Dental safety syringe

A dental safety syringe comprising a barrel assembly and a cooperatively configured plunger assembly slidably engageable with the barrel assembly:

• the barrel assembly further comprising a reusable barrel with a longitudinally extending window and projecting lugs, and a removable needle cartridge insertable into the reusable barrel through the window;
• and
• the cooperatively configured plunger assembly further comprising a plunger body with open proximal and distal ends, an outside surface and slots disposed on the outside surface, a plunger rod slidably insertable into the plunger body having a proximal end and a distal end, and having a thumb ring attached to the proximal end of the plunger rod and a harpoon attached to the distal end of the plunger rod;
• wherein the removable needle cartridge is disposed forwardly of an ampule containing a medication and further comprises a needle, a needle holder biased rearwardly by a compressible spring disposed inside the removable needle cartridge and a distal end from which the needle can be made to project forwardly while administering the medication from the ampule and then subsequently withdrawn into the removable needle cartridge to avoid contamination following or between injections;
• and
• wherein the projecting lugs of the reusable barrel of the barrel assembly are cooperatively engageable and alignable with the slots disposed on the outside surface of the plunger body and configured to allow both axial and rotational movement of the plunger body relative to the reusable barrel to move the needle to initiate withdrawal of the needle into the removable needle cartridge and reusable barrel whenever the plunger body is moved rearwardly relative to the reusable barrel.