US Patent 6997714 Method and apparatus for evacuation of root canal

After the working of a root canal by instruments to remove material and shape the walls of the canal, a microaspirator is inserted into the canal extending to about 5 mm from the apex and a vacuum is applied which sucks up some of the debris in the canal. Then a tube is inserted in the exposed opening of the canal with the vacuum still applied. Irrigant is supplied by the needle by an opening in the needle, but not under pressure. As the irrigant is supplied, it is drawn down to end of the aspirator by the vacuum which exists in the canal and up into the aspirator. The aspirator is removed and a second, smaller aspirator with a hole in its wall near its sealed end is inserted into the canal until it almost reaches the apex.