Dentistry – Apparatus – Hand manipulatable implement
Reexamination Certificate
1999-03-06
2001-07-10
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Hand manipulatable implement
C433S143000
Reexamination Certificate
active
06257887
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to dental instruments and, more particularly, to hand held instruments having an elongated handle fitted with a working tip at one end or with working tips at both ends.
2. Brief Description of the Prior Art
Dental hand instruments are typically fabricated with elongated handles of stainless steel, chromed brass, or aluminum having a round or octagonal cross section of about ¼ inch diameter. Depending on the use of the instrument, the handle is fitted with a working tip of stainless steel, carbon steel, or other metal such as carbide at one end or with such working tips at both ends. Typical working tips include those employed in periodontics, hygienics and diagnostics such as curettes, scalers, probes, and explorers; in operatives such as angle formers, chisels, trimmers, excavators and carvers, and hatchet and hoe instruments; in endodontics such as dryers and spreaders and pluggers. A common factor in the use of instruments employing such tips is that the instruments must be gripped tightly and that the gripping fingers undergo repetitive movement while under substantial strain. Increasing symptoms of hand fatigue, cramping, strain and carpel tunnel syndrome are being reported with repetitive use of these standard instruments over extended periods of time, as is required in the daily practice of dentistry. The common practice of using latex gloves as protection may be a causative factor in the increase of these symptoms inasmuch as a hand held instrument is more difficult to manipulate with a gloved hand, perhaps requiring holding the instrument with greater force than would be required of a non-gloved hand. Use of latex gloves also reduces tactile sensitivity.
Increasing the diameter of the elongated handle from the standard ¼ to {fraction (5/16)} inch would appear to be indicated. However, increasing the diameter increases the weight of the instrument, adding to hand fatigue. Moreover, the resulting increase in weight dampens the tactile sensitivity of the working tip, leading to increased hand fatigue.
Some attempts have been made to substitute elongated plastic handles for the standard stainless steel handle. However such attempts have resulted in numerous problems such as an incapability to withstand sterilization procedures, resulting in one-use throw-away instruments. This inefficiency becomes even more significant in the case of double ended instruments since discarding loses the benefit of the remaining serviceability of both tips. The ability to provide replaceable tips and to choose any particular combination of tips is also lost. Poorly designed handle surfaces has resulted in increased hand strain and fatigue, undesirable handle flexibility and dampening of the tactile sensitivity of the working tip.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a dental hand held instrument that satisfactorily solves the abovementioned difficulties experienced by prior instruments including the provision of a multi-piece handle allowing for replaceable tips, and mixing and matching any combination of working points while maintaining threaded areas free from debris and pathogens. It is another object to provide a dental hand instrument with a larger handle diameter that reduces hand strain and fatigue but that does not dampen the tactile sensitivity of the working tip. It is a further object to provide an elongated handle fabricated from a thermosetting plastic wherein the handle can be either molded in an injection molding process, or machined from rod stock. It is still another object of the present invention to provide a dental hand instrument wherein the elongated handle is fabricated from a thermosetting plastic and wherein stainless steel working tips are joined with the handle in a sanitary joint that will not harbor bacteria and other pathogens. These and other objects and advantages will become apparent from a consideration of the following description of a preferred embodiment of the invention.
In accordance with these objects, the invention provides a dental hand instrument comprising an elongated handle formed of a thermosetting plastic and a metal working tip inserted into an end of the handle. The handle has a bore provided in the end to accommodate a shank end of the tip. The handle and the tip are subjected to heat treatment to partially melt a portion of the thermosetting plastic adjacent to the shank end so as to firmly secure the tip in the handle and so as to bind the shank in solid plastic-to-metal contact along the shank end. The shank end of the tip is provided with a non slip surface that is encompassed and embedded in the thermosetting plastic so that the tip will not turn during use.
In one embodiment an improved replaceable tip instrument is provided utilizing a multi-piece handle including one or more replaceable tip sections with working tips fixed to the handle section in a manner according to the present invention. The independently exchangeable tips allow the user to mix and match any combination of working points and allows for replacement of worn or broken points as needed without losing the benefit of the remaining serviceability of opposing points in the case of double ended instruments. In addition, attachment of the handle section to the main handle portion allows for flush mounted in-line identification rings with improved wear and sterilization characteristics.
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Heckerman Brad B.
Jenkins Russ
Meuchels Dennis
Smithers Jeff
American Eagle Instruments, Inc.
Dowrey & Associates
Wilson John J.
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