Dentistry – Apparatus – Having intra-oral dispensing means
Reexamination Certificate
2000-03-23
2001-11-13
Lewis, Ralph A. (Department: 3732)
Dentistry
Apparatus
Having intra-oral dispensing means
C433S082000, C433S099000
Reexamination Certificate
active
06315557
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates rotary dental cutting instruments and, more specifically, to rotary cutting instruments having irrigating features and to the controls used for the rotating cutting tool and the supply of irrigating liquid to the repair site on a tooth.
BACKGROUND OF THE INVENTION
Many current and past motorized handpieces have been used by dental professionals to rotate a file or other cutting instrument and to simultaneously supply an irrigating liquid, such as in the form of a water jet, to rinse the repair site during the cutting operation. These instruments are especially useful during root canal procedures. The water jet commences upon activation of the handpiece motor and, therefore, commences simultaneously with rotation of the cutting tool.
Unfortunately, the simultaneous activation of the motor and initiation of the irrigating liquid causes the liquid to strike the rotating cutting tool before the tip of the cutting tool can be located at the repair site, such as within the root canal of a tooth. The resulting spray makes it difficult to see the repair site, such as the root canal opening, and this, in turn, makes insertion of the rotating cutting tool into the root canal potentially more error prone. Also, the user typically clamps the file within the jaws of the instrument by briefly activating the motor with the tip located outside the patient's mouth. This leads to an undesirable spray of liquid outside the patient's mouth as well.
For the foregoing reasons, and to solve various problems in this area, it would be desirable to provide a rotary dental instrument and methods which allow the dental professional to present the cutting tool at the repair site prior to an automatic initiation of the irrigating liquid.
SUMMARY OF THE INVENTION
The present invention provides a rotary dental instrument for rotating a cutting tool at a repair site, such as in a root canal of a patient's tooth, and providing an irrigating liquid to the repair site in an automatic, but delayed manner following activation of the cutting tool. Preferably, the delay provides a sufficient time period to allow the cutting tool to be precisely positioned at or within the repair site before commencement of the irrigating liquid discharge. The delay can also allow the user to briefly activate the motor, without simultaneous liquid discharge to tighten the jaws around the cutting tool at the instrument tip.
More specifically, the instrument comprises a handpiece having a rotating element for receiving and rotating a cutting tool and at least one irrigating port for discharging the irrigating liquid generally at the repair site. A motor is electrically coupled to the rotating element for rotating the cutting tool. A pressurized irrigating liquid supply is fluidly coupled to the irrigating port and supplies the irrigating liquid through the irrigating port in a pressurized manner. In the preferred embodiments, the pressurized irrigating liquid supply includes a pump having a liquid output coupled in fluid communication with the irrigating port. A control is operatively coupled with the motor and the pressurized irrigating liquid supply. The control automatically starts discharge of the irrigating liquid from the irrigating port at a predetermined time after starting operation of the motor. This provides an automatic delay between rotation of the rotating element and discharge of the irrigating liquid from the irrigating port. The predetermined time which provides for the delay may be chosen as a time period allowing the dental professional using the instrument to rotate the cutting tool or the rotatable element holding the cutting tool for any desired purpose prior to initiation of the liquid discharge.
Two alternative manners of providing for the delay are currently preferred. In one embodiment, the control receives an input from a user and, in response to the input, the control sends respective signals to initiate the operation of the motor and the pump. The signal sent to initiate operation of the pump is delayed with respect to the signal sent to initiate operation of the motor. As one of several different possible examples, this delay may be provided by an electronic timer, such as a one-shot timer, which receives a signal from a controller and, after a predetermined time, such as about one second, sends the signal to a device, such as a relay, which closes to start the pump. In another embodiment, a power delay device may be used to delay transmission of electrical power to the pump until a predetermined time after initiation of the motor driving the cutting tool. This power delay device may include a timer coupled with a power relay, for example, in which the timer receives the signal from the controller upon activation of the motor driving the cutting tool and, after the predetermined time, activates the power relay to close the power circuit which includes the pump. In this embodiment, the signal from the controller is not delayed but rather the high voltage power itself is delayed by the power delay device. It will be appreciated that many other control schemes may be used to provide for the automatic delay contemplated by the present invention and that the two embodiments detailed herein, i.e., the signal delay and the power delay, may be modified or substituted in many ways while still falling within the inventive concepts.
The invention further contemplates a method of performing a cutting operation on the tooth of a patient with an instrument as generally discussed above. The method includes providing a starting input to the electrically operated rotary instrument to thereby rotate an element thereof holding a cutting tool, waiting a predetermined amount of time after the rotating element begins rotating, and automatically discharging the irrigating liquid proximate the cutting tool after the predetermined amount of time has elapsed.
Additional features, objectives and advantages of the invention will become more readily apparent to those of ordinary skill in the art upon review the following detailed description of the preferred embodiments, taken in conjunction with the drawings.
REFERENCES:
patent: 4117861 (1978-10-01), Betush
patent: 4276023 (1981-06-01), Phillips et al.
patent: 4276024 (1981-06-01), Warrin
patent: 5338194 (1994-08-01), Strohmaier
patent: 5538423 (1996-07-01), Coss et al.
patent: 5934904 (1999-08-01), Elrod et al.
Lewis Ralph A.
Ormco Corporation
Wood Herron & Evans LLP
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