Abstract: Objective To develop the primary culture technique of rat ameloblasts and observe the influence of different concentrations of sodium fluoride on ameloblast activity in vitro culture to furnish basis for the study of dental fluorosis formation. Methods Take 10 ~ 15 d’ old Wistar rat molar tooth germ tissue for primary culture. The enzymes digesting method was used to isolate and culture the ameloblasts. Then ameloblasts were exposed to different concentrations of NaF(0,0.4,0.8,1.6,3.2,6.4 mmol/L) for 24,48 and 72 hours. CCK-8 was used to detect cell activity. Results The proliferation of ameloblasts was promoted by NaF at 0.4, and 0.8 mmol/L, and the effect was strengthened as time increased whereas it was inhibited by 1.6, 3.2 and 6.4mmol/L NaF. With the increase of NaF concentration and the time, the inhibitory action was also strengthened and became more obvious. Conclusions Fluoride concentration has a biphasic effect on on ameloblast activity in vitro culture: At low doses, it promotes cell proliferation while at high doses it has negative effects.

Objective: To explore the construction of mechanical model of straight wire appliance for mandibular arch by three-dimensional finite element modeling. Methods Scanning of images of individual madible and dentition with normal occlusion was made through muti-slice spiral CT scanner. Data were imported into mimics software in the format of DICOM. Difference in gray values was used to reconstruct mandibular jaw and dentition. Cloud data of jaw and dentition points were imported into geomagic studio 8.0 in the format of txt to construct triangular meshes. Carry out NURBS surface fitting to generate entity model of jaw and dentition. Data were imported into ansys software in the format of igs. Build the model of straight-wire bracket and arch wire in ansys. In geomagic studio 8.0, augment root surfaces by 0.25 mm to generate the periodontal membrane, and carry out Boolean operation to generate assembly model of teeth, jaws, periodontium, brackets and wires. Result A three-dimentional finite element model of straight wire appliance was constructed. In ansys, partition the model, divide the meshes, and impose certain constraints and loads, then mechanical analysis of three-dimensional finite element could be carried out. Conclusion Building three-dimensional finite element model of straight wire appliance by spiral CT imaging and by combing merits of mimics, geomagic studio and ansys is precise, effective, simple, practical, operable and less time consuming.

[Objective] To develop the Chinese version of Stouthard’s Dental Anxiety Inventory (DAI), and to test the psychometric properties so as to evaluate the feasibility of the scale for Chinese population. Methods The English version of DAI was translated into Chinese, back translated and further adjusted according to the cross-cultural adaption of the scales in psychometrics. The Chinese version of DAI was then used to investigate dental anxiety among 940 adult patients and to examine psychometric properties such as reliability and validity. In addition, interrelationship between Corah’s dental Anxiety Scale (DAS) and Stale-Trait Anxiety Inventory (STAI) was analyzed.Results The Chinese version of DAI showed the test-retest reliability coefficient of 0.943, the internal consistency coefficient of 0.956, andthe construct validity coefficient of 0.961. Five factors were selected from Factor Analysis, which accounted for 60.541% of the total variance. These five factors were: fear of the treatment methods of particular doctors, anxiety for the treatment process, general dental anxiety, fear of dentists and their comments and horror of the treatment process. The distribution of these five factors was consistent with the theoretical structure assumption. The Chinese version of DAI significantly associated with the score of trait anxiety scale in DAS and STAI(P<0.01). Conclusions The Chinese version of DAI demonstrated the reliability and validity, which proven to be a dental anxiety scale that suitable for the use of Chinese population.

Objective：Using the technology of CBCT and the clinical observation, to research changes of symptoms and bone structure imagings of temporomandibular joint(TMJ) after occlusal reconstruction. Methods：Choose 20 patients who need occlusal reconstruction from January to December in 2011. Check the symptoms and bone structure by CBCT of TMJ before and after 3 months occlusal reconstruction. Measure the joint space by reconstructing image perpendicular to the long axis of condyle. Statistical analysis the results to find correlation and linear regression equation. Results：After 3 months occlusal reconstruction, masticatory muscle and joint pain were significantly reduced, but joint clicking doesn’t ameliorated obviously.The results of CBCT imaging showed the anterior joint space significantly decreased and the posterior space enlarged. There was significant correlation between posterior joint space variation and occlusal increased distance. Conclusions：There are reference value of measuring TMJ space for decising the amount of occlusal increased distance.

[Abstracts] Objective To compare the efficacy and the safety of Cyclosporine with Fluocinolone acetonide for erosive oral lichen planus. Methods Randomized controlled trial design: A total of 60 erosive OLP patients were randomly divided into two groups(use random table),every group 30 patients,were given Cyclosporine(test group) and Fluocinolone acetonide ointment(control group) respectively for 6 weeks.The efficacy and safety were evaluated at the end of treatment. After 3 months make a review. Results Effective rate of test group was 93.3%, control group 96.7%. Visual Analogue Score of test group was 24.73± 15.65 ,control group 34.27±16.36.After treatment there were not signi?cantly different between two medicine to Promote lesion healing（X2=0.351, P＞0.05）. Cyclosporine was better than Fluocinolone acetonide in relieve pain（P＜0.05）.The incidence of adverse reaction of Cyclosporine was less than Fluocinolone acetonide during treatment process.The After 3 month: Effective rate of test group 96.7%, control group 80.0%. Test group VAS 26.63±17.01，control group37.37±18.43。 Cyclosporine was better than Fluocinolone acetonide in promote lesion healing（X2=4.043, P＜0.05） and relieve pain（P＜0.05）.Conclusion Cyclosporine has more positive efficacy and safety than Fluocinolone acetonide. Cyclosporine worthy of further clinical application.

Abstract: Objective To compare and analyse the flexure strength and elastic modulus of 4 kinds of dental fiber posts frequently used in clinics. Methods The flexural strength and elastic modulus of Style Post (group A), Parapost Fiber Whiter (group B), Fiber Kor (group C) and Twin-Luscent Anchor (group D) fiber posts were measured through three-point bending test with 10 firber posts in each group. The results were statistically analyzed. Results The flexure strength of group A was the highest, while that of group B and group C was the lowest, and there were no statistical differences among the groups (P>0.05). There were no significant differences between group A and group D in elastic modulus (P>0.05), and the elastic modulus of group A and group D were both lower than that of the other two groups (P<0.05). Multitudinous cracks were observed in group B and C from SEM photos and there was a great degree of rupture generally . Conclusion The the flexure strength and elastic modulus of 4 kinds of glass fiber posts are significantly different. The flexural strength and fiber/matrix ratios are linearly dependent.

Abstract Objective To study the expression of TLR4 in rat pulpitis model induced by endotoxin (LPS) so as to evaluate the possible role of TLR4 in rat pulpitis and conjecture its significance in the development of pulpitis. Methods Make the slides of rat molar pulpitis tissue induced by LPS, and examine the expression of TLR4 in rat pulpitis immunohistochemically. Results 1d group: TLR4 was moderately positive in odontoblasts and moderately to stongly positive in the pulp fibroblasts. 3~7d group: the positive expression reduced in odontoblasts and pulp fibroblasts. 2 weeks group: necrosis expanded and was homogeneously weakly positive; odontoblasts, pulp fibroblasts and endothelial cells reduced and were positve; reparative dentin was weakly positive. 3 weeks group: most of the necrosis was homogeneously weakly positive. Conclusion TLR4 is dynamically expressed in the generation and development of rat pulpitis. TLR4 may take part in the regulation of generation, development and repair of pulpitis.

Objective Various approaches were adopted to treat the surfaces of artificial demineralized enamel lesions. By observing the penetration effects we could get more viable foundation for the clinical application. Methods 32 intact first premolars and first molars were selected from orthodontic extraction. They were placed in the artificial demineralization solution for 14 days to form initial artificial enamel caries. The teeth were divided into four groups randomly, and surfaces of teeth in each group were dealed with 15% hydrochloric acid, 37% phosphate and polished by Opalustre, stained by NaFl, penetrated with Icon and processed with light solidification. By observed under CLSM microscope, the impact of four treatment methods on penetration depths was compared. Results There were significant differences in depths of penetration between hydrochloric acid group and phosphoric acid group（P<0.05）.The hydrochloric acid group got a better result. There were significant differences between the two polished groups in the depths of penetration（P<0.05）. Increasing grinding time could increase the penetration effect. There were significant differences in penetration depths between polished group 2 and hydrochloric acid group or phosphoric acid group（P<0.05）. Polishing 40 seconds with Opalustre produced a better result. Conclusions The highly calcified layer is a barrier impeding the Icon to penetrate. The penetration effect of the hydrochloric acid treatment is better than that of the phosphoric acid treatment. By grinding for forty seconds of the barrier, the penetration effect is significantly better than that dealt for twenty seconds. So grinding can be considered as an alternative or a complement of pretreatment method in clinical treatment.

Abstract： Objective To establish 3-D finite element mode of mandibular fixed denture with loose tooth as abutment and discuss its rationality in order to provide further clinical basis and guidance. Methods By SCT scanning technology in combination with PHOTOSHOP CS2 and ANSYS11.0 software, establish composite mandibular fixed bridge model. Results While the looseness was I°, the stress of abutment teeth obviously increased, and stress concentration was observed through stress clouds; While the looseness was or , the stress also increased to different degrees but no sudden increase of stress was observed. Conclusion When the abutment teeth at the two ends of composite fixed bridge are loose, especially when single rooted teeth are loose, the range of stress is extraordinary big, and they alone are not suitable to be abutment. Multi-rooted teeth have small effect on stress distribution, so they alone can be abutment. When the abutment teeth in the middle of composite fixed bridge were loose, no matter the looseness was I° orⅡ° , they can not cause visible stress centralization, so they can be abutment.

Objective　To investigate the effect of neoadjuvant chemotherapy on survivin expression in oral squamous cell carcinoma. Methods　A total of 18 biopsy confirmed cases of OSCC were included. DFP program (cisplatin, 5-fluorouracil, bleomycin) was adopted and two courses of neoadjuvant chemotherapy were performed before operation. Tumor tissue before and after neoadjuvant chemotherapy was got, and normal lip tissue needless in cheilorrhaphy cut off from 10 cases was regarded as control group of normal oral tissue. The expression of Survivin was analyzed in the three groups by immunohistochemistry. Results　The expression rates of survivn positive cells in normal oral mucosa, OSCC before neoadjuvant chemotherapy and OSCC after neoadjuvant chemotherapy were 14.50±1.96%, 57.78±3.39% and 45.72±2.32% respectively (P<0.05), with conparison among groups F=814.37，P<0.05. The average optical densities of Survivin in normal oral mucosa, OSCC before neoadjuvant chemotherapy and OSCC after neoadjuvant chemotherapy were 12.75±1.13, 77.90±12.64 and 47.17±15.08 respectively, with conparison among groups F=90.98，P<0.05. Conclusion　 The expression of Surviving decreases obviously after neoadjuvant chemotherapy (DFP program).

Objective To compare the clinical effects of auxiliary expansion arch and modified horizontal palatal bar on maxillary expansion. Methods 35 patients were randomly divided into two groups for expanding the maxillary dentition. One group used auxiliary expansion arches and the other used modified horizontal palatal bars. The changes in dental arch widths were compared after the therapy. Results In the auxiliary expansion arch group, the dental arch width was significantly increased between second premolars and first molars (about 4 mm), but not between the first premolars (about 2 mm). While in the modified horizontal palatal bar group, the dental arch width all significantly increased about 4 mm between first and second premolars and between first molars. Conclusions The auxiliary expansion arch and the modified horizontal palatal bar are both effective for expanding maxillary dentition in mild-moderate dental crowding patients. Clinicians may choose appropriate method according to patients’ characteristics.

Abstract：Objective To assess the effect of occlusal splint removable partial denture and soft resilient splint therapy for temporomandibular disorders with badly decreased vertical dimension. Methods 16 patients suffering from temporomandibular disorders with badly decreased vertical dimension were treated by occlusal splint removable partial denture and soft resilient splint. Those patients were followed up for three months and half a year after the treatment .Both the clinical examination and Fricton’s Craniomandibular Index(CMI) were used to evaluated the clinical effect. Result The 16 patients’ Fricton index descent obviously after they were treated, which group with 6 months was superior to that with 3 months. And all the items are significantly discriminated between the group with 3 months and control group without treatment (P < 0.05), and 6 months and control group (P < 0.05),however, the items of JP, MP, PI of 3 months and 6 months are not(P>0.05). Conclusion Occlusal splint removable partial denture is not only appropriate for dentition defect and severely worn dentition but also effective for the treatment of TMD with soft resilient splint. splint.

[Abstract] Objective To evaluate the influence of the electric-heating polymerlization methods on the flexural strength of 2 denture base polymers. Methods Two denture-base resins were selected, and the species were prepared by traditional water-bath methods or electric-heating methods and which were divided into 4 groups：Nissin water-bath group, Heraeus water-bath group, Nissin electric-heating group and Heraeus electric-heating group (n=10). The flexural strength of species were evaluated. Statistical software (SPSS13.0) was used (α=0.05) in data analysis. The section of species were observed with environment scanning electron microscope. Results The flexural strength of each species fulfilled the requirement of Chinese Pharmaceutical industry Standards YY0270 – 2003. The flexural strength of the Nissin species prepared by electric-heating were a little higher [(93.28±4.80) MPa], and the differences were significant (P<0.05). At the same time, there was no differences between the other groups. But there were obvious differences between each groups in the microstructure of sections. Conclusion There was no significant influence of the electric-heating polymerlization methods on the flexural strength of the denture base polymers. The flexural strength of all the species fulfilled the Standards YY0270 – 2003.

【Abstract】 Objective To explore the feasibility of integrating GuttaFlow technique into Thermoplasticized Gutta-percha Obtura Ⅱ technique. Methods Five groups of extracted human teeth with single root(totally 70) were respectively obturated with Obtura Ⅱ( group A), Touch-heat+ Obtura Ⅱ(group B), GuttaFlow+ Obtura Ⅱ technique (group C), cold lateral condensation (group D) and nothing (groupE). After condensation, the coronal part of each root was immersed in 1mol/L glucose solution and the apical part in 1ml distilled water. Glucose solution was forced under a 15cm pressure toward the apical part of the root. Leakage along the root filling was measured by the concentration of glucose in apical reservoir 1, 2, 4, 7, 10, 15, 20, 25 and 30 days respectively after the treatment. Results The microleakage has continuously increased with the increase of time and there was no significant difference in the leakage among three test groups(A,B,C) after condensation(P＞0.05). Conclusions It is feasible to integrate GuttaFlow technique into Thermoplasticized Gutta-percha Obtura Ⅱ technique.

Objective: The purpose of this study was to investigate the diagnosis with X-ray films and CBCT. It was to investigate radiographic features of the C-shaped canal system in mandibular second molars and their relationship to the canal anatomy. Methods: There were 110 extracted mandibular second molars for periodontal inflammation reasons in our hospital clinic patients. After taking their buccal –lingual radiograph. Each tooth was scanned with CBCT. Analyze the rate of diagnosing C-shaped root canal system and their types through preoperative radiographs and CBCT. Result: Among those 110 mandibular second molars, we coule diagnose 46 out through the preoperative radiographs and 66 through the CBCT. Each mandibular second molar with C-shaped canale diagnosed by CBCT was assigned to three categories : Type Ⅰ(Merging Type,26), Type Ⅱ(Symmetrical Type ,22), Type Ⅲ (Asymmetrical Type ,18).CBCT showed that in the type Ⅰcategory , C4 canal configurations were mostly found in the apical area. In type Ⅱ ,C3 were the main canal shapes over the whole canal length. In type Ⅲ, C1 and C2 were the main canal shapes in the coronal canal portion. Conclusion: These suggested that the mandibular second molars with C-shaped canal system have a series of radiographic characteristics, and it was possible to predict the presence and the configuration of most C-shaped canals by X-ray films. But if you want to learn detailed information, CBCT would be needed to use.

Objective To quantitatively evaluate the sealing efficiency of the most common root canal treatment methods so as to provide a theoretical basis for clinical targeted selection of root canal treatment methods by cone- beam compute tomography. Methods Forty-five extracted single root anterior teeth and premolars were randomly divided into three groups, 15 in each. The first group was instrumented with NiTi K-files and filled by lateral compaction.The second group was instrumented with ProTaper NiTi rotary files and filled by lateral compaction.The last group was instrumented with ProTaper NiTi rotary files and filled by continuous warm vertical condensation. The root canal volume after preparation and filling of each canal was measured by cone-beam compute tomography and the percentage of obturated volume (POV) of an overall root canal was calculated. The POV of coronal third, middle third and apical third of root canals could be also obtained. Wilconxon-Mann-Whitney U analysis was performed. Results The first and the second group had no statistically significant difference in the POV of the overall, coronal third, middle third and apical third of the root canals (P> 0.05). The POV of the overall, coronal third, middle third and apical third of the root canals in the third group were greater than those in the other two groups (P < 0.05). Conclusions Using the same root canal filling method (LC), the sealing efficiency of root canal is not affected by the different root canal preparation methods. The group instrumented with ProTaper NiTi rotary files and filled by Warm vertical condensation has the best sealing efficiency.