Dentistry – Apparatus – Having means to emit radiation or facilitate viewing of the...
Reexamination Certificate
1999-07-28
2001-02-27
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Apparatus
Having means to emit radiation or facilitate viewing of the...
C433S027000
Reexamination Certificate
active
06193510
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to medical devices (including dental devices) of the type that include a patient-contact element that should be replaced at intervals.
BACKGROUND OF THE INVENTION
The invention has been devised primarily in the context of light curing guns for dental filling materials. An example of a gun of this type is disclosed in U.S. Pat. No. 5,803,729 (Tsimerman). In a typical light curing gun, light from a halogen bulb is reflected into a light guide, by which the light is directed onto the dental filling material to be cured. Since the light guide necessarily enters the mouth of the patient, it should be sterile. If the same light guide is used repeatedly, it should be sterilized or replaced between patients. As disclosed in the Tsimerman patent, the light guide is simply push-fitted into a sleeve that provides a receptacle in the nose cone of the gun. Accordingly, it is quite a simple matter to change the light guide.
Traditionally, fibre optic light guides have been used. Performance of the curing light is significantly affected by the degree of transmission of light through a fibre optic light guide. Sterilization of these light guides results in decreased light transmission. In addition, cleaning and maintenance of fibre optic light guides is time consuming and costly.
Plastic disposable light guides were introduced several years ago. Re-use of non-sterilized light guides, which might even occur accidentally, would be hazardous to both the patient and to the dentist in view of the strict infection control guidelines of recent years. However, plastic light guides do not respond well to sterilization processes that employ heat. Lengthy immersion in cold sterilizing solutions causes cracking and yellowing of the plastic.
Similar considerations apply in relation to other medical devices that have replaceable patient-contact elements. Examples are electric toothbrushes where the toothbrush head typically is replaceable and dental irrigation devices having water nozzles. Sterility may not be as critical in these cases in the sense that there would normally be only a single user for one brush head. Nevertheless, toothbrush heads and nozzles do degrade with time and should periodically be replaced. Some types of medical syringe have dispensing tips that require replacement from time to time.
An object of the present invention is to provide means for at least indicating to the user of the device that the patient contact element should be replaced.
SUMMARY OF THE INVENTION
Accordingly, the invention provides the combination of a medical device and a patient contact element for use with the device, in which the device includes a receptacle for replaceably receiving the element. The element is encoded with a unique identifying code and the device includes a reader for the code. A data processor compares the code with codes previously read by that reader and provides a signal if the code is a new code. The device also includes a timer which is responsive to that signal and which provides a time-out signal after expiry of a predetermined time period selected as appropriate for replacement of the patient contact element. The time-out signal activates means for indicating to a user that the element should be replaced.
Preferably, this indication is provided by disabling the device until the patient contact element has been replaced. In the case of a device that is power operated, such as the light curing gun, the gun can be disabled simply by interrupting the power supply to the light. The dentist would then be forced to replace the patient contact element (light guide) before the light gun could be used again. In other cases, it may be sufficient to provide the user with a visual and/or audible signal to indicate that the patient contact element should be replaced.
The encoding/reading functions required pursuant to the invention can be provided using conventional technology such as bar coding or microchip coding, for example, as is used in conjunction with credit and other cards. Similar technology is also used in anti-theft devices for motor vehicles where a specially encoded ignition key must be used before a vehicle can be started.
In the context of light curing guns, it is thought that bar coding may be the preferred approach. Each light guide (sometimes called a “tip”) can be encoded using code tape or a surface applied code. The nose cone of the light gun then incorporates a bar code reader. When the data processor receives a code from the reader, it compares this code with codes stored in its memory. If the code is a “new code”, the processor sends a signal to trigger the timer which then starts to count down the working time of the tip (a constant stored in the processor's memory). This may happen immediately or only after first light exposure through the light guide. After the working time has expired, the processor interrupts the power supply to the light gun, effectively preventing further use of the gun. The only way in which the light gun can be re-activated is to insert a new light guide, which will send a new code to the processor.
Typically, the processor is a microprocessor incorporated in the light gun itself, or in an ancillary unit (e.g. housing power supply and control equipment). The microprocessor will include timer means. Reasonable memory capability will allow up to 1,000,000 codes to be stored. Once the memory is full, the next tip inserted will erase and reset the memory. The code may comprise 24-33 binary digits which will provide for 16 million-one billion codes.
REFERENCES:
patent: 4835372 (1989-05-01), Gombrich et al.
patent: 5715831 (1998-02-01), Johnson
patent: 6113549 (2000-09-01), Johnson
Bereskin & Parr
Lucchesi Nicholas D.
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