Penetration of disposable needles.

Six types of disposable injection needles were tested clinically for the intensity of pain caused, and their penetration capacity measured. The force nedded differed greatly with different needle types (120-250 mN). The design of the needle point was observed to have the greatest effect on the pentration capacity and the intensity of pain. To penetrate the tissue well, the needle point should have secondary bevels at the tip of the bevelled surface. The majority of the needles fulfilled this requirement.