Dentistry – Apparatus – Tool bit
Reexamination Certificate
1999-04-28
2001-01-30
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Tool bit
Reexamination Certificate
active
06179616
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a dental drill. More specifically, the present invention relates to a dental drill having a shaft and a cutting portion with cutting edges.
2. Background Information
In the dental field, drills are commonly used, among other things, for drilling out fillings in teeth. In many cases the fillings consist of amalgam which contains a high amount of mercury. When such fillings are drilled out, minute mercury-containing particles or pieces are formed. These minute mercury-containing particles or pieces may be swallowed by the patient, as well as mercury vapors which may be inhaled by the patient and/or the dentist, possibly resulting in mercury poisoning. Hence, in the case of conventionally used drills, there exists a risk that patients and dentists might be exposed to a high mercury load.
Moreover, as for dental preparatory techniques, it is important that as little as possible of the healthy tooth material be removed while the fillings are being drilled. As a result, the tooth is just damaged to the necessary degree on the one hand and the subsequent treatment of the tooth is facilitated on the other hand, since the existing healthy tooth material remains to a maximum degree.
German Publication DE 195 02 030 A1 already discloses a drill for metal working in which two main cutting edges are provided at the front side converge in the central axis and pass into two secondary cutting edges of a cutting portion on their radially outer end portions. The cutting portion does not comprise any additional cutting edges.
In view of the above, there exists a need for a dental drill which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a dental drill which while having a simple structure and being easy to handle can be produced at low costs and permits a rapid drilling of fillings with little strain on the patient.
According to the invention this object is achieved through the features of the main claim. The subclaims show advantageous developments of the invention.
Hence, according to the invention a dental drill is provided with a shaft and a cutting portion equipped with cutting edges. At the front side the dental drill comprises two main cutting edges and a transitional cutting edge. Several additional cutting edges are arranged laterally on the cutting portion or head. The main cutting edges of the dental drill converge in a central axis of the dental drill and directly pass into two lateral cutting edges. In an advantageous embodiment the main cutting edges form a tip or a transitional cutting edge which is semicircular when viewed laterally.
The dental drill of the invention is characterized by a number of considerable advantages. Due to the fact that the two main cutting edges are arranged at the front area of the cutting portion, the drilling performance of the dental drill in the axial direction is excellent. Since the two main cutting edges are advantageously configured such that they converge and meet at the central axis of the dental drill, the drill cuts across the whole area of the main cutting edge. This means that the inventive drill need not comprise any transverse cutting edge. As a consequence, the disadvantageous effect of the transverse cutting edge, which normally interconnects the, two main cutting edges and only squeezes the material to be drilled in the area of the transverse cutting edge can be avoided. As a result, the dental drill exhibits excellent cutting effects and fillings can be drilled out very rapidly. Since at least two additional cutting edges into which the two main cutting edges directly extend are provided laterally on the cutting portion, a dentist can also remove filling material by preparatory techniques exploiting lateral contact. Hence, the dentist in sectioning the filling can produce relatively large pieces of material, which can then be sucked off from the patient's mouth in an easy and reliable manner e.g. by means of a suction device or can be removed from the mouth by rinsing the same. The risk that drilled filling material will be swallowed by the patient can thus be considerably reduced.
The lateral cutting edges are advantageously arranged along helical lines. As a result, the lateral cutting portion can be produced relatively easily and an adequate transverse cutting force is imparted to the drill to remove material in a time saving manner by way of a preparatory technique exploiting lateral contact. Such an arrangement also helps to suppress vibrations and the occurrence of drilling noise.
Advantageously, the lateral cutting edges comprise radial incisions. As a result, the friction on the lateral area of the drill is reduced, resulting in less frictional heat and thus a smaller amount of mercury vapor. Hence, in particular in amalgam fillings the mercury load on the patient and the dentist due to mercury vapors can be minimized. The production of frictional forces can be influenced at the lateral cutting edges by identical or different distances of the individual sections and can thus be optimized in a simple manner for the respective demands, e.g. different depths or sizes of the fillings.
To keep the amount of heat produced by the lateral cutting edges as small as possible, the incisions are arranged on the lateral cutting edges relative to a line perpendicular to the central axis at an angle ranging from 5° to 15°. Hence, the incisions of the individual lateral cutting edges are arranged in offset fashion in the longitudinal direction of the dental drill.
In a preferred embodiment the dental drill comprises four lateral cutting edges and four helical grooves. As a result, the production of relatively large pieces of material can be ensured while fillings are being drilled. At the same time, a high removal rate is achieved, so that a filling can be drilled out within a short period of time. This saves time during treatment and also shortens inconvenient situations for the patient, e.g. the mouth need no longer be kept open for long periods of time. Hence, optimum cutting parameters and minimum strain on the patient can be achieved.
Hence, the use of the drill according to the invention results, in particular, in economic advantages due to a shorter treatment time and a longer service life.
To ensure a high cutting performance, the lateral cutting edges are shaped as a staggered or diamond toothing according to a further embodiment of the invention. During the drilling operation relatively large pieces of the filling are thereby produced and the occurrence of mercury vapors is minimized. Technical preparatory work by lateral contact in virtually all positions of the drill relative to the tooth or filling is also made possible thereby. Hence, such a drill is particularly suited for drilling fillings in mouth areas, which are difficult to reach.
Depending on the intended use, the main cutting edges are straight or curved. Thus, different advantageous geometries can be ensured for the cutting portion and, in particular, for the front side of the cutting portion. Depending on the intended use or type of filling, a drill according to the invention can thus have an optimum geometry.
The drill according to the invention may have different shapes; it may e.g. be provided with a cylindrical or tapering cutting portion or with a cylindrical or tapering shaft. For instance, cemented carbide, stainless steel or tool steel may be used as the material for a dental drill according to the present invention.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.
REFERENCES:
patent: 3443459 (
Bumgarner Melba
Gebr. Brasseler GmbH & Co. KG
Shinjyu Global IP Counselors, LLP
Wilson John J.
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