Objective：To obtain human dental follicle cells with RUNX2 gene mutation. Methods：Patients with cleidocranial dysplasia were collected, and RUNX2 gene mutation was identified. The dental follicle cells were cultured from unerupted dental follicle in vitro, and the same mutation site was identified. Results：The novel insertion mutation was identified as c.309_310insTG in exon 2 of RUNX2 gene by genome detection with whole blood, and the dental follicle cells with the same mutation were successfully cultured and identified. The expression of RUNX2 was decreased in RUNX2+/m dental follicle cells. Conclusions：Human dental follicle cells with RUNX2 mutation were successfully cultured and identified, and it contributes to the further function study of RUNX2 gene during tooth eruption.

Objective: To construct overexpression vectors targeting rat Satb2 gene and study the transfection effect of Satb2 in bone marrow stromal cells(BMSCs). Methods: The Satb2 gene was insert into plasmid GV208 . The plasmid was detected by DNA sequencing. The recombined plasmid GV208-Satb2 was transfected into 293 T cell line. Virus yielded by 293T cell was transfected into rat BMSCs. The expression of Satb2 was detected by Western bolt. Results: The Satb2 was correctly cloned into the GV208 plasmid and confirmed by DNA sequencing. The result of Western blot showed that GV208-Satb2 significantly up-regulated the expression of Satb2 in rat BMSCs. Conclusions: Over-expression vector targeting rat Satb2 gene had been constructed successfully and efficiently up- regulated the expression of Satb2 in rat BMSCs.

Objective：To investigate the proliferation and osteo/odongenic differentiation of human periodontal ligament stem cells (PDLSC) in different developing stages, and to provide the candidate cell sources for tooth engineering. Methods：Cells were respectively isolated from developing teeth with open apical foramen and developed teeth with closed apical foramen. Methyltetrazolium (MTT) assay was performed to observe the proliferation features of the two kinds of human periodontal ligament stem cells. And their alkaline phosphotase (ALP) activities were evaluated using an ALP assay kit. Alizarin red staining was used to observe the mineralization abilities of the two kinds of cells. Furthermore, dentin matrix protein 1 (DMP1), dentin sialoprotein (DSP), runt-related transcription factor 2 (RUNX2) and osterix (OSX) were assessed by Western blot to evaluate the osteo/odongenic differentiation capacities of two kinds of PDLSC. Results： PDLSC from developing teeth presented with a faster proliferation rate, higher ALP activity and mineralization ability, and upregulated proteins expression of DMP1, RUNX2, DSP and OSX in vitro, as compared with PDLSC from developed teeth（P <0.05）. Conclusions：The developing stages can affect the proliferation and osteo/odongenic differentiation of PDLSC. After the completion of root development, the proliferation ability and osteo/odongenic differentiation capacity of PDLSC decreased due to the changes in the microenvironment at different developing stages.

Objective：To determine Candida albicans biofilm ergosterol with high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) methods, and to compare the two methods. Methods：Candida albicans fluconazole-resistant strains were induced by Candida albicans SC5314 with gradually increased fluconazole concentration, and identified by the KONT MIC determination system. Biofilm was formed at 6, 12, 24h. The concentration of ergosterol was determined with HPLC and GC-MS methods. Results：Ergosterol concentration was detected with HPLC, and the concentration of lowest sensitivity is 0.05 mg/L, but it was not detected successfully by GC-MS. Conclusions：HPLC was an ideal way to determine the Candida albicans ergosterol concentration.

Objective：To investigate the stress distributions in an all-ceramic crown of the upper central incisor with different core ceramics under load. Methods：The 3-dimensional finite element model of layered crown was constructed using CAD software. This crown model was made with gold, zirconia, and alumina core and veneering porcelains. A loading simulating the maximum bite force (200 N) was applied to the crown at different locations (incisal edge, lingual fossa, lingual margin). The stress values of full crown was calculated and expressed, as stress intensity, in MPa. Results：The simulation showed that, the tendency of stress distributions in an all-ceramic crown with different core materials was similar. The MPS (maximal principal stress) value was located in the region submitted to the load and the proximal margin. As the elastic modulus of core materials increased, the maximal stress value of von Mises in veneer decreased, however that in core increased. Moreover, the MPS in core/veneer interface, core/tooth preparation interface, and proximal margin increased, but the MPS in veneer decreased. Conclusions：The use of core materials with high elastic modulus would reduce the risk of veneer chipping.

[Abstract] Objective: The purpose of this research is to study the expression changes of OPN in periodontal ligament of rats during orthodontic tooth movement. Methods: 40 SD rats were randomly grouped according to tooth movement days, such as 8h,24h,3d,7d. The orthodontic appliance was placed between the upper incisors and the upper left first molar of each rat, while those whose upper right first molar has no orthodontic appliance as the control group．The expressions of OPN were performed by immunohistochemistry. Results: Significant expressions of OPN were found in periodontal fibroblasts of the tension side after mechanical stress, while the control group OPN was expressed at a low level in the periodontal ligament. Conclusions: OPN plays a key role in alveolar bone remodeling during orthodontic tooth movement.

Objective：To study the applicability of Demirjian’s method for age estimation in children of Nanjing．Methods： 644 panoramic radiographs(378 boys and 266 girls) which were collected from the stomatological Hospital of Jiangsu Province were involved in this study with chronological age from 3 to 16 years. Paired t-test was performed between the chronological age and the age determined by Demirjian’s method. Single-factor model was used to explore the relationships of the two kinds of age. Results：For the marked difference between the chronological age and determined age(P<0.01),Demirjian’s method was not suitable to the children in Nanjing. We set up the mathematical model between tooth maturity and natural age of children in Nanjing, then got the curve-fitting equation. For boys: Y=43.37*Sin(0.02579X-1.138)+30.6*SIN(0.04275X+0.9984)+3.019*SIN(0.08706X+1.649), and for girls: Y=55.93*SIN(0.04001X-1.642)+90.97*SIN(0.05389X+0.7095)+44.25*SIN(0.06254X+3.384).The Results of paired t-test between chronological age and predicted age from quadratic equation showed that there was no significant difference in boys and girls(P>0.05). Conclusions：Through the establishment of mathematical model between tooth maturity and natural age in this study, we can determine the natural age from 3 to 16 in Nanjing children more accurately by utilizing tooth maturity.

Objective：To determine the change of morphology and micro-tensile strength between fresh and aged composite resin. Methods：After being stored in distilled water at 37 ℃ for a month, ten specimens were used as substrate for the new Z350 composite to adhere to. Specimens were then tested for the micro-tensile bond strength (μTBS) in a universal testing machine at a crosshead speed of 1 mm/min until failure. The surface and incisal surface morphology was analyzed using stereoscopic microscope and scanning electron microscope. Results：μTBS of aged composite resin was significantly lower than that of the fresh resin composite. The nano particles vanished from the resin matrix on the surface of aged composite resin. A rough resin-resin interface appeared between fresh and aged composite resin. Conclusions：The surface of aged composite resin may affect the bond strength between fresh and aged composite resin.

iRoot root canal sealing paste (iRoot SP), a new bioceramic material, has been applied in filling and repairing canals. This review will make an introduction of the research on physical, chemical, biological properties and clinical application of iRoot SP for the past three years, which has preliminarily shown its superiority.