Any rough or prickly envelope of the seeds of plants, whether a pericarp, a persistent calyx, or an involucre, as of the chestnut and burdock; a seed vessel having hooks or prickles. Also, any weed which bears burs.
A rotary dental instrument, held and revolved in a handpiece. Used to remove carious material within decayed teeth to reduce decayed or fractured hard tissues, to form the design of the cavity preparation, and to finish and polish teeth and restorations. Can be made of high-speed steel, carbide or diamond coated material.
Blow-up-ratio - As the heated polymer exits the die, it expands to it's cooled state. It is effectively blown up to it's full size, where the film cools and the size is locked in. A BUR of 2.5 to 3 is desireable. It is calculated as the bubble diameter divided by the die diameter.