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Table of Content
20 December 2008, Volume 26 Issue 06
  • Z2 appliance:The pre-adjusted appliance based on Chinese normal occlusion
    ZENG Xiang-long, GAO Xue-mei
    West China Journal of Stomatology. 2008, 26(06):  573-579. 
    Abstract ( 1874 )   HTML ( 8 )   PDF(pc) (309KB) ( 698 )   Save
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    Z2 appliance is the pre-adjusted appliance designed for Chinese orthodontic patients. The prescription of the appliance is based on Chinese normal occlusion, which is much different from the West in the first and the second orders as well as the third one. The appliance routinely includes 20 brackets and 8 molar buccal tubers with 3 standard arch forms. Clinically, continued light force is used in whole treatment. The side-effects such as forward tipping of incisors, bite deepening and loss of molar anchorage are reduced further due to fewer tips built into the anterior brackets as well as lower friction elastometric modules used during aligning and leveling. In condition of arch are leveled completely, 0.48 mm×0.64 mm stainless steel archwire with 1.47 N retraction force is the best combination for sliding mechanics, which is proved by 3D nonlinear finite element study. Self drilling micro-screw is used for maximum anchorage. In finishing stage 0.53 mm ×0.64 mm NT arch wire is added in order to get full torque expressing. The research of Chinese pre-adjusted appliance has been lasted for more than 10 years in the department  and clinical studies on Z2 appliance show that with minimal wire bending, treatment is more efficient and result is igh quality and more consistent for Chinese orthodontic patients.

    Expression of mammalian target of rapamycin and p70 S6 kinase in rabbit periodontal tissues remodeling uring orthodontic tooth movement
    LIU Yi1, GUO Ya-feng2
    West China Journal of Stomatology. 2008, 26(06):  580-583. 
    Abstract ( 1109 )   HTML ( 1 )   PDF(pc) (311KB) ( 468 )   Save
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    Objective To study the role of mammalian target of rapamycin(mTOR) and p70 S6 kinase(p70 S6K) in periodontal tissues remodeling during orthodontic tooth movement. Methods Twenty -four rabbits were chosen to establish rabbit models for the study. The right maxillary teeth of each animal treated by orthodontics were the test sides, and the untreated left teeth were the control sides. The animals were sacrificed at 3, 5, 7, 14 d, espectively. The prepared tissue specimens were processed for the study of the change in the histologic morphology ith HE staining and the expression of p70 S6K in periodontal tissues by reverse transcription-polymerase chain eaction(RT-PCR) and Western blot techniques. Results In the test side, the tranecula of bone became porous nd cells arrayed disorderly, resorption of alveolar bone was observed in histological study. There were many holes n the alveolar bone, osteoblasts were occasionally observed. RT-PCR showed that the expression of p70 S6K mRNA ramatically changed at 3 d. The expression of p70 S6K mRNA in treating periodontal tissues was higher than the ontrol side, especially at 7 d, and then decreased. Compared with the control side, there was significant difference n statistical analysis(P <0.01). The expression of Western blot was same as the RT -PCR. Conclusion Higher xpression of mTOR and p70 S6K during orthodontic tooth movement especially plays an important role in the process f periodontium remodeling.

    Finite element analysis of the effects of implant thread locations on stress distribution
    ZHAO Jing -hui, ZHOU Yan-min, LI Chun-yan
    West China Journal of Stomatology. 2008, 26(06):  584-587. 
    Abstract ( 1148 )   HTML ( 0 )   PDF(pc) (240KB) ( 513 )   Save
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    Objective To investigate the effects of different implant thread locations on stress distribution in implant and bone under concentrated load, and discuss the best design of location of implant thread. Methods The stress in implant-bone interface of implants with different thread locations(model A, B, C, D), which were loaded in axial and oblique 45° to axle, were analyzed by Solidworks 2005 plus and Cosmos/works 7.0 software. Results The stresses in cervical cortical bone of implant with model C were lower than others. But under oblique load, the stresses of implant and cancellous bone in model C were higher than model A. The stresses distribution of model B was obviously concentrated, and under axial load, all kinds of stresses in this model were higher than others. The stress distribution in model A and D were more even, the stress concentrated more on implant neck, upper part of cortical bone and the lowest thread on implant. The stresses in interface under oblique load were much higher than those under axial load. Conclusion The location of thread has effect on stress distribution in implant-bone interface. More attention should be paid to it when we design implants, and we should try to avoid oblique load in implant prosthodontics.

    Effects of mechanical stress on the formation and expression of Cbfα1 in vitro
    WANG Xue-jin, HAO Xiaoning, LIU Wei, PENG Wei, XU Ying-hua
    West China Journal of Stomatology. 2008, 26(06):  588-590. 
    Abstract ( 1099 )   HTML ( 0 )   PDF(pc) (235KB) ( 525 )   Save
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    Objective To evaluate the effects of mechanical stress on the formation and expression of core binding factor α1(Cbfα1) in MG-63 cells cultured on titanium in vitro. Methods MG-63 cells cultured on the titanium were subjected to a centrifugal force(2.205 N) 15 min per 4 hours and collected after 4, 8 and 12 hours. The formation and expression of Cbfα1 were examined by immunofluorescence staining and reverse transcription-polymerase chain reaction(RT-PCR). Results Both the cells with or without centrifugal force created the fluorescence in the nucleus and the immunofluorescence intensity of Cbfα1 in MG-63 cells with centrifugal force were higher than those without centrifugal force(P<0.05). Meanwhile, both the cells with or without centrifugal force expressed the mRNA of Cbfα1 and the relative mRNA level of Cbfα1 in MG-63 cells with centrifugal force were higher than those without centrifugal force, and the differences were great significant(P<0.05). Conclusion Mechanical stress are beneficial to the formation and expression of Cbfα1.

    Expression and significance of vascular cell adhesion molecule-1 in human oral squamous cell carcinoma
    SUN Le-gang1,WANG Fang1,LIU Ling2,SONG Yu-feng3,YANG You-cheng1,WANG Li-fang1
    West China Journal of Stomatology. 2008, 26(06):  591-594. 
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    Objective To study the expression and the location of vascular cell adhesion molecule-1(VCAM-1) gene and its clinical significance in human oral squamous cell carcinoma(OSCC). Methods In situ hybridization, PV-9000 polymer detection system for immunohistochemical staining was used to detect the expression and the location of VCAM-1 mRNA and VCAM-1 protein in 48 cases of OSCC and 10 cases of normal controls. Statistical analysis was performed using chi-square test in SPSS 13.0. Results VCAM-1 protein was mainly expressed in tumor cell cytoplasm and membrane, VCAM-1 mRNA was mainly expressed in tumor cell cytoplasm. The expression rate of VCAM-1 mRNA and VCAM-1 protein was significantly higher in OSCC than that in normal oral mucosa(P<0.01). The expression of VCAM-1 mRNA was positively correlated with that of VCAM-1 protein(P<0.01). In the clinicopathologic factors, lymph node metastasis and depth of infiltration were closely correlated with VCAM-1 expression (P<0.01). The expression of VCAM-1 was significantly higher in tumor with lymph node metastasis than in tumor without lymph node metastasis(P<0.01). Conclusion Overexpression of VCAM-1 gene in OSCC may play a potential role in the development of OSCC. The overexpression of VCAM-1 gene in OSCC may be related to the tumor infiltration and metastasis.

    Experimental study of Ti-24Nb-4Zr-7.9Sn alloy after treated with micro-arc oxidation in vivo
    LIU Zhengming, GAO Bo, ZHANG Li -zhao
    West China Journal of Stomatology. 2008, 26(06):  595-598. 
    Abstract ( 1137 )   HTML ( 0 )   PDF(pc) (307KB) ( 401 )   Save
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    Objective To study the biocompatibility of Ti-24Nb-4Zr-7.9Sn(TNZS) alloy treated with micro-arc oxidation(MAO). Methods The tibia bones of New Zealand rabbits were used to build the animal model. TNZS and MAO-TNZS samples were implanted into one side of tibia, pure titanium samples were implanted into the other side as control. After 4 and 26 weeks, radiographs and HE staining technique was used to observe the dynamic remodeling process of bone-implant interface. Results As the cure time increased, it was showed well biocompatibility of all implants. X-ray indicated that there was no permeable area produced around the three different materials at each time point. The density of bone matrix and arrangement of bone trabecula was almost the same as in the host bone. It was revealed by histological examination that the MAO-TNZS greatly prompted the bonding ability between implant and surrounding hard tissues. Four weeks after implantation, fine attachment was found at the bone-implant interface of all the implants and the fibrous tissue at the interface was gradually remodeled to form new bone. Twenty-six weeks later, MAO-TNZS showed that a biological fixation was created between bone and oxidation layer, while a layer of fibers formed between non-coated TNZS and titanium implants surrounding bone. Conclusion The Ti-24Nb-4Zr-7.9Sn after treated with micro-arc oxidation shows good biocompatibility and can stimulate the bone growth in the bone-implant region, which provides support for clinical usage tests of TNZS alloy as implant after treated with micro-arc oxidation.

    Differentiation and functional expression of highly purified osteoclast-like cells in vitro
    LIU Wen-jia1, WANG Xiao-geng1, ZHOU Hong1, LI Ang2
    West China Journal of Stomatology. 2008, 26(06):  599-603. 
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    Objective To establish a culture method for a large amount of highly purified osteoclast-like cells in vitro. To investigate the gene expression of some osteoclast marker enzymes. To lay the foundation for the further study of the signal path on the differentiation and formation of osteoclast-like cells. Methods The bone marrow mononuclear cells of rat were treated with 30 ng/mL macrophagecolony-stimulating factor(M-CSF) and 50 ng/mL receptor activator of NF-кB ligand(RANKL) and cultured for 6 days. After culturing, cells were evaluated by morphology observation, tartrate-resistant acid phosphatase(TRAP) staining, Giemsa staining, pit staining, and the gene expression of some osteoclast marker enzymes. Results The TRAP-positive mononuclear cells were more frequently observed than the multinucleated cells and pit staining could be seen on the dentine slice. The transcription expression of TRAP, matrix metalloproteinase-9(MMP-9), membrane-type1-matrix metalloproteinase(MT1-MMP) and cathepsin K were detected by RT-PCR. Conclusion The cooperation of M-CSF and RANKL could induce a large amount of highly purified osteoclast-like cells formation in rat bone marrow culture. The typical characteristics of osteoclast-like cells were demonstrated and the enriched osteoclast-like cells expressed TRAP, MMP-9, MT1-MMP and cathepsin K.

    The expression of Maspin protein in oral squamous cell carcinoma and its significance
    SHUI Hua-hua1,2, LUO Ling1, LIANG Shang-zheng1, HUANG Li1, LI Wei1
    West China Journal of Stomatology. 2008, 26(06):  604-606. 
    Abstract ( 1291 )   HTML ( 0 )   PDF(pc) (242KB) ( 452 )   Save
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    Objective To investigate the role of Maspin protein in the development of oral squamous cell carcinoma(OSCC), with the effort to realize practical diagnosis use of them. Methods The expression status of Maspin protein in 45 cases of OSCC, 33 cases of paratumor tissue and 15 cases of normal tissue was examined by immunohistochemical staining. Results The positive rates of Maspin protein were 86.67%(13/15), 72.73%(24/33) and 37.78%(17/45) in normal tissue, paratumor tissue and OSCC. The expression of Maspin protein increased respectively in OSCC, paratumor tissue and normal tissue. The expression were different between OSCC and normal tissue, OSCC and paratumor tissue, paratumor tissue and normal tissue(P<0.05). The expression of Maspin protein was correlated with lymph node metastasis, histological grade(P<0.05), but not with TNM staging(P>0.05). Conclusion Maspin protein may play an important role in the development of OSCC. The expression level of Maspin protein detected in early time might be a useful prognostic marker for the diagnosis of lymph node metastasis.

    Detection and prevention of early caries after fluoride dentifrice application using quantitative light-induced fluorescence in vivo
    FENG Yan1,2, YIN Wei2, HU De-yu2, Yunpo Zhang3,Iain A. Pretty4, Roger P. Ellwood4
    West China Journal of Stomatology. 2008, 26(06):  607-610. 
    Abstract ( 990 )   HTML ( 1 )   PDF(pc) (215KB) ( 495 )   Save
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    Objective To evaluate the capability of quantitative light-induced fluorescence(QLF) for monitoring the remineralization of lesions lengthways and distinguishing the effect of different fluorides. Methods Following baseline early caries examination, 305 school students(age from 11 to 14 years old)were qualified from Chengdu area. The schools in which the subjects studied were randomized into three groups: NaF group, MFP group and nonfluoride group. The subjects of three groups brushed the teeth with 1 450 mg/L sodium fluoride dentifrice, 1 450 mg/L sodium monofluorophosphate dentifrice and non -fluoride dentifrice, respectively. QLF images of early lesions on smooth surfaces of the maxillary anterior teeth were taken at baseline, three and six months after the initiation of experiment. These images were analyzed by the trained examiner with the area of lesion(Area), fluorescence loss (△F) and gross fluorescence loss quantity(△Q). Results 296 school students completed the study. After three months, the lesions on smooth surfaces got better in all three groups. The change of Area, △F and lg△Q amongst three groups had no statistical significance(P>0.05). After six months, the lesions on smooth surfaces also got better in all three groups than at baseline. The change of Area, △F and lg△Q of the lesions in NaF group and MFP group exhibited significant decreases than that of no-fluoride dentifrice group(P<0.05). But no significantly difference was found between NaF group and MFP group(P>0.05). Conclusion As a diagnostic method which could quantify the miner content, QLF system has the capability of monitoring the variations of lesions lengthways.

    Application of multislice helical computed tomography in maxillofacial distraction osteogenesis
    NIU Xuegang1, ZHAO Yi-min2, HAN Xiao-xian1, HAO Yong3, MEN Shen-li3
    West China Journal of Stomatology. 2008, 26(06):  611-614. 
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    Objective To develop the method and investigate the value of the application of multislice helical computed tomography(CT) in the maxillofacial distraction osteogenesis. Methods Twelve cases of maxillofacial distraction osteogenesis(3 in zygoma, 2 in maxilla, and 7 in mandible) were scanned by the multislice helical CT, then the reconstruction of three dimensional and fault image and the relative measurement were carried out to study the effect of distraction and osteogenesis. Results The three dimensional image provided clear and high resolution stereoscopic view that the effect of distraction osteogenesis could be evaluated easily and exactly. The fault image could be set up in private computer by Mimics and the measurements, such as distance, thickness and density, could be performed as expected. The effect of 12 cases was satisfied, and the average distracted distance was 16.73 mm. Conclusion Basing on multislice helical CT scanning, the high resolution image reconstruction and relative measurement data could be obtained which could meet the need of clear and direct observation. Its application in the maxillofacial distraction osteogenesis is expecting and promising.

    Study on mandibular rotation in 13 female subjects aged from 9.5 to 15.5
    GU Yan
    West China Journal of Stomatology. 2008, 26(06):  615-617. 
    Abstract ( 1266 )   HTML ( 0 )   PDF(pc) (191KB) ( 542 )   Save
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    Objective To evaluate the mandibular rotation in females aged from 9.5 to 15.5 years. Methods The sample was obtained from Mathews′s implant study with longitudinal cephalometric records of 13 untreated Caucasian female subjects. The cephalograms taken annually from 9.5 to 15.5 years old were traced and analyzed with Dentofacial Software. Paired-t test was performed to identify the significant growth changes in different age groups. Results Significant change in lower anterior facial height, posterior facial height, ramus length and mandibular implant plane angle were noted in aged 9.5-11.5. Significant change in lower anterior facial height, posterior facial height and ramus length were noted in aged 11.5 -13.5. Significant change in mandibular plane angle and mandibular implant plane angle and significant increase in posterior facial height were observed in aged 13.5-15.5. Conclusion The results of this study verify that remodeling on the lower border of mandible influences total mandibular rotation.

    Clinical research of craniofacial bone autograft using mandibular outer cortex
    ZHAO Yan-feng1, LIU Xiaojing2, LU Ping1, ZHOU Xiao-nan1, GUI Lai3
    West China Journal of Stomatology. 2008, 26(06):  618-621. 
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    Objective To illustrate the volume changes of mandibular outer cortex after been grafted to different recipient sites of facies cranii. Methods Six cases underwent onlay bone graft to the angle and body part of  mandible and malar surface simultaneously by using mandibular outer cortex. Three dimensional computed tomography (3D-CT) datum of immediate postoperative and 6 months postoperative of each case were collected systematically. By true-up and dissection techniques based on 3D-CT, volume changes of bone graft at different recipient sites were observed and analyzed 6 months postoperative. Results 6 months after onlay bone grafted, bone resorption occurred. To different recipient sites, bone resorption rate was unequal. At the mandible area, bone resorption rate was 20.8%± 7.2%, the main site of resorption was at the lower and posterior border of mandible. At the anterior part of maxilla, bone resorption rate was 11.2%±2.3%. Statistics showed significant difference of resorption rate between the two sites (P<0.05). Conclusion Bone resorption of mandibular outer cortex after onlay graft treatment is variant according to different craniofacial recipient sites. The difference of mechanical environment at variant recipient sites is considered to be an influencing factor. Quantization of bone resorption rate can guide a better clinical use.

    A primary study of color tolerance of anterior tooth crown prosthesis
    GE Qi-min, ZHANG Fu-qiang
    West China Journal of Stomatology. 2008, 26(06):  622-625. 
    Abstract ( 989 )   HTML ( 0 )   PDF(pc) (176KB) ( 560 )   Save
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    Objective To study the color tolerance of anterior ceramic crown and seek an effective approach for color -matching of oral prostheses. Methods 30 single maxillary incisor ceramic prostheses and the corresponding nature teeth were measured by a digital camera in a steady environment for image taking and color measurement, which based on the standard recommended by CIE. The color tolerance was analyzed in two groups based on satisfaction and dissatisfaction of prostheses color-matching. Results The △E of satisfaction group was 2.550 3, while the △E of dissatisfaction group was 4.077 2. There was significant difference between chromatic aberration of satisfaction group and dissatisfaction group(P<0.01). When the lightness and saturation of prosthesis were higher than nature teeth, there was no significant difference between △L*、△b*、△C* of satisfaction group and dissatisfaction group(P>0.05). When the lightness and saturation of prosthesis were smaller than nature teeth, there was significant difference between △L*、△b*、△C* of satisfaction group and dissatisfaction group(P<0.01). There was significant difference between △a*, △H° of satisfaction group and dissatisfaction group(P<0.05,P<0.01). Conclusion Control of color difference is the key for shade matching of anterior tooth prosthesis. Applying the color tolerance is beneficial to improving the prosthesis quality.

    Clinical evaluation on the root canal therapy bypassing intracanal separated instruments
    LI Yuan -gao, WANG Ji-chao, ZHOU Xin
    West China Journal of Stomatology. 2008, 26(06):  626-629. 
    Abstract ( 1096 )   HTML ( 3 )   PDF(pc) (162KB) ( 619 )   Save
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    Objective To study and evaluate the clinical effect of root canal therapy bypassing intracanal separated instruments. Methods 32 teeth were selected as the test group, from which the intracanal separated instruments couldn′t be taken out, adopted the method of root canal preparation and obturation bypassing broken instruments. Meanwhile, 13 teeth were selected as the control group, in which the fractured instruments couldn′t be taken out from root canal, and not be cured bypassing broken instruments. 30 teeth were selected as the conventional therapy group, in which the instruments were not fractured, the routine root canal therapy were adopted. The clinical efficacy of three groups were observed and evaluated through periapical index and clinical examination two years later. Results After two years, 25 teeth were followed up in test group, the success rate of root canal therapy was 80.00%; 11 teeth were followed up in control group, the success rate of root canal therapy was 36.36%. All of the failed cases in two groups were the teeth with broken instruments in tip of root canal. In conventional therapy group, 22 teeth were followed up, and the success rate of root canal therapy was 90.91%. Conclusion Root canal therapy bypassing intracanal separated instruments is a feasible and effective method in treating the teeth with broken instruments.

    A comparison study on the effect of self-etching adhesive and phosphoric acid fissure sealant in children
    ZHANG Sun, QIN Man, LI Jing
    West China Journal of Stomatology. 2008, 26(06):  630-632. 
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    Objective To compare the retention and caries prevention of fissure sealant on the primary molars etched with self-etching adhesive and phosphoric acid in children. Methods 43 children younger than 42 months with more than 4 decayed teeth were studied. The split-mouth design was used in this study. The second and/or first primary molars were randomly assigned into self-etching adhesive group in one side of mouth, and phosphoric acid group in the other side. Sealants were applied on 69 pair primary molars according to manufacturer′ s instruction with dental cotton-roll isolation. The children were followed up every 3 months, and the sealants were observed and evaluated. In the case caries occurred, the teeth were restored. Results After 3 months, the retention rate was 93% in self-etching adhesive group and 100% in phosphoric acid group. At 6, 12 and 18 months, the retention rate of self-etching adhesive group was statistically lower than that of phosphoric acid group(P<0.05) by Wilcoxon signed ranks test. Caries occurred in both groups and self-etching adhesive group had more caries than phosphoric acid group. Though its retention rate was low, self-etching adhesive was suitable for young children because it was timesaving and its bonding procedures were simple without discomfort rinsing. Conclusion The retention rate of sealant with self-etching adhesive was lower than that with phosphoric acid. The phosphoric acid is suitable for pit and fissure sealant. If self-etching adhesive is  sed for sealing primary molars of young children for a limited period of time, it should be reviewed every 3 months.

    Fracture resistance and failure modes of endodontically treated human teeth restored with four different post-core systems
    YANG Zheng1, HOU Yong-fu1, PAN Xiao-bo2
    West China Journal of Stomatology. 2008, 26(06):  633-635. 
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    Objective To compare the fracture resistance and failure modes of endodontically treated human upper premolars restored with different post -core systems. Methods 32 extracted human upper premolars were endodontically treated and crowns were sectioned at 2 mm above the labial cement enamel junction(CEJ). The teeth were randomly and equally divided into 4 groups: Group A, teeth restored with cast metal post and metal crown; group B, Tenax Fiber White fiber post and metal crown; group C, EverStick fiber post 1.5 mm in diameter and metal crown; group D, EverStick fiber post 1.5 mm in diameter and add another 1.2 mm diameter EverStick fiber post and metal crown. All the teeth were embedded in acrylic resin blocks, and were subjected to a compressive load at 1 mm/min crosshead speed which delivered at a 45° to the long axis until the first sign of failure was noted. The fracture load and the mode of fracture were recorded. Results Fracture resistances of the four groups of restored teeth were not significantly different(P>0.05). However, fracture modes in fiber post groups were nearer to CEJ than cast metal post group. Conclusion Fracture resistance of endodontically treated teeth restored with Ever- Stick fiber post is enhanced that it can meet the clinical need, although the flexural resistance of EverStick fiber post itself is the weakest. Fracture modes of all fiber post groups are more favorable than cast metal post group.

    The application of cone-beam computed tomography and nine partition method on alveolar bone for locating the unerupted teeth
    ZHANG Zhi-yong, KUANG Zhe
    West China Journal of Stomatology. 2008, 26(06):  636-639. 
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    Objective To investigate the clinical value of cone -beam computed tomography(CBCT) and nine partition method on alveolar bone for locating the relative orientation of the unerupted teeth. Methods 125 bone unerupted teeth of 99 cases were collected. The bone unerupted teeth zones were scaned by CBCT. The dental corona and root apex of these bone unerupted teeth were classified by the new nine partition method. Results In 125 bone unerupted teeth, 107 teeth located in maxilla, 18 teeth located in mandible. More frequent appearances(35.6%) in the alveolar bone were inner-middle and outer-superior. The representation of 125 bone unerupted teeth seen in surgery was the same with that of the CBCT before exodontia. The accurate rate of diagnosis was 100%. Conclusion CBCT is the most accurate and effective methods to determine the authentic orientation of the bone unerupted teeth. The nine partition method of alveolar bone has clinical value of accurate authentic orientation of the bone unerupted teeth in oral and maxillofacial surgery and orthodontics.

    The characteristics of masticatory muscle activity in bruxers
    LI Xue -ling, LIN Xue -feng, TENG Wei, LI Shao-hua
    West China Journal of Stomatology. 2008, 26(06):  640-643. 
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    Objective To evaluate the effects of bruxism on masticatory muscle electromyographic(EMG) activity. Methods Twenty-four bruxers and sixteen asymptomatic control subjects were included through questionnaire and clinical examination. EMG activity was recorded by placing surface electrodes on bilateral anterior temporalis(TA), masseters(MM), anterior digastrics(DA) and sternocleidomastoid(SCM) muscles. EMG activities at rest, during maximal voluntary clenching in intercuspal position and swallowing were recorded by means of Bio PAK system. Results EMG activities of TA and MM at rest were significantly higher in bruxism group than in control group(P< 0.05). When subjects clenched their teeth in intercuspal position, the activities of TA and MM were much lower in bruxism group than in control one(P<0.05). EMG activity during swallowing was no significant difference between the two groups. The asymmetry index of bilateral TA and MM in bruxism group was a little higher than the control group, but there was no significant difference between the two groups(P >0.05). Conclusion Masticatory muscle dysfunction of bruxers is mainly represented as higher potential in postural position and lower potential during maximal voluntary clenching in intercuspal position of anterior temporalis and masseters.

    Psychological impact on the adolescent patients at the beginning of the fixed orthodontic treatment
    HOU Jing-qiu1,2, YAN Zheng-bin1, ZHANG Ye3, PENG Hui1, LAI Wen-li2
    West China Journal of Stomatology. 2008, 26(06):  644-647. 
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    Objective To assess whether there is a short negative psychological influence on adolescent patients at the beginning of the fixed orthodontic treatment. Methods 150 patients(average 14.8 years old) were selected. All the patients accepted the fixed appliance treatment. They completed a questionnaire regarding anxiety and depression at the first day when they came to the hospital(T1) and 7 days after fixed appliance insertion(T2). 129 effective questionnaires were received. The scales of anxiety and depression of subjects were assessed according to the questionnaires. Results Comparing the scales of questionnaires before treatment(T1) and 7 days after placement of fixed appliance(T2), there was a significant increase in anxiety and depression scales in female patients, extraction cases and patients who were unwilling to see an orthodontist. Conclusion There is a certain extent of negative psychological influence on adolescent patients during fixed orthodontic treatment. At the first week after the placement of fixed appliance, three kinds of subjects, female patients, extraction cases and patients who were unwilling to see an orthodontist would suffer from anxiety and depression in emotional reflection.

    Relationship of Porphyromonas gingivalis PG0717 gene with chronic periodontitis
    LIU Jing-bo1, LIN Li1, LI Chen2, YU Ning1, PAN Ya-ping1
    West China Journal of Stomatology. 2008, 26(06):  648-651. 
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    Objective The aim of the present study was to investigate PG0717 gene of Porphyromonas gingivalis (P.gingivalis) in subgingival plaque of the chronic periodontitis patients and periodontal healthy subjects, and to find out the relationship of detection rate of PG0717 and periodontal clinical parameters. Methods A total of 540 subgingival plaque samples were collected from 180 subjects including chronic periodontitis(CP) patients(n=90) and periodontal healthy individuals(n =90). The periodontal clinical parameters including probing depth(PD), clinical attachment loss(CAL), and bleeding on probing(BOP) were estimated by Florida probe. The extracted DNA samples of P.gingivalis positive was amplified with the sequence specific primers designed to obtain the PG0717 gene. Results In subgingival plaque of P.gingivalis positive, the detection rate of PG0717 in CP group was significantly higher than that in periodontal healthy subjects(56.22% versus 41.27%, 掊2=4.50, P<0.05). The detection rate of PG0717 in CP group showed the increasing tendency in accordance with the depth of PD and CAL. A higher detection rate of PG0717 was observed in the sites of BOP positive than that in BOP negative(57.73% versus 14.29%, 掊2=42.01, P<0.01). Conclusion The findings suggest that the PG0717 gene may influence the virulence of P.gingivalis.

    Interleukin-8 regulations of oral epithelial cells by Porphyromonas gingivalis with different fimA genotypes
    GUO Yong-hua1,2, WU Ya-fei3, LIU Tian-jia3, ZHANG Jing-yi1, XIAO Xiao-rong1, ZHAO Lei3
    West China Journal of Stomatology. 2008, 26(06):  652-655. 
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    Objective The expression of heterogenic virulence properties depends on its clonal diversity. The aim of the study was to investigate the mechanism of interleukin -8(IL -8) regulations of oral epithelial cells by challenge of Porphyromonas gingivalis(P.gingivalis) with different fimA genotypes, discuss the relation between fimA genotype and its pathogenicity. Methods P.gingivalis ATCC 33277(type Ⅰ), W83(type Ⅳ), 47A -1(type Ⅳ) were assessed for their inductions of IL-8 expression in human oral epithelial cells(KB cell line, ATCC CCL- 17). KB cells without stimulation of P.gingivalis were used as control group. IL -8 mRNA expression was de - termined by reverse transcription polymerase chain reaction(RT -PCR) at different time intervals(1, 3, 6, 24 h) following continuous co culture of bacteria with KB cell line, and IL -8 protein levels in culture supernatant was determined by enzyme-linked immunosorbent assay.  esults IL-8 mRNA levels were up-regulated and reached its high peak at 1 h following both genotypes infection, then decreased to base level till 24 h. Attenuation of IL-8 protein levels was down-regulated when KB cell co-cultured with both genotypes for 3 h till 24 h, and type Ⅳ was lower than type Ⅰ. IL-8 and IL-6 mRNA expression were not consistent with their protein levels, which indicated post -transcriptional regulations. Conclusion fimA genotypes of P.gingivalis are related with the effect of IL -8 inductions, which indicates fimA genotype is associated with pathogenesis of P.gingivalis.

    Effects of mineralization liquid on rat′ s osteoblast proliferation and differentiation
    YANG Xiao -yu1, LIU Chang-hong1, LIANG Xing2, SUN Jun2
    West China Journal of Stomatology. 2008, 26(06):  656-659. 
    Abstract ( 1200 )   HTML ( 0 )   PDF(pc) (335KB) ( 374 )   Save
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    Objective To compare the rat osteoblast proliferation and differentiation in the mineralization condition and non-mineralization condition, and to prove the feasible time of adding the mineralization liquid to the cell surroundings. Methods SD rat′s calvarial osteoblast was primary cultured and passaged to the 4th generation. After proliferation stabilized, the 4th generation rat′s osteoblast was cultured in the mineralization condition and nonmineralization condition. The cellular modality was observed by inverted microscopy analyzing system. Proliferation was described by MTT chromatometry and growth curve. Expression of alkaline phosphatase(ALP) was proved by alkaline phosphatase staining, mineralized nodus alizarin red staining and enzyme -linked immunosorbent assay (ELISA). The cell apoptosis and proliferation were examined by flow cytometry. Results The proliferation of osteoblast went to the flat stage about in the 8th day. After in the mineralization condition 3 weeks, a number of mineralized nodus formed. After the osteoblast proliferation almost stabilized, the mineralization group and the nonmineralization group had the similar proliferation index(PI), but in the mineralization group, the expression of alkaline phosphatase of the osteoblast was more and kept longer than the last group. Conclusion After the osteoblast  proliferation almost stabilized, adding the mineralization liquid would not influence the proliferation, but accelerate the osteoblast alkaline phosphatase expression and mineralized nodus amount. It proved that the feasible time to add the mineralization liquid was after the cell proliferation almost stabilized.

    Experimental study of preparing curved root canals with different instrument
    YIN Ling-yun, XIE Xiao-li, CHEN Min-min, LIU Liu-hui, LING Tian-you
    West China Journal of Stomatology. 2008, 26(06):  660-663. 
    Abstract ( 1002 )   HTML ( 5 )   PDF(pc) (207KB) ( 777 )   Save
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    Objective To compare the shaping ability and the influence on apical foramen among hand ProTaper, stainless steel K-files and rotary ProTaper in preparing different curved root canal. Methods Forty simulated resin root canal blocks were randomly divided into four groups and prepared by hand ProTaper, stainless steel K-file and rotary ProTaper, respectively. Of them, 12 blocks in group A, B, C consist of six 20° curved root canals and six 30° curved root canals each group. The curvature of the other 4 blocks in group D was less than 5°. Taking photos of the models to the root canal orthotopically and apical foramen using digital camera before and after instrumentation. Finally, the transportation of root canal and the size of apical foramen were analyzed using special image software Auto-CAD. Results The transportation of center in group B was the highest than that in group A and group C(P<0.05). In some portions of root canal, the transportation of center in group C was higher than that in group A. The size of the apical foramen in group B was significantly bigger than the other groups and the size of the apical foramen in 30° root canal was significantly bigger than that in 20° root canal after instrumentation(P< 0.05). There was no significantly different between group A and group C, though the size of apical foramen in group C was bigger than that in group A at the same curvature, and that in 30° root canal was bigger than in 20° root canal(P>0.05). Conclusion Both of the two instruments engender root canal transportation, and curvature is the main reason of transportation. Comparing with stainless steel K-files, NiTi files can maintain the shape of the root canal and apical foramen well.

    Effect of loop configuration on appliance stiffness of stainless steel round wire
    LIU Xiao-lin1, HAN Xianglong2, BAI Ding3, ZHANG Hong-rong4, HE Yan2, YE Yu2
    West China Journal of Stomatology. 2008, 26(06):  664-666. 
    Abstract ( 951 )   HTML ( 0 )   PDF(pc) (192KB) ( 399 )   Save
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    Objective To investigate the effect of loop configuration on appliance stiffness of stainless steel round wire. Methods Some stainless steel round wires with various cross-sectional dimension(0.36, 0.41, 0.46 mm) were selected. Box loops, double horizontal loops, and double vertical loops were manufactured according to established parameters, and loading experiments were carried out with a micro-orthodontic archwire testing apparatus. Results When the cross-sectional dimension and the span were identical, the appliance stiffness of the box loops, double horizontal loops, and double vertical loops increased successively. Conclusion Configuration of loops exert a great influence on appliance stiffness, and the mechanical properties of box loop are optimal. The force generated by box loop was lighter, slowly decreasing, and easier to be controlled. The activation range of box loop(0.41 mm) was appropriate when the produced optimal moment was between 0.01~0.02 N·m. Box loop(0.41 mm) is preferred to rectify the individual tooth with mild or moderate mesiodistal displacement.

    Differential analyses of mRNA expression of gtfs from Streptococcus mutans in different pH condition
    LU Yu1,2, LIU Tian -jia3,YANG Jin -bo3
    West China Journal of Stomatology. 2008, 26(06):  667-669. 
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    Objective To determine the expression level of each gtf under different pH cultural conditions and to find the relationship between gtf expression levels with environmental pH in different strains of Streptococcus mutans (S.mutans). Methods S.mutans form clinical isolation with different extracellular polysaccharides(EPS) producibility and UA159 were selected. Their ability to produce EPS under pH5.5 and pH7 were tested. Then in two strains, the relative quantity of gtfA, gtfB, gtfC, gtfD′ s mRNA which were related to S.mutan′ s ability to produce EPC, were examined by real-time reverse transcription-polymerase chain reaction(real-time RT-PCR) methods under different pH culture condition. Results At pH5.5, expression levels of gtfA, gtfB, gtfD were increased while that of gtfC were decreased in both strains, and that of gtfB, gtfC were higher in strain which produces more ECP. Conclusion The expression levels of gtfs related closely to the cariogenicity of S.mutan.

    Biologic analysis of recombinant human adenovirus-p53 injection in patients with oral leukoplakia
    ZHANG Song-tao1,2, ZHANG Yuan-yuan3, LI Xiao-yu2, LI Long-jiang2,4, LI Yi2, GAO Ning2, ZHANG Zhuang2
    West China Journal of Stomatology. 2008, 26(06):  670-672. 
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    Objective Advances in tumor biology and clinical trials indicate that p53 transfer is an alternative therapy for head and neck squamous cell carcinoma. The aim of this study is to evaluate the biologic activity of multiple intraepithelial injections of Ad-p53 in patients with dysplastic oral leukoplakia, which is the most common premalignant lesion of the oral squamous cell carcinoma. Methods From 2006 to 2007, 18 Chinese patientsclinically and histopathologically diagnosed as dysplastic oral leukoplakia were recruited for this study. On a 15-day cycle, intraepithelial injections of Ad-p53 were administered once every three days at dose levels dependent upon lesion size/dose escalation sequence(1×108 vp). 24-48 h after the last injection, incisional biopsy were performed, and immunohistochemistry was used to examine the protein expression of P53 and P21CIP/WAF. Results In the postreatment patients, P53 protein and P21CIP/WAF protein expression were significantly enhanced(100%, 89.9%, respectively) and statistical analysis revealed the expression of P53 protein had a positive correlation with that of P21CIP/WAF protein(r=0.598, P<0.01). Conclusion Intraepithelial injections of gendicine is biologically active in patients with dysplastic oral leukoplakia. It may be a promising treatment for oral leukoplakia.

    Establishment and identification of transiently expression system of bone marrow stromal cells modified by steoprotegerin gene
    ZHAO Chun-hui1, CAO Xiao-ma1,2, MEI Ling-xuan1
    West China Journal of Stomatology. 2008, 26(06):  673-676. 
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    Objective In oder to treat periodontitis by using tissue engineering and gene engineering technology, he article established an transient expression system of bone marrow stromal cells(BMSC) modified by osteoprotegerin OPG) gene and detected its expression using eukaryotic secreted expression pSecTag2/B-OPG plasmid. Methods y solation and culture of BMSC in vitro, the identified recombined plasmid was transiently transfected into BMSC y Lipofectamine 2000 and OPG expression in BMSC was determined by RT-PCR and Western blot in 6 weeks. esults The fragments of the recombinant plasmid digested with Hind Ⅲ,EcoR I and BamHⅠ and examined by 0 g/L agarose electrophoresis, were consistent with predicted size. The sequence of OPG was identical to the equence provided by GeneBank [gi:33878056]. OPG transcribing in BMSC was confirmed by RT -PCR and OPG ustainable expressing in BMSC was detected by Western blot in 39 days. Conclusion The transiently expression ystem of BMSC modified by OPG gene was successfully established.

    A case of repairing face slant diastema by rotating push of nasal bottom skin flap
    HAN Yong -hong, HUANG Hao-hong, YANG De-ming, XU Wen-hua.
    West China Journal of Stomatology. 2008, 26(06):  677-678. 
    Abstract ( 915 )   HTML ( 0 )   PDF(pc) (154KB) ( 438 )   Save
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    We use Z type skin flap to repair face slant diastema by combining nasal bottom and infraorbital border. The therapeutic efficacy was satisfactory. The dislocated nostril, eversioned eyelid and lowered eyeball was resettled.

    A case report of fixed restoration of hereditary opalescent dentin
    LIU Kun, ZHANG Hui-min, YANG Peng, XU Kai
    West China Journal of Stomatology. 2008, 26(06):  678-680. 
    Abstract ( 1423 )   HTML ( 1 )   PDF(pc) (222KB) ( 472 )   Save
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    Hereditary dentinogenesis imperfecta is a rare autosomal dominant hereditary disease. This article reported a case of hereditary opalescent dentin and discussed the clinical features and treatment.

    A case of vertebral traumatic pseudoaneurysm
    XUAN Yun -ze, CHE Feng -zhe, SHEN Zai -xian
    West China Journal of Stomatology. 2008, 26(06):  680-681. 
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    Pseudoaneurysm often occurred after trauma and infection. It was seen commonly on limb arteries but rarely on vertebral artery. The case was diagnosed two months after trauma. The pulsatile mass and vascular murmur found through preoperative examination confirmed from the vertebral artery. No complication was observed after surgery.