Penetration resistance of dental injection needles

A laboratory test of the sharpness and penetration resistance of different brands of dental needles was undertaken. Both properties are essential when pain during injection is discussed. Using a Strograph in combination with a piece of stretched chamois leather resembling the mucous membrane, graphs were obtained for each needle tested and evaluated with reference to maximum penetration resistance at the actual point of puncture and to the smoothness of the further insertion through the leather. The findings gave a relative characteristic of each product based on a trial of 20 needles selected at random from each batch of 100 needles.