Fuel and related compositions
Patent
1993-02-05
1995-01-31
Hirsch, Paul J.
Fuel and related compositions
433 64, A61C 1100
Patent
active
053854705
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a articulator for simulating jaw movements, comprising an upper and a lower part for carrying an upper-jaw and/or a lower-jaw model and connected by joints permitting one or more swivelling and linear motions. The invention also relates to a face bow comprising a curved transfer member surrounding the face and for transferring and fitting a model jaw in the correct spatial orientation relative to the skull in an aforementioned jaw articulator; the end regions of the transfer member are equipped with scanners for locating the pivot axis of the hinge of the jaw, in order to attach it to the transfer member at the reference points of the hinge axis.
BACKGROUND ART
Devices of this kind are known in dental technology (compare W. Hoffmann-Axthelm "Lexikon der Zahnmedizin", Quintessens-Verlags GmbH Berlin, 1983; "Einfuhrung in die Zahnersatzkunde", Verlag Urban und Schwarzenberg, 1975).
The jaw articulator is for simulating movements of the hinge of the jaw when dental and jaw models are inserted, and the articulator can practically completely simulate the motion of the jaws relative to one another outside the mouth. The main problem in jaw articulation is to provide an average simulation of substantially all movements of the human lower jaw relative to the upper jaw. Articulators known for this purpose have very many adjustment facilities. The adjustment is made in accordance with a pantographic (three-dimensional) recording of the individual movements of the patient's lower jaw made by the dentist. The recording is lengthy and expensive, taking about 2 to 3 hours for obtaining the information from the patient. The subsequent programming of the articulator in accordance with the pantograph takes about 3 to 5 hours.
In other known articulators, the slope of the joint path is adjustable in the sagittal direction. The motion of the condyle can also be limited, i.e. adjusted, in the transverse direction (Bennett angle). The parts of the joints in these simulators, known as Arcom articulators, are designed in accordance with anatomical conditions, i.e. the condyles are disposed on the lower part of the articulator and the condyle casing or joint box with the device for adjusting the Bennett angle are disposed on the upper part of the articulator. However, these known articulators enable the respective ball or condyle to move laterally only; in which case the straight track of the second joint box or condyle moves in the median direction. Furthermore the balls are tightly encapsulated in their boxes, and consequently do not have degrees of freedom for components of motion in other directions.
SUMMARY OF THE INVENTION
Accordingly the invention is based on the problem of constructing an articulator having sufficient reserves for motion of the jaw, in order to model a dental prosthesis which is comfortable for the patient to wear and is physiologically compatible. To this end, as proposed according to the invention in the case of an articulator having the initially-dimensioned features, in the joint the lower part is guided relative to the upper part in one or more directions comprising components of motion in the cranial and/or dorsal direction and corresponding to surtrusion and/or retrusion.
This guidance of the lower part of the articulator relative to the upper part in the joint permits average Bennett motions backwards or retrusively and/or upwards or surtrusively when modelling dental prostheses. This is a method of eliminating errors in simulating the occlusion of the upper or lower jaw; such errors would otherwise necessitate careful regrinding by the dentist and might possibly damage or destroy the entire masticatory system.
DETAILED DESCRIPTION OF PRINCIPLES OF THE INVENTION
In an embodiment of this inventive idea, the joint is formed with one or more linear guides which deviate surtrusively and/or retrusively from the direction of a common hinge-like axis connecting the joints. Angles of about 13.degree.-17.degree., more particularly 15.degree., have b
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Foster Frank H.
Hirsch Paul J.
Lucchesi Nicholas D.
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