A novel zinc oxide eugenol modified by polyhexamethylene biguanide: Physical and antimicrobial properties.

This study was to prepare and screen a novel root canal sealing agent modified by polyhexamethylene biguanide (PHMB) that was in accordance with the ISO 6876:2001 standard and to study its physical and antimicrobial properties. The modified sealers were produced by mixing a certain amount of zinc oxide with eugenol containing different concentrations of PHMB (0.05, 0.1, 0.2, 0.4, 0.6 and 0.8%) at a ratio of 1:1 (w/v). The setting time, flow, film thickness, solubility and dimensional change after solidifying were assessed to screen out the modified sealing agents that the physical properties met the mentioned standards. The modified direct contact test (DCT) was used to evaluate the antimicrobial activity against Enterococcus faecalis. The results suggested that when the concentrations of PHMB were 0.05, 0.1 and 0.2%, the modified root canal sealers showed the best performance in physical and antimicrobial properties.

[Effects of staurosporine on the contraction of self-assembled constructs of goat temporomandibular joint disc cells].

OBJECTIVE: The effects of the staurosporine on contraction of self-assembled constructs and extracellular matrix syntheses of goat temporomandibular joint discs were investigated. METHODS: Goat temporomandibular joint disc cells were isolated and cultured to P3, and 5.5×106 cells were combined with different concentrations of staurosporine (0, 0.1, 1, 10, 100 nmol·L⁻¹) in agarose wells and cultured for one week. The samples were frozen and sectioned. Safranin-O,  Picro-sirius red and immunohistochemical staining were performed to observe the distributions of the extracellular matrix and the expression of alpha-smooth muscle actin (α-SMA). Enzyme linked immunosorbent assay (ELISA) and Blyscan kits were utilized to quan--titatively detect the contents of type Ⅰ collagen (ColⅠ) and glycosaminoglycans (GAGs). RESULTS: Each group of goat temporo-mandibular joint disc cells in the agarose wells were gathered to self-assemble into a disc-shaped base for 4 hours and then to gradually contract into a round shape. The Picro-sirius red staining was strong and indicated collagen distribution. The Safranin-O staining observed GAGs throughout the entire construct. The expression of ColⅠ was strongly posi-tive in the staurosporine groups; however, the expression of α-SMA was weak. ColⅠ and GAGs contents in the stau-rosporine groups were greater than that of the control group, especially in the 10 nmol·L⁻¹ group (P<0.01). CONCLUSIONS: Staurosporine has a certain effect on the shrinkage of self-assembled constructs; however, such effect is not prominent. Staurosporine contributes to the construction synthesis of extracellular matrix.

[Influence on mechanical properties and microstructure of nano-zirconia toughened alumina ceramics with nano-zirconia content].

OBJECTIVE: To investigate the mechanical properties and microstructure of nano -zirconia toughened alumina ceramics with variety of nano-zirconia content in centrifugal infiltrate casting processing of dental all-ceramic. METHODS: Composite powder with different ethanol-water ratio, obtained serosity from ball milling and centrifugal infiltrate cast processing of green, then sintered at 1 450 degrees C for 8 h. The physical and mechanical properties of the sintered sample after milling and polishing were tested. Microstructures of the surface and fracture of the sintered sample were investigated by SEM. RESULTS: The experimental results showed that there had statistical significience (P < 0.01) on static three-point flexure strength and Vickers Hardness in three kinds of different nano-zirconia content sintered sample. Fracture toughness of 20% group was different from other two groups, while 10% group had not difference from 30% group (P < 0.05). The mechanical properties of this ceramic with 20% nano-zirconia was the best of the three, the static three-point flexure strength was (433 +/- 19) MPa and fracture toughness was (7.50 +/- 0.56) MPa x min 1/2. The intra/inter structure, fracture of intragranular and intergranular on the surface and fracture of sintered sample in microstrucre was also found. CONCLUSION: Intra/inter structure has strengthen toughness in ceramics. It has better toughness with 20% nano-zirconia, is suitable dental all-ceramic restoratives.