Safety syringe

A dental safety syringe comprising:

• a plunger assembly having:
• a thumb ring;
• a piston rod extending from the thumb ring;
• and
• a harpoon on an end of the piston rod, distal to the ring;
• a push lever circumscribing and slidably coupled to the piston rod, wherein a first arm of the push lever extends away from the piston rod on a left side of the piston rod and a second arm of the push lever extends away from the piston rod on a right side of the piston rod;
• a carpule retainer circumscribing and slidably coupled to the piston rod, the carpule retainer positioned between the harpoon and the piston push lever;
• and
• a carpule spring circumscribing the piston rod and positioned between the carpule retainer and the push lever, the carpule spring configured to bias the carpule retainer away from the push lever;
• wherein the plunger assembly comprising an extended position wherein the thumb ring is fully extended and a compressed position wherein the thumb ring is fully compressed;
• a barrel assembly detachably coupled to the plunger assembly, the plunger assembly positioned inside a first end of the barrel assembly, the barrel assembly having:
• a carpule barrel sized to receive a carpule;
• a needle adapter threadedly coupled to the carpule barrel at an end of the carpule barrel distal to the plunger assembly;
• a sliding barrel circumscribing a portion of the carpule barrel and slidably coupled to the carpule barrel;
• a first finger grip extending from the sliding barrel on a left side of the sliding barrel and second finger grip extending from the sliding barrel on a right side of the sliding barrel, each of the first finger grip and the second finger grip having a first side closest to the push lever and a second side farther away from the push lever compared to the first side;
• a trigger, positioned adjacent to the second side of the first finger grip and pivotably coupled to and extending through a finger grip collar connecting the first finger grip to the second finger grip, the trigger comprising an actuator at a first end closest the second side of the first finger grip and a latch at a second end of the trigger that extends through the sliding barrel and selectively engages with a corresponding latch of the carpule barrel;
• a push lever lock directly coupled to the second finger grip and positioned separate from the sliding barrel on the first side of the second finger grip, the push lever lock having a sloped leading edge, biased to a locked position, and configured to engage with the push lever when the push lever is pushed into an active position where the first arm and the second arm are, respectively, in contact with the first finger grip and the second finger grip;
• and
• a safety cover detachably coupled to the sliding barrel distal to the plunger assembly and is configured to extend past a syringe needle attached to the needle adapter when the push lever is in an inactive position and expose the syringe needle when the push lever is in an active position;
• wherein the safety syringe is manipulatable with a single hand from a first state in which the push lever is in the inactive position, to a second state in which the push lever is in the active position and the needle is exposed, to a third state in which contents of the carpule is expelled, and to a fourth state in which the push lever is retracted from the active position to the inactive position after the contents of the carpule is expelled.