Optimization of materials for a user-formed mouthguard
A mouthguard that can be custom formed by the user at the time of need to achieve optimum fit and protection is required for sports and clinical applications. This study has evaluated two silicone-based polymer systems found sufficiently workable to be molded to the user's mouth. Compositions were optimized for setting time and mechanical properties by varying the proportions of catalyst, cross-linking agent, and filler. Mechanical tests showed the optimized silicones to have lower tensile and tear strengths and higher penetration and rebound than most present mouthguard materials. Detailed measurements of compressive stress-strain, coupled with a stress analysis of conditions in actual mouthguard use, indicate that the optimized silicone polymers possess more than adequate strength and durability for a user-formed mouthguard.
Mouthguard materials: their physical and mechanical properties.
Physical and mechanical tests were used to determine the properties of 57 different mouthguard materials. Finding or fabricating a mouthguard material that is durable, protective and stable, inexpensive enough to be available to all sports enthusiasts, and simple enough in design and delivery to make it disposable is the challenge that underlies this study. Physical and mechanical tests were used to learn the basic properties of 57 different mouthguard products. The results from these measurements may be helpful as a guide for establishing material standards and specifications for the fabrication of mouth protectors.
Avian infectious bronchitis.
Avian infectious bronchitis (IB) is caused by the gammacoronavirus infectious bronchitis virus (IBV). The virus causes infections mainly in chickens and is a significant pathogen of commercial meat and egg type birds. IB is an acute, contagious disease characterised primarily by respiratory signs in growing chickens. In hens, decreased egg production and quality are often observed. Some strains of the virus are nephropathogenic and produce interstitial nephritis and mortality. The severity of IBV-induced respiratory disease is enhanced by the presence of other pathogens, including bacteria, leading to chronic complicated airsacculitis. Diagnosis of IB requires virus isolation or demonstration of viral nucleic acid from diseased flocks. Demonstration of a rising serum antibody response may also be useful. The widespread use of live and inactivated vaccines may complicate both the interpretation of virus isolation and serology findings. The occurrence of antigenic variant strains may overcome immunity induced by vaccination.