Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-07-27
2001-06-12
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06245043
ABSTRACT:
The present invention relates to an injector for use in dentistry, for performing intramedullary or intradiploic injections of anesthetic or for performing injections into soft tissue.
BACKGROUND OF THE INVENTION
In dental surgery, the conventional solution is to use a syringe to inject a determined quantity of liquid anesthetic into the gum of the patient at a certain distance from the tooth that is to be attended to. However, that procedure suffers from drawbacks such as a considerable latency time between injection and anesthetic action, and of a quantity of anesthetic being injected that is larger than necessary. To remedy those drawbacks, proposals have already been made to provide intradiploic anesthesia whereby injection takes place directly into the marrow of the maxillary bone after passing through the cortical substance. The action of the anesthetic is thus more effective. To this effect, it is known to cause the injection needle to rotate so as to facilitate penetration of the needle through the cortical substance which is a hard region. After which a piston is displaced which bears against the moving end of the cartridge containing the anesthetic.
Proposals have already been made, in particular in U.S. Pat. No. 5,173,050 to perform such anesthesia in two stages. Initially the cortical substance is pierced, after which the injector is withdrawn and the perforation needle is replaced by an injection needle. However it is very difficult to find the perforation again so as to proceed with injection.
An injector that enables such anesthesia to be performed without needing to remove the perforation needle is described in FR-A-2 581 548. In that patent, the means for rotating the cartridge and for moving the moving end of the cartridge are constituted by two micro-motors, with the mechanical link between the cartridge and the motor for rotating said cartridge being obtained by means of gears. The same applies to driving the piston which is obtained via stepdown gearing. It is thus possible to obtain injection that is continuous and regular, which was not the case with hand syringes. However, it turns out that those drives give rise to undesirable noise, since the motor is rotating at very high speeds of several tens of thousands of revolutions per minute.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention thus seeks to mitigate those drawbacks. It is based on the idea that all of the forces to be transmitted need to be transmitted on the axis of the injector while avoiding any mechanical transmission which quite often gives rise to eccentricity in the applied forces, giving rise to breakage of the cartridge.
According to the invention, an injector having one motor for rotating a piston and a second motor for driving said piston in translation, the piston being in contact with the moving end of a cartridge which is fixed in removable manner to the body of the injector, is wherein the motor for driving the piston in translation lies on the same axis as the piston and is mounted inside the cylindrical body of the injector, drive in translation being the result of the drive shaft driving a screw which co-operates with an inside thread of the body of the injector, with operation of the motors being under the control of an electronics card.
Preferably, the drive screw of the motor has a hub through which fixing screws pass.
The force applied to the end of the cartridge or container is accurately coaxial therewith and the drive in translation takes place without slip.
According to another characteristic of the invention, the control of the injection motor is programmed so that the volume injected is progressive, thereby very significantly reducing the pain.
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Duane Morris & Heckscher LLP
Mendez Manuel
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