JPH0233257B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of polishing an inner crown fixed to an abutment tooth in order to attach an outer crown of a removable bridge (prior art) A removable bridge is used by attaching the outer crown that constitutes it to the inner crown that is fixed to the abutment tooth in a removable manner.There are various shapes of the outer peripheral surface of the inner crown. The so-called conus type internal crown has a number of advantages such as the ability to maintain the external crown relative to the internal crown, the ability to adjust this maintaining force, and the fact that it does not place a large burden on the abutment tooth when it is attached or removed. has been frequently used recently. This conus-type inner crown is one in which the outer peripheral surface of the inner crown is formed into a conical shape toward the occlusal surface.

However, removable bridge internal crowns are internal crowns made of precious metal, etc. that are removed and covered with natural teeth, and are designed to match the shape of each individual tooth, rather than having a conical shape with concentric axes, the outer peripheral surface is only at the conus angle. Form a sloped shape.

In this conus type internal crown, the retention force is influenced by the magnitude of the inclination angle (generally referred to as the conus angle) of the outer circumferential surface of the internal crown with respect to a plane perpendicular to the occlusal surface. In other words, according to the wedge theory, as the conus angle increases, the sustaining force decreases rapidly,
Considering the retention force and the fitability of the external crown, 6° is considered to be the most desirable.

The inner crown is cast using the abutment tooth of the plaster model taken from the patient as the original shape, and the outer circumferential surface of the inner crown is polished into a conical shape toward the occlusal surface. I was going there.

However, with this free-hand method, it is difficult for anyone except a very skilled person to polish the conus angle of the inner crown to the desired angle of 6° over the entire circumference. If the conus angles differ locally, the outer crown will not be able to be attached or removed smoothly, and the retention force will be partially uneven, resulting in a large burden being placed on the abutment tooth when the outer crown is attached or removed. Moreover, as a matter of course, the outer crown is cast using the inner crown as the original shape, so considering that the accuracy of the conus angle of the inner crown is directly copied to the outer crown, in the case of a conus type removable bridge, The polishing accuracy of the outer circumferential surface of the inner crown is an extremely important factor.

In addition, Utility Application No. 57-69373 (Utility Application No. 174108-1983)
The dental cutting aid disclosed in the publication uses an air turbine to cut multiple teeth in parallel, and is completely different from the method of polishing the inner crown of a removable bridge. Also, JP-A-60-
The small-diameter drill polishing device shown in Publication No. 16350 is configured so that it can only polish items with concentric shafts, so it is not possible to polish conical shafts with conical shafts according to the shape of individual teeth, such as the inner crown of a removable bridge. It cannot be used as a means for grinding a truncated conical shape with multiple centers. That is, even if the polishing machine is adjustable to a predetermined inclination angle and the workpiece is polished to a predetermined inclination angle, the shaft wall surface of the eccentric shaft cannot be polished to the same angle.

(Problems to be Solved by the Invention) In view of the above-mentioned problems, the present invention aims to achieve a desired conus angle over the entire circumference by mechanical polishing using a simple device, without polishing the inner crown by free hand. It was created for the purpose of high-precision polishing.

(Means for Solving the Problems) The present invention involves leaving sprue marks formed almost perpendicular to the occlusal surface when casting the inner crown, or removing the sprue marks of the cast inner crown once. After the inner crown of the lever is tried into the patient's mouth, the removed sprue mark is reattached to the inner crown, and the inner crown is supported by the inner crown supporter through the sprue mark, and the polishing surface of the polishing wheel is polished. The inner crown is rotated with the outer circumferential surface of the inner crown tilted by the conus angle, and the inner crown supported by the inner crown supporter is pressed against the polishing surface of the polishing wheel and rotated gradually, so that the outer circumferential surface of the inner crown is directed toward the occlusal surface. This is a method of polishing an inner crown in a removable bridge, which is characterized by polishing to form a polished surface having a predetermined conus angle.

(Embodiment) FIG. 1 shows a polishing method according to a first embodiment of the present invention in which an inner crown is polished with the tooth neck facing upward.

A polishing tool fixing plate 2 is fixed to the surface plate 1, a polishing tool 3 is fixed to the polishing tool fixing plate 2 so as to be able to adjust a fixed angle, and a polishing wheel 5 is attached to a rotating shaft 4 of the polishing tool 3. This polishing wheel 5 is the third
As shown in the figure, coated abrasive paper is pasted on the plate surface of the disc body 6 to form a polishing surface 7, and the disc body 6
A rotating shaft 8 is attached to the center of the shaft.

As is clear from FIG. 1, the tip portion of the polishing tool 3 (the portion to which the rotating shaft 4 is attached) faces slightly upwards than the tail portion, and the axis of the rotating shaft 8 of the polishing wheel 5 9 is inclined with respect to the horizontal line 10 by 6 degrees, which is the conus angle θ of the inner crown A.

On the other hand, when casting the inner crown A, a sprue mark 11 formed almost perpendicular to the occlusal surface is left, and the sprue mark 11 is attached to the chuck of the inner crown supporter 12 so that the sprue mark 11 becomes almost vertical. The inner crown A is supported by the inner crown supporter 12 by being held between the portions 13. The tooth neck 14 of this internal crown A faces downward. This inner crown support 12 is provided with a sliding plate 15,
When polishing the inner crown A, this sliding plate 15 slides on the surface plate 1.

Inner crown A was cast using the original shape of the abutment tooth (not shown) of a plaster model taken from the patient.
As shown in the figure, sprue marks 11 remain and the thickness is cast to allow for polishing allowance.

Then, while rotating the polishing wheel 5, the inner crown A supported by the inner crown supporter 12 is placed on the polishing wheel 5.
When the outer circumferential surface of the inner crown A is polished by gradually rotating the inner crown support 12 firmly pressed against the surface plate 1 while pressing it against the polishing surface 7 of the Since the crown A is tilted by 6 degrees, which is the conus angle θ, the outer circumferential surface of the polished inner crown A is tilted by a predetermined conus angle toward the occlusal surface, forming an inclined trapezoid that matches the shape of each tooth. The conus angle θ of the outer peripheral surface of the inner crown A that is formed and polished is necessarily exactly 6°, and is constant over the entire circumference.

Furthermore, since the angle of inclination of the polishing surface 7 of the polishing wheel 5 with respect to the vertical plane is constant, and the inner crown A is firmly fixed to the inner crown supporter 12 via the sprue marks 11, the polished inner The outer peripheral surface of the crown A has a mirror-like surface and is a well-polished surface with almost no polishing marks remaining.

After polishing the outer peripheral surface of the inner crown A, the sprue mark 11
The inner crown A with a conus angle θ of 6° as shown in FIG. 5 is completed by cutting out and polishing the upper surface with free hand.

In the polishing method of the first embodiment, the tooth neck 14 of the internal crown A is
Since it faces upward, there is an advantage that polishing can be performed while looking at the tooth neck 14.

Further, FIG. 2 shows a polishing method according to a second embodiment of the present invention in which the inner crown is polished with the tooth neck facing downward, and the same parts as in the first embodiment are given the same reference numerals and will be explained. do.

The tip portion of the polishing tool 3 (the portion to which the rotating shaft 4 is attached) points slightly downward than the tail portion, and the axis 9 of the rotating shaft 8 of the polishing wheel 5 is aligned with the inner crown relative to the horizontal line 10. It is inclined by 6 degrees, which is the conus angle θ of A, in a direction opposite to that of the first embodiment.

In the second embodiment, a first arm 17 is attached to a column 16 fixed to a surface plate 1 so as to be able to move up and down and rotate freely, and a second arm 17 is attached to the tip of the first arm 17.
An arm 18 is rotatably attached to the second arm 18, and an inner crown support 19 is vertically and rotatably attached to the distal end of the second arm 18. A chuck part 20 of the inner crown supporter 19 faces downward, and the inner crown A is supported by the chuck part 20 holding the sprue mark 11 left on the inner crown A almost vertically. Therefore, the tooth neck 14 of the inner crown A faces downward.

Then, in the same manner as in the first embodiment, while pressing the inner crown A supported by the inner crown support 19 against the polishing surface 7 of the polishing wheel 5 and gradually rotating the inner crown support 19, the outer peripheral surface of the inner crown A is pressed. When polished, the outer circumferential surface of the polished inner crown A is inclined by a predetermined conus angle toward the occlusal surface, forming an inclined trapezoid that matches the shape of each tooth, and the conus angle θ of the outer circumferential surface is It is exactly 6 degrees.

In either embodiment, by adjusting the inclination angle of the polishing surface 7 of the polishing wheel 5 with respect to the vertical plane, the conus angle θ of the outer peripheral surface of the inner crown A to be polished can be freely adjusted.

As shown in FIG. 6, the internal crown A polished by the polishing method of the present invention is applied to each abutment tooth C in the patient's oral cavity, and if it is found to be suitable, the internal crown A is polished by the polishing method of the present invention.
is fixed to each abutment tooth C of the patient via adhesive, and an outer crown B is cast using this inner crown A as the original shape, and a removable bridge is manufactured by assembling a plurality of outer crowns B into a bridge shape. Each outer crown B constituting this removable bridge is attached to an inner crown A fixed to an abutment tooth C of the patient. In this case, the outer crown B is cast using the inner crown A whose outer circumferential surface is mirror-polished as its original shape, so that the outer crown B having a highly accurate inner circumferential surface is cast. As a result, the outer crown can be smoothly attached and detached from the inner crown, and the load placed on the abutment tooth during attachment and detachment is reduced.

In addition, in the above explanation, the outer circumferential surface of the inner crown is polished and then the inner crown is trial-fitted to the patient's abutment tooth. The sprue mark removed after being tried into the oral cavity of the patient may be reattached to the inner crown, and the outer circumferential surface of the inner crown may be polished using the fixed sprue mark.

Furthermore, with the sprue traces held almost horizontally so that the neck of the inner crown faces laterally, the inner crown is supported by the inner crown supporter through the sprue traces, and the axis of the rotation axis of the polishing wheel is The outer peripheral surface of the inner crown may be polished by rotating this polishing wheel while being inclined by the conus angle of the inner crown with respect to the vertical line.

(Effects) (1) The present invention utilizes sprue marks formed almost perpendicular to the occlusal surface during casting of the inner crown to support the inner crown with the inner crown supporter and polish the polishing surface of the polishing wheel. The outer circumferential surface of the inner crown is tilted by the conus angle, and the inner crown supported by the inner crown support is pressed against the inclined polishing surface of the polishing wheel and gradually rotated, so that the outer circumferential surface of the inner crown is aligned with the occlusal surface. Since the teeth are mechanically polished so that they are tilted at a predetermined conus angle to form a sloped trapezoid that matches the shape of each individual tooth, operator skill is an issue, unlike the traditional free-hand polishing method. The outer circumferential surface of the inner crown can be precisely polished to the desired conus angle over the entire circumference, and the inclination angle of the polishing surface of the polishing wheel remains constant, resulting in extremely good mirror-like polishing. A surface is obtained.

(2) In addition, since the outer crown is cast using the inner crown whose outer circumferential surface has been polished to a mirror finish as the original shape, an outer cap with a highly accurate inner circumferential surface is cast, and as a result, the outer crown is This makes it easier to put on and take off the tooth, reducing the burden on the abutment teeth when putting on and taking it off.

[Brief explanation of drawings]

FIG. 1 is a front view showing a method of polishing an inner cap A according to a first embodiment of the present invention, and FIG. 2 is a front view showing a method of polishing an inner cap A according to a second embodiment of the present invention. 3
The figure is a perspective view of the polishing wheel 5, FIG. 4 is a sectional view of the inner crown A before polishing, FIG. 5 is a sectional view of the completed inner crown A, and FIG. Root tooth C
FIG. 3 is a cross-sectional view of the state in which the outer crown B is attached to the inner crown A fixed to the inner crown A and the state in which the outer crown B is removed. (Explanation of symbols of main parts), A: Inner crown, B: Outer crown, C: Abutment tooth, θ: Conus angle of inner crown, 5:
Polishing wheel, 7: Polishing surface, 8: Rotating shaft of polishing wheel, 9: Axis center of rotating shaft of polishing wheel, 1
0: horizontal line, 11: sprue trace, 12, 19: inner crown support.

Claims (1)

[Scope of Claims] 1. In a method of polishing an inner crown constituting a removable dental bridge, the sprue marks formed almost perpendicular to the occlusal surface are left as they are when the inner crown is cast, or The sprue mark of the inner crown that has been removed is removed, and this inner crown is tried into the patient's mouth.The removed sprue mark is then reattached to the inner crown, and the chuck with this sprue mark attached is supported vertically, and the chuck is A surface plate that can be driven on a flat surface while being pressed against the polishing surface of a polishing wheel that contacts the contour of the outer peripheral surface of the inner crown in a tangential direction perpendicular to the direction of the rotation axis. While the inner crown is held by the inner crown supporter installed vertically above, the rotation axis of the polishing tool with the polishing wheel attached to the tip is set from the horizontal direction to the outer peripheral surface of the inner crown. The outer circumferential surface of the inner crown is polished by applying the polishing surface of the polishing wheel to the outer circumferential surface of the inner crown while supporting the inner crown at an angle corresponding to the inclination angle of the outer circumferential surface of the inner crown with respect to the vertical plane. 1. A method for polishing an internal crown in a removable bridge, the method comprising: forming a polished surface having a predetermined conus angle toward the occlusal surface.