Dentistry – Apparatus – Having gauge or guide
Reexamination Certificate
2001-09-06
2004-01-06
Shaver, Kevin (Department: 3732)
Dentistry
Apparatus
Having gauge or guide
Reexamination Certificate
active
06672869
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a plug connection for jaw stump models for the releasable securing of tooth crown segments or jaw segments to a model base, with a plug pin and a sleeve.
2. Description of the Related Art
In the context of dental treatment, if it is necessary to replace one or more teeth, or possibly even the replacement of a jaw segment, then the implants provided need to be specially manufactured and adapted for the patient in each instance. For this purpose, a dental impression of the patient is often produced, which then serves as an initial mold for a jaw stump model. This jaw stump model is an identical reproduction of the patient's set of teeth. The region which is to be replaced in the patient's oral cavity by the implant, for example a tooth crown segment, is removed from the model. A prefabricated implant blank can then be adapted step by step to the model, until it obtains the shape required for the patient's treatment. The implant, which is specially prepared in this manner for the patient, can then be operatively secured in the oral cavity of the patient, without the need for complex preparation of the implant or secondary working.
For the adaptation of the implant to the jaw stump model, which precedes the surgical intervention, it is first necessary to secure the implant to the model. However, it is almost always necessary, during the course of the step by step adaptation and secondary improvement, for the implant to be removed from the model several times, and then secured to the model again. In this respect, it is necessary to ensure that the implant is secured to the jaw stump model again in exactly the same position following each interim removal. Otherwise, it would not be possible to precisely adapt the implant to the model and therefore to the patient.
For this reason, it is known to secure plug pins in the implant, by means of which the implant can be fitted into corresponding bores in the model. However, given that the model may be made of plaster, for example, there is a risk of the bores becoming damaged during each securing or removal of the implant as a result of material wear, so that precise positioning of the implant is not guaranteed on a long-term basis.
Plug connections are described, for example, in Laid-Open Specification EP 0 335 285 A2, which, in addition to a plug pin, also comprise a sleeve which is embedded in the jaw stump model. The sleeve is made of sufficiently resistant material, such as metal, and prevents possible damage to the jaw stump model by the plug pin.
Because a rotationally symmetrical plug connection of this type cannot prevent rotary movements of the implant about the pin axis, additional measures are required for reliable and reproducible securing of the implant to the jaw stump model. Thus, it is known to prevent a rotary movement of the implant by means of two plug connections fitted adjacent one another (DT 26 25 950 A1). However, this is associated with a high labor outlay, and requires a large amount of space, which is not always possible or tenable.
If the sleeve and the plug pin are not aligned exactly axially parallel in plug connections of this type, then the plug pin often tilts in the sleeve during securing and removal of the implant from the model. The resulting stresses can damage both the jaw stump model and, in particular, the securing of the plug pin in the implant, which can result in a loss of precision in the manufacture of the implant. The more plug connections used for an implant, in order, for example, to rule out rotary movements of the implant, the higher the requirements for exact alignment of the plug connections in order to prevent stresses or tilting.
In a known plug connection (DE 43 00 926 A1), the plug pin has a slightly conical design, so that sufficiently secure positive and frictional locking between the plug pin and the sleeve is only produced once the plug pin has fully penetrated the similarly conically tapering sleeve. By means of knob-like raised elements on the inside of the sleeve, made of plastics material, the retaining force of the plug pin in the sleeve can be increased. However, here, too, a secure connection of the plug pin in the sleeve is only guaranteed in the case of an exact axially parallel alignment of the two parts. In addition, in order to prevent a rotary movement of the implant, it is necessary to secure the latter to the model by means of at least two plug connections of the above type.
Ever advancing developments in dental medicine, in the use of implants, demand increasing precision in the manufacture and adaptation of the implants. As a result of the constant and high loading of a fitted implant in the oral cavity, for example during chewing, a best-possible adaptation of the implant to the respective patient is a prerequisite for a secure connection of the implant to the jaw of the patient which can withstand these stresses on a long-term basis.
It is therefore an object of the invention to design a plug connection for jaw stump models, of the generic type, so that a reliable and easily releasable securing of the implant to the model base is possible, rotary movement of the implant about the axis of the plug connection being eliminated. Furthermore, stresses and tilting of the plug pin in the sleeve are eliminated, even in cases where the two parts are not aligned exactly axially parallel.
SUMMARY OF THE INVENTION
This and other objects are achieved according to the invention, in which the plug pin is connected in a snap-locking fashion with the sleeve, and in which rotational locking prevents rotary movement of the plug pin in the sleeve.
The present invention thus relates to a plug pin, connected in a snap-lock fashion with the sleeve, whereby rotational locking prevents a rotary movement of the plug pin in the sleeve. A snap-lock connection of the plug pin and the sleeve results in a sufficiently stable securing of the implant to the model base. Consequently, the plug pin can be constructed in such a manner that it can be introduced almost fully into the sleeve with a clearance significantly facilitating handling. Only in the end position prescribed by the snap-lock connection is the plug pin fixed in a predetermined position. In order to remove the implant, it is only necessary to release the snap-lock connection between the plug pin and the sleeve. The plug pin can then be fully withdrawn from the sleeve, without thereby generating stresses or without the danger of the plug pin tilting with the sleeve. As a result of this snap-lock connection, a uniform penetration depth of the plug pin in the sleeve is automatically ensured. Only once the implant is arranged in the provided position on the model base is the snap-locking connection between the plug pin and sleeve produced.
As a result of the rotational locking, a rotary movement of the plug pin in the sleeve is ruled out. Consequently, it is possible, using a single plug connection, to prevent rotary movement of the implant secured to the model base. Additional plug connections are therefore unnecessary. In addition to resulting in a saving in labor and materials, this also means that a plug connection of this type can also be used in the case of very small implants having a small contact surface area with the model base.
The maximum penetration depth of the plug pin in the sleeve is defined by an abutment. An abutment of this type can be provided using simple means in manufacturing technology, for example by the length of the plug pin or a projection projecting radially from the plug pin. In this manner, in addition to the snap-locking connection, the maximum penetration depth of the plug pin in the sleeve can be reliably and precisely determined using little outlay.
According to an advantageous embodiment of the inventive idea, the plug pin comprises, at its end facing the sleeve, a spring element with recesses for a snap-locking connection with the sleeve. When the plug pin is introduced into the sleeve, the spring elemen
Birkholz Ulrich
Hentschel Wilfried
Kremer Egbert
Rabenstein Norbert
Bumgarner Melba
Shaver Kevin
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