Properties of athletic mouth protectors and materials.
The properties of a variety of mouth protectors and sheet materials used to fabricate custom mouth protectors were determined in order to recommend limits for a specification. Hardness, water sorption, water solubility, impact absorption, and tear strength were measured, and limits for these properties were suggested.
Antimicrobial activity of ethylene-vinyl acetate containing bioactive filler against oral bacteria.
We developed an ethylene vinyl acetate (EVA) containing surface pre-reacted glass-ionomer (S-PRG) filler, as a new mouthguard material for preventing intraoral bacterial infection. We examined its physical properties, antimicrobial activity against a major cariogenic bacterium Streptococcus mutans and a periodontopathogen Porphyromonas gingivalis, and its cytotoxicity toward human gingival epithelial cells. S-PRG filler was added to EVA copolymer at 5, 10, 20, or 40 wt% and was processed into disc-shaped test specimens. Only minor differences between the Shore hardness and rebound resilience properties of EVA materials with and without the S-PRG filler were observed. The specimens with S-PRG filler showed bacteriostatic activity toward S. mutans and P. gingivalis and inhibited S. mutans biofilm formation. No cytotoxicity against the gingival epithelial cells was observed. Our findings show that EVA containing S-PRG filler has antimicrobial activity toward pathogenic oral bacteria and may be an effective material for maintaining the oral health of athletes.
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.