Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2000-03-08
2001-05-08
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06227859
ABSTRACT:
TECHNICAL FIELD
The invention relates to a dental implant. The implant can be used as an intraosteal implant and can be inserted into the bone of an upper or lower jaw. A secondary part can be fastened to the implant to serve for holding, and/or for the construction of, a dental prosthesis, i.e., a prosthesis with a single artificial tooth or a number of artificial teeth. The implant can furthermore serve to hold a special superstructure forming, for example, an entire single artificial tooth.
STATE OF THE ART
A device disclosed in DE 41 27 849 A has an implant and a secondary or holding part. The implant has an axial blind bore with a polygonal section. The secondary part has a polyhedral section fitting into the polyhedral section of the blind bore. The polyhedral sections are configured as dodecahedral sections, so that the secondary part can be set selectively in any one of twelve positions, i.e., can be joined non-rotationally to the implant. In many cases, however, it would be desirable if the secondary part could be joined in only a single, clearly defined position to the implant. Also, the dodecahedral mating sections provide but a relatively imprecise definition of the rotational position due to the necessary clearance. The polyhedral section of the blind bore is rather long and extends all the way to the mouth of the blind bore, so that the secondary part is never held well and accurately above the blind bore. Also, the secondary part is glued into the implant and accordingly can no longer be removed from it.
A device disclosed in EP 0 685 208 A likewise has an implant and a secondary part. The implant has an axis and a bore coaxial with it which has a tapering section and an internal thread. The secondary part can be inserted partially into the bore in the implant and has an external thread which can be driven into its internal thread. The secondary part is rotated about its axis when it is screwed into the implant, until it contacts with a tapered section the tapered section of the bore. The rotational position in relation to the axis of the secondary part which results in the assembled state depends on the production tolerances and on the torque with which the secondary part is screwed into the implant. So this implant does not permit any precise setting of the rotational position of a secondary part reaching into the bore in the implant.
DE 195 34 979 C has disclosed a device with an implant and a spacer sleeve. The implant has an axial blind bore. Its inside surface is provided with six grooves distributed about the axis of the implant. The spacer sleeve reaches into the blind bore of the implant and has lugs engaging in its grooves, so that the spacer sleeve can be set in six different rotational positions. This implant thus does not define any single, definite rotational position. Also the spacer sleeve is guided laterally only in a short cylindrical guiding portion of the bore, which has a relatively small diameter, and is supported against forces directed approximately squarely to the axis of the implant. If such forces act on a dental prosthesis held by the spacer sleeve, a long lever arm is created between the point of attack of these forces and the guiding portion of the bore, so that very great torques must be transferred from the spacer sleeve to the implant in the guiding portion of the blind bore. This, combined with the small dimensions of the guiding portion, results in a great danger that the prosthesis under stress will perform small movements—so-called micromovements—with respect to the implant, and thus a failure of the dental treatment is caused.
BRIEF DESCRIPTION OF THE INVENTION
The invention is therefore addressed to the problem of creating a dental implant which eliminates the disadvantages of the known implants, and especially makes it possible to connect to the implant a secondary and/or superstructural part, depending on its shape and intended use, in only one, clearly defined rotational position or in one which can be selected from any of several possible rotational positions.
This problem is solved according to the invention by a dental implant with an axis and a bore coaxial with this axis for fastening a secondary and/or superstructural component, wherein the bore has a positioning section with projections and interstices alternating with one another around the axis, and the dental implant is characterized in that the interstices have a plurality of first interstices of equal size and a second interstice which in at least one direction has a larger dimension than the first interstices.
The invention further relates to a device with a dental implant and with a secondary and/or superstructural part, the device according to the invention being characterized in that it has a connecting section intended to reach into the bore in the implant and to be fastened in the latter.
Advantageous embodiments of the implant and the device will appear from the dependent claims.
The first and second interstices of the dental implant according to the invention make it possible to fasten to one and the same implant secondary and/or superstructural components of optionally different configuration, which, depending on their configuration, are able to assume only a single rotational position defined by the positioning section of the implant, or which can assume a rotational position selected from several possible rotational positions, or whose rotational position is not defined by the positioning section.
The implant is preferably elongated and generally rotationally symmetrical with its axis. The bore is preferably a blind bore and has a mouth situated at one end of the implant. Each interstice of the implant is preferably straight and parallel as well as symmetrical with a plane passing through the said axis and through the middle of the groove in question. The positioning section of the implant is furthermore generally cylindrical, for example, so that the projections present between the interstices of the implant have an apex lying in a cylindrical surface coaxial with the axis. The positioning section of the implant, however, can possibly be generally conical instead of cylindrical, narrowing away from the mouth of the bore, and can have projections which separate the interstices from one another and have apexes lying in a conical surface.
The positioning section of the implant preferably defines a pitch circle, both in the case of generally cylindrical and in the case of generally conical shape, which is coaxial with the axis and conforms with the apexes of the projections of the implant. In a preferred embodiment, the second interstice is wider and/or deeper than the first interstices. The first interstices adjacent one another are at equal distances apart as measured along the pitch circle, and together they define a pitch circle division or—simply—a division. For clarification let it also be noted that the division is equal to the nth part of a full circle, n being a whole number and preferably at least 6, or better at least 10, and amounting to no more than 72, for example. The second, wider and/or deeper interstice has a dimension measured along the pitch circle that is preferably greater than one division, for example approximately or exactly equal to the sum of the dimension of a first interstice measured along the pitch circle and of one whole division or several whole divisions.
A secondary part designed to be fastened to the implant can have an inside section or connecting section, and an outside or head section. When the secondary part is fastened to the implant the inside or connecting section is situated in the bore in the implant and the outside or head section outside of the implant. The secondary parts can be configured differently according to the intended use and the medical indications. The inside or connecting section of the secondary part can have, for example, a positioning section with projections distributed along its circumference, and separated from one another by interstices. When the secondary part is fastened to the impl
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Lewis Ralph A.
Sutter Franz
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