Facing crown and wax cover for making facing crown

Abstract

To provide a facing crown capable of making the strength of an upper jaw front tooth equal to the occlusal force of a molar, and a wax cover capable of efficiently shaping a wax pattern formed in the process of manufacturing the facing crown.SOLUTION: A facing crown 30 to be attached to an upper jaw front tooth 11 is provided with a metal frame 32, and a step part 34 with which the top part of a lower jaw front tooth 21 is brought into contact is formed on the tongue side of the metal frame 32 when attached to the oral cavity. In a wax cover 40 used when the facing crown 30 is manufactured, a molding stepped part 45 having a shape similar to the shape of a stepped part 34 of the metal frame 32 is formed in a cutting edge part 44 of the wax cover 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a veneer crown to be attached to an upper front tooth and a wax carver for making the veneer crown. [Background technology]

[0002] Human teeth are broadly divided into front teeth and molars, each with a different function: front teeth are primarily used to bite food, while molars are primarily used to grind food. 7 is a schematic diagram showing the state of occlusion of a person's teeth. In FIG. 7, a person's teeth grow on an upper jaw 110 and a lower jaw 120, respectively. In the upper jaw 110, a range F of approximately four teeth on the left side of the drawing is the upper jaw anterior teeth 111, and a range M of approximately four teeth on the right side of the drawing is the upper jaw molars 112. In the lower jaw 120, similar to the upper jaw 110, approximately four teeth on the left side in the drawing are lower jaw anterior teeth 121, and approximately four teeth on the right side in the drawing are lower jaw molars 122. In the figure, reference numeral 113 denotes the alveolar bone of the upper jaw 110, and reference numeral 114 denotes the gingiva of the upper jaw 110. Reference numeral 123 denotes the alveolar bone of the lower jaw 120, and reference numeral 124 denotes the gingiva of the lower jaw 120. The directions of force acting in the occlusion between the maxillary anterior teeth 111 and the mandibular anterior teeth 121 and the occlusion between the maxillary molar teeth 112 and the mandibular molar teeth 122 are indicated by arrows in FIG. Detailed structure of other teeth has been omitted.

[0003] FIG. 8(A) shows the occlusion state of an upper front tooth 111 and a lower front tooth 121, and FIG. 8(B) shows the occlusion state of an upper molar tooth 112 and a lower molar tooth 122. 8(A), the apex of the mandibular front tooth 121 abuts against the tongue side of the maxillary front tooth 111, i.e., the inner surface of the oral cavity. Also, in (B), the maxillary molar 112 and the mandibular molar 122 have cusps 115, 125 and fissures 116, 126, respectively, and the cusp 115 of the maxillary molar 112 and the fissure 126 of the mandibular molar 122 mate with each other, and the fissure 116 of the maxillary molar 112 and the cusp 125 of the mandibular molar 122 mate with each other.

[0004] 7 and 8, the maxillary front teeth 111 are slightly inclined toward the lip, i.e., toward the outside of the oral cavity, so the tops of the mandibular front teeth 121 abut against the maxillary front teeth 111 in a manner that pushes the maxillary front teeth 111 up from below. As a result, a occlusal force is applied to the maxillary front teeth 111 at an angle that is different from the tooth axis, which makes the maxillary front teeth 111 prone to injury such as mobility and root fracture, which is a problem in dental treatment.

[0005] When a maxillary anterior tooth 111 is damaged, a conventional treatment is prosthetic treatment using a veneer crown 130 shown in Figures 9 and 10. The veneer crown 130 is cemented to the root 111A of the damaged maxillary anterior tooth 111. The facing crown 130 is composed of a post core 131 whose base is inserted into the tooth root 111A, a metal frame 132 fitted onto the post core 131, and a facing portion 133 made of hard resin, ceramic, etc., which is fixed from the upper end of the metal frame 132 to the outer surface on the lip side. At this time, as can be seen from the photograph of FIG. 10, the metal frame 132 has no particular steps or the like, similar to the original lingual surface of the maxillary anterior tooth 111, and has a smooth surface shape.

[0006] Furthermore, the upper and lower molars 112 and 122 play a role in providing occlusal support to support the bite, but in many cases, the molars 112, 122 are the first to be lost due to caries or periodontal disease. When either the upper or lower molars 112, 122 are lost, occlusal support is lost, which not only makes chewing difficult but also places a burden on the front teeth 111, 121 from the molars 112, 122.

[0007] In this case, the conventional facing crown 130 as described above has the drawback that it cannot withstand the strong occlusal force of the molars 112, 122 because the metal frame 132 does not have the cusps and fissures of the molars 112, 122. For this reason, there has been a demand for a dental technical means that can withstand the strong occlusal force of the molars 112, 122 for people who have lost some of their molars 112, 122.

[0008] Furthermore, there are no documents in the patent literature that relate to inventions of dental technical means that enable people who have lost some of their molars to exert as strong a biting force as if they had molars. Summary of the Invention [Problem to be solved by the invention]

[0009] The first object of the present invention is to provide a veneer crown that is attached to the maxillary anterior teeth and that can give the maxillary anterior teeth strength to withstand the biting force equivalent to that of molars, thereby improving chewing efficiency.

[0010] A second object of the present invention is to provide a wax carver for making facing crowns that can efficiently shape the outer shape of the wax pattern created during the facing crown manufacturing process when making the facing crown of the present invention. [Means for solving the problem]

[0011] In order to achieve the first object, the present invention provides a veneer crown to be attached to the maxillary anterior teeth, the veneer crown having a metal frame, and a stepped portion formed on the tongue side of the metal frame when the metal frame is attached to the oral cavity, against which the tops of the mandibular anterior teeth abut.

[0012] In the present invention, the step portion preferably has a cusp-like protrusion formed on the tongue side when the device is worn in the oral cavity, and a fissure-like recess formed on the lip side when the device is worn in the oral cavity.

[0013] In the present invention, it is preferable that the vestibular crown is formed as a continuous connected crown spanning a plurality of maxillary anterior teeth, and that the cusp-like protrusions are formed continuously on the lingual side of the connected crown.

[0014] In order to achieve the second object, the present invention provides a wax carver used when making a facing crown, the wax carver having a cutting edge for wax molding, and the cutting edge has a molding step formed thereon that is similar in shape to the step of the metal frame. [Effects of the Invention]

[0015] According to the vestibular crown of the present invention, a step portion is formed on the inside of the oral cavity of the vestibular crown against which the tops of the mandibular anterior teeth abut, thereby providing the maxillary anterior teeth with strength to withstand the biting force equivalent to that of molars, thereby providing a vestibular crown that improves chewing efficiency. Furthermore, according to the wax carver of the present invention used when making facing crowns, the cutting edge of the wax carver is configured with a molding step formed in it that is similar in shape to the step of the metal frame, so that a wax carver for making facing crowns can be provided that can efficiently shape the outer shape of the wax pattern created during the manufacturing process of the facing crown. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic side view showing one embodiment of a facing crown according to the present invention. [Figure 2] 1 is a photograph taken from inside the oral cavity showing the entire state in which the present embodiment has been attached to the front teeth. [Figure 3] 1 is a photograph showing a specific embodiment of a facing crown according to the present invention as viewed from inside the oral cavity. [Figure 4] 4 is a photograph of the embodiment of FIG. 3 as seen from the opposite side. [Figure 5] 1 shows one embodiment of a wax carver used for making a veneer crown according to the present invention, where (A) is a front view showing the overall configuration, and (B) is an enlarged end view along line XX of (A) with a portion omitted. [Figure 6] 1 is a side view showing a state in which one embodiment of a wax carver according to the present invention is used. FIG. [Figure 7] 1 is a schematic diagram showing the bite state of a person's teeth. [Figure 8] The figures show the occlusion states of the front teeth and molars, with (A) being a schematic diagram showing the occlusion state of the front teeth and (B) being a schematic diagram showing the occlusion state of the molars. [Figure 9] FIG. 1 is a schematic side view showing a conventional facing crown. [Figure 10] This is a photograph taken from inside the oral cavity showing a conventional veneer crown attached to a front tooth. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of a facing crown according to the present invention will be described with reference to FIGS.

[0018] In Figures 1 and 2, human teeth grow in an upper jaw 10 and a lower jaw 20, and on the lip side of the upper jaw 10 and the lower jaw 20, i.e., outside the oral cavity, the upper jaw 10 has upper front teeth 11 and the lower jaw 20 has lower front teeth 21. In the upper jaw 10, a facing crown 30 according to this embodiment is attached to the upper front tooth 11 that forms the abutment tooth. The facing crown 30 comprises a post core 31, a metal frame 32, and a facing portion 33. The base of the post core 31 is embedded in and adhesively fixed to the root 11A of the maxillary anterior tooth 11, and the metal frame 32 is bonded to the post core 31. The facing portion 33 is fixed from the upper end of the metal frame 32 to the outer surface on the lip side. The facing portion 33 is made of a material such as hard resin or ceramic that is commonly used for dental implants and crowns. In the figure, 13 is the alveolar bone of the upper jaw 10, and 14 is the gingiva of the upper jaw 10. Also, 23 is the alveolar bone of the lower jaw 20, and 24 is the gingiva of the lower jaw 20. The detailed structure of other teeth has been omitted. Also, Figure 1 shows a pulpless tooth where the pulp (nerve of the tooth) has been removed, but the structure of the veneer crown is the same as that shown in Figure 1 even for a pulp-containing tooth where the pulp has been preserved.

[0019] When the metal frame 32 is attached to the mouth, a step 34 is formed on the tongue side, i.e., the inside of the mouth. The step 34 has a fissure-like recess 34A on the occlusal surface of a molar and a lingual cusp-like protrusion 34B. The top of the lower front tooth 21 is engaged with the step portion 34 . The fissure-like recesses 34A and lingual cusp-like protrusions 34B of the step portion 34 allow the engagement between the metal frame 32 and the mandibular anterior teeth 21 to correspond to the engagement between the cusps and fissures of the maxillary molars and mandibular molars, respectively. This allows the maxillary anterior teeth 11 to have strength that can withstand the biting force equivalent to that of molars.

[0020] When applying the veneer crowns 30 to actual maxillary anterior teeth 11, as is clear from the photograph in Figure 2, the veneer crowns 30 are formed as connected crowns to continuously prosthesize a plurality of maxillary anterior teeth 11. Of the maxillary anterior teeth 11 to be prosthesised by the veneer crowns 30, several relatively healthy maxillary anterior teeth 11, i.e., 2 to 6 maxillary anterior teeth 11, constitute the abutment teeth. In the embodiment shown in the photograph, the veneer crown 30 is formed as a continuous connected crown that extends from the center to the upper right third maxillary anterior tooth 11 to the upper left third maxillary premolar and the left fourth maxillary premolar.

[0021] Figure 3 is a photograph of a specific embodiment of a veneer crown 30, viewed from the inside of the mouth, before being attached to the maxillary anterior tooth 11, and Figure 4 is a photograph of the specific embodiment of Figure 3, viewed from the opposite side. As is clear from these figures (photographs), the vestibular crowns 30 are formed as continuous connected crowns, including five artificial teeth to replace missing teeth, on each side of the center of the maxilla 10. Three prosthetic teeth on each side of the center of the maxilla 10 are used to replace maxillary anterior teeth 11, and the fourth and fifth prosthetic teeth are used to replace premolars. When fabricating the vestibular crowns 30 in the prosthetic treatment of the maxillary anterior teeth 11, it is not necessary to form all of the maxillary anterior teeth 11 as abutment teeth, and if the condition of several of the abutment teeth is above a predetermined sound condition, these maxillary anterior teeth 11 can be used to bond the vestibular crowns 30. For example, in a case where occlusal support for either the left or right molar has been lost, if two or more maxillary anterior teeth 11 remain, and there is only slight mobility of each abutment tooth, and the tooth structure of the crown and root remains in good condition and is in occlusion, these can be used as abutment teeth, and the veneer crown 30 of this embodiment can be used in prosthetic treatment of the maxillary anterior teeth 11. Furthermore, as shown in Figure 4, even if there is a missing tooth, as long as the requirements for a bridge are met, the facing crown 30 of this embodiment can be used for the facing crown of the bridge and the artificial front teeth. In Figure 4, the missing teeth are the third from the left (upper left 3), the fifth from the left (upper left 1), and the seventh from the left (upper right 2). Here, the numbers in parentheses indicate the dental formula.

[0022] According to the present embodiment described above, the following effects are obtained. According to the vestibular crown 30 of this embodiment, a step portion 34 is provided in the metal frame 32, which forms a fissure-like recess 34A and a lingual cusp-like protrusion 34B.Therefore, when the upper and lower anterior teeth 11 and 21 are engaged with each other, the upward thrust force of the lower anterior teeth 21 against the upper anterior teeth 11 from below can be absorbed as an occlusal force in the tooth axis direction via the step portion 34. In other words, the lingual cusp-like protrusion 34B can bring the occlusal force, which is normally applied at an angle to the axis of the maxillary anterior teeth 11, closer to perpendicular to the axis, and in this state, the maxillary anterior teeth 11 can withstand the occlusal force of the mandibular anterior teeth 21. Therefore, even when the bite force is applied when the upper jaw front teeth 11 and the lower jaw front teeth 21 are brought into contact with each other, injuries such as movement of the upper jaw front teeth 11 and root fracture can be significantly reduced. Therefore, the maxillary front teeth 11 can be substantially endowed with strength capable of withstanding a occlusal force comparable to that of molars, thereby improving masticatory efficiency. This can improve the quality of life (QOL) of people who have lost the occlusal support of their molars.

[0023] Furthermore, the vestibular crown 30 of this embodiment is a connected crown in which multiple maxillary anterior teeth 11 are connected together, so the maxillary anterior teeth 11 can be protected from movement and root fracture more effectively than if the maxillary anterior teeth 11 were preserved as a single crown, thereby improving the prognosis of dental treatment. In other words, by connecting the single-rooted maxillary anterior teeth 11, they can be made multi-rooted like molars, and their strength can be increased. In this case, if there are any maxillary molars remaining, it is also possible to form a continuous vestibular crown 30 including the maxillary molars, as necessary, rather than just connecting the maxillary anterior teeth 11. By forming a vestibular crown 30 including the maxillary molars in this way, the bite force strength of the maxillary anterior teeth 11 can be further improved.

[0024] Furthermore, in the vestibular crown 30 of this embodiment, a lingual cusp-like protrusion 34B is provided on the lingual side of the maxillary anterior tooth 11, and by connecting these, an occlusal surface-like shape can be obtained, thereby further improving chewing efficiency.

[0025] The veneer crown 30 of this embodiment is formed as a connected crown in which multiple maxillary anterior teeth 11 are connected, but depending on the condition of the patient's teeth, it can also be formed as a single crown. However, if it is a connected crown, it can be effective in performing more advanced prosthetic treatment for the maxillary anterior teeth 11. Furthermore, this embodiment can also be applied to bridge treatment of the maxillary front teeth 11. In this case, if the maxillary front teeth 11 are missing, this can be applied by using artificial teeth to compensate for the missing parts. In this way, this embodiment can be applied to bridge treatment of the maxillary front teeth 11 regardless of whether the maxillary front teeth 11 are missing or not, and can increase the strength of the bridge in either case.

[0026] Next, an embodiment of a wax carver used in producing a facing crown according to this embodiment will be described.

[0027] An embodiment of a wax carver according to the present invention is shown in Figure 5. Figure 5(A) shows a front view of the entire wax carver according to this embodiment, and (B) shows an enlarged end view of (A) taken along line XX with a portion omitted.

[0028] In FIG. 5, a wax carver 40 is made of a metal material such as stainless steel, and includes a round shaft-shaped handle 41 and a head 42 connected to the handle 41. A twill knurling 43 is formed in the middle of the handle 41 to prevent slipping.

[0029] A cutting edge 44 is formed on one side surface of the head 42. A molding step 45 is formed in the middle of the cutting edge 44. The molding step portion 45 has a projection 45A and a recess 45B of a similar shape corresponding to the fissure-like recess 34A and the cusp-like projection 34B formed in the step portion 34 of the facing crown 30.

[0030] Next, a method of using the wax carver 40 according to this embodiment will be described.

[0031] To create the veneer crown 30, first, as is the usual method, an impression is taken of the patient's teeth, and then information is collected to reproduce various elements such as the patient's jaw position, tooth orientation, and temporomandibular joint function and movement as accurately as possible outside the body, i.e., an occlusion registration is taken.

[0032] Based on these impressions and bite registrations, a wax-up is performed in the form of a connected crown, a facing crown 30, in the technical procedure. In this wax-up, unlike a typical facing crown, a protrusion corresponding to the lingual cusp-like protrusion 34B is formed on the lingual side surface of the metal frame 32 of the facing crown 30, and the necessary amount of wax is applied to a position corresponding to the lingual side surface of the facing crown 30. In this embodiment, in which the facing crown 30 is manufactured as a connected crown, the protrusion corresponding to the lingual cusp-like protrusion 34B is applied continuously to the lingual side of the connected crown. 6 shows a state in which a wax-up has been performed on a model of the maxillary anterior teeth 11. That is, wax 50 is attached to the tip side of the model of the maxillary anterior teeth 11. A raised portion of wax corresponding to the stepped portion 34 of the facing crown 30 is applied to the lingual side of this wax 50, forming a stepped portion 51. The step portion 51 has a recess 51A and a protrusion 51B that are similar to the fissure-like recess 34A and the cusp-like protrusion 34B of the step portion 34 of the facing crown 30.

[0033] The process of forming the step portion 51 in the wax 50 is significantly different from the process of forming a conventional facing crown, and is not easy even for an experienced dental technician. That is, conventional wax carvers for shaping wax have cutting edges shaped like arrowheads, needles, or spatulas, and it is extremely difficult to form the lingual cusp-like protrusion 34B using these conventional wax carvers.

[0034] Therefore, the wax carver 40 of this embodiment is used to prepare a shape on the lingual side surface of the wax 50 that is similar to the lingual oral-like protrusion 34B of the facing crown 30. In this embodiment, the cutting edge portion 44 of the wax carver 40 has a molding step portion 45 formed in advance, so after performing an appropriate wax-up on the lingual side of the wax 50, by pressing the cutting edge portion 44 of the wax carver 40 against the waxed-up portion and moving it to a shape that follows the inner lingual surface of the patient's mouth, it is possible to very easily obtain a step portion 51 that is close to the shape required for the lingual side of the wax 50. Thereafter, if necessary, a precise step portion 51 can be easily formed by carrying out some shaping.

[0035] Using the wax 50 with the step portion 51 formed as described above, the metal frame 32 is made by dental precision casting using the lost wax method as usual, and the facing portion 33 is faced with hard resin or the like to complete the facing crown 30. The completed veneer crown 30 is adjusted to fit the shape of the patient's teeth and is then cemented into the oral cavity, completing the veneer crown fitting process.

[0036] The wax carver 40 of this embodiment described above has the following advantages. The facing crown 30 created according to the present invention has a specially shaped step 34 formed on the lingual side of the metal frame 32, which would be extremely difficult to create with a conventional wax carver. However, with the wax carver 40 of this embodiment, the step 51 can be very easily formed in the wax 50 using the molding step 45. Therefore, if dental precision casting is performed using this wax 50, the step 34 can be easily formed in the metal frame 32, significantly improving the work efficiency of creating the facing crown 30.

[0037] In particular, when the facing crown 30 is not a single crown but a connected crown, it is necessary to provide a continuous lingual cusp-like protrusion 34B along the lingual side of the connected crown of the facing crown 30, but by using the wax carver 40 of this embodiment, the continuous protrusion 34B can be easily produced. Furthermore, by using the wax carver 40 of this embodiment, anyone can create wax 50 in a standard shape, and there is no need to require dental technicians to have a high level of skill. Furthermore, if the shape of the molding step portion 45 of the wax cover 40 of this embodiment is set to an optimal shape in advance, it will serve as a standard for imparting this shape, allowing technical operations to be carried out efficiently. In this case, if the shape of the step portion 34 of the facing crown 30 is divided into multiple patterns according to the condition of the patient's teeth and wax carvers 40 having forming step portions 45 shaped according to each pattern are prepared in advance, the facing crown 30 can be manufactured more efficiently.

[0038] The above describes in detail the embodiments of the veneer crown 30 and wax carver for making veneer crowns according to the present invention with reference to the drawings. However, the specific configuration of the present invention is not limited to these embodiments, and even if there are design changes within the scope of the present invention that do not deviate from the gist of the present invention, they are still included in the present invention.

[0039] For example, the stepped portion 34 of the facing crown 30 is not limited to a shape clearly defined by the recess 34A and the protrusion 34B, but may have a step large enough to receive the apex of the mandibular anterior tooth 21 when the apex of the mandibular anterior tooth 21 abuts against the stepped portion 34. Furthermore, when the facing crown 30 is made as a connected crown, the cusp-like protrusion 34B does not necessarily need to be made continuous; it may be made in an interrupted state. However, making the protrusion 34B continuous makes it easier to make it. This is particularly true when using the wax carver 40 of this embodiment.

[0040] The wax carver 40 of this embodiment has a head 42 and a cutting blade 44 at one end of the handle 41, but the head 42 and cutting blade 44 may be provided at both ends of the handle 41, and the cutting blades 44 may have different shapes. In this case, the cutting blade 44 at one end may be used for rough cutting, and the cutting blade 44 at the other end may be used for precision shaping. Also, one cutting blade may be formed into an arrowhead shape, spatula shape, or the like, as in conventional wax carvers.

[0041] Furthermore, the materials for the metal frame 32 and the facing portion 33 of the facing crown 30 can be materials used for ordinary facing crowns, and may also be newly developed materials. [Explanation of symbols]

[0042] 10 Upper jaw 11 Upper incisors 20 Lower jaw 21 Lower incisor 30 muzzleloader 32 Metal Frame 33 Muzzle 34 Step 34A Fissure-like depression 34B Cusp-like protrusion 40 Wax Carver 41 Handle 42 Head 44 Cutting edge 45 Step for molding 45A protrusion 45B recess 50 wax 51 Step 51A Recess 51B Protrusion

Claims

1. A veneer crown to be attached to an upper front tooth, said veneer crown having a metal frame, and a stepped portion formed on the tongue side of said metal frame when the veneer crown is attached to the oral cavity, against which the top of the lower front tooth abuts.

2. 2. The veneer crown according to claim 1, wherein the step portion has a cusp-like protrusion formed on the tongue side when the veneer crown is worn in the oral cavity, and a fissure-like recess formed on the lip side when the veneer crown is worn in the oral cavity.

3. 3. The veneer crown according to claim 2, wherein the veneer crown is formed as a continuous connected crown spanning a plurality of the maxillary anterior teeth, and the cusp-like protrusion is formed continuously on the lingual side of the connected crown.

4. 4. A wax carver for use in making a facing crown according to any one of claims 1 to 3, wherein the wax carver has a cutting edge for shaping wax, and the cutting edge has a shaping step formed thereon that is similar in shape to the step of the metal frame.

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