A standard dental syringe is made up of an outer cylinder with a plunger at one end, and a carpule which contains liquid medication to be injected into a patient is replaceably positioned within the barrel and includes a needle slidably mounted at one end of the carpule in communication with the fluid medication which is contained in a fluid chamber sealed off at each end by a plug so that when the plunger is advanced into engagement with a first plug at one end of the carpule the liquid medication is delivered through the needle and upon completion of the plunger stroke, a barbed extension of the slidable first plug member will move into engagement with the needle-retaining second plug member so that upon retraction of the plunger the needle-retaining plug member will be retracted along with the slidable first plug member. The needle is guided through a funnel-shaped sleeve assembly at the end of the barrel so that following the injection procedure the needle can be retracted and the portion of the guide can be removed so that the entire exposed end of the needle can be cut off following which both of the plug members and remainder of the needle can be once again retracted into the carpule assembly and removed from the barrel and replaced by a new carpule assembly.
