Abrading – Abrading process
Reexamination Certificate
2000-03-23
2004-04-27
Morgan, Eileen P. (Department: 3723)
Abrading
Abrading process
C451S054000, C451S165000, C451S910000, C433S119000, C433S125000
Reexamination Certificate
active
06726531
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to tools that are moveable on work surfaces to perform operations thereon, and more particularly to tools of the type having safe areas and active areas to remove rough surface areas and provide a smooth surface.
BACKGROUND OF THE INVENTION
Tools are utilized by many different crafts persons for working on various types of materials to fabricate an object with the desired shape or form. While the majority of tools are utilized by machinists and other crafts persons working in similar trades, various types of tools are also utilized on a daily basis by artists, carpenters, cabinet makers, engineers, physicians, dentists, etc. Depending on the application to which the tool is applied, the particular devices may be moved by hand, rotated, reciprocated or otherwise vibrated to operate upon the surface of the workpiece.
In many applications, there is a need to smooth an otherwise rough workpiece surface. Hand files, sanders, shapers, planers, etc., are well adapted for creating a smooth workpiece surface. While these and other tools are well adapted for carrying out this function, the operation of such type of tools requires a certain degree of skill to prevent an excessive amount of material from being removed from the workpiece to prepare a smooth surface. In other words, in utilizing many of these smoothing-type tools, the operator must be careful to halt the operation once the surface is smooth, otherwise, the continued operation of the equipment will only unnecessarily remove further material from the workpiece.
In the dental field, doctors routinely utilize ultrasonic scalers to remove brittle calculus, tartar, altered cementum and other accumulated residue from a patient's tooth. During supragingival scaling or root planing, the material to be removed is universally rough with multiple jagged and protruding edges. The buildup on the enamel of a tooth is undesirable which, if not removed, can be damaging to the tooth and gingival tissue. The ultrasonic scaler is equipped with a tip which mechanically vibrates at a high frequency. When brought into contact with the hardened residue, the brittle material is fractured and eroded and removed from the tooth. The end of the metal tip of the ultrasonic scaler insert fractures and breaks the brittle buildup with a micro-hammer action. This method of removing calculus from a patient's tooth is well documented in the dental literature. In order to facilitate the removal of calculus and other materials formed over time on a patient's tooth, the ultrasonic tip can be coated with diamond particles, such as disclosed in U.S. Pat. No. 4,731,019 by Martini. The diamond particles covering the ultrasonic scaler tip function to accelerate the abrasion of the brittle calculus. Indeed, an extreme amount of care must be exercised by the doctor in the utilization of this tool, otherwise, the surface of the tooth will be abraded and damaged. It can be appreciated that the doctor or assistant must be very attentive when utilizing this ultrasonic tool, otherwise, the tooth, bone or other hard surface will be damaged beyond repair. It will also be appreciated that when the tip of this tool is utilized on that part of the tooth in the gingival pocket, excessive tooth abrasion can occur because the surgeon is unable to visually observe the tooth surface being operated upon. As a result, diamond coated ultrasonic tips have been limited to a small specialty area of dentistry by experienced doctors, namely, the periodontal surgical area.
Ultrasonic operated devices utilize tips that are constructed of specified lengths so as to be tuned A tuned tip provides optimum magnitude vibrations and thus is effective to micro-hammer object surfaces. Standard ultrasonic tips are effective only along about 4-6 mm at the end of the tip to remove accretions on a tooth surface. The other portion of the ultrasonic tip is less effective as an instrument to remove calculus and tartar buildup on tooth surfaces.
It is well known in the art to bond diamond particles to tool bits, and the like, in order to accelerate abrasion of the workpiece and extend the life of the tool. Diamond whetstones are such type of tools. These tools are fabricated by bonding a diamond abrasive in raised islands on the surface of the tool. The raised islands of diamond particles are effective to erode the surface of the workpiece. Again, the surface of the workpiece continues to be eroded as long as the operator moves the whetstone over the surface of the workpiece.
As noted above, ultrasonic scaler tips that are covered with a diamond abrasive grit currently exist. Abrasive or sharp edges on the surface of a scaler tip have been shown to be an effective means of removing tartar and roughness from the tooth surface. However, studies have demonstrated that abrasive areas and sharp edges, when vibrated by an ultrasonic scaler and placed directly against the tooth surface, will damage the surfaces of the tooth and root. In other words, not only the calculus, tartar, and other unwanted rough surfaces will be removed as desired, but a significant portion of the tooth surface will also be removed, thus causing permanent damage to the tooth.
From the foregoing, it can be seen that a need exists for a tool that removes roughened areas of a workpiece surface, but once a smooth surface is achieved, further erosion of the surface does not occur, even if the tool continues to be moved over the work surface. Another need exists for a tool that can be used by a technician to smooth surfaces of workpieces without utilizing a high degree of skill. Another need exists for an ultrasonic tip which, when used on tooth surface that cannot be easily observed, does not continue to erode the surface of a tooth once a smooth surface is achieved.
SUMMARY OF THE INVENTION
In accordance with the principles and concepts of the invention, there is provided a tool with safe and active areas that overcome the disadvantages attendant with the known prior art tools. In one embodiment, there is provided a tool for removing rough areas from a workpiece until the workpiece is smooth. The tool includes a safe area which, when engaged with the workpiece, does not erode or abrade the surface of the workpiece. The tool also includes an active area formed as a depression in the safe area. The active area has formed therein an abrasive mechanism for abrading rough areas of the workpiece that protrude therein. In one feature of the invention, once the active area functions to remove the rough areas of the workpiece, it no longer engages the workpiece surface, whereupon the safe area of the tool comes into contact with the smooth workpiece and further removal of the workpiece material is prevented.
In a preferred embodiment of the invention, a scaling tip is fitted into or attached to various forms of ultrasonic transducers utilized in the removal of calculus and roughness from teeth and other hard tissues. In such ultrasonic instruments, the ultrasonic energy can be transmitted from a generator of ultrasonic energy, such as a magnetostrictive pile or a piezoelectric element, to metal scaler tips of various standard shapes to access different areas of the tooth surface. The metal scaler tips may additionally be smooth or may contain grooves or ridges to channel coolant water to the end of the scaler tip.
In accordance with the invention, a scaler tip which can be of various shapes, includes a metal tip having one or more shallow depressions on the portion of the tip that contacts the tooth surface. Within these depressions is an active surface that has formed an abrasive or cutting surface. This active surface may include either a coating of abrasive material such as diamond grit, or a sharpened edge of the metal of the scaler tip. The diamond grit or sharpened edge does not extend above the smooth safe areas of the scaler tip. By limiting the areas covered by abrasive, the scaler tip of the invention is safe for use on the tooth surface and does not exces
Chauza Roger N.
Chauza & Handley LLP
Morgan Eileen P.
LandOfFree
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