Dentistry – Method or material for testing – treating – restoring – or...
Reexamination Certificate
2000-10-31
2001-11-20
O'Connor, Cary E. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
C433S075000
Reexamination Certificate
active
06319006
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for producing a drill assistance device in order to precisely place a pilot hole for a tooth implant, wherein the pilot hole for the tooth implant is aligned relative to the teeth that still remain in the jaw.
WO 99/32045 discloses a method for producing a dental drill assistance device for tooth implants. In accordance with such method, a three-dimensional computer image is modeled using an image of the jaw relative to an imprint surface. With the computer graphics generated in this manner at least one bore hole position is determined, with the bore hole position being specified in three dimensions, including the bore hole end point and the bore hole length in relation to the jaw imprint. Subsequently, at least one set of implant bore hole coordinates is fed into a computer-controlled precision machine tool. Envisioned on a drill body is a first surface which corresponds with the imprint surface of the jaw. Using the precision machine tool, a drill guide base is prepared inside the drill body for each of the previously entered sets of bore hole coordinates with the corresponding bore hole position and bore hole orientation previously determined using the section of the jaw.
According to this known method the position and the orientation of the bore hole are determined by way of an imprint that is taken from the jaw bone. When placing tooth implants the shape and the size of the implant is exactly planned using x-ray pictures. The implant position in the jaw is predetermined with as much precision as possible. In use are drill templates which are intended to allow the placement of an exactly positioned bore hole. Ordinarily it is difficult, however, to determine the position of a pilot hole exactly during the drilling process because the information that is contained in the x-ray cannot be exactly transferred to the optical images which the physician sees while drilling. The physician relies on experience, in particular with respect to the position and the path of the nerve tracts that run along the jaw bone. Thus, we have the unsatisfactory result that, on the one hand, the implants are planned and manufactured very exactly and precise to the last detail but, on the other hand, their positioning in the jaw area has been effected to date on the basis of individual experience, which can vary considerably among different dentists.
A method and an apparatus for the localization of tooth implants and a device for the allocation of coordinates became known in the art from German published patent application 197 25 197. This method and apparatus for the localization of tooth implants process metrologically collected anatomical data reflecting the nature of the jaw bone of the respective patient. Based on the stored data sectional drawing information is generated which is used to define the implant location. Using an allocated reference system of coordinates, the actual bone geometry, the metrological information, the design of a plaster model of the jaw and the geometry of an operational assistant template can be placed in relation to one another with such a level of precision that a highly accurate placement of a bore hole in the jaw bone, which will receive the tooth implant, is supported. The transfer of the respective coordinate information to the assistance devices and processing installations that are in use is supported by a mechanical transfer element, which can, for instance, have an arc-shaped design containing an adapter that can be introduced into the mouth of the patient.
Other processes for implant bore holes in the jaw are known from U.S. Pat. No. 5,888,065 which forego a precise determination of the pilot hole position altogether.
SUMMARY OF THE INVENTION
Based on the problem outlined above and the solutions known from the state of the art, it is the object of the present invention to provide a drill assistance device that will allow the exact drilling of a pilot hole for a tooth implant in relation to the teeth that still remain in the jaw.
In accordance with the invention this objective is achieved by carrying out the following process steps during the production process for a drill assistance device for a tooth implant:
The taking of x-ray pictures of the jaw and the compilation of corresponding measured data records;
The generation of three-dimensional optical measuring data of the visible surfaces of the jaw and teeth and the compilation of a corresponding data record;
The correlation of the measured data records from the x-ray picture and of the measured data records from the three-dimensional optical measuring;
The planning of the implant type and of the implant position (location, angle), preferably using the x-ray data;
The calculation of the position (location, angle, depth) of the implant pilot hole relative to the recorded surfaces of the neighboring teeth;
The production of a drill template containing the negatives of the surfaces of the adjacent teeth and featuring an opening located at a predetermined location.
Using the method according to the invention, the x-ray and the actual optical proportions inside the patient's mouth are interconnected by linking the two images in such a way that a drill assistance device in form of a drill template can be made available which contains the pilot hole that is necessary for fastening the implant in its optimal position, based on the location of the neighboring teeth. The dentist heeds the support that is provided by the drill assistance device for the pilot hole and thus ensures that the nerve strands running inside the jaw, whose position cannot be derived from the three-dimensional surface measurement but is known nevertheless from the x-ray, will not be disturbed.
Further in accordance with the invention the x-ray can be a panoramic tomography picture, a tomosynthetic image or an image produced by means of computer tomography. Preferably the occlusal surfaces of the remaining teeth that are adjacent the implant are measured by the three-dimensional optical measuring of visible surfaces. Based on the correlation of the measured data records of the x-ray and of the measured data records of the three-dimensional optical image the visible proportions as well as the proportions that are not visible to the human eye, i.e., for example, the nerve paths, in the implant area become known and consequently allow the safe placement of a pilot hole into the jaw.
To correlate the x-ray picture with the three-dimensional optical image of the visible structures it is possible to use markers. These markers, for instance, they can be ball-shaped bodies, are visible on the x-ray as well as on the three-dimensional optical image of the jaw. By superimposing the markers the user can easily generate an interactive correlation of the x-ray picture and of the three-dimensional optical image of the visible structures.
Correlating the measured data records of the x-ray picture and of the three-dimensional optical image can also be accomplished if measured data records of the three-dimensional optical image are converted to pseudo-x-ray pictures, assuming standard x-ray absorption values. Looked at from several directions it is possible to bring the actual x-ray and the pseudo-x-ray to overlap, for example by way of longitudinal and transverse sections of the panoramic x-ray picture. A correlation can also be achieved if, at least in part, the surface shapes are extracted from the x-ray pictures as they are recorded in the optical image, and then they are superimposed with the data of the optical image. This can be accomplished automatically or interactively.
Based on the x-ray data the implant can be determined and positioned in ways that are known in the art. Using the information that was obtained with respect to the surface structure, i.e., the occlusal surfaces of neighboring teeth, it is possible to grind out on a CAD/CAM unit an implant assistance device in the form of a drill template. The shape of the still remaining adjacent teeth is represented as a negative
Pfeiffer Joachim
Scherer Franz
Dykema Gossett PLLC
O'Connor Cary E.
Sirona Dental Systems GmbH
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