Compressive Strength of Dental Anaesthesia Needles

Objective: To compare the effect of compressive forces on dental anaesthesia needles of different gauges and lengths manufactured by seven different manufacturers. Methods: Dental anaesthesia needles of gauges 25G, 27G and 30G and varying lengths between 21mm and 35mm were randomly selected from those manufactured by each of the seven different manufacturers. They were tested using a Shimpo Digital Force Gauge Model FGV-20, fitted with the relevant accessories. Results: For a given length, needles with the higher gauge tended to distort more readily than those with a lower gauge. For a given gauge, needles with the longer length tended to distort more readily than those with a shorter length. For a given lenth and a given gauge, the needles from some manufacturers tended to distort more readily than those of others. Conclusion: There is considerable variation in the ability of needles to resist deformation, and this is dependant on the length, gauge and manufacturer.