BACKGROUND: Titanium alloy implant has been widely used in the clinic. But there are few reports addressing on corrosion performance of medical titanium alloy dental implant, in particular in different physiological electrolytes. OBJECTIVE: To investigate the corrosion behaviors of medical titanium alloys in physiological saline, simulated saliva, and simulated body fluid. DESIGN, TIME AND SETTING: A randomized grouping, controlled observation was performed at the School of Stomatology, Lanzhou University and State Key Laboratory of Solid Lubdcation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences between November 2008 and March 2009. MATERIALS: Medical titanium alloys (Ti-6Al-4V) were cut into 10 mm×10 min×1 mm sheets and were randomly divided into 3 groups, with 10 sheets in each group. METHODS: Corrosion performance of titanium alloys in physiological saline, simulated saliva, and simulated body fluid was investigated using electrochemical measurements. Following electrochemical corrosion, surface morphologies and wettability of samples were also observed using scanning electron microscope and CA-A type contact angle tester. MAIN OUTCOME MEASURES: Tafel curve, surface morphology, and contact angle of medical titanium alloys in three physiological electrolytes after 4 days of electrochemical corrosion. RESULTS: The corrosion of titanium alloys was most severe in simulated saliva, followed by simulated body fluid, and mildest in physiological saline. Scanning electron microscope results demonstrated that medical titanium alloy surface exhibited many holes after corrosion by physiological saline, showed rough surface with a slightly changed number of holes after corrosion by simulated body fluid, and presented with an increased number of holes, with aperture greatly increased in some holes after corrosion by simulated saliva. The contact angles of titanium alloys were all reduced after corrosion of three electrolytes. CONCLUSION: The corrosion of titanium alloy was most serious in simulated saliva. Thus, corresponding protection measures should be given in clinical application.

BACKGROUND: Bone-induced protein and its carrier are widely used at present; however, the source is limited, and the preparation is complex. Demineralized dental matrix (DDM) is a natural compound containing many osteoinductional proteins and carriers, thus DDM is an ideal material as the substitute of allogenic bone transplantation.OBJECTIVE: By co-culture of MC-3T3 osteoblast and DDM, to evaluate the biocompatibility of DDM via measuring proliferation and alkaline phosphatase (ALP) activity of osteoblast.DESIGN, TIME AND SETTING: A randomized controlled experiment was performed in Stomatology Hospital of Lanzhou University and Stomatology Hospital of Liwan from November 2007 to May 2009.MATERIALS: DDM was supported by Shenzhen Chuangbo Biological Products Development Co., Ltd.; hydroxyapatite (HAP) was supported by Nanjing Emperor Nano Material Co., Ltd.METHODS: 0.1 g HAP and DDM were added in to a 24-well plate, three wells per samples, and the MC-3T3 osteoblasts were seeded onto the surface of samples. After culturing for 2, 4, and 6 days, the cell proliferation percentage was calculated according to MTT assay. ALP activity was evaluated by the quantitative ALP assay.MAIN OUTCOME MEASURES: The effect of DDM on the proliferation and ALP activity of osteoblasts.RESULTS: The proliferation of osteoblasts in DDM group was obviously higher than that in HAP group. With culture time increasing, the ALP activity of osteoblasts in two groups was all augmented, and DDM group was higher than HAP group. There was significant difference between the two groups (P < 0.05).CONCLUSION: DDM can promote adhesion and proliferation of osteoblasts, and promote osteoblastic growth, displaying a great biocompatibility.