# US 6,221,055 B1 · Retractable dental syringe > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,221,055 B1 - Document ID: US6221055B1 - Status: Granted - Kind: B1 - Application number: 09/410,301 - Filed: 1999-10-01 - Granted: 2001-04-24 - Earliest claimed: 1998-03-04 - Assignees: Retractable Technologies, Inc. - Inventors: Thomas J. Shaw; Ni Zhu - Web page: https://patentgrep.com/patent/US6221055B1 ## CPC - A61M 5/3232: {Semi-automatic needle retraction, i.e. in which triggering of the needle retraction requires a deliberate action by the user, e.g. manual release of spring-biased retraction means} - A61M 5/24: Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or cartridges, e.g. automatic - A61M 5/3234: {Fully automatic needle retraction, i.e. in which triggering of the needle does not require a deliberate action by the user} - A61M 5/3137: {with finger grip means, e.g. for easy manipulation of the syringe rod} - A61M 5/502: {for blocking the piston} - A61M 5/508: {Means for preventing re-use by disrupting the piston seal, e.g. by puncturing} - A61M 2005/2407: {from the rear} - A61M 2005/2414: {from the side} - A61M 2005/3117: {Means preventing contamination of the medicament compartment of a syringe} - A61M 2005/3121: {via the proximal end of a syringe, i.e. syringe end opposite to needle cannula mounting end} - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract A single use retractable medical device dispenses fluids from a separable carpule. A retraction mechanism having a spring loaded needle holder with a double ended needle is mounted in the front of a housing by means of a push ring (separable member) slidingly mounted on a widened portion of the needle holder. An outer edge of the push ring grips or is restrained by the inner wall surface of the housing to hold the needle holder in place. A carpule positioned through an opening in back of the housing is operated by a plunger which drives a separable two-part piston to unload medicine from the carpule through the needle. At the end of an injection, the plunger is depressed further. The carpule moves forward to remove the push ring thereby freeing the needle holder for retraction into the carpule through the front opening of the carpule. As the needle is retracted into the housing from one end, the edge of the thumb cap of the plunger disappears into an opening at the opposite end of the housing. The back of the housing may have the traditional thumb ring or it may have a “disappearing” thumb cap which is received into a widened opening in the back of the housing to thwart removal. ## Claims ### Claim 1 A retractable dental syringe, comprising: a carpule having a fluid chamber and a front seal and a rear seal for holding fluid in the chamber; a tubular housing which accepts the carpule, the tubular housing having a front end portion holding a retractably mounted needle in fluid communication with the fluid chamber for dispensing fluid contents of the carpule; a depressible plunger which presses against the rear seal to dispense fluid from the carpule; and the carpule being adapted to release and receive the retractably mounted needle once the fluid id dispensed as the plunger and the carpule are moving forward in response to depression of the plunger. ### Claim 2 (depends on 1) The dental syringe of claim 1 wherein the tubular housing has an open side through which the carpule is accepted. ### Claim 3 (depends on 1) The dental syringe of claim 1 wherein the needle is retractably mounted by means of a ring member in combination with a needle holder. ### Claim 4 (depends on 3) The dental syringe of claim 3 wherein moving the carpule releases and receives the needle by moving the ring member and relatively moving the front seal thereby freeing the needle holder to pass into the fluid chamber of the carpule. ### Claim 5 (depends on 3) The dental syringe of claim 3 whereby the needle holder is mounted in the front of the tubular housing and whereby movement of the carpule in response to the plunger causes the front seal to be dislodged by the needle holder thereby creating an open space so that the needle holder can retract the needle into the carpule. ### Claim 6 (depends on 1) The dental syringe of claim 1 wherein the carpule has a mouth which is adapted to release and receive the retractably mounted needle once the fluid is dispensed in response to further depression of the plunger. ### Claim 7 (depends on 6) The dental syringe of claim 6 wherein the tubular housing and depressible plunger are provided with catches to keep the plunger in the housing after the needle is retracted into the carpule. ### Claim 8 (depends on 6) The dental syringe of claim 6 wherein the carpule has a tubular wall which defines the fluid chamber and the depressible plunger has a front portion comprising an elongated tubular wall portion which slides in proximity to the wall of the carpule inside the carpule. ### Claim 9 (depends on 1) The dental syringe of claim 1 wherein the rear seal comprises a slidable separable two-part seal comprising a core part and a rim part and wherein the depressible plunger presses against the rim part. ### Claim 10 (depends on 9) The dental syringe of claim 9 wherein the syringe is emptied by depressing the plunger until the two-part seal is moved to the front end portion of the tubular housing and whereupon further depression of the plunger moves the carpule in a direction towards the needle without moving the core part of the two-part seal whereby an opening is created for retraction of the needle into the carpule. ### Claim 11 A retractable dental syringe, comprising: a tubular housing adapted to accept a carpule, the tubular housing having a front portion, an intermediate portion and a rear portion; a carpule having a fluid chamber, a front seal and a rear seal for enclosing fluid in the chamber, the carpule having a mouth in front and being sized to fit said housing; a depressible plunger which empties the carpule by moving the rear seal forward to an end-of-injection position; needle structure in fluid communication with the carpule, the needle structure being retractably mounted in the front of the housing for retraction into the carpule; whereby the mouth of the carpule is adapted to release the retractable needle for retraction into the carpule in response to depression of the plunger beyond the end-of-injection position of the plunger. ### Claim 12 (depends on 11) The dental syringe of claim 11 wherein the carpule is positionable for use in the intermediate portion of the tubular housing. ### Claim 13 (depends on 12) The dental syringe of claim 12 wherein the carpule is sized to substantially occupy the intermediate portion of the housing. ### Claim 14 (depends on 13) The dental syringe of claim 13 wherein cooperating catches are provided on the housing and the depressible plunger to keep the plunger in the housing after the plunger reaches the end-of-injection position. ### Claim 15 (depends on 11) The dental syringe of claim 11 wherein the carpule has a tubular wall which forms the fluid chamber and wherein the depressible plunger has a front portion comprising an elongated tubular wall portion which slides in proximity to the wall of the fluid chamber inside the carpule. ### Claim 16 (depends on 15) The dental syringe of claim 15 wherein the carpule may be installed and removed through the side of the housing. ### Claim 17 (depends on 11) The dental syringe of claim 11 wherein the needle structure comprises a hard part which holds a needle and a releasable part which holds the hard part in position. ### Claim 18 (depends on 17) The dental syringe of claim 17 wherein the mouth of the carpule moves the releasable part forward after the end-of-injection position is reached during continued depression of the plunger. ### Claim 19 (depends on 18) The dental syringe of claim 18 wherein the releasable part that is moved by the mouth of the carpule comprises an “O” ring. ### Claim 20 (depends on 18) The dental syringe of claim 18 wherein the releasable part comprises a ring member which frictionally engages the hard part of the needle structure along a substantial common interface. ### Claim 21 A method of operating a syringe, comprising: providing an elongated tubular housing having a front portion containing a retractable needle structure having a retractable needle holding part and a separable part which releases the needle holding part and needle for retraction; providing a carpule for the tubular housing, the carpule having a mouth in front with a front seal and a back portion with a slidable and separable two-part seal, the carpule having a fluid chamber between said seals in fluid communication with the needle; providing a depressible plunger having a tubular front portion in pressing contact with one part of the separable two-part seal; depressing the plunger to move the two-part seal forward to a sufficient extent as to expel substantially all fluid from the fluid chamber through the needle; and moving the carpule toward the needle structure in response to additional depression of the plunger to thereby automatically retract the needle holding part into the carpule through the mouth of the carpule. ### Claim 22 (depends on 21) The method of claim 21, wherein the step of moving the carpule toward the needle structure is accompanied by the steps of: moving the separable part relative to the needle holding part, and moving one part of the separable two-part seal relative to the other part of said seal. ### Claim 23 (depends on 22) The method of claim 22 wherein the step of moving the carpule toward the needle structure includes the step of moving the front seal from the mouth of the carpule in a direction away from the needle holding structure. ### Claim 24 (depends on 21) The method of claim 21 wherein: the step of providing a needle holding structure includes the step of providing a separable part comprising a ring member; and the step of automatically retracting the needle holding part into the carpule includes the step of separating the ring member from the needle holding part. ### Claim 25 (depends on 23) The method of claim 23 wherein the step of moving the front seal out of the mouth of the carpule includes the step of moving the front seal relative to said other part of the separable two-part seal in a direction away from the needle holding structure.