A comparison of the aspirating abilities of re-usable and partly disposable dental cartridge syringes in vitro

Objectives To compare the ability of re-usable and partly disposable dental cartridge syringes to aspirate in vitro. Methods A laboratory investigation comparing two re-usable (Astra and Rotor) and one partly disposable (Ultra Safety-plus) dental cartridge syringes. Forces needed to move the cartridge plunger and forces required to produce aspiration of Bonneyʹs Blue dye were measured using an Instron testing machine. Results There were significant differences in the forces needed to produce aspiration in the different systems (F=194, p<0.001). The Astra system needed the least force to produce aspiration. The forces required to aspirate in the Rotor and Ultra Safety-plus systems did not differ. Each system aspirated effectively in vitro at the initial aspiration manoeuvre. The forces available for subsequent aspiration attempts varied with the speed of cartridge plunger movement. The volume of local anaesthetic cartridge used did not affect the force needed to produce aspiration in the Ultra Safety-plus syringe. The method of testing free-flow of solution through the needle affected the force generated at subsequent plunger movements. Conclusions The re-usable and partly disposable syringes investigated aspirated effectively at the initial aspiration manoeuvre. The force available to produce aspiration at subsequent attempts varies with the speed of injection. The method of testing free-flow of solution through the needle in a loaded syringe affects the force available at the first aspiration manoeuvre.