Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2000-06-16
2002-05-07
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S213000
Reexamination Certificate
active
06382975
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a dental implant drill guide. The invention also relates to a dental implant superstructure.
BACKGROUND OF THE INVENTION
It is known in the art to secure dental prostheses using dental implants secured in the upper or lower jawbone. It is also known in the art to mount a framework or superstructure to a number of implants, the superstructure being used to evenly support a set of false teeth or denture prostheses. Accurate placement within the jawbone of the implants is a difficult task. In International Patent Application No. PCT/IT94/00059, published Nov. 24, 1994 as WO 94/26200, there is described an adjustable guiding device for positioning dental implants in which it is possible for the dental surgeon to adjust a drill axis for each implant before proceeding to use the guiding device or drill template to guide the surgeon's drill for the purposes of preparing the drill hole for the implant. The guiding device disclosed in the International publication helps the dental surgeon to decide on the drill axis after viewing radiographic images of the radio-opaque tubular drill guide superposed the bone structure.
In the known prior art, the oral surgeon typically has difficulty deciding on a drill axis for the implants since the ideal position for the implants should be decided with knowledge of the jawbone structure into which the implant is to be inserted, knowledge of the position within the jawbone structure of the nerve tissue, the gum surface and the required position and dimensions of the false teeth or dentures to be supported by the dental implant. Of course, in the conventional manner of selecting the implant axis, the dentist or dental surgeon simply makes a best guess in light of his knowledge of the patient. Of course, this leads, in certain cases, to imperfections in the dental prosthesis. The imperfections may be lack of ideal support, unfavorable angulation of an implant causing a weakness in the implant which may cause failure over time, or a visually perceptible defect in the appearance of the prosthesis.
In the conventional method for the construction of the superstructure, a physical model of the patient's gums and dental implant heads is prepared on which the superstructure is built manually using molding and other techniques known in the art. The craftsman or technician skilled at manufacturing such dental superstructures takes into consideration the size and shape of the desired dentures to be placed over the superstructure when crafting the same. The procedure for manufacturing dental implant superstructures as is conventionally known in the art is time-consuming and sometimes results in imperfect structures or defects in the visual appearance of the dentures to be placed over the superstructure.
In U.S. Pat. No. 5,401,170 granted Mar. 28, 1995 to Nonomura, there is disclosed a method and apparatus for measuring by camera image the implant heads of the implants in the patient's mouth for the purposes of cutting a frame on which the prosthetic teeth will be arranged and baked. In the method disclosed, the construction of the frame or superstructure is carried out in the absence of a reference to the shape and position of the patient's ideal teeth position. Thus, as the dentures or artificial teeth are crafted on the frame or superstructure, care would be required during the manual process to ensure that the position of the teeth on the frame will match the opposed set of teeth in the patient's mouth.
OBJECTS OF THE INVENTION
It is a first object of the present invention to provide a method of manufacturing a dental implant drill guide or drill template which will result in a precise and accurate drill guide for selected drill holes. It is furthermore an object of the present invention to provide a method of manufacturing a dental implant superstructure in which information concerning the position of a plurality of dental implants mounted in a jawbone, the gum surface covering the jawbone and the fixed denture shape is all taken into consideration during the specification of the shape of the superstructure before the superstructure is precision made.
It is yet another object of the present invention to provide such methods which provide better accuracy and faster results than conventional methods.
It is yet another object of the present invention to provide a dental implant drill guide which is precise and easy to use such that drilling of the dental implant holes does not require expert skill and knowledge beyond the skill of basic dental surgery. It is furthermore an object of the present invention to provide tools which will reduce the number of visits a patient needs to make to the dental surgeon in order to have dental implants and a dental implant superstructure inserted.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a method of manufacturing a dental implant drill guide, comprising the steps of: (a) imaging a jawbone and tissue structure with a reference to a gum surface to produce a three-dimensional computer graphics model; (b) selecting at least one implant drill hole position for at least one dental implant using the said mode, the position being specified in three dimensions, including a hole termination point and orientation, and being referenced to the gum surface reference; (c) entering at least one set of implant drill hole position coordinates into a CNC device; (d) providing a drill template body having a first surface for mating with a gum surface of the jawbone; and (e) using the CNC device to provide a fixed orientation drill guide socket in the template body for each one of the at least one drill hole positions entered in step (c) with a corresponding position and orientation.
According to a second aspect of the present invention, there is provided a method of manufacturing a dental implant superstructure having a plurality of dental implant abutting flanges and a gum tissue overlying bridge to which a dental prosthesis can be attached, the method comprising the steps of: (a) obtaining an image of a gum surface; (b) obtaining an image of dentures or teeth to be placed over the gum surface; (c) obtaining dental implant position data defining a position and angular orientation of a plurality of dental implants mounted in a jawbone covered by the gum surface; (d) referencing the gum surface image, the teeth or denture image and the implant position data with respect to a common frame of reference; (e) generating a computer graphics model of the gum surface, the dentures or teeth and the dental implants; (f) selecting a shape of the overlying bridge using the model and specifying shape data; and (g) entering the shape data into a precision superstructure manufacturing device.
In the method of manufacturing a dental implant drill guide according to the present invention, the patient is typically edentured, namely, the patient has had all teeth pulled from the jawbone, and the jawbone has been given time to heal since the teeth were pulled. If the patient decides to proceed with dental implants and the placement of a superstructure for solidly securing dentures over the gum, a period of about 12 months is provided for from the time of pulling any remaining teeth from the jawbone before proceeding with the operation of inserting implants into the jawbone.
A medical image of the jawbone and tissue structure is obtained by using x-ray imaging, MRI or possibly nuclear imaging techniques to produce a three-dimensional computer graphics model which has a reference to the gum surface or some other fixed reference with respect to the patient's jawbone. Preferably, a radiographic scanner guide is used which is molded to conform to the shape of the patient's gums and which includes radio-opaque spheres whose positions with respect to the gum surface is known.
The primary advantage of the invention is that the oral surgeon may select the optimum position for dental implants using the three-dimen
Anglehart James
Lewis Ralph A.
Swabey Ogilvy Renault
Technique d'Usinage Sinlab Inc.
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