Plastic dental local anaesthetic cartridges: a laboratory investigation

The pressures applied to the bungs of glass and plastic dental local anaesthetic cartridges which were necessary to cause failure of the system were measured. Plastic cartridges did not fracture, but they failed due to leakage of solution around the bung at pressures less than those needed to break glass cartridges. At the peak injection pressures which may be obtained during intraligamentary injections, it was established that the theoretical incidence of failure was 1.4% for glass and 75.1% for plastic cartridges.