Anesthetic cartridge system under evaluation

The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage.Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year.These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states "The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product." However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence.It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated.