Aspirating dental syringe with needle shield

A self-shielding syringe, comprising:

• a body having proximal and distal ends and a cavity therein for receiving a medical cartridge, the distal end having an opening through which a needle may extend;
• a shield slidably attached to the body and slidable between a retracted position wherein a needle extending from the distal end of the body is exposed through a distal end of the shield, and an extended position wherein a needle is substantially covered by the shield;
• a cooperating detent and detent pocket on the shield and body for holding the shield in the extended position, the shield having a deflectable portion for selectively disengaging the detent from the detent pocket to allow retraction of the shield from the extended position;
• and
• a latch on the shield for lockably preventing deflection of the deflectable portion to prevent subsequent disengagement of the detent from the detent pocket, thereby substantially permanently locking the shield in the extended position.

A self-shielding dental syringe, comprising:

• a body having proximal and distal ends and a cavity therein for receiving a medical cartridge;
• a needle cannula on the distal end of the body having a proximal portion extending proximally into the cavity, and a distal portion extending distally beyond the distal end of the body;
• a plunger assembly substantially permanently attached to the proximal end of the body for distally directing a piston in a cartridge received in the cavity to deliver medication from the cartridge through the needle;
• a shield slidably attached to the body;
• cooperating detents and detent pockets on the body and shield to temporarily hold the shield in a retracted position wherein the distal portion of the needle is exposed, to temporarily hold the shield in an intermediate guarded position wherein the distal portion of the needle is substantially covered, and to substantially permanently lock the shield in a fully extended position distally beyond the intermediate position.

A method for injecting a medication into a patient using a syringe having a slidable shield thereon in a retracted position wherein a needle of the syringe is exposed, the method comprising:

• injecting medication from the syringe into a patient through the needle;
• advancing the shield axially until cooperating detents on the syringe engage to secure the shield in an extended position that substantially covers the needle;
• and
• engaging a latch to substantially permanently lock the cooperating detents in engagement, thereby substantially permanently locking the shield in the extended position.