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In this study, we prepared a blended nanofiber scaffold using synthetic and natural polymers, polyurethane (PU) and gelatin respectively, using the electrospinning method to prepare a material for wound dressing. In order to confirm the properties of this gelatin/PU blended nanofiber scaffold, we performed scanning electron microscopy, atomic force microscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, thermal gravimetric analysis, contact angle, water uptake, mechanical property, recovery, and degradation tests, and cellular response. The results obtained indicate that the mean diameter of these nanofibers was uniformly electrospun and ranged from 0.4 to 2.1 microm. According to the results, when the amount of gelatin in the blended solution decreased, the contact angle increased and water uptake of the scaffold decreased concurrently. In the mechanical tests, the blended nanofibrous scaffolds were elastic, and elasticity increased as the total amount of PU increased. Moreover, as the total amount of gelatin increased, the cell proliferation increased with the same amount of culture time. Therefore, this gelatin/PU blended nanofiber scaffold has potential application for use as a wound dressing.

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The purpose of this study was to analyse the traumatic dental injuries (TDI) of Korean preschoolers by investigating the occurrence, type, area, cause, injured region, seasonal variation and the interval between injury and treatment. In this study, data from 1856 preschoolers aged 4 months to 6 years and 11 months (mean age : 3.6 +/- 1.6) were used, out of a total of 2761 patients who attended the Department of Pediatric Dentistry, Kyung Hee Dental Hospital for TDI between January 1998 and December 2007. All the data were statistically analysed using the anova and chi-square statics. Most of the patients were 1-2, 2-3 years old (24.5%, 25.4%) and boys were 1.67 times more likely to have TDI. The most common cause, location and seasonal variation of the trauma, were respectively falling (50.8%), at home (48.8%) and late spring. The treatment intervals usually occurred within a day. Most of the injuries involved single (47%) or double (38%) tooth/teeth. However, car accidents or sports trauma often involved multiple teeth. In both primary and permanent dentition, the most common teeth injured were maxillary central incisors (72.6%), and periodontal injury was caused by subluxation or concussion. Among the various types of hard tissue injuries, enamel fracture in the primary dentition (35.0%) and enamel-dentin fracture in the permanent dentition (45.8%) were the most common types.

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