Dentistry – Apparatus
Reexamination Certificate
2002-06-07
2004-11-23
O'Connor, Cary E. (Department: 3732)
Dentistry
Apparatus
C433S049000, C433S050000
Reexamination Certificate
active
06821115
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an apparatus for preparing at least one tooth for receiving a crown, bridge and the like. The tooth is prepared using a mould model at least including one model tooth. Crowns and bridges and other dental elements are used for the reconstruction of defect teeth and of gaps between teeth in human sets of teeth. A crown is used in combination with a single tooth, and a bridge is used to expend over a plurality of teeth.
BACKGROUND OF THE INVENTION
It is generally known in the art to reconstruct a tooth with a crown as follows:
The dentist first prepares the tooth to be reconstructed by grinding the tooth until a stub is received. Material of the tooth is removed to attain enough room for the crown. Grinding a tooth to form a stub requires substantial skills and concentration. Grinding is conducted by the dentist and in the mouth of the patient. Consequently, it is sometimes hard to correctly see the tooth, and reactions of the patient lower the quality of the preparation result. The required time for preparation is also influenced by the mouth anatomy, for example by adjacent teeth. After having prepared the tooth to form a tooth stub, a mould is produced in the mouth of the patient to attain a negative form corresponding to the tooth stub. The mould is then filled with plaster in a laboratory. Consequently, one attains a positive model, meaning a model tooth made of plaster. A technical crown is produced on this model tooth stub. The crown will be later placed upon the tooth stub, and it will be connected thereto using cement or different connection means. The exactness attainable with this known method is limited. Usually, extra work in the mouth of the patient is required. Especially, there may be problems in the region of the rim of the crown, meaning at the place where the crown closely contacts the natural tooth material.
A method of patient specific manufacture of and treatment with dental prosthetic work pieces is known from German Patent No. 44 43 921 C1 corresponding to European Patent No. 0 796 063 B1 and International Application PCT/EP95/04764 published under WO 96/17561. The method involves, first, taking an initial impression of the jaw to be treated including the checkbite in the mouth without earlier preparation steps. Then, a positive mould model of the jaw is produced followed by grinding of the mould model. The model in the resulting state is then stored by optical and/or mechanical scanning of the geometrical configuration of the mould model. Then, exclusively using the mould model, a crown or a bridge is produced in the known way. In the following, it is necessary to grind the natural tooth in the jaw of the patient using the stored data of the mould model, and to insert the crown or the bridge. In the known method, it is unclear in which way it is desired to attain a relation between the mould model and the tooth in the jaw of the patient. It is also unclear in which way the required intra oral milling unit is to be anchored and positioned, respectively, in the mouth of the patient.
SUMMARY OF THE INVENTION
The present invention relates to an apparatus for preparing at least one tooth for receiving a dental element such as a crown, bridge and the like using a mould model at least including one model tooth. The apparatus includes at least one positioning body, at least one parallelizing body, at least one mould spoon including threaded sockets and removable segments, at least one preparation base bar including sliding elements, at least one tub, at least one transmitting unit, at least one transport arm mechanism, at least one unit including position stabilizing arms, a plurality of model transfer bodies, and at least one copying grinding unit.
The present invention also relates to an apparatus for preparing at least one human tooth for receiving a dental element using a mould model at least including one model tooth. The apparatus includes at least one positioning body being designed to be inserted into an impression of a tooth to be prepared, a mould spoon including a spoon base and a plurality of segments and being designed to produce a mould model including at least one model tooth being designed to be connected to the positioning body, the segments being designed to be filled with a hardenable mass and being designed and arranged to be separately removable from the spoon base, the spoon base including a plurality of threaded sockets, at least one parallelizing body being designed to be placed upon the positioning body being connected to the model tooth to define a preparation axis, at least one preparation base bar being designed to be connected to the threaded sockets and including sliding elements, at least one transmitting unit being designed to be placed upon the parallelizing body and on the preparation base bar to transfer a reference plane perpendicular to the preparation axis to the preparation base bar, at least one tub being designed to be arranged on one of the threaded sockets to be filled with a hardenable mass, at least one transport arm mechanism being designed to be placed upon the transmitting unit and to align the plane of the preparation base bar to be parallel to the reference plane, at least one unit including position stabilizing arms and being designed to be placed upon the sliding elements, a plurality of model transfer bodies being designed to transmit a copying model of the prepared mould model to the mould spoon with positional accuracy, and at least one copying grinding unit being designed to grind the at least one tooth to be prepared scanning the copying model.
The present invention also relates to a mould spoon for producing a mould model of at least one human tooth to be prepared for receiving an dental element. The mould spoon includes a spoon base and a plurality of segments being connected to the spoon base, being filled with an impression mass, being designed to take an impression of the least one human tooth to be prepared and being designed and arranged to be separately removable from the spoon base.
The novel apparatus includes a plurality of elements and units. These elements and units are coordinated in a way to determine a preparation axis and a reference plane being located to be perpendicular with respect to the preparation axis. The elements and units of the novel apparatus are positioned and aligned in the reference plane and with respect to the reference plane, respectively. In this way, there is a family of parallel planes all being parallel with respect to the reference plane. The directions in these parallel planes are respectively maintained and transmitted to attain mutual orientation and to find, determine and find again the places at which process steps are to be conducted in an exact way. With the novel apparatus, it is possible to conduct most of the process steps outside of the mouth of the patient. Consequently, those process steps may be conducted at greater exactness and without negative influences by the patient.
The novel system includes a positioning body and an associated parallelizing body for each natural tooth. A common mould spoon or cast spoon with a mould base forms the base for this process. The preparation base bar and the sliding elements placed thereon are aligned and fixed to be parallel with respect to the reference plane. A tub serves to receive a copying model also being fixed in the tub with respect to the reference plane. A transmitting unit, a transport arm mechanism and at least one unit including position stabilizing arms for each tooth to be prepared serve to transmit the different parallel planes. Furthermore, the novel apparatus includes model transfer bodies to support the copying model at an exact position with respect to the preparation model at the mould spoon. Furthermore, the novel apparatus includes a copying grinding unit being designed and arranged to prepare the natural teeth, the copying model being used as a template. Exact positioning between the copying model and the natural teeth is impor
O'Connor Cary E.
Thomas Kayden Horstemeyer & Risley
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