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In ligament reconstruction involving anterior cruciate ligament surgery, biological fixation between the transferred ligament and bone tissue is critical for achieving successful outcomes. Here, we administered chitin fabrics into the bone tunnels and evaluated their efficacy in promoting biological fixation. An animal model on the rat's patellar ligament was employed. First, bone tunnels were created in the lateral condyle of the femur. The ligament was then separated from the tibial tuberosity, and half was inserted into the tunnel and fixed with the use of end button. Animals in the experimental group were treated with microfiber nonwoven chitin fabric, whereas control animals received no treatment. Specimens were collected at 2, 4, and 6 weeks after surgery, and the fixation strength was measured by mechanical tests. Histological sections were prepared from samples prepared 4 weeks after surgery, and the diameter of bone tunnel and the width ratio of collagenous tissue in the bone tunnel were measured. Administration of chitin significantly increased the mean fixation strength at 4 and 6 weeks after surgery. Furthermore, chitin also promoted bone formation in the bone tunnel and increased the density of collagen fibers. Thus, microfiber nonwoven chitin fabric enhanced the biological fixation of the ligament to the bone tissue. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2355-2360, 2018., (© 2017 Wiley Periodicals, Inc.)

The disintegration of glass ionomer cements was evaluated with referred to the amounts of component elements of powders dissolved into solutions at various starting times of immersion. Glass ionomer cement products, three for luting and three for filling, were used. The starting times of immersion in solutions were; setting time and 10, 30 and 60 minutes and 24 hours after start of mixing. After the immersion in 30 ml of distilled water and physiological saline solution for 1 week, these solutions were analyzed by an atomic absorption spectrophotometer to determine the amounts of Ca, Al and Si. The amount of each element dissolved was highest when immersion in the solutions was started at the setting time except for Ca dissolved in physiological saline solution, and it tended to decrease as the start of immersion in the solutions was delayed. Some products contained Sr instead of Ca. The results indicated that glass ionomer cement should be protected from exposure to oral fluids for about 30 minutes in clinical use.

The authors have been developing an improved method that an alginate mix is applied to gelled agar to obtain precise impressions. In the present study, the bond strength of the improved method was investigated. Thirty-one agar impression materials and thirteen alginate impression materials were used. The tensile-bond strength between an alginate (VAd) and various agars (exp. 1), and between an agar (DBRS) and various alginates (exp. 2), was measured by means of the Instron Testing Machine (model 1123) operated at a cross-head speed of 500 mm/min. The bond strength varied with the combinations of the products of agar and alginate. The bond strength of some combinations was higher than the stress in removing impressions from the mouth. Comparing the products of the same manufacture, the bond strength varied with the different colors (composition) of agar, but didn't vary with the different types of cartridge++ or syringe. The result suggested that the bond strength between agar and alginate depended, not only on the agar, but also on the alginate.

Effects of heating and urea on the heat-stable alkaline proteinase from white croaker and chum salmon muscle were compared in order to know the regulating mechanism of the proteinase. Chum salmon proteinase required a higher temperature for activity and was more heat-stable than white croaker proteinase. In the presence of 5M urea, the activity was observed to some degree at 37 degrees C only in white croaker proteinase, while both proteinases lost their activities at usual assay temperature around 60 degrees C. These results suggest that the stability of the regulatory and catalytic subunits of the proteinases is somewhat different among fish species.