were respectively 100%(51), 46136% (51), 16116%(3) and 19105%(4), which showed a significant therapeutic effect, respectively. And 40(78143%), 19(17127%), 2(11111%) and 0(0%) of them completely disappeared. There was no serious side effect with Pingyangmycin-injection treatment, such as pulmonary fibrosis. Conclusion:The treatment of injection of Pingyangmycin is a selective primary method of lymphangiomas, which can reduce the size of lymphangiomas, and make them completely disappeared.

    A Quantitatively Pathological Study on Malignant Ameloblastomas
    Liu Jinzhong, Wang Shuozhi, Chen Xinming
    West China Journal of Stomatology. 2002, 20(03):  187-189. 
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    Objective:The purpose of this study was to investigate the role of nuclear morphometric parameters, DNA content and Ag- NOR count in the differentiating malignant and benign ameloblastomas.Methods:Totally 17 cases of malignant ameloblastomas were examined by using HE, AgNOR and DNA stain methods. Morphometric parameters of cell nuclei, DNA content and AgNOR countwere quantitatively studied by using an image analysis system.Results:Seven parameters (area, perimeter, equal diameter, minor diameter, mean diameter, round index, axis ratio) out of ten shape factors were significantly different between malignant and benign ameloblastoma (P<0101). AgNOR count and DNA index in malignant ameloblastoma were significantly higher than those in benign ameloblastoma (P<0101). Logistic regression equationwas established, according to nuclearmorphormetric pa- rameters and DNA index.Conclusion:Quantitative analysis of DAN content, nuclear morphmetric parameters and AgNOR count may be helpful in differentiating malignant and benign ameloblastomas.

    The Evaluation of Color for the Clinical Application of Thinner Porcelain Laminate Restoration
    Yang Zheng, Mu Yandong,Luo Yun, et al
    West China Journal of Stomatology. 2002, 20(03):  190-192. 
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    Objective:The aim of this study was to evaluate the clinical application of the thinner porcelain laminate restoration, which is initiated in the WestChina College of Stomatology, Sichuan University.Methods:The colorof 51 ceramic veneerswas evaluated using the chromatic instrument and visual observation.Results:Among factors affecting the clinical results of the porcelain lami- nate, the hue of ceramic materials and bond composites played a more important role than the dentition. The brightness of ceramic materials and bond compositeswere closely correlated with the whole restoration brightness. There was also a close correlation be- tween the brightness and the bond composite.Conclusion:Satisfactory restoration results can be achieved by clinical application of thinner porcelain laminate.

    Flowcytometry DNA Analysis of Oral and Maxillofacial Non-Hodgkincs Lymphoma
    Ma Li, He Zhixiu, Wu Lanyan et al
    West China Journal of Stomatology. 2002, 20(03):  193-196. 
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    Objective:The purpose of this studywas to investigate the relationship between the results of flowcytometry analyses of differ- ent clinical stage, location, pathologic grade and cell origin of oral and maxillofacial non-Hodgkincs lymphoma (NHL), and the diagnostic value of flowcytometry analysis in lymphoma.Method:This study analyzed 50 oral and maxillofacial NHL cases and 10 reactive lymph nodes (formalin fixed and paraffin embedded) by flowcytometry (FCM).Results:Reactive lymph nodes were all diploid. The diploid rate of NHLwas 54%, and aneuploidy rate was 46%. There was statistically significant difference between reactive lymph nodes and NHLin the DNA ploidy status and cell cycle data (SPF, CV, S+G2/M, DI). The S phase fraction (SPF) and S+G2/M had close relationshipwith the grade of NHL. SPF value and DNA ploidy status had no obvious relationship with the prognosis.Conclusion:The results suggested that the FCMhad diagnostic value inNHL, especiallywhen the morphologi- cal diagnosis was difficult. Although the cell cycle data had no prognostic value, SPF and SPF+G2/M can show the proliferative status of NHL, which can help clinical doctor select therapeutic method.

    A Longitudinal Study of 5 Cephalometric Plane Angles in Female Children from 7 to 12 Years Old
    Peng Jing, Deng Hui, Cao Caifang
    West China Journal of Stomatology. 2002, 20(03):  197-199. 
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    Objective:The aim of this study was to find the laws of angular changes of 5 cephalometric planes in children with mixed dentitions.Methods:Nineteen female children were annually examined with X-ray, and the cephalometric analysiswas performed in continuous 4 years. Of these children, 10 childrenwere investigated from the age of 7 years old, and the other9 children from 9 years old. The two groups were longitudinally studied. All of the children were observed almost at the same age (9~10 years old) in the two groups, and the resultswere analyzedwithmixed longitudinal methods. All datawere analyzedwithSPSS 8.0 soft- ware.Results:In the observation period, the angular relationship of FH to BaN remain constant among 5 cephalometric planes, and FHto SNwas almost in the same situation.Conclusion:In mixed dentition, the angular relationship of FH, BaN and SN barely change.

    A Study of Ultrasound Images under 3 Different Functional Mandibular Positions in Young Females
    Che Xiaoxia, Luo Songjiao, Li Yongzhong
    West China Journal of Stomatology. 2002, 20(03):  200-202. 
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    Objective:The aim of this studywas to establish the average of superfacial massetermuscle of young femaleswith normal oc- clusion, and further supply a clue for dentists to evaluate the muscle function of patients with malocclusion.Methods:Totally 31 young females were investigated in this study, whose mean age was21years and 4 months old. Ultrasound technique was applied to obtain the ultrasound parameters of images, including area, width, mean thickness, maximal thickness of the cross-section and the length of the vertical-section of the massetermuscle under relaxing, maximal clenching and maximal protruding condition. The data were analyzed using ANOVA analysis.Results:The mean value and standard deviation of every parameterwere figured out and it was found that there was a significant difference between relaxing and maximal clenching as well as maximal protruding.Conclu- sion:The result indicates that ultrasonic technique is an effective method for describing superfacial masseter muscle morphology and diagnosing its function.

    Changes in the Inferior Alveolar Vessels and Angiogenesis Following Mandibular Lengthening with Different Rates of Distraction
    Tang Zhenglong, Zou Shujuan, Hu Jing, et al
    West China Journal of Stomatology. 2002, 20(03):  203-205. 
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    Objective:The purpose of this study was to study the changes in the inferior alveolar vessels and angiogenesis following mandibular lengthening with different rates of distraction.Methods:Bilateral mandibular corticotomieswere performed in 6 goats. The mandibles in 6 goats were legnthened 10.0 mm using a custom-made distractorwith different rates of distraction (1.0 mm/d [n=3] and 2.0 mm/d [n=3]); the other2 nondistracted mandibles served as control. The goatswith distracted mandibleswere killed at2 weeks after completion of distraction. The inferior alveolar vesselswith distracted calluseswere harvested and processed for histologic and morphometric evaluation.Results:No pathological changes in the inferior alveolar vessels were found following mandibular osteodistraction. However, the number of microvessels within distraction gap in the animals distracted at a rate of 1.0 mm/day was greater than that in the goats distracted using a rate of 2.0 mm/day, and more mature newly formed bone trabeculae was observed.Conclusion:There were no significant changes in the inferior alveolar vessels aftermandibular lengthening with dis- traction osteogenesis, but rapid distraction may have adverse effects on the aniogenesis in the distraction gap.

    Distraction Osteogenesis for the Repair of Cleft Palate----An Ultrastructural Study
    Chen Gang, Liu Baolin, Wang Dazhang et al
    West China Journal of Stomatology. 2002, 20(03):  206-208. 
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    Objective:The aim of this study was to explore ultrastructural characters of the newly formed bone in the correction of cleft palate (CP) bone defect by distraction osteogenesis (DO).Methods:The CP experimental animal models (12 cats) were estab- lished surgically, and were divided randomly into the experimental group (10 cats), in which the hard palate bone defects were corrected with DO procedure at the rate of 0.4 mm@2/day. The specimen retrieval with euthanasia was carried out at 2, 4, 6, 8, 12 weeks after completion of distraction. Ultrastructural study was then performed; the experimental control group (2 cats) was kept for 6 weeks before euthanasia without any correction, the other extra 2 cats were used as the negative control.Results:New bone formation appeared in early 2 weeks. Exclusively intramembranous bone formation was observed in all specimens. The re- modeling activities were keep observed throughout the period of study, and the bone structure matured gradually till 12 weeks after the completion of DO. No repairwas observed in experimental control group.Conclusion:The reconstruction of CP bone defectby means of DO could get active intramembranous bone formation and remodeling, which adapted to normal functional activities.

    Characteristics of BMP Expression and X-ray Films in Distraction Osteogenesis for Repair of Cleft Palate----An Immunohistochemical and Roentgenographic Study
    Chen Gang, Liu Baolin, Wang Dazhang et al
    West China Journal of Stomatology. 2002, 20(03):  209-212. 
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    Objective:The purpose of this study was to observe the roentgenographic characters of distraction osteogenesis (DO) correc- tion of cleftpalate (CP), to study the expression of BMP proportional to fixation period time intervals, and to explore the newbone formation mechanism in CleftPalate bone shelf.Methods:12 catswere used to establish the CP animal model surgically, and then were assigned randomly to (1) Experimental group(12 cats): CP defects were DO repaired at the rate and rhythm of 0.4 mm@ 2/day. Specimen retrieval at 2, 4, 6, 8, 12 weeks after completion of distraction, roentgenography and Anti-BMP immunohisto- chemistry studies were performed; (2) Experimental control group (2 cats): CP defects without any treatment procedures, and (3) Empty control group of 2 cats.Results:Anti-BMP immunohistochemistry study showed positive DAB dye in early 2 weeks and most extensively positive expression of BMP in 4 to 6 weeks. The expression of BMPwore off gradually through 8 to 12 weeks. The roentgenography showed that the newly mineralized bone was developed from the cut bone edges bilaterally to the central transpar- ent zone, and the newly formed bone bridged the defect area completely at the end of the study. The CP bone defect was recon- structed and the distraction gap was filled with de nove osteogenesis. No new bone formationwas observed in experimental control group.Conclusion:The process of new bone formation in the distraction area is dynamic. Being stimulated primarily, the process was kept highly active till quiescence phase finally. The X-ray examination shows that there is distinctively low roentgenopeque. Nevertheless, roentgenography is so far a very effective and convenient method to evaluate and monitor the DO correction efficiency.

    The Effects of the Mechanical Stress on the Cytoskeleton Filament F-actin of Osteoblast-like Cells in vitro
    Chen Guoping, Zhou Zheng, Zheng Yi,et al
    West China Journal of Stomatology. 2002, 20(03):  213-215. 
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    Objective:Mechanical stimulation alters cellcs metabolism, but little is known about the effects of mechanical strain on the cytoskeleton of osteoblasts. This study was to investigate the changes of F-actin, a cytoskeleton protein of rat-derived osteoblast- like cell line UMR-106, and to provide theoretical basisforfurtherinvestigation ofmechanism of bone-remodeling.Methods:Cen- trifugation was used to inflict UMR-106 the top-bottom axial stress (225@g) expected and, confocal laser scanning microscope (LSCM) was used to examine the morphological changes 15, 30min, and 1, 4, 6, 12, and 24hr afterundergoing physical strain. Unstrained cells were used as the controls respectively. The distribution of F- actin was observed after immunofluorescent staining and electronic photo was scanned for further analysis of osteoblastscaverage fluorescence by spectrofluorimetric quantification.Re- sults:Except the 24hr group, the actin filaments of the strained osteoblastswere much shorter, more flimsy and tenuous than that of untreated osteoblasts and unlike the normal distribution of bundles or membrane-like of the control group, and they were ar- ranged without direction. Its quantified fluorescence was significantly less than that of the controls. But the 24hr group showed a normal distribution and a stronger fluorescence.Conclusion:It is concluded that the cytoskeleton of the strained osteoblasts has a reduced number of F-actin fibers and a unique abnormal morphology and could recover in 24hr.

    Experimental Research on Degradation and Biocompatibility of Super-high-molecular-weight Poly-DL-lactic Acid
    West China Journal of Stomatology. 2002, 20(03):  216-218. 
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    Objective:The super-high-molecular-weightpoly-DL-lactic acid (PDLLA), with the molecularweightof 900 kD, is a newly emerging biomaterial and potentially used in the therapy of bone fracture because of its excellentmechanical property. However the biocompatibility of this material has notbeen reported so far, therefore this experimentwas designed to examine whether the super- high-molecular-weight PDLLAwas harmful to creatures, when itwas implanted in the body of animals for a long period.Methods: The material was prepared in small cuboids, with the size of 1.0 mm@1.5 mm@2.0 mm, and these blockswere implanted into the masseteric space of SD rats and, the activity of the SD-rats was monitored continuously. The animals were sacrificed in the 3rd, 6th, 9th, 12th months after the operation and, the specimens were taken out from the animals. The examination included anatomical, pathological and haematological methods. The datawere analyzedwith SPSS 8.0.Results:The wound healedwell af- ter the operation. Super-high-molecular-weightPDLLAdegraded 6 months after the implantation. In the 3rd month after the opera- tion, a thin fiber membrane around the materialswas formed. In the 6th month, the membrane was much thinner than that in the 3rd month and completely disappeared in the 9th month. The pathological examination showed that slightly inflammatory reaction appeared in the tissue around these blocks in the 3rd month, butthe inflammatory reactionswere gradually remitted in the following 6th, 9th and 12th months. Further, the haematological examination did not show any abnormity during the 12-month observation period.Conclusion:The super-high-molecular-weight PDLLA can be degrade when it is implanted into the body of creatures, which proves its good biocompatibility.

    A Survey on Dental Knowledge and Behavior of Mothers and Teachers of School Children
    Jiang Han, Tai Baojun, Du Minquan, et al
    West China Journal of Stomatology. 2002, 20(03):  219-220. 
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    Objective:The purpose of this survey was to assess dental knowledge and behaviors of the teachers and mothers of school children.Methods:All data was collected from 1365 mothers of firstgrade students and 215 schoolteachers in Yichang, Hubei by using questionnaires and, analyzed using SPSS software.Results:The level of dental knowledge was higher among schoolteachers than among mothers; the motherswere mostly informed through television/book (62.4% /51.5%), while teachers received infor- mation from various sources, including the dentists (75.3%). Most of the children (94.0%) didnct have practical support from their parents in daily tooth cleaning. Only 18.9% of them visited the dentist at leastonce peryear.Conclusion:This finding sug- gested thatwe should emphasize oral healthy education among mothers and schoolteachers, in order to promote school-based oral health education program.