Biodegradable composite membrane containing oriented needle-like apatites was successfully prepared as follows. The solution of dichloromethane and poly-lactic acid/poly-glycolic acid (PLGA) copolymer was infiltrated to the hydrothermal-electrochemically deposited apatite and dried in air. After hardening of the film, the composite membrane was prepared by delamination from the titanium plate. The weight changes and the tensile strengths changes of the composite membrane suggest that the apatite inhibited the composite from degradation due to the hydrolysis of PLGA, and the strength became quite small with the degradation after 2-week soaking in vitro. Histological observation in the soft tissue of rats showed that the around of specimens in both the membranes with and without apatite were covered with fibrous connective tissue. In the hard tissue, the defect in the dura mater was filled with new bone in the membrane with apatite, whereas there was some indication of granulation tissue reaction in the membrane without apatite.
The aim of this study was to evaluate the biological effect of immobilized cell-adhesive protein onto titanium using tresyl chloride-activated technique. Titanium sputter-coated glass (Ti-glass) was used as a substrate. Tresyl chloride was directly applied onto Ti-glass. Fibronectin or collagen was immobilized to tresylated Ti-glass. The measurement of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared reflection-adsorption spectroscopy confirmed the immobilization of fibronectin or collagen onto tresylated Ti-glass. The immobilization of fibronectin was not effective for enhancing the initial attachment of human gingival fibroblasts, but collagen immobilization was effective. The observation of scanning electron microscope also revealed that collagen immobilization affected the morphological changes of attached human fibroblast. In conclusion, the present study supported that collagen immobilization onto Ti-glass using tresyl chloride-activation technique improved the activity of human gingival fibroblasts during initial attachment.
In the present study, the in vitro osteogenic differentiating potential of rat dental pulp stem cells was examined. The induction was carried out under the same inducing system as used for bone marrow cells. Alkaline phosphatase (ALP) activity and mineralization were measured at 1, 2, 3, and 6 weeks after the induction. The level of ALP activity was very high at 1 week after induction and the level was maintained for 3 weeks, however the level of ALP activity was dramatically decreased (to 50%) after 6 weeks. Although mineralization was detected at low levels after 3 weeks, it became expanded to up to 29 nodules mineralized at 6 weeks after induction, as determined by von Kossa staining. It was shown that in vitro osteogenic differentiation of rat dental pulp stem cells was induced following the increase of the ALP activity at an early stage of the induction.
Microgravity in space has been reported to enhance bone resorption in vitro and in vivo, however, the gravity effect on bone remodeling is not well understood. In particular, there are only a few reports about gravity effect on osteoclasts. In the present study, we examined the hypergravity effect on mRNA expressions of osteoclast marker enzymes such as TRAP (tartrate-resistant acid phosphatase) and cathepsin K. Osteoclasts were exposed to 30 x g for 2 hr or 18 hr. Results suggested that hypergravity enhanced the mRNA expression of both enzymes with different manner; the expression of the TRAP showed a slight increase, that of the cathepsin K showed a non-monotonous time course with maximum hypergravity effect for short time (2 hr) incubation.
The aim of this study was investigate the influence of the degree of damage suffered by MC3T3-E1 cells, which are osteoblast-like cells derived from the mouse, as compared to the degree of damage incurred by Balb c/3T3 cells. Immediately after loading, the amount of lactate dehydrogenase (LDH) increased in proportion to the load. In four days cultivation, no significant departure from the absorbance of the control group was observed other than in the 40g group, but in the MC3T3-E1 cells the amount of LDH was as great as that immediately after loading, whereas in the Balb c/3T3 cells the amount decreased to about 70%. A comparison of the two types of cells has revealed that the MC3T3-E1 cells, which take part in the bone formation, can withstand slightly less loading than the Balb c/3T3 cells.
Researchers throughout the world are focusing on tissue engineering. As readers are well aware, it is also being applied to dental research. Though the term “tissue engineering” is generally used, the exact translation of the Japanese term would be “tissue reconstruction.” The editors at the Journal of Oral Tissue Engineering asked me to write a review in English. Since many college professors are included in the readership, I have chosen a topic relating to English education for dental students. Communicative English is very popular among students. For an effective learning experience, a number of teaching skills need to be considered. A combination of phonetics and Oral Anatomy is used to help the students understand subtle differences in pronunciation. To improve articulation, interpreter training methods and essay writing are implemented to teach linear thesis development. To deal with the problem of passivity, students are encouraged to practice asking questions in English.