PURPOSE: The purpose of this study was to research the properties of some chemically cured methacrylate polymers such as MMA, HEMA, TEG-DMA, bis-GMA, GMA. MATERIAL AND METHOD: 5 kinds of methacrylates were selected and added 2% tertiary amine and benzoyl peroxide to make a chemically curable polymer. 25 micron crushed silicas which are treated with silane were selected as filler, they were added into methacrylate monomer until the consistency did not changed by the load of 500gram. All of the experimental resins were 5 kinds, and a serial test was done with 3 kinds of items including the filler contents, the tensile strength, and the bond strength. The number of specimen were 10 for each group. Filler contents were obtained by reducing the specimens to ashes at 600 degrees C for 1 hour. The specimens with the dimension of 6mm in diameter and 3mm thick were immersed in 37+/-1degrees C distilled water for 24 hours before test, and tensile strength were measured with cross-head speed 1mm/min. Shear bond strength were measured on the specimens attached to bovine enamel etched with 37% phosphoric acid for 1 minute. RESULTS: 1. Maximum filler incorporation was the highest as 75.5% on MMA, and the least as 53.4% on bis- GMA(p<0.0001). 2. The tensile stregth were MMA 141.3, GMA 154.3, TEG-DMA 157.4, bis-GMA 161.4 MPa, and HEMA showed the highest value, 226.9MPa(p=0.0004). 3. The bond strength were GMA 10.1, TEG-DMA 11.7, HEMA 12.2, bis-GMA 13.3 MPa, and MMA showed the highest value, 15.3MPa, however statistical significances were not (p=0.3838). 4. TEG-DMA and HEMA were not different on the aspect of maximum filler contents and shear bond strength(p>0.05). CONCLUSION: HEMA can be used as an another diluent substituting TEG-DMA with the increased strength and with the constant bond strength and the constant filler contents.
Benzoyl Peroxide ; Bisphenol A-Glycidyl Methacrylate ; Dental Enamel ; Methacrylates ; Polymers* ; Silicon Dioxide ; Tensile Strength ; Water

BACKGROUND/AIMS: Double balloon enteroscopy (DBE) is an effective modality for making the diagnosis and managing suspected small bowel bleeding. However, there is limited data on the follow-up results after DBE. The aim of this study was to evaluate the long-term clinical outcome after DBE in patients with suspected small bowel bleeding. METHODS: We retrospectively analyzed the rebleeding rate of 60 consecutive patients (M:F=39:21, age: 13~85 years) who underwent DBE because of suspected small bowel bleeding at Asan Medical Center during a 3 year period. RESULTS: The median follow-up period was 552 days. Bleeding sources were detected by DBE in 41 patients. The cumulative rebleeding rate at 6, 12 and 24 months was 22%, 27% and 30%, respectively. There was no significant difference in the cumulative rebleeding rate between the patients with bleeding sources detected by the initial DBE and those without bleeding sources detected by the initial DBE. The cumulative rebleeding rate at 6 and 12 months was significantly higher for the patients with vascular or superficial mucosal lesions than for the patients with tumors or other lesions (p=0.013). CONCLUSIONS: The rebleeding risk after DBE is not low for patients with suspected small bowel bleeding. The rebleeding risk is especially high for patients with vascular or superficial mucosal lesions, and this may necessitate careful follow-up.
Double-Balloon Enteroscopy ; Follow-Up Studies ; Hemorrhage ; Humans ; Retrospective Studies