Dental injection gun

Claim 1

A dental injection gun comprising a frame having a portion thereof shaped to provide a pistol grip, an elongate sleeve holder integral with the frame and being oriented substantially perpendicularly relative to the pistol grip portion of the frame, an elongate sleeve adapted to hold a syringe and being detachably connected to said sleeve holder for axial alignment therewith and extension therefrom, an elongate rod received in said sleeve holder for movement relative thereto and being adapted to act at one end thereof on a charge of anesthetic in said sleeve when moved in a predetermined direction relative to said sleeve holder, said rod being formed with a plurality of ridges on its outer surface which ridges extend generally transverse to the axis of the elongate rod and terminating in an enlarged head at that end of the rod opposite said one end thereof, actuating means for actuating said rod and comprising lever arms one of which is a trigger arm extending in the general direction of said pistol grip and being pivotally mounted to said frame with one end thereof proximate said rod and its opposite free end normally urged in a direction away from the pistol grip portion of the frame, said lever arms including a double arm bracket pivotally mounted at one end thereof to said one end of said trigger arm, a lug disposed generally transversely to the axis of the rod and being mounted to the opposite end of the bracket for pivotal movement about an axis transverse to the axis of the rod, said lug being formed with a hole of a diameter slightly larger than the largest diameter of the ridges on said rod, the latter passing through said hole in said lug, and torsion spring means for normally urging said lug into an inclined position in a direction opposite to the direction of advancement of said rod by said actuating means and in which position of the lug the surface defining said hole being in gripping engagement with the ridges on the rod, said lug being movable into an oppositely inclined position through an intermediate perpendicular position.