JPH0728880B2 - Denture holder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for holding removable dentures, and more particularly to a device for fixing removable dentures to existing fixed teeth.

[0002]

2. Description of the Related Art Dentures are mounted in the mouth and fixed adjacent to fixed teeth. Such a denture is configured such that the denture can be fixed to the fixed tooth if it is removable. For example, a partial denture or removable bridge member must be placed and fixedly held in the mouth. However, they must be removable for cleaning and maintenance. All of these give fixed and removable features. However, the ultimate goal of these devices is to hold the denture in a fixed position during actual use so as to avoid rotation, lateral movement or displacement of the removable denture in its mouth from its correct position. Is. Any of these displacements cause the patient anxiety and discomfort during normal use. If the holding device allows such displacement,
The denture is bent or damaged, and similarly the fixed tooth to which the denture is connected is broken or damaged from the other surface. In addition, any rotation or movement is unreliable to the user, who may feel that the denture may fall out or slip, or be embarrassed. In this way, the user will never get a feeling of fixation of the denture, unless the denture is not fully displaced and is held by the fixed tooth. Therefore, this kind of holding device is designed so that the close engaging mechanism can be attached and detached and tightly engaged by elastic deformation of the constituent metal material.

A typical example of the holding device is shown in FIGS. This is a matrix 2 fixed to the side of the fixed tooth 1.
And a Patricks 4 fixed in the denture 3 and the base tube portion 4a of the Patricks 4 has a denture 3
The tubular portion 4a, which is to be fixed to the metal floor or to be fixed with an adhesive resin, is detachably fastened and fixed to the shaped threaded coving 5 through the fastening screw 6 with respect to the shaped threaded coving 5. The main parts of the Patricks 4 are two tip swelling legs 4b, 4b facing each other through a slit 7, and these swelling parts fit into the matrix 2. For this reason, the lower ends of the legs 4b, 4b are provided with tapered portions 4c,
It is 4c. The legs 4b, 4b exert a maintaining force for tightly fixing the matrix 2 by virtue of the elastic force acting in the direction of separating from each other. An activation screw 8 for finely adjusting the maintenance force is provided at a base portion between the tip bulging legs 4b, 4b. In addition, in the holding device, various releasable locking mechanisms (for example, a plunger that engages with an overrunning weir or a rounded hollow) is provided for more reliably fixing the male-female fitting above. Etc.) may be attached.

Since it is necessary to rely on elastic deformation during attachment / detachment and locking of the denture in this way, it is necessary to apply a rather large force to the denture during attachment / detachment. In view of the fact that the spring stress is weakened and the life is short due to repeated elastic deformation, the metal on the elastic deforming side of the holding device is a shape memory alloy whose martensite transformation temperature is set to a predetermined temperature. It has been proposed to memorize the shape at the time of tight fitting. When mounting a denture due to this, if the metal is slightly deformed, the denture can be fitted without applying any special force, and the denture can be set at a predetermined position. Also, by heating the metal with hot water or the like to a temperature higher than the martensitic transformation temperature, it is possible to restore a memorized shape and realize a close fitting, and when removing the denture, cool the metal by including cold water in the oral cavity. Since the shape memory alloy has reduced rigidity and is easily elastically deformed, when the denture is moved, it is easily elastically deformed and the denture can be removed without difficulty. Since it is not necessary to elastically deform the denture, the denture can be reliably fixed by repeated use over a long period of time.

[0005]

Since the conventional holding device using the shape memory alloy utilizes the shape memory effect, it can be largely deformed with a small force because it is at room temperature when mounted. , Easy to install. However, in order to fix the holding device, it is necessary to raise the temperature above the shape recovery temperature (reverse transformation end temperature, A _f point). The A _f point of the shape memory alloy used in this holding device is 4
Since the temperature is around 0 ° C., it is necessary to set the oral cavity temperature (37 ° C.) or higher in order to completely fix the holding device. Therefore, in order to guarantee that the shape memory alloy completely recovers its shape and the holding device is fixed, it is necessary to eat warm food and drink, which is troublesome. This also means that the fixing is insufficient and the holding is unstable at the stage of mounting the holding device or for a while thereafter. Further, when removing the denture, it is necessary to include cold water. However, it is extremely troublesome to put hot and cold substances into the oral cavity when attaching and detaching. The present invention has been made in view of such problems of the prior art, the object of the present invention, at room temperature, without the need to put hot or cold foods into the oral cavity at all. An object of the present invention is to provide a removable denture holding device that can be easily attached and detached.

[0006]

In order to achieve the above object, in the denture holding device according to the present invention, the dense engagement mechanism can be attached and detached and tightly engaged depending on the elastic deformation of the constituent metal material. In a denture holding device consisting of a matrix fixed to the side of a fixed tooth and Patricks fixed in the denture designed in the above, a metal material required to undergo elastic deformation is subjected to a martensite reverse transformation end temperature. Is a superelastic alloy material adjusted so that slip deformation does not appear at a stress lower than that that induces martensitic transformation at room temperature or below and above the maximum temperature in the oral cavity.

[0007]

The member of the denture holding device constructed as described above that requires elastic deformation is a superelastic material, and this superelastic material causes a specific elastic deformation called superelasticity. This is a phenomenon in which a strain causes a large deformation of 5 to 8% by a certain force (stress), and then the shape is completely recovered only by removing the force. Therefore, even if a large elastic deformation is caused, the force does not become large unlike ordinary elastic deformation, and the attachment / detachment is easy. Furthermore, with ordinary elastic deformation, it is at most 0.3.
Since the shape recovers only a strain of about%, if further deformation is applied, plastic deformation occurs and shape recovery does not occur, and the holding function deteriorates. With a superelastic material, the recoverable strain is as much as 20 times that in the case of elastic deformation, and no deformation beyond the superelastic deformation is applied during normal use. Since the shape recovery temperature of the superelastic material is set lower than the temperature at which it is deformed, the martensite reverse transformation end temperature of the material used here is room temperature or lower. For this reason, complete fixing is completed at the stage of mounting, so there is no unstable fixing state until the temperature rises like in the case of shape memory alloy, and it is unnecessary to eat warm food and drink. Is. Further, considering the fixing force in the oral cavity, the force generated by the shape memory alloy and the superelastic material is proportional to the difference between the use temperature and the martensite transformation start temperature. Generally, since the martensitic transformation start temperature of the superelastic material is lower than that of the shape memory alloy, the fixing force of the superelastic material is larger than that of the shape memory alloy and the maintenance is stable.

The martensitic transformation will be described below. The martensitic transformation is a type of crystal structure phase transformation in the solid phase and occurs without diffusion of atoms, so that the atoms move in cooperation with each other. As a result, pseudo-shear deformation with a slight volume change occurs. The temperature at which martensitic transformation occurs is determined by the relationship between electrical resistance and temperature. As an example, FIG. 4 shows the result of the Ti-50.0 at% Ni alloy heat-treated at 1,000 ° C. As it cools, the temperature at which the electrical resistance suddenly begins to fall is the M _s point at which martensitic transformation begins,
The ending temperature is the M _f point. The mother phase is above M _s points,
Below the M _f point, the martensite phase is stable and M _s
Both phases coexist between the point and the M _f point. Conversely, when gradually heated at a temperature A _s point increase in electrical resistance starts to become steep,
The martensite phase starts the reverse transformation to the parent phase, and the reverse transformation ends at the point A _f that coincides with the cooling curve. When heating,
Both phases can coexist between the points A _s and A _f . Generally, the martensitic transformation that appears in shape memory alloys is
Particularly, it is called thermoelastic martensitic transformation, and the temperature history of transformation and reverse transformation is small, and is about several degrees to several tens of degrees. Furthermore, in the thermoelastic martensitic transformation, the interface between the martensitic phase and the matrix phase is well matched, and the martensitic phase itself rearranges easily with low stress, so dislocations that cause permanent deformation are not formed. . Such a feature is one of the necessary conditions for the shape memory effect. On the other hand, the martensitic transformation used for the purpose of strengthening general steel has a temperature history about one digit larger. Further in this case,
The conformity of the interface between the martensite phase and the matrix phase is poor, a large amount of defects such as dislocations are formed to cause permanent deformation, and the martensite phase itself is hard, so that the shape memory effect does not appear.
The history of discovery and utilization of such a non-thermoelastic martensitic transformation is old, and in familiar examples, it was empirically used in the strengthening method by quenching of Japanese swords. Next, the necessity of shape recovery will be described below. The shape recovery force of the shape memory alloy occurs when the martensite phase, which is stable on the low temperature side, undergoes reverse transformation by heating to the mother phase, which is stable at the high temperature. However, in general, reversibility of crystal structure does not necessarily mean reversibility of shape. This can be explained using the simple two-dimensional crystal model of FIG. FIG. 5A shows the crystal structure of the mother phase of the high temperature phase, and when this is cooled, it becomes a martensite phase as shown in FIG. 5B. White circles and black circles are different alloy elements. The Ti-Ni alloys correspond to Ti and Ni, respectively.
In most shape memory alloys, the crystals have a regular structure,
Each alloy element has a regular arrangement. Here, in order to facilitate understanding, a change in crystal structure and a change in macro shape are drawn so as to correspond to each other. As a result, the sample shape undergoes shear deformation as indicated by the arrow accompanying the transformation. For simplicity, first consider the case where the black and white elements are not distinguished. Martensite crystal unit cells are drawn with thick lines like. The arrows and have the same absolute value and are in opposite directions. Therefore, when this unit cell is reverse-transformed in the direction of the arrow, it returns to the unit cell of the parent phase shown by the thick line in FIG. The shape can be recovered. However, in general, there are multiple ways to return to the original unit cell shape. As described above, assuming an irregular structure, for example, by displacing the bold line portion indicated by in FIG. 5B in the direction of the arrow by the same amount as before, the same unit cell as in the original is obtained in FIG. 5C. It is obtained as shown by the broken line. However, the shape of the sample at this time has not been recovered as it was, and the shape memory effect does not appear. But,
As in the case of many shape memory alloys, in the case of an ordered structure, it is necessary to undergo reverse transformation in the direction of the arrow in FIG. Considering the ordered arrangement of each atom, the unit cell of the original matrix is as shown by the broken line in Fig. 5 (a), and the unit cell of Fig. 5 (c) in the new crystal is As shown by the thick line, the size is half that of the original matrix, resulting in a different crystal structure. As a result, the free energy is high, no such selection is made, and it is advantageous for the atom to always return to its original position. For this reason, many shape memory alloys have a regular structure. The mechanism of the shape memory effect and the deformation behavior will be described using a two-dimensional crystal model. First, when the parent phase shown in FIG. 6A is cooled below the M _f point, the crystal structure of the martensite phase as shown in FIG. 6B is changed. In a three-dimensional actual crystal, martensite brother crystals with 24 orientations are formed. Sibling crystals are martensite crystals that have the same crystal structure but different crystal orientations. In (b), sibling crystals of two types of orientations shown by A and B are formed.
Seen from the original matrix, the individual siblings generate shear strain.Since the siblings formed by cooling are self-adjusted to relax each other's strains, macroscopic In reality, the sample shape has not changed. On the other hand, in the thermoelastic martensitic transformation that appears in shape memory alloys,
Since the boundary between A and B moves easily with low stress, the martensite phase sample is soft like rubber. When an external force is applied, a sibling crystal A having a preferential orientation with respect to the external force grows as shown in (c), and the sample is macroscopically shear-deformed. When this sample is heated, all the martensite crystals undergo reverse transformation into the parent phase, and as a result, the sample shape is completely restored as shown in (a). This is the shape memory effect. The martensitic transformation generally occurs by cooling to below the transformation temperature, but the transformation can be induced even when the transformation temperature is exceeded by applying an external force. This is because, as described above, the martensitic transformation is caused by the shear deformation, and the external force assists the transformation. Therefore, when an external force is applied at a temperature of A _f point or higher, the path of the broken line is directly traced from (a) to (c), only the martensite siblings A of the preferred orientation are formed, and the sample is subjected to macroscopic shear strain. Occurs. At a temperature higher than the reverse transformation temperature, the martensite phase is energetically unstable, so even if only external force is removed, the martensite phase is reverse transformed to the parent phase along the path from (c) to (a), and the shape returns to the original shape. This is superelasticity. In this way, the same sample, due to the relative relationship between transformation temperature and deformation temperature,
The shape memory effect and superelasticity are exhibited, and in any case, the cause of the shape recovery is due to the restoring force of the martensite phase to return to the matrix phase, and it is said that there is a sibling relationship. I can say. The transformation temperature can be arbitrarily changed depending on the alloy composition, the work heat treatment condition, the addition of the third element, etc., so that the shape memory effect and the superelasticity can be used at any temperature.
Next, the deformation behavior when the martensitic transformation becomes the deformation mode will be described. In this case, unlike ordinary metals and alloys, the deformation behavior becomes extremely sensitive to temperature. FIG. 7 is a schematic diagram of a stress-strain curve obtained when a sample having the transformation behavior shown in FIG. 4 is deformed at various temperatures.
Shown in. When the deformation temperature is represented by T, in the temperature range of T <M _s , many thermally formed martensite siblings are rearranged into siblings that have a preferred orientation with respect to external force Progresses. In this case,
As shown in (a), the shape does not return to the original shape even if external force is removed,
The shape is recovered as shown by the broken line only after heating to a temperature of A _f point or higher. In the temperature range of M _s <T <A _f, the martensite phase is induced by an external force, but in this case also, the reverse transformation does not occur only by unloading, so the strain apparently remains,
The stress-strain curve is shown in Fig. 7 (a) as shown in Fig. 7 (b).
It has a similar shape to. When heated above the A _f point, shape recovery also occurs in this case as shown by the broken line. In the temperature range of A _s <T <A _f, is part of the martensite phase was stress-induced,
As it undergoes reverse transformation by unloading and the rest remains, Fig. 7 (c)
Like, superelasticity and shape memory effect coexist. A _f <T
In the temperature range of, complete superelasticity appears as shown in FIG. When T is equal to or higher than the M _s point, the martensite phase induces stress, and this martensite-induced stress (σ _M ) is T
Increases linearly with. Therefore, T increases (T
_{When S} <T, σ _M may be higher than the critical stress of slip (σ _S ). In this case (T _S <T), FIG.
As in (e), the stress-strain curve shows permanent deformation, and the shape recovery does not occur even when heated. Therefore, how to raise σ _S is one of the important issues in material development. The respective paths corresponding to the deformations at various temperatures described above are shown in FIG. 8 on the stress-temperature relationship diagram. In the figure, σ _M and σ _S are also drawn. The mother phase (B2) and the martensite phase (M) are separated at the boundary of σ _M ,
This figure represents a state diagram when stress and temperature are variables.

Thus, a denture holding device which can be attached and detached at room temperature and whose function is not deteriorated by repeated use is realized.

[0010]

EXAMPLES Examples will be described. The metal material is required the elastic deformation of the tight engagement fitting mechanism relying on the elastic deformation of the constituent metal material removably and denture retaining device which is designed so as to fit tightly engaged A _f point 25 ° C. or less Ti-x% Ni
(Atom%, x = 39 % to 51.5%) Alloy and Ti-Ni to which other elements are added by 10% or less based on the alloy
A multi-component alloy is used which is capable of exhibiting a superelastic effect at room temperature. Other elements include Al, Co, Cu, V,
One or a few kinds of Cr, Mn, Fe, Mo, W, etc. are added. In addition, in this type of alloy, unless special processing is usually performed, slip deformation does not appear at a stress lower than that inducing martensitic transformation at the maximum temperature in the oral cavity, and normal oral cavity We enjoyed quick attachment and detachment and reliable holding under temperature due to the super-elastic effect.

[0011]

Since the present invention is constructed as described above, it has the following effects. It becomes unnecessary to heat or cool the inside of the mouth during attachment / detachment and holding, and the convenience of use is significantly improved.

[Brief description of drawings]

FIG. 1 is an overhead view of a main part of a typical denture holding device.

FIG. 2 is a perspective view of the same.

FIG. 3 is a developed perspective view of the same.

FIG. 4 is a diagram for explaining superelasticity.

FIG. 5 is a similar explanatory chart.

FIG. 6 is also a diagram for explanation.

FIG. 7 is also a diagram for explanation.

FIG. 8 is also a diagram for explanation.

[Explanation of symbols]

 1 Fixed Tooth 2 Matrix 3 Denture 4 Patricks 4a Base Cylindrical 4b Tip Swelling Leg 4c Tapered 5 Threaded Coving 5a Fitting 6 Fastening Screw 7 Slit 8 Activation Screw

Claims (3)

[Claims] 1. A tight engagement mechanism is designed so that it can be attached and detached and tightly engaged by relying on elastic deformation of its constituent metal materials.
Fixed to the side of the fixed tooth matrix and fixed in the denture
In a denture retainer consisting of a combination with Patricks, which induces martensitic transformation of a metal material requiring elastic deformation at a martensite reverse transformation end temperature of room temperature or lower and at or above the maximum temperature in the oral cavity. A denture holding device that is made of a superelastic alloy material adjusted so that slip deformation does not appear at a lower stress. 2. A Ti-x% Ni (atomic%, x = 39% to 51.5) whose superconducting alloy material has a reverse transformation end point of 25 ° C. or less.
%) The denture holder according to claim 1, which is made of an alloy. 3. A Ti-x% Ni (atomic%, x = 39% to 51.5) whose superconducting alloy material has a reverse transformation end point of 25 ° C. or lower.
%) Based on the alloy, T added with about 10% or less of other elements
The denture holding device according to claim 1, wherein the denture holding device is an i-Ni multi-component alloy.