Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2000-03-31
2002-06-04
Wilson, John J. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S181000
Reexamination Certificate
active
06398553
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a T-plate for detachable fixing of false tooth components to one another or to the remaining teeth, with a female part that displays a recess, a male part that displays an attachment section that can engage the recess in the female part and a continuous slot, which slot extends at least through the attachment section and divides this into two parts, and a spreading device that spreads the two attachment parts and displays a first spreading means arranged in the slot and situated in engagement with both attachment-section parts.
In such a T-plate the spreading means serves to produce a frictional engagement between the male part and the female part by spreading the two attachment-section parts of the male part, which parts are separated by the slot, whereby the male part is fixed to the female part.
Such a T-plate is known from EP 0 239 821 A1, in which the spreading means is formed by a screw with a cone arranged in its shaft region, which screw is insertable into the slot in a manner parallel to the base of the slot and thus in the longitudinal direction of the slot, so that when the screw has been driven in, the cone is located in the central region of the slot.
Disclosed in DE 196 11 354 A1 is a further T-plate that likewise displays a conical screw as a spreading means. In this known T-plate the cone is formed by the head of the screw and the screw extends through the slot transversely to the base of the slot and thus perpendicularly to the slot, and is situated with its free end in a screw engagement with an anchoring element attached to the removable false teeth.
With the known arrangements, it has proved to be disadvantageous that the spreading of the fixing-section parts that are separated and spaced apart by the slot is not parallel over the length of the slot and thus over the length of the fixing section. This leads to a frictional force that is unevenly distributed over the length of the fixing section. That is, with increasing distance from the spreading means the clamping force decreases considerably, which has a negative effect on the clamping characteristics of the fixing section and thus on the reliability of the holding of the male part on the female part.
SUMMARY OF THE INVENTION
It is thus the object of the present invention to increase the reliability of the clamping hold in a T-plate of the type specified in the introduction.
This object is achieved in a T-plate of the type specified in the introduction by the fact that the spreading device displays, in addition to the first spreading means, at least one second spreading means arranged in the slot at a distance from the first spreading means.
By means of the additional arrangement, according to the invention, of least one additional spreading means, an essentially parallel spreading can be realized, and consequently a distinctly more uniform distribution of the frictional force over the length of the attachment section compared to the prior art, so that even at the ends of the slot the frictional force is not significantly less than at the middle of the slot, but rather is approximately equally great. In doing so, the invention makes use of the knowledge that although the attachment-section parts that are separated by the slot must be elastic in order to be spread apart, this elasticity, however, leads in turn to an undesired flexibility of the attachment-section parts, which flexibility is greater the greater is the distance from the spreading means, and precisely this effect is responsible for the undesired reduction of the frictional force. The flexibility that leads to the lessening of the frictional force is henceforth reduced according to the invention through the arrangement of at least one additional spreading means, without the loss thereby of the elasticity of the attachment-section parts, which elasticity is necessary for the spreading of the attachment-section parts and thus for the production of the desired frictional force. Thus, by means of the invention a frictional force is generated that over the entire length of the slot, or rather of the attachment-section parts of the male part, possesses essentially the same, desired strength, whereby a more effective and reliable clamping hold is realized in comparison to the prior art.
Since precisely the ends of the attachment-section parts are especially flexible, the first spreading means is preferably to be arranged at one end of the slot and the second spreading means at the other end of the slot.
Appropriately, the spreading means should be insertable into the ends of the slot.
An embodiment of the invention that is particularly preferable at present is distinguished by the fact that the spreading means are designed in each case as an axially movable cone. Through the use of cones as spreading means, the desired spreading of the attachment-section parts can be realized in an especially easy manner, since with an axial movement of the cones in the direction of their pointed or narrow ends, the cones come to lie against the inner surface section of the slot and with continued movement act as wedges and widen the slot.
Here, the cones are preferably to be pointed in opposite directions and the spreading arrangement to display a coupling device that effects a movement of the two cones in opposite directions.
In a further development of this embodiment, the slot is widened and in each case displays a section forming a hollow space essentially corresponding to the cones, in which space the cones are arranged.
Appropriately, the cones should be insertable into the slot with their narrow ends and at least one end of the slot widened into a section forming a cone-shaped hollow space that essentially corresponds to one of the cones.
An especially simple and thus effective and advantageous construction of the coupling means can be realized through designing the coupling means as a threaded bolt, in which case the desired axial movement of the cones can be effected through turning the threaded bolt. The threaded bolt should display a head that is formed by the first cone, and the second cone should be designed as a nut that can be screwed onto the threaded bolt, whereby the two cones are oriented with their pointed ends towards each other and therefore arranged so as to be correspondingly movable towards each other. In addition, this construction forms an arrangement that is especially easy to operate, since the threaded bolt is inserted with its free end into one end of the slot and at the other end of the slot is arranged the cone-shaped nut, into which the free end of the threaded bolt screws; through the turning in and tightening of the threaded bolt the two cones come into contact with the corresponding inner surfaces of the slot and widen the latter, which leads to the desired parallel spreading of the attachment-section parts and thus to the production of a friction of the attachment-section parts of the male part in the recess of the female part, which friction is essentially uniform over the length of the attachment-section parts. Of course, as an alternative both cones can, for example, be designed as nuts that can be screwed onto the threaded bolt.
Finally, the slot in the attachment-section parts of the male part is to be formed so deep that it not only divides the attachment section, insertable into the female part, of the male part into two parts, but also divides a section of the male part that borders the attachment section. In this region of the male part, and thus outside the attachment section, the spreading means are preferably to be arranged. As a result the attachment-section parts are not so rigid and enable an improved insertion of the male part with the attachment section into the recess in the female part, whereby a possible premature wearing out is avoided and an optimal fit and level of friction are ensured.
Conventionally, an anchoring element is fixed to the male part. Preferably, on the male part a longitudinal ridge can be formed, onto which the anchoring element is pushe
Altera Law Group LLC.
Rubeling Gunter
Wilson John J.
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