Abstract: A hand held dental injection device including a conduit having an inlet and an outlet. A rotatable conveying screw having conveyance flutes is positioned within the conduit for conveying thermoplastic material received from the inlet of the conduit alongside the screw through the conduit and out the outlet with the conveyance flutes. A heating system heats the thermoplastic material. A needle is mounted to the outlet of the conduit for directing the thermoplastic material into dental cavities.

Abstract: A hollow jointless needle formed from a single piece of conductive metal for injecting thermoplastic material into a dental cavity includes a flange for securing the needle to an injection device. The flange extends transversely relative to the longitudinal axis of the needle. A first needle portion having a first diameter extends from the flange along the longitudinal axis. A second needle portion extending along the longitudinal axis is connected to the first needle portion by a first transition region. The second needle portion has a second diameter which is smaller than the first diameter of the first needle portion.

Abstract: A hollow jointless needle formed from a single piece of conductive metal for injecting thermoplastic material into a dental cavity includes a flange for securing the needle to an injection device. The flange extends transversely relative to the longitudinal axis of the needle. A first needle portion having a first diameter extends from the flange along the longitudinal axis. A second needle portion extending along the longitudinal axis is connected to the first needle portion by a first transition region. The second needle portion has a second diameter which is smaller than the first diameter of the first needle portion.

Abstract: A syringe for extruding heated thermoplastic materials through a hollow needle is disclosed. This syringe is particularly useful in obturating root canal cavities, or other dental cavities, with gutta-percha or similar materials.

Abstract: An electrically heated endodontic syringe for injecting thermoplastic material, such as gutta percha, into a root canal cavity includes a syringe barrel for holding a supply of thermoplastic material, a heater body threadedly attached at one end to the syringe barrel and an injection needle threadedly secured to the other end of the heater body by means of a hub. A manual plunger is provided in the syringe barrel for ejecting thermoplastic material from the barrel through the heater body, hub and needle into the root canal cavity. The barrel and plunger are made of materials having a low coefficient thermal conductivity of less than about 20 Btu/(hr)(ft.sup.2) (F..degree./ft) and a thermally insulating washer is positioned between the barrel and the heater body to minimize heat transfer to the barrel. The heater body, hub and needle are made of materials having a high coefficient of thermal conductivity of at least about 200 Btu/(hr) (ft.sup.2) (.degree.F./ft) to maximize heat flow to the needle.