Objective To establish the model of chondrocyte cultured in vitro,and to study the biological differences between fibrocartilage and hyaline cartilage. Methods Condylar cartilage and epiphysis cartilage were aseptically dissected from 4weekold New Zealand white rabbit.Cells were obtained by enzyme digestion and cultured in vitro until the 10th passage.The fibrocartilage cells and hyaline cartilage cells were observed and analyzed by inverted microscope,alcian blue staining and immunohistochemical staining.Cells growth curves were made with the method of cell counting.Quantitative realtime PCR and western blot technique were used to detect and analyze the expression of collagen Ⅰ,collagen Ⅱ,collagen Ⅹ,SOX9 and Aggrecan.Oneway ANOVA with SPSS13.0 software package was performed. Results With the increase of subcultures,both fibrocartilage cells and hyaline cartilage cells changed morphologically into fibroblastlike cells,especially after P2.Detection of gene and protein level has demonstrated that the dedifferentiation of chondrocytes was obvious after P2 generation.The chondrocytes staining was positive in the slides of cells.Quantitative realtime PCR and western blot both showed that the expressions of colagenⅠ,collagen Ⅱ,collagen Ⅹ,SOX9 and Aggrecan in fibrocartilage were significantly different from those in hyaline cartilage.The expression of colagenⅠin fibrocartilage was higher than that in hyaline cartilage while other expressions were lower. Conclusions It is a simple and effective way to culture chondrocytes in vitro in this study.Our research confirms that the tendency of dedifferentiation would occur in both fibrocartilage cells and hyaline cartilage cells.There are essential differences between fibrocartilage and hyaline cartilage in biological characteristics.

Objective To evaluate the shortterm clinical efficacy of CEREC AC chair side immediate allceramic restorations. Methods 82 defective teeth from 59 patients were collected and CEREC AC was used to make immediate allceramic restorations including 21 inlays,30 onlays,8 veneers and 23 crowns.The milling time was recorded and the clinical efficacy was analyzed with modified USPHS criteria in 3 and 6 months. Results The average milling time was less than 9 minutes.Most of the restorations scored A using modified USPHS criteria. Conclusions CEREC AC system chair side immediate allceramic restorations can obtain satisfactory shortterm clinical outcomes.

Objective To evaluate the effectiveness of superior and inferior temporomandibular joint space injection of sodium Hyaluronate for temporomandibular disorders treatment. Methods Searching various databases such as Embase,Cochrane Library,Pubmed,Wanfang and Weipu etc.for papers on superior and inferior joint compartment injection of sodium Hyaluronate for temporomandibular arthrosis treatment RCT,which were published from 1995 to Dec.16th,2011.After paper selection in accordance with inclusion and exclusion criteria,data extraction and the quality evaluation,REVMAN software was used for Meta analysis. Results A total of 4 RCTs involving 514 patients were included.The Meta analysis showed that there was a significant reduction of TMJ pain in the inferior joint injection group compared with the superior joint injection group. Conclusions This study showed that inferior joint space injection of sodium hyaluronate is an effective way for temporomandibular arthrosis treatment,thus it has certain application value.

Objective To explore the clinical mechanism of application of miniscrew implant anchorageassisted correction for adult Class Ⅱ Division 2 malocclusion. Methods Twelve cases of Class Ⅱ Division 2 malocclusion patients were selected,including 4 male patients and 8 female patients,aging from 18 to 38 years old,with an average age of 21.0 years old.Miniscrew implant anchorages were applied to help the whole upper dentition move backwards and control anterior teeth intrusion.The changes of patients' teeth,hard and soft tissues before and after treatment were analyzed. Results The dental crown of maxillary central incisor in sagittal direction kept still basically,the tooth root moved 3.63 mm on average with tipping ratio of 6050% and anterior teeth intrusion of 4.60 mm.The crown of maxillary first premolar moved 3.25 mm,the tooth root 3.65 mm with the average tipping ratio of 112.3% and the crown of tooth was intruded for 2.90 mm.The crown of maxillary first molar was distalized for 3.11 mm,the tooth root was distalized for 3.21 mm,with average tipping ratio of 103.2% and the crown of tooth was intruded for 1.17 mm.The crown of maxillary second molar has moved 3.22 mm,and the tooth root was distalized for 3.15 mm averagely,with average tipping ratio of 97.8%,being intruded for 0.69 mm. Conclusions The application of miniscrew implant anchorage is effective for group distal movement of maxillary dentition,anterior teeth intrusion and the reconstruction of the maxillary anterior alveolar bone.It is an effective way of nontooth extraction correction for Class Ⅱ Division 2 malocclusion cases.

HE Sheng，HU Jing，SONG Jian,YE Bin.(State Key Laboratory of Oral Diseases,Sichuan University,Chengdu 610041,China) Abstract：Objective To assess the effect of parathyroid hormone(PTH) intermittent administration on bone regeneration after rapid mandibular distraction osteogenesis(DO) in rabbits. Methods Unilateral mandibular rapid DO was performed on 24 adult New Zealand white rabbits and they were randomly divided into two groups.At the beginning of the distraction,the experimental group was subcutaneously administered PTH daily for 30 days while the control group was injected with physiological saline.Rabbits sacrificed 6 weeks after the completion of DO.The distracted mandibular bones were collected and the calluses were processed with microCT,histology and biomechanical testing.Bone mineral density (BMD) in surrounding segments of the distraction gap was evaluated by dual energy xray absorptiometry (DEXA). Results The figures of microCT showed better growth and remodeling of regeneration of the experimental group than the control group.The result of the micro CT analysis showed greater parameters of the experimental group in bone volume fraction((48.30±3.46)%),bone connectivity density（(9.77±1.81）mm-3）,trabecular thickness（(0.25±0.01)mm） and number（(2.25±0.26)mm-1）than the control group(which were respectively （37.55±3.72）%,（7.89±1.73）mm-3,（0.12±0.03）mm，（1.27±0.27）mm-1）（P<0.01),yet the trabecular spacing of the experimental group((0.26±0.03)mm)was less than that of the control group ((0.30±0.04)mm)(P<0.01).Histological Examination showed a more mature newly formed bone in experimental group.PTH treated animals showed greater mechanical properties((378.30±29.10)N) and higher BMD（0.26±0.01）g/cm2) than the control group(which respectively were(196.60±14.50)N，(0.17±0.01)g/cm2)(P<0.01). Conclusions PTH enhances new bone formation and meanwhile prevents disuse osteopenia of surrounding segments of distraction gap in a rapid mandibular DO model.

Objective To explore the effect of ADAMTs5 on cartilage degradation by measuring the expression of ADAMTs5 in condylar cartilage of temporomandibular joint osteoarthritis(TMJOA) rats. Methods 32 rats were divided into four groups(control group 1,2week group,control group 2 and 4week group),and each group had 8 rats.Collagenase injection method was used to build up the TMJOA model.Western blot and RTPCR were used to test the expression of ADAMTs5 in protein and mRNA levels respectively. Results No significant changes were observed in the expression of ADAMTs5 in protein levels between the control group and 2week group,but the expression of ADAMTs5 in 4week group increased significantly.Compared with the control group,the expression of ADAMTs5 mRNA in 2week and 4week groups increased to different degrees,which wasn′t in accordance with protein expression tendency. Conclusions The expression of ADAMTs5 increases significantly in the early stage of TMJOA,which indicates that ADAMTs5 may play an important part in the beginning of condylar cartilage degradation.

Objective To study the significance of computed tomography (CT) in the diagnosis and treatment of severe neck multiple space infections. Methods A total of 10 patients with severe neck multiple space infections，admitted to the 252nd Hospital of PLA from January 2008 to December 2011,were investigated.Computed tomography scans of the neck were performed and the images were analyzed. Surgical incisions were planned based on the tomographic and clinical findings. Repeated CT examinations were also carried out in patients with no clinical improvement for additional drainage. Results Among the 10 patients,CT scans in 6 patients with necrotizing cellulitis demonstrated large quantities of gas along fascial planes and irregular jagged edge around the gas chamber. In another 4 patients with abscess,CT scans demonstrated diffuse swelling of muscles and solid tissues without clear boundary. Colliquativehypodensity region could be observed in the space. All the patients underwent surgical drainage. Low submandibular incision were performed in 2 patients,paralleled transcervical incisions in 5,and modified Crile incision in 3. 7 cases were saved successfully,3 patients died of multiorgans failure. The overall mortality rate is 30%. Conclusions CT scan is the first choice of imaging examination for correct evaluation of affected space in deep neck infections.Its main value lies in effectiveness in determining all the affected sites so as to provide basis for surgical incision,exposure and drainage of affected space.In the treatment,it′s important to perform CT reexamination according to illness state to estimate the control and development of the infection. A further incision should be performed when necessary. In addition,CT scan is auxiliary in initial evaluation of types of infected bacteria,illness state,and preliminary judgment of prognosis.

Objective Study of different bonding methods and thermal cycle on breaking strength of Cerec allceramic crowns after bonding. Methods 80 in vitro premolars were selected for Cerec allceramic crown preparation and were randomly divided into 4 groups（n=20） according to their luting agent:Group 1:VariolinkN resin binder and silane coupling agent; Group 2:VariolinkN resin based luting material; Group 3:Bisco Choice TM2 resin adhesive and silane coupling agent; Group 4:Bisco ChoiceTM 2 resin adhesive.Each group was divided into A(without thermal cycling) and B(with thermal cycling) subgroups.The maximum breaking strength of the allceramic crowns was tested by the universal mechanical testing machine,the bond failure forms were recorded,and statistical analysis was done thereafter. Results Group 1,using the Variolink N resin based luting material and silane coupling agent,got the highest fracture strength of Cerec allceramic crowns among all the luting agents.Non thermal cycling subgroup was higher than that of thermal cycling subgroup in flexural strength of allceramic crowns.The difference was statistically significant (P<0.05). Conclusions The dualcured resin based luting cement system is the ideal choice for dental feldspathic ceramic bonding,and can get a higher breaking strength.The breaking strength of Cerec allceramic crowns can be reduced by thermal cycling.

Objective To evaluate the safety of articaine in cardiovascular patients with dental anxiety (DA) during tooth extraction according to the change of heart rate and blood pressure. Methods 152 cardiovascular patients with dental anxiety requiring tooth extraction were selected by Modified Dental Anxiety Scale (DAS),and they were randomly divided into articaine infiltrateanesthesia group and lidocaine blockanesthesia group.The blood pressure (BP) and heart rate (HR) were monitored by electrocardiogram monitor in the whole process of extraction,and then the differences of BP and HR between two groups were analyzed statistically. Results Tooth extraction in all patients was successfully completed.In the articaine group,systolic blood pressure,diastolic blood pressure and heart rate were significantly higher during anesthesia and tooth extraction than those of lidocaine group(P<0.01); The BP and HA in the articaine group showed no statistically significant difference from the data of lidocaine group before anesthesia and after tooth extraction (P>0.05). Conclusions In order to prevent cardiovascular and cerebrovascular accidents,articaine should be highly cautiously used in cardiovascular patients associated with dental anxiety during tooth extraction.

Objective To compare the effects of recording teeth by two superscriptsubscript tooth notation systems. Methods The first superscriptsubscript tooth notation system uses T and t as identification characters of teeth to be recorded.T represents the permanent teeth and t represents the deciduous teeth.From the midline posteriorly digits 1-8 and digits 1-5 represent the names of permanent teeth and deciduous teeth respectively.The second superscriptsubscript tooth notation system only uses T as identification character of teeth to be recorded.From the midline posteriorly digits 1-8 and English letters A-E represent names of permanent teeth and deciduous teeth respectively.The teeth were recorded as superscript and subscript on the right or left sides of identification characters by two superscriptsubscript tooth notation systems respectively. Results The teeth in the dentitions can be recorded accurately by writing the assigned digits or English letters as superscript or subscript on right or left sides of identification characters by two superscriptsubscript tooth notation systems,but the effect of the first superscriptsubscript tooth notation system is better in inputting，printing and habits of identification. Conclusions The first superscriptsubscript tooth notation system is a better method for recording teeth.

Objective Toexplore the relevance between P53protein expression and oral squamous cell carcinomainChina. Methods The CNKI、CBM、Wangfang and VIP Database were searched to collect published literature from 1994 to 2011 and Metaanalysis was done. Results 30 publications were finally included in this study.There were 1206 cases of OSCC and 1150 normal controls.The average of positive expression rate of P53 protein in cases of OSCC was 60%.OR and 95% CI was 5.49(3.89,7.76).P53 protein expression and OSCC histological differentiation (P=0.07),lymph node Metastasis (P=0.15),clinical stage(P=0.15) were not correlated. Conclusions Based on domestic research results at present,expression of P53 protein is connected with oral squamous cell carcinoma,and it can be considered as molecular marker of oral squamous cell carcinoma.

Objective To investigate the influence of oral health education intervention on oral orthodontic treatment in teenagers. Methods The clinical data of one hundred and sixty oral orthodontic teenagers from December 2010 to December 2011 in Department of Stomatology in our hospital were collected.They were divided into the control group and experimental group by random number table.The control group continued their original habits,and were offered conventional oral health education intervention,while the experimental group were given standardized oral health education intervention.The gingival index,plaque index and oral orthodontic treatment courses after six months′ intervention. Results After six months′ intervention,the gingival index,plaque index of the experimental group were significantly lower than those in the control group (P<0.05). Conclusions Strengthening oral health education can obviously decrease gum index and plaque index.

Parotid gland neoplasm is usually unilateral clinically.The incidence rate of bilateral parotid gland tumors is low.Furthurmore,the incidence of different types of bilateral parotid gland tumors is extremely low.A case of different pathological types of bilateral parotid tumors is reported,one side of which is adenoid cystic carcinoma and the other is parotid gland cyst.A retrospective study is carried out in accordance with previous literatures.The case analysis,the cause,the diagnosis and the treatment are discussed.The patients who suffer from bilateral parotid gland neoplasm should be scrutinized,so that the surgeon could choose the best treatment for them.