RESUMEN
Aesthetic and comfortable transparent retainers and clear plastic appliances are becoming increasingly popular, and their components, especially thermoplastic materials, are gradually attracting widespread interest. Orthodontic thermoplastic materials are versatile polymers, and thus their properties, such as force delivery, force relaxation, and aging properties have been comprehensively studied. Meanwhile, blending modification technology has been applied for the acquisition of novel materials with enhanced characteristics. In this paper, we review the types and properties of thermoplastic materials, the development process they undergo, factors that influence their properties, and some development prospects.
Asunto(s)
Estética Dental , Ensayo de Materiales , Retenedores Ortodóncicos , Plásticos , PolímerosRESUMEN
Objective To compare the air permeability,water absorption and water locking properties of two different foam dressings,thus to provide theoretical and experimental evidence to alternative optimization for acute and chronic wound.Methods Five Mepilex foam dressings(group 1) and PermaFoam Comfort dressings(group 2) each was selected.Simulated wound exudation was made by NaCl and CaCl·H2O.The water-absorbing rate of dressings at post immersion 24 h (PIH),the water-absorbing speed of dressings at post immersion 1,5,10,20 min,the diffusion diameter of exudation dripped on the surface of dressings for 5 min,the beaker filled with exudation was sealed tightly by dressing for 24 h,and the weight was gotten before and after 24 h.Statistical analysis was performed.Results (1) The water-absorbing rate:the group 1(616±19)% was significantly higher than (313±13)% of the group 2 (t=29.137,P0.05).Conclusion The Mepilex foam dressing is more suitable for the early stage of acute wound with large exudation in short time,while the PermaFoam Comfort dressings is better for chronic wound or the later period of acute with less exudation in a relative slow seepage velocity.