Objective:To explore the effects of different combination of Er∶YAG laser irradiation parameters on the dentinal tu-bule sealing.Methods:160 dentin discs with 2 mm thickness were etched with 0.5 mmol/L EDTA to establish the dentine hyper-sensitivity models.The discs were randomly divided into 16 groups(n=10).The R02 and R14 handpieces were used to deliver Er∶YAG laser to the dentin discs according to the different output power(W),irradiation distance(cm)and irradiation time(s/cm2).Then,the samples of each group were divided into immediate irradiation subgroup and acid etching and wear subgroup(n=5).The dentinal tubules were observed with SEM,and the exposed area,the sealed rate and the occlusion depth of dentinal tubules were e-valuated with ImageE-Pro Plus 6.0 software.Results:The dentinal tubules in the control group opened uniformly with clear perime-ter,they were enlarged and opened after acid etching and tooth brushing.The dentinal tubules shrinked or sealed well with the melt layer after treatment by Er∶YAG laser irradiation with either parameter combination.Especially,uniform and seamless melt layer as well as similar dentin surface morphology before and post the acid etching and tooth brushing were obtained when the dentin discs were exposed to the following Er∶YAG laser irradiation parameter combinations,i.e.(R02,0.5 W,3 cm,20 s/cm2),(R14,0.5 W,3 cm,20 s/cm2)and(R14,0.6 W,3 cm,20 s/cm2).Significantly decreased exposed area and increased seal rate in the dentinal tubules treated in the above 3 laser irradiation parameter combina-tion groups were observed than those in the other groups(P＜0.05).Morphological analysis confirmed that whether the acid etching and tooth brushing were exerted.The occlusion depth of dentin tubule was more than 2.0 μm in the dentinal tubules treated in the above 3 groups.Conclusion:Er∶YAG laser irradiation parameter combinations of R02,0.5 W,3 cm,20 s/cm2,R14,0.5 W,3 cm,20 s/cm2 and R14,0.6 W,3 cm,20 s/cm2 are suitable for the best dentin tubule sealing.

Objective:To explore the effects of different combination of Er∶YAG laser irradiation parameters on the dentinal tu-bule sealing.Methods:160 dentin discs with 2 mm thickness were etched with 0.5 mmol/L EDTA to establish the dentine hyper-sensitivity models.The discs were randomly divided into 16 groups(n=10).The R02 and R14 handpieces were used to deliver Er∶YAG laser to the dentin discs according to the different output power(W),irradiation distance(cm)and irradiation time(s/cm2).Then,the samples of each group were divided into immediate irradiation subgroup and acid etching and wear subgroup(n=5).The dentinal tubules were observed with SEM,and the exposed area,the sealed rate and the occlusion depth of dentinal tubules were e-valuated with ImageE-Pro Plus 6.0 software.Results:The dentinal tubules in the control group opened uniformly with clear perime-ter,they were enlarged and opened after acid etching and tooth brushing.The dentinal tubules shrinked or sealed well with the melt layer after treatment by Er∶YAG laser irradiation with either parameter combination.Especially,uniform and seamless melt layer as well as similar dentin surface morphology before and post the acid etching and tooth brushing were obtained when the dentin discs were exposed to the following Er∶YAG laser irradiation parameter combinations,i.e.(R02,0.5 W,3 cm,20 s/cm2),(R14,0.5 W,3 cm,20 s/cm2)and(R14,0.6 W,3 cm,20 s/cm2).Significantly decreased exposed area and increased seal rate in the dentinal tubules treated in the above 3 laser irradiation parameter combina-tion groups were observed than those in the other groups(P＜0.05).Morphological analysis confirmed that whether the acid etching and tooth brushing were exerted.The occlusion depth of dentin tubule was more than 2.0 μm in the dentinal tubules treated in the above 3 groups.Conclusion:Er∶YAG laser irradiation parameter combinations of R02,0.5 W,3 cm,20 s/cm2,R14,0.5 W,3 cm,20 s/cm2 and R14,0.6 W,3 cm,20 s/cm2 are suitable for the best dentin tubule sealing.

GCC/PKG/VASP,PKA/VASP et.al are associated with the occurrence and development of colorectal cancer.As one of the important signaling molecules of above signal pathways,VASP has constributed to the invasion,metastasis,apoptosis,angiogenesis and other events of colorectal cancer.The role of VASP signaling pathways in the development of CRC and its potential clinlic significance are reviewed in this article.

Objective To investigate the biomechanical properties of principal tensile trabecular bone in proximal femur and provide experimental evidences explaining the osteonecrosis of femoral head resulting from femoral neck fracture.Methods Eight human cadaveric femurs,with no deformities,fractures,and other lesions,were selected.The principal tensile trabecular bone system was devided into three parts from the exterior to the interior.Specimens were taken in each part along or perpendicular to the direction of principal tensile trabecular,respectively.Mechanics tests were performed by BOSE Enduratec ELF 3200.The ultimate tensile and compressive strength,yield tensile and compressive strength and elastic modulus of principal tensile trabecular bone in proximal femur were obtained.Results The tensile properties were higher than compressive properties in exterior parts,especially the tensile biomechanical properties along the direction of principal tensile were significantly higher than the compressive biomechanical properties in that direction.In the meddle part,the compressive properties were higher than the tensile properties both along the directions of principal compression and principal tension.In the interior part,the compressive properties were higher than the tensile properties along the direction of principal compressive trabecular bones,the tensile properties were higher than the compressive properties along the direction of principal tensile trabecular bone.Conclusion The major function of exterior part of principal tensile trabecular bone is loading tensile stress,that of the middle part is loading compressive stress,and that of the interior part is loading compressive stress along the direction of principal compression,while the major function along the direction of principal tensile trabecular bone is loading tensile stress,which indicate that the structure of trabecular bone is anisotropic and adapted to its function.