Not applicable
The present invention relates generally to dental devices used to assist the dental practitioner in measuring critical features in the design of prosthetic teeth.
The devices and procedures of the present invention are advantageous to dental professionals, particularly gnathologists, restorative dentists or a dentist working with dental technicians to create models and prosthetic teeth. Gnathology is the study of the masticatory system, including its physiology, functional disturbances, and treatment. Because it is not part of regular dental school training at present, most learn by participating in “study clubs” with experienced mentors. Gnathology requires extremely accurate dentistry.
At present, there are several devices and methods used to measure features of a person's face to create symmetric and functional prosthetic teeth e.g. crowns, veneers and dentures. The lack of a straightforward and accurate system for adapting individual features of a patient's face, mouth and teeth is a source of frustration for dentists, dental technicians and patients. The present invention is a system to assist the dental technician in fabricating the appropriate dental prostheses and is intended to eliminate the necessity of having to reproduce the dental prostheses after they have been fabricated because they do not fit well or are not aesthetically pleasing. The challenge for the dental professionals and technicians is that faces, teeth, and skulls are not completely symmetrical and vary substantially from patient to patient.
A facebow is a device which is used to translate the relationship between the upper jaw and axis of rotation of the lower jaw to a dental articulator. The facebow typically has a sliding adjustable stylus which is positioned on each temporormandibular (TMJ) joint. The facebow measurements are generally used to establish a relationship between the maxillary arch and the center of rotation of the (facial) condyles. A condylar joint is a modified biaxial ball and socket joint in which the joint surfaces are elongated or ellipsoidal. The center of rotation of the condylar joint is determined by rotation of the medial pole of the condyle rotating against the triangular glenoid fossa in the skull.
The facebow measurements are then transferred to a dental articulator to enable the articulator to simulate the movement of the jaw with the prosthetic teeth. The facebow includes a bite fork which is held by the anterior maxillary (upper front) teeth of the patient. The bite fork enables the dental professional in the measurement of the incisal plane angle. In fabricating the prosthetic teeth, the bite fork is usually mounted on the lower frame of the dental articulator in a position to receive the upper dental cast of the patient's teeth.
An earbow is an instrument which allows the dental professional to relate an upper arch or an upper cast to an anatomic average position of the condylar or axis of the TMJ using the ear hole, rather than the center of the axis of rotation of the TMJ.
The prior art procedures are somewhat complicated and time consuming, in some instances requiring a number of components which should be sterilized before each use. As a result, many dental practitioners do not use the dental articulator but instead, may try much less accurate techniques. Even when the dental articulator is used, prior art devices often use arbitrary measurements.
For example, in Lindekugel U.S. Pat. No. 6,152,732, the bite fork is oriented by measuring 43 millimeters above the lateral incisor edge on the right; central or lateral incisors which are used as a third reference point. The first reference point in prior art procedures is positioned just underneath the right eye of the patient. The location of the reference point is typically noted by a mark, such as an ink mark on the patient's face. The facebow in the other prior art procedures has a reference pointer which swings inwardly towards the patient's face to the reference point underneath the patient's eye. The patient can be disturbed by this motion which often results in inaccurate facebow placement since the patient frequently moves in response to the use of the pointer.
Further, many prior art procedures use a true hinge axis facebow such that the articulator is oriented to the hinge axis plane rather than the interpupillary line. The patient's jaw or hinge axis is rarely, if ever, parallel to the interpupillary line. It is difficult to use the hinge plane axis as the reference line to create the most pleasing, symmetrical and esthetic smile line. The objective of the present invention is to provide unique tools to make the necessary measurements with simplified procedures to create functional and aesthetically pleasing prosthetic teeth. A further objective of the present invention is to create an ideal smile line following the esthetic curve of the lower lip during a full smile. An aesthetic ideal can be achieved by creating anterior teeth with an incisal edge and a smile line which is related to the interpupillary line or the inner canthus line.
In order to systematize the process and make accurate measurements in accordance with the present invention, it is necessary to determine the line made by connecting the pupil of each eye which forms the interpupillary line. The interpupillary line is used as the reference plane from which the angle of the incisal plane is measured. A second line, the incisal line, is the line which intersects the bottom of both incisors. The incisal line is approximately parallel to the interpupillary line, but it is seldom completely parallel in people. The inner canthus line may also be used as a reference. The canthus is where the upper and lower eyelids meet near the bridge of the nose. The inner canthus line is formed by drawing a line through the inner canthus of each eye.
The dental professional takes an ear bow or facebow measurement of the patient's face. The earbow has an arm which is generally parallel to the interpupillary line and a bite fork which is attached to the arm. When the facebow or earbow is mounted to any semi-adjustable or adjustable articulator, it will orient the upper and lower member of the articulator holding the molded jaw and teeth such that they are parallel to the interpupillary line.
The smile guide shown in
The most pleasing smiles (and faces) are symmetrical: the incisal lines of the upper front teeth should be parallel to the interpupillary line and the midline of the central incisors is perpendicular to the interpupillary line. [The midline is the line between the two central incisors] The smile guide is very effective in determining the measurements of the incisal lines in relation to the interpupillary line and how the midline is aligned in relation to the interpupillary line. In cases where the patient's smile does not fall within the pleasing smile standards and is unattractive, the smile guide can relate the degree of tilting of the incisal line and the midline with respect to the interpupillary line.
Using the facebow of the present invention, the adjustable side arms are placed on the hinge axis points on each side of the face and to a selected third reference point of the patient. A first reference rod is attached to the bite fork and is horizontally oriented across the face. A second reference rod is perpendicular to the first reference rod (vertically oriented to the face). The upper portion of the second reference rod is placed at the selected third reference point. A third reference rod or the interpupillary line indicator is removeably connected perpendicularly to the second reference rod. The interpupillary line indicator is adjusted with a stylus so that it coincides with the patient's interpupillary line and the device is locked into that position. The facebow is mounted to either the fully adjustable articulator of the present invention or the conventional semi-adjustable articulator. The semi-adjustable, conventional articulator is used with the less accurate earbow.
The fully adjustable articulator of the present invention when used with the facebow permits the dental professional to locate the actual hinge axis of the patient, the hinge angle and the range of motion of the patient's jaw. The jaw is a joint which both articulates and glides. Therefore, using fully-adjustable articulator, the facebow and the smile guide, the patient's jaw and teeth can be accurately reproduced. The articulator rests on a bench top which may not be completely level. A line level device is placed on the lab bench and if the bench is not perfectly level, a (preferably) erasable line is placed next to the margin of the level bubble. The level is then placed on the stylus of the pupillary line indicator and the leveling screws of the articulator are adjusted until the level conforms to the reading provided when the level was placed on the lab bench.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
The dentist typically supplies the technician with a full face photograph at 100% scale of the patient smiling while showing as much of the anterior teeth as possible. An exaggerated or “forced smile” can be effectively used as part of the procedure to create the photograph for the dental technician. The smile guide 100 shown in
Referring to
The interpupillary line 134 and the incisal line 136 connecting two points under the front incisors are drawn on the patient's photograph. The longitudinal base 110 of the smile guide 100 is aligned with the interpupillary line 134 as shown in
The fully-adjustable articulator of the present invention has hinges 150 and 152, as shown in
The true axis facebow 156 of the present invention is shown in
As shown in
Particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the invention.
The above detailed description of the embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above or to the particular field of usage mentioned in this disclosure. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Also, the teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.
Changes can be made to the invention in light of the above “Detailed Description.” While the above description details certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the above appears in text, the invention can be practiced in many ways. Therefore, implementation details may vary considerably while still being encompassed by the invention disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated.
This application claims the benefit of U.S. Provisional Patent Application 61/266,436 filed on Dec. 3, 2009.
Number | Date | Country | |
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61266436 | Dec 2009 | US |