JP7434697B2 - dental handpiece - Google Patents

Description

The present invention relates to a dental handpiece that uses vibration to remove tartar and clean root canals.

The handpiece, which uses vibrations to remove tartar and clean root canals, has a built-in vibration cartridge that includes a vibration source and a vibration transmission section that transmits the generated vibrations toward the tip of the handpiece. has been done. A screw hole for attaching a tip tool is provided at the tip of the vibrating cartridge, and a tip tool suitable for the purpose can be attached to the vibrating cartridge by screwing (for example, Patent Document 1 by the applicant of the present invention). ).

In order to prevent the vibration cartridge from rotating together with the rotation of the accessory tool when attaching or removing the accessory tool to the vibration cartridge with a screw, the vibration cartridge has a The casing of the handpiece is provided with detents (usually a pair) that protrude in a columnar manner in the radial direction, and detent storage portions (usually a pair) that can accommodate the detents. An annular elastic body (for example, an O-ring) is attached to the rotation stopper so that the vibration of the vibration cartridge is not transmitted to the housing (Patent Documents 1 to 3).

For example, in Patent Documents 1 and 2, two cylindrical detents with a circular cross-sectional shape are provided, and an O-ring is attached to each detent (Fig. 2 of Patent Document 1, Patent Document 2 paragraph 0027). In Patent Document 3, two column-shaped detents with an oval or track-shaped cross-sectional shape (a shape in which two parallel straight lines are connected by a semicircle, a semiellipse, or an arc) are provided, and the detents are An O-ring is attached to each (FIG. 6 of Patent Document 3).

While observing many handpieces that were brought in for repair, the applicant noticed that there were many cases in which the anti-rotation O-ring broke in two, regardless of the reason for the repair. . If the O-ring breaks, not only will the vibration of the vibrating cartridge be transmitted to the housing, but it will also cause the vibrating cartridge to rotate or shift more easily, causing problems when attaching/detaching the tip tool or using the handpiece. A problem arises in that it becomes difficult to control the vibrating cartridge to a desired position.

In Patent Document 3, since the scaler tip is frequently attached and detached, the O-ring is repeatedly overcompressed, and the O-ring is damaged or deformed, resulting in increased noise due to vibration and damage to the mechanism. Problems such as accelerated wear have been pointed out. Patent Document 3 solves this problem by providing a control means to prevent overcompression of the O-ring (elastic body), but the provision of a new means has the disadvantage of complicating the structure. .

JP 2019-037293 Publication Japanese Patent Application Publication No. 2002-065699 Japanese Patent Application Publication No. 2004-351104

An object of the present invention is to provide a structure that can prevent the annular elastic body attached to the rotation stopper of the vibration cartridge from breaking, without requiring a complicated structure, in a dental handpiece that requires frequent attachment and detachment of the tip tool. It's about doing.

The object of the invention is the invention:
[1] A dental handpiece (10) including a housing (1) and a vibration cartridge (2) built into the housing and provided with a screw hole (28) for attaching a tip tool and a vibration source. The vibrating cartridge (2) has a detent (21) that protrudes in a columnar shape in the radial direction with respect to the shaft and prevents rotation of the vibrating cartridge about the axis within the housing. , the casing (1) has a detent storage part (11) that accommodates the detent in its inner wall and can prevent the rotation of the vibration cartridge within the casing, and the dental hand The piece (10) further includes an annular elastic body (3) removably attached to the detent, and is used when attaching or removing the tip tool to the screw hole inside the side surface of the detent (21). In this case, the shape of the side surface (21a (pressing surface)) that indirectly contacts the inner surface of the detent storage part with the elastic body in between, and the inner surface of the detent storage part (11) that faces this side surface. The dental handpiece, wherein the shape of (11a (pressure receiving surface)) is such that the elastic body can be sandwiched in a linear or planar shape during the attachment or detachment;
[2] The dental handpiece according to [1], wherein the end surface (21b) of the rotation stopper (21) has a rounded outer circumference;
[3] The dental handpiece according to [1] or [2], wherein an overcompression reducing groove (29) capable of reducing overcompression of the elastic body is provided on a side surface of the detent (21);
This can be solved by

According to the present invention, even in a dental handpiece that requires frequent attachment and removal of the tip tool, the possibility of breakage of the annular elastic body attached to the rotation stopper of the vibration cartridge is reduced, and the product life until breakage is extended. Therefore, the frequency of replacing the annular elastic body can be kept low.

FIG. 2 is a partially cutaway side view showing the main parts of one embodiment of the handpiece according to the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. 2 is a sectional view taken along line BB in FIG. 1. FIG. (a) is a partially cutaway perspective view schematically showing the shape of one embodiment of the detent in the present invention, and (b) is a state in which the tip tool is attached (a state in which no force is applied to the elastic body). ), and (c) is a schematic vertical cross-sectional view when the tip tool is attached and detached (in a state where force is applied to the elastic body). (a) is a perspective view schematically showing the shape of another embodiment of the detent in the present invention, (b) is a schematic vertical cross-sectional view with a tip tool attached, and (c) FIG. 2 is a schematic vertical cross-sectional view of the tip tool when it is attached and detached. (d) and (e) are perspective views schematically showing the shape of still another embodiment. FIG. 2 is a cross-sectional view and a vertical cross-sectional view schematically showing the shape and mechanism of action of the detent disclosed in Patent Document 1. (a) and (b) are a cross-sectional view and a vertical cross-sectional view with the tip tool attached, and (c) and (d) are a cross-sectional view and a vertical cross-sectional view when the tip tool is attached and detached. . FIG. 6 is a cross-sectional view and a vertical cross-sectional view schematically showing the shape and mechanism of action of the detent disclosed in FIG. 6 of Patent Document 3. (a) and (b) are a cross-sectional view and a vertical cross-sectional view with the tip tool attached, and (c) and (d) are a cross-sectional view and a vertical cross-sectional view when the tip tool is attached and detached. . FIG. 2 is a schematic longitudinal cross-sectional view of a detent having a rounded outer periphery, which is one of the preferred embodiments of the present invention; FIG. , (b) is a detent having an R shape. (a) is a schematic perspective view of a detent provided with an overcompression reducing groove, which is one of the preferred embodiments of the present invention, (b) is a partial vertical cross-sectional view of (a), and (c) is a sectional view taken along line CC in (b). (a) is a perspective view schematically showing the shape of the detent used in Test Example 2, (b) is an end view of (a), and (c) is a line AA in (b). FIG. 3(d) is a cross-sectional view taken along line BB in FIG. (a) is a perspective view schematically showing the shape of another detent used in Test Example 2, (b) is an end view of (a), and (c) is an A-- It is a sectional view taken along line A, and (d) is a sectional view taken along line BB of (b).

The dental handpiece of the present invention (hereinafter also referred to as the handpiece of the present invention) will be described below with reference to the accompanying drawings, but the present invention is not limited to the embodiments shown in the accompanying drawings.

FIG. 1 is a partially cutaway partial side view showing the main parts of one embodiment of the handpiece according to the present invention, and the cutout portion is a sectional view. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. Note that in each cross-sectional view, hatching may be omitted to make the structure easier to understand.

FIG. 1 shows the structure of the main parts of the handpiece 10 with the tip tool removed. The housing 1 has an internal space 24 passing through the interior in the axial direction, and a vibration cartridge 2 including a vibration transmission section 26, a vibration source (not shown), etc. is housed in the internal space. Can be done. Note that the vibrating cartridge portion is indicated by a thick line.

A screw hole 28 for attaching a tip tool is provided at the tip of the vibration transmission section 26. Further, the vibration transmission section is provided with a pair of columnar detents 21 having a substantially rectangular or square cross-sectional shape, and each detent is provided with an annular elastic body 3 (for example, an O-ring). is installed.

On the other hand, when the vibration cartridge is placed in a predetermined position inside the housing, the housing 1 accommodates one of the detents and prevents the rotation of the vibration cartridge within the housing (around the axis of the vibration cartridge). A rotation stopper storage section 11 that can prevent rotation is provided on the inner wall of the casing so as to correspond to each rotation stop. The anti-rotation storage section communicates with the internal space of the casing, and can also be regarded as a part of the internal space.

In the handpiece of the present invention, as shown in FIG. When attaching or detaching a tool (hereinafter collectively referred to as "attachment/detachment of the tip tool"), the side surface 21a (hereinafter referred to as The shape of the detent (referred to as the "pressing surface") and the shape of the inner surface 11a of the detent storage section (hereinafter referred to as the "pressure receiving surface" of the detent storage portion) opposing this side surface are determined by the mounting or A shape is adopted that allows the elastic body to be inserted linearly or planarly during removal.

In this specification, "a shape that can hold an elastic body linearly or planarly" means that force is applied in the direction from the pressing surface of the detent to the pressure receiving surface of the detent storage part when attaching or removing the tip tool. In this case, the force is not concentrated at one specific point on the pressing surface and at one specific point on the pressure receiving surface, and the elastic body is moved between a continuous straight line or a specific surface area on the pressing surface and the opposing pressure receiving surface. It means a shape that can disperse force along the straight line by being sandwiched.

For example, the cross-sectional shape shown in FIG. 4 is approximately rectangular or approximately square, and the longitudinal section is taken along a plane perpendicular to the axis of the vibrating cartridge (hereinafter simply referred to as "vertical section" means this longitudinal section). In a prismatic detent that is approximately rectangular or square in shape, when the tip tool is attached or removed (FIG. 4c), the detent tilts and the space surrounded by the pressing surface 21a and the pressure receiving surface 11a becomes narrow. Therefore, the portion of the elastic body close to the detent end surface (hereinafter referred to as the upper part for convenience) is greatly deformed, and the outer periphery of the detent end surface (21b) where the distance between the pressing surface and the pressure receiving surface is the shortest (X shown in FIG. 4) ) and the opposing pressure-receiving surface 11a, the elastic body 3 is linearly sandwiched, so that the force applied to the elastic body can be linearly distributed.

In addition, in the detent shown in FIG. 5 whose cross-sectional shape is approximately rectangular or approximately square, the upper half of the vertical cross-sectional shape is approximately trapezoidal, and the lower half of the vertical cross-sectional shape is approximately rectangular or approximately square, the tip When the tool is attached or removed (Fig. 5c), the detent is tilted and the space surrounded by the pressing surface and the pressure receiving surface becomes narrow, so the upper part of the elastic body deforms greatly and the surface area of the upper half of the detent side (Fig. 5b) and the opposing pressure-receiving surface, or the upper end of the region Y (i.e., the outer periphery of the anti-rotation end surface) or the region Y Since the elastic body is linearly sandwiched between the lower end (i.e., the boundary between the substantially trapezoidal part and the substantially rectangular or square part) and the opposing pressure receiving surface, the force applied to the elastic body can be dispersed linearly or planarly.
Similarly, in the case of a truncated pyramid (truncated pyramid) detent whose cross-sectional shape is approximately rectangular or approximately square and whose vertical cross-sectional shape is approximately trapezoid, the elastic body is used when attaching and detaching the tip tool. It can be inserted linearly or planarly.

As described above, other shapes of the detent that can pinch the elastic body linearly or planarly when attaching and detaching the tip tool include, for example, the cross-sectional shape shown in Fig. 5d is oval or track shape (parallel). A shape in which two straight lines are connected by a semicircle, semiellipse, or circular arc.However, the positional relationship between the straight line part and the semicircle, semiellipse, or circular arc part is such that the straight line part has an elastic body in between. A columnar shape having a substantially rectangular or substantially square cross-sectional shape as shown in FIG. One example is the shape. In addition, in these cases, the shape shown in FIGS. 4 and 5 can be adopted as the shape of the inner surface of the detent storage part.

On the other hand, Patent Document 1 discloses a cylindrical detent 21 having a circular cross-sectional shape and a substantially rectangular or substantially square vertical cross-sectional shape, as shown in FIG. In this detent, the shape of the pressure-receiving surface 11a in the detent housing is flat, so when the detent is tilted when the tip tool is attached or removed, as shown in FIG. 6c, when viewed from the end face direction of the detent, , the elastic body 3 is sandwiched between one point on the outer periphery of the anti-rotation end surface (Z shown in FIG. 6c) and a specific point on the opposing pressure receiving surface. On the other hand, as shown in FIG. 6d, when viewed from the axial direction of the vibration cartridge, there is a point on the outer periphery of the detent end surface where the distance between the pressing surface and the pressure receiving surface is the shortest (Z shown in FIG. 6d), and a point opposite thereto. The elastic body 3 is sandwiched between a specific point on the pressure receiving surface. Therefore, the force is concentrated at one point on the elastic body, and the elastic body is likely to break due to repeated attachment and detachment, as shown in the examples described later.

Further, in FIG. 6 of Patent Document 3, the cross-sectional shape is oval or track-shaped as shown in FIG. A columnar detent 21 having a semi-elliptical or arcuate portion, which is arranged so as to indirectly contact the inner surface of the detent housing with the elastic body 3 in between, and whose vertical cross-sectional shape is approximately rectangular or approximately square. A combination of this and a detent storage portion in which the pressure receiving surface 11a is a concave curved surface is disclosed. When viewed from the end face direction of the detent (Fig. 7a, Fig. 7c), assuming that the distance between both curved surfaces is such that they can make surface contact with each other when no force is applied to the elastic body (Fig. 7a), the O-ring When a force is applied to the curved surface (Fig. 7c), the distance between the two curved surfaces becomes smaller, so the state of surface contact is eliminated, and the force is concentrated at one specific point. On the other hand, if the detent is tilted when attaching or removing the tip tool, as shown in Fig. 7d, a point on the outer periphery of the detent end surface where the distance between the pressing surface and the pressure receiving surface is the shortest when viewed from the axial direction of the vibration cartridge. (Z shown in FIG. 7) and a specific point on the pressure-receiving surface facing the elastic body. Therefore, the force is concentrated at one point on the elastic body, deforming the elastic body, and it is expected that the elastic body will be more likely to break due to repeated attachment and detachment. In Patent Document 3, breakage of the elastic body is prevented by a protrusion to which no elastic body is attached.

In the handpiece of the present invention, as will be described later, if desired, the outer periphery of the end surface of the detent, that is, the ridgeline between the side surface and the end surface of the detent, may have an angle in all or part thereof (preferably over the entire circumference). The shape of the pressing surface and the shape of the pressure-receiving surface, which have rounded corners, can be used to form a shape with rounded corners, but even in this case, the shape of the pressing surface and the shape of the pressure-receiving surface, which have rounded corners, may cause the elastic body to form a linear shape when the tip tool is attached or detached. Or adopt a shape that can be sandwiched in a plane.
In addition, in the handpiece of the present invention, as will be described later, if desired, a groove is provided on the side surface of the detent to reduce overcompression of the elastic body and/or to prevent displacement of the elastic body. However, in this case as well, the shape of the pressing surface provided with the groove and the shape of the pressure receiving surface must be such that the elastic body can be sandwiched in a linear or planar shape when attaching and detaching the tip tool. Adopt.

In the handpiece of the present invention, if desired, at the outer periphery of the end surface 21b of the detent 21, that is, at the ridgeline between the side surface 21c of the detent 21 and the end surface, a corner (preferably over the entire circumference) may be formed. ) can be taken. Examples of the rounded shape include a chamfered shape 22a shown in FIG. 8a and a rounded shape 22b shown in FIG. 8b.

In this specification, "chamfering" means cutting off a corner of a ridgeline to form a flat surface.
Moreover, in this specification, "adding an R" or "R chamfering" means cutting the corners of the ridgeline to make them rounded.

In the handpiece of the present invention, the degree of chamfering and radius is determined as long as the elastic body attached to the detent does not shift or come off from the predetermined position when the tip tool is attached or detached or when the handpiece is used. It is not particularly limited, and can be appropriately determined using the effect of suppressing elastic body breakage as an index.

In the handpiece of the present invention, the reason why the possibility of breakage of the annular elastic body can be reduced and the product life until breakage can be extended by taking the corner of the outer periphery of the detent end face that is a distance from the elastic body is as follows. Although it is currently unknown, in the internal space formed between the end face and side surface of the detent and the inner wall of the detent housing, when the tip tool is attached or removed, the detent and the elastic body attached to it vary. It is thought that the shape of the outer periphery of the end surface of the detent will affect the breakage of the elastic body because the positional relationship between the elastic body and the detent changes (for example, it shifts diagonally or upward) when a force is applied from the direction of the detent. ing.

In the handpiece of the present invention, if desired, an elastic material is provided on the side surface of the detent, over the entire circumference thereof, or on a part thereof (for example, only on two opposing sides as shown in FIG. 9). An overcompression reduction groove 29 can be provided that can reduce compression. The overcompression reducing groove can also function as a displacement prevention groove that prevents displacement of the elastic body.
The shape and size of the overcompression reducing groove are not particularly limited as long as they can reduce overcompression and prevention of slippage of the elastic body. For example, the shape and size of the detent, the shape of the elastic body, etc. It can be determined appropriately taking into consideration the size and the like. For example, in the vibrating cartridge shown in FIG. 9, the cross-sectional shape of the detent is substantially rectangular or square, and two opposing side surfaces are provided with grooves extending in the axial direction of the vibrating cartridge.
In the handpiece of the present invention, by providing the overcompression reducing groove as desired, it is possible to reduce the load applied to the elastic body when attaching and detaching the tip tool, or to reduce the load applied to the elastic body when attaching and detaching the tip tool. Since it is possible to suppress changes in the positional relationship between the body and the rotation stopper, we believe that the possibility of breakage of the elastic body can be reduced and the product life until breakage can be extended.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these are not intended to limit the scope of the present invention.

《Test Example 1》
In this test example, a commercially available dental handpiece, Sonic End (manufactured by Micron), was used to verify the resistance of O-rings to breakage for four types of vibration cartridges with different detent shapes. Note that since this was a breaking test, an O-ring with lower strength than general O-rings used in commercially available products was used.

The vibration cartridge of the handpiece can be separated into a vibration transmitting part and a vibration source, and the vibration transmitting part incorporated in a commercial product (the cross-sectional shape of the detent is circular, and the outer periphery of the end face of the detent is Not chamfered.Hereinafter, in addition to detent A (comparative example)), detent B (the cross-sectional shape of the detent is circular and the outer periphery of the end face of the detent is chamfered (comparative example)), Detent C (the cross-sectional shape of the detent is approximately rectangular or approximately square (the long side is in the axial direction of the vibration cartridge, and the outer periphery of the end surface of the detent is not chamfered (example)), detent D ( Each vibration transmitting section was prepared in which the cross-sectional shape of the detent was approximately rectangular or square, and the outer periphery of the end face of the detent was chamfered (Example). The shape of the pressure-receiving surface in the detent storage section is flat, as shown in FIGS. 2 and 3.

After attaching an O-ring to the rotation stopper of each vibration transmitting part and attaching it to the handpiece, attaching and removing the tip tool is one work process, and every time this one work process is repeated 10 times, vibration is transmitted from the handpiece. The O-ring was removed and the condition of the O-ring was observed to see if there were any cracks and how many times the O-ring had to break.
Table 1 shows the relative number of times until the O-ring breaks at each stop, when the number of times until the O-ring breaks at stop A is 1. Note that the relative number of times “>10” in Table 1 indicates that no breakage occurred when the relative number of times was 10 times.

In comparing detent B and detent C, detent C had a higher final relative number of rotations, but since the occurrence of cracks was confirmed early, it was found that without chamfering, regardless of the cross-sectional shape, detent C had a higher final relative frequency. It was confirmed that the O-ring was more likely to crack.
The crack grows and the O-ring breaks, but when the cross-sectional shape is circular, the force concentrates on the crack, and the O-ring breaks in a small number of times (detent A, detent B).
When the cross-sectional shape is approximately rectangular or approximately square, even if a crack occurs, it is difficult for force to concentrate on the crack, and the number of times it takes to break is large.

《Test Example 2》
In this test example, the cross-sectional shape (the cross-sectional shape before the overcompression reduction groove is provided) of the detents (a pair of two) is approximately rectangular or approximately square, and only one of the detents has a side surface. Overcompression reducing grooves extending in the axial direction of the cartridge are provided on two opposing surfaces (the surfaces where the direction of the groove is the same as the axial direction of the vibration cartridge when an overcompression reducing groove is provided). The provided detents E (both non-grooved detents and grooved detents are examples; Fig. 10), the cross-sectional shape of the detents (two pairs) (the cross-sectional shape before providing the overcompression reduction grooves) ) are all circular, and only one of the detents is provided with two opposing overcompression reducing grooves on its side surface (detent without groove: comparative example, detent with groove: EXAMPLE: The resistance of the O-ring to breakage was verified in the same manner as in Test Example 1, except that each vibration transmitting section equipped with the above-mentioned vibration transmitting section (FIG. 11) was used. Note that the groove provided in the detent E is a concave curved surface whose cross section is an arc, as shown in the longitudinal cross-sectional view BB in FIG. As shown at BB, the cross section is a concave curved surface having an arcuate shape.

With the detent E having a substantially rectangular or substantially square cross-sectional shape, the O-ring did not break even when the tip tool was attached and removed 150 times, regardless of the presence or absence of a groove. On the other hand, in the detent F having a circular cross-sectional shape, even when the detent without the overcompression reducing groove broke, the detent provided with the overcompression reducing groove did not break.

INDUSTRIAL APPLICABILITY The present invention can be used in the field of dental medical equipment.

10...Dental handpiece;
1... Housing; 11... Anti-rotation storage part; 11a... Pressure receiving surface;
2... Vibration cartridge; 21... Stopper; 21a... Pressing surface;
21b... end face; 21c... side surface; 22a... chamfering; 22b... R chamfering;
24...inner space; 26...vibration transmission section;
28... Screw hole; 29... Overcompression reduction groove;
3...Elastic body

Claims (3)

A dental handpiece (10) comprising a housing (1) and a vibration cartridge (2) built into the housing and provided with a screw hole (28) for attaching a tip tool and a vibration source. ,
The vibrating cartridge (2) has a detent (21) that protrudes in a columnar shape in the radial direction with respect to the shaft and prevents rotation of the vibrating cartridge about the axis within the housing,
The casing (1) has a detent housing part (11) that accommodates the detent in its inner wall and can prevent the vibration cartridge from rotating within the casing;
The dental handpiece (10) further includes an annular elastic body (3) removably attached to the detent,
Among the side surfaces of the detent (21), a side surface (21a) that indirectly contacts the inner surface of the detent storage portion with the elastic body in between when attaching or removing the tip tool to the screw hole. The shape of the pressing surface) and the shape of the inner surface (11a (pressure receiving surface)) of the detent storage part (11) opposite to this side surface are such that the elastic body is not shaped like a line or a plane during the installation or removal. The dental handpiece has a shape that allows it to be held in place. The dental handpiece according to claim 1, wherein the end surface (21b) of the detent (21) has a rounded outer circumference. The dental handpiece according to claim 1 or 2, wherein an overcompression reducing groove (29) capable of reducing overcompression of the elastic body is provided on a side surface of the rotation stopper (21).