CN105640659B

CN105640659B - The screw of the dismountable dental prosthesis system of superstructure and correlation

Info

Publication number: CN105640659B
Application number: CN201410650618.2A
Authority: CN
Inventors: 杉山贵彦
Original assignee: MANPUNENG ENTERPRISES Co Ltd
Current assignee: MANPUNENG ENTERPRISES Co Ltd
Priority date: 2014-11-14
Filing date: 2014-11-14
Publication date: 2017-09-01
Anticipated expiration: 2034-11-14
Also published as: CN105640659A

Abstract

The present invention proposes the screw of a kind of detachable dental prosthesis system and correlation.Detachable dental prosthesis system includes bearing, superstructure and screw.Bearing, which is included on abutment interface and hollow cavity, and the seating wall of hollow cavity, screw hole.Superstructure is provided with accommodating area and the medial surface around accommodating area.Screw includes screw terminal and screw rod.Screw terminal includes contact site and guidance part, and guidance part is located between contact site and screw rod.When screw is arranged in screw hole, the local of screw terminal can outwardly protruding from hollow cavity.When superstructure entangles bearing, the regional area of the outer surface of hollow cavity can be in contact with the regional area of the medial surface of superstructure, and screw terminal can prop up the opposite side of medial surface, to exert a force onto medial surface, superstructure is fastened on bearing.

Description

The screw of the dismountable dental prosthesis system of superstructure and correlation

Technical field

The relevant dental prosthesis system (prosthodontic device) of the present invention, espespecially a kind of dismountable artificial tooth of superstructure The screw of device and correlation.

Background technology

In order to pursue attractive in appearance or improve the reasons such as oral hygiene, many people can select to repair defect in the way of planting tooth Tooth.Traditional plant tooth mode can utilize sticker filling superstructure (suprastructure) and bearing (abutment) Between gap so that superstructure is fixed on bearing by sticker.

However, after sticker is once solidify, being just difficult to remove superstructure from bearing, causing artificial tooth periphery easy Periodontosis is produced because thoroughly cleaning is difficult, and then shortens the useful life of artificial tooth.If forcing for physically to upper Cage structure applies the structure or appearance damage that strength easily causes superstructure so that superstructure to be removed from bearing, then, Or cause the structural damage of bearing.

The content of the invention

In view of this, the dental prosthesis system that easily can be removed superstructure from bearing when needed how is provided, actually The problem of industry has to be solved.

This specification provides a kind of embodiment of detachable dental prosthesis system, and it is included：One bearing, plants for connecting a dentistry Body, and comprising an abutment interface and a hollow cavity, wherein, the hollow cavity has a perforate and an outer surface, and in this There is a screw hole on the seating wall of cavity body；One superstructure, is provided with an accommodating area and the medial surface around the accommodating area；With And a screw, comprising a screw terminal and a screw rod, the screw terminal includes and is provided with spiral shell on a contact site and a guidance part, the screw rod Line, the contact site has a top surface, and the guidance part is located between the contact site and the screw rod, and when the screw is arranged at the screw When in hole, the local of the screw terminal can outwardly protrude from this of the hollow cavity, but the screw can't be on this Cage structure；Wherein, when the superstructure entangles the bearing, the regional area of the outer surface of the hollow cavity can be with the top The regional area of the medial surface of construction is in contact, and the screw terminal can prop up the opposite side of the medial surface, positive to apply one Power on the medial surface, thereby make the superstructure with can detachable manner be fastened on the bearing.

This specification separately provides a kind of embodiment for the screw being used in a detachable dental prosthesis system.The detachable artificial tooth dress Put comprising a bearing and a superstructure, the bearing is used to connect a dental implant, and hollow comprising an abutment interface and one Cavity, the hollow cavity has a perforate and an outer surface, and has a screw hole, the top structure on the seating wall of the hollow cavity Make and be provided with an accommodating area and the medial surface around the accommodating area.The screw is included：One screw terminal, leads comprising a contact site with one Draw portion；And a screw rod, it is provided with screw thread；Wherein, the contact site have a top surface, the guidance part be located at the contact site with Between the screw rod, and when the screw is arranged in the screw hole, local appearance understood from the hollow cavity of the screw terminal Protrusion is faced out, but the screw can't run through the superstructure；Wherein, when the superstructure entangles the bearing, this is hollow The regional area of the outer surface of cavity can be in contact with the regional area of the medial surface of the superstructure, and the screw terminal meeting The opposite side of the medial surface is propped up, to apply a positive force to the medial surface, thereby makes the superstructure with can detachable manner It is fastened on the bearing.

One of advantage of above-described embodiment, be when superstructure entangles bearing, can be by screw terminal to superstructure The positive force that medial surface is applied, easily by superstructure with can detachable manner be fastened on bearing.

Another advantage of above-described embodiment, is that only need to apply appropriate strength to superstructure when needed, just can will be upper Cage structure is separated with bearing, structure or outward appearance without damaging superstructure and bearing, is remarkably contributing to carry out dental prosthesis system The cleaning on periphery is acted with sterilization, it helps carry out the reparation or replacing action of superstructure.

Other advantages of the present invention will in more detail be explained by the following description and accompanying drawing.

Brief description of the drawings

Accompanying drawing described herein is used for providing further understanding of the present application, constitutes the part of the application, this Shen Schematic description and description please is used to explain the application, does not constitute the improper restriction to the application.

Fig. 1 is the diagrammatic cross-section after the detachable dental prosthesis system simplification of one embodiment of the invention.

Fig. 2 is the schematic appearance after the embodiment simplification of the screw in Fig. 1.

Fig. 3 is the side schematic view after the embodiment simplification of the screw in Fig. 1.

Fig. 4 to Fig. 7 is the signal after the embodiment simplification for the method that the screw in Fig. 1 is attached on bearing seating wall Figure.

After one embodiment of methods of the Fig. 8 for the detachable dental prosthesis system in Fig. 1 is fixed on dental implant simplifies Schematic diagram.

【Symbol description】

100 detachable dental prosthesis systems

102 alveolar bones

104 dental implants

106 teeth

110 bearings

111 abutment interfaces

112 hollow cavities

113 perforates

114 outer surfaces

115 seating walls

120 superstructures

121 accommodating areas

122 medial surfaces

130 screws

132 screw terminals

134 screw rods

140 bearing screws

222 contact sites

224 guidance parts

226 top surfaces

228 wells

230 screw threads

416 bearing screw holes

517 screw holes

618 guiding areas

Embodiment

Illustrate embodiments of the invention below in conjunction with relevant drawings.In the accompanying drawings, identical label represent it is identical or Similar element or method flow.

Fig. 1 is the diagrammatic cross-section after the simplification of detachable dental prosthesis system 100 of one embodiment of the invention.As shown in figure 1, can Dismantle dental prosthesis system 100 and include the superstructure (suprastructure) 120 of a bearing (abutment) 110, one and a spiral shell Silk (screw) 130.Bearing 110 is used to connect the dental implant (implant) 104 in embedded alveolar bone (bone) 102, and Include an abutment interface (abutment collar) 111 and a hollow cavity (hollow chamber) 112.Superstructure 120 are provided with an accommodating area (receiving region) 121 and the medial surface (inner surface) around accommodating area 121 122.Screw 130 includes a screw terminal (screw head) 132 and a screw rod (screw rod) 134.In the present embodiment, prop up The hollow cavity 112 of seat 110 has a perforate 113 and an outer surface 114, and the seating wall (abutment of hollow cavity 112 Wall) 115 it is provided with a screw hole (screw hole).

As shown in figure 1, can be via the perforate 113 on hollow cavity 112 by a bearing screw (abutment screw) 140 Stretch into hollow cavity 112, and bearing screw 140 is run through into abutment interface 111 to lock in dental implant 104, thereby will Bearing 110 is fixed on dental implant 104.

Collocation Fig. 2 to Fig. 3 is further illustrated into the embodiment of screw 130 below.Fig. 2 is screw 130 of the invention An embodiment simplify after schematic appearance.Illustrate side after Fig. 3 simplifies for an embodiment of the screw 130 of the present invention Figure.

As shown in Figures 2 and 3, screw terminal 132 includes a contact site (contact member) 222 and a guidance part (guiding member)224.Contact site 222 has a top surface 226, guidance part 224 be located at contact site 222 and screw rod 134 it Between, and guidance part 224 has a lead angle (chamfer) structure.Screw thread (screw thread) 230 is provided with screw rod 134.

In the embodiment of fig. 2, the side view of the contact site 222 of screw terminal 132 is rectangle.As shown in Fig. 2 screw terminal A well (tool slot) 228 is additionally provided with 132.In implementation, the shape of well 228 can with but be not limited to a word Shape, cross, triangle, hexagon or star, make operator can be using the hand-held tools such as corresponding screwdriver insertion instrument In groove 228, the screw hole that screw 130 is locked on the seating wall 115 of said hollow cavity 112.In addition, well 228 is also It may be designed to run through whole screw 130, to save the inventory needed for making screw 130.

Fig. 4 to Fig. 7 is refer to, and it is method screw 130 being attached on the seating wall 115 of bearing 110 that it is depicted Schematic diagram after the simplification of one embodiment.

Fig. 4 is the diagrammatic cross-section after the embodiment simplification of the bearing 110 of the present invention.In the present embodiment, bearing 110 Abutment interface 111 on be provided through the bearing screw hole (abutment screw hole) of abutment interface 111 416。

As shown in figure 5, the seating wall 115 that screw 130 is attached into bearing 110 is gone forward, can be first in hollow cavity 112 A screw hole 517 is formed on seating wall 115.In implementation, screw hole 517 can be determined according to the length of the screw rod 134 of screw 130 Depth.For example, in certain embodiments, screw hole 517 can be realized with the blind hole of seating wall 115 is not extended through.At other In embodiment, screw hole 517 can then be realized with the perforation through seating wall 115.

Then, as shown in fig. 6, formed using proper implements in screw hole 517 size and shape all with screw 130 The guiding area (guiding region) 618 that is engaged of guidance part 224.For example, the guiding area 618 in the present embodiment is circle Shape, the diameter of guiding area 618 diameter identical or slightly larger than guidance part 224 with the diameter of the guidance part 224 of screw 130, and The diameter of both guiding area 618 and guidance part 224 is both greater than the diameter of screw rod 134.

In the screw hole 517 being attached to screw 130 on foregoing seating wall 115, the lead angle structure of guidance part 224 is with leading Draw the collocation between area 618, can auxiliary operator by screw 130 be easier and more accurately lock in screw hole 517, with reduce The problem of screw 130 is offset.

When screw 130 is arranged in screw hole 517, the local of screw terminal 132 can be from the outer surface of hollow cavity 112 114 is outstanding.For example, as shown in fig. 7, when screw 130 is arranged in screw hole 517, guidance part 224 can be located at guiding area In 618, and the meeting of contact site 222 is outstanding from the outer surface 114 of hollow cavity 112.

When superstructure 120 entangles bearing 110, the regional area of the outer surface 114 of hollow cavity 112 can be with top structure The regional area for making 120 medial surface 122 is in contact, and screw terminal 132 can prop up the opposite side of medial surface 122, to apply one Positive force on medial surface 122, thereby make superstructure 120 with can detachable manner be fastened on bearing 110.

For example, Fig. 8 illustrates the embodiment letter for the method being fixed on detachable dental prosthesis system 100 on dental implant 104 Schematic diagram after change.As it was previously stated, operator can stretch into bearing screw 140 via perforate 113 hollow cavity of bearing 110 In 112, bearing screw 140 is then passed through into the bearing screw hole 416 of abutment interface 111 and locked in dental implant 104, by Bearing 110 is fixed on dental implant 104 by this.

Then, operator only needs to the accommodating area 121 of superstructure 120 being directed at bearing 110, and by superstructure 120 Direction toward bearing 110 is pushed to entangle bearing 110, and the regional area of the outer surface 114 of hollow cavity 112 will be with top structure The regional area for making 120 medial surface 122 is in contact.Now, the contact site 222 of screw terminal 132 will prop up accommodating area 121 The opposite side of medial surface 122, to apply positive force to medial surface 122.Consequently, it is possible to just can be by the outer of hollow cavity 112 Frictional force between the medial surface 122 of surface 114 and superstructure 120, and the contact site 222 of screw terminal 132 and accommodating area Stress between 121 medial surface 122, easily by superstructure 120 with can detachable manner be fastened on bearing 110.

If need to separate superstructure 120 with bearing 110 in the future, operator need to only apply to superstructure 120 Appropriate strength is pushed away toward the direction for leaving bearing 110, just can overcome superstructure 120 and bearing 110 and screw 130 between the two Frictional force and superstructure 120 is separated with bearing 110, and the structure or outer of superstructure 120 and bearing 110 will not be damaged See.

Therefore, the foregoing mode that superstructure 120 and bearing 110 are engaged by screw 130, helps to carry out detachably The cleaning of the perienchyma of dental prosthesis system 100, sterilization or treatment, help the detachable dental prosthesis system 100 of progress and adjacent teeth 106 Between gap cleaning or treatment, also contribute to carry out superstructure 120 reparation or replacing.

It note that the screw terminal 132 of screw 130 can only prop up top when superstructure 120 is fastened on bearing 110 The medial surface of the accommodating area 121 of construction 120, but screw 130 will not run through superstructure 120, so screw 130 will not be exposed to Outside superstructure 120, the structure and integrality of superstructure 120 will not be also destroyed.

In addition, not any shape, the screw of size can realize the function of foregoing screw 130.In fact, screw 130 Shape and size could be more widely used between different bearing and superstructure, below by being specifically designed Embodiment to screw 130 is described further.

In implementation, appropriate design carried out to the length of the screw rod 134 of screw 130, be just avoided that to foregoing bearing spiral shell The installing of silk 140 or removal cause to hinder.

For example, in certain embodiments, can be by the Design of length of screw rod 134 into one of the internal diameter less than hollow cavity 112 Half.

In further embodiments, can be by the Design of length of screw rod 134 into the seating wall 115 for being slightly less than hollow cavity 112 Thickness.

In some embodiments, then can be by the Design of length of screw rod 134 into the seating wall 115 less than hollow cavity 112 The 150% of thickness.

By test of many times, find the Design of length of screw rod 134 between 0.5 millimeter (millimeter) to 3.5 millis Between rice, most a variety of existing seat structures can be supported, application it is widest in area.

In addition, can also appropriate design be carried out to the thread turns on screw rod 134 (thread turns) or pitch, with Lift stability when screw 130 locks with the screw hole 517 on foregoing seating wall 115.

For example, through test, it is found that the thread turns on screw rod 134 is designed between 1.5 to 6, can effectively carry Rise the tight ness rating between screw 130 and screw hole 517 and avoid the internal thread of screw hole 517 to be damaged simultaneously, can thereby extend screw 130 useful life.

In addition, the pitch of screw rod 134 is designed into the mode between 0.1 millimeter to 1.0 millimeters, also can effectively it be lifted Tight ness rating between screw 130 and screw hole 517 simultaneously avoids the internal thread of screw hole 517 from being damaged simultaneously.

In implementation, the diameter of screw terminal 132 is preferably devised between 0.5 to 3.0 millimeter, is preferably engaged with providing Effect.

The shape that note that the bearing 110 in previous embodiment is an exemplary embodiment, not limits to the present invention Actual embodiment.For example, the external form or shape, the size of hollow cavity 112 of bearing 110, all can according to being actually needed and Adjusted.

From preceding description, operator only needs to the accommodating area 121 of superstructure 120 being directed at bearing 110, and will be upper The direction of cage structure 120 toward bearing 110 is pushed to entangle bearing 110, just can by hollow cavity 112 outer surface 114 with it is upper Frictional force between the medial surface 122 of cage structure 120, and contact site 222 and the accommodating area 121 of screw terminal 132 medial surface Stress between 122, easily by superstructure 120 with can detachable manner be fastened on bearing 110.

If need to separate superstructure 120 with bearing 110 in the future, operator also need to only apply to superstructure 120 Plus appropriate strength is pushed away toward the direction for leaving bearing 110, just can be separated superstructure 120 with bearing 110, and will not damage The structure or outward appearance of cage structure 120 and bearing 110.

In foregoing section Example, the side view of the contact site 222 of screw terminal 132 is designed as rectangle.So The not simple design alternative of design method, but pass through test and find that such screw terminal design method can provide more Operator is given using elasticity so that operator can be according to the shape for being actually needed appropriateness finishing contact site 222, to be more suitable for top Gap length between the shape or superstructure 120 and bearing 110 of the accommodating area 121 of structure 120, uses lifting top Engaging effect between structure 120 and bearing 110.

The structure of foregoing screw 130 is applied to the bearing of many different structures, with being quite widely applied elasticity.

Furthermore, because foregoing screw 130 is hidden in the accommodating area 121 of superstructure 120, top will not be exposed to Outside construction 120, admittedly can by superstructure 120 protection, and be not easy impaired or get rusty, can effectively extend detachable artificial tooth The useful life of device 100.

Further, since screw 130 will not be exposed to outside superstructure 120, so not interfering with attractive in appearance, it will not also draw The intraoral foreign body sensation of patient is sent out, the usage comfort of artificial tooth can be improved.

Some vocabulary have been used in specification and claims to censure specific element.However, affiliated technology neck The technical staff in domain is, it is to be appreciated that same element may be called with different nouns.Specification and claims are simultaneously Not in the way of the difference of title is as differentiation element, but it is used as the benchmark of differentiation with the difference of element functionally. "comprising" mentioned by specification and claims is open term, therefore should be construed to " include but be not limited to ".Separately Outside, " coupling " is herein comprising any direct and indirect connection means.Therefore, if the first element is coupled to second yuan described in text Part, then represent the first element can by being electrically connected with or being wirelessly transferred, the signal connected mode such as optical delivery and be directly connected In the second element, or by other elements or connection means, electrical or signal is connected to second element indirectly.

It is used herein " and/or " describing mode, include any group of one of cited or multiple projects Close.In addition, unless specialized in specification, otherwise the term of any odd number lattice all includes the connotation of plural lattice simultaneously.

In " element " (element) one word of specification and claims mentioned in, component is contained (component), the concept of layer construction (layer) or region (region).

The size and relative size of some elements of accompanying drawing can be amplified, or the shape of some elements can be simple Change, more clearly to express the content of embodiment.Therefore, unless applicant specializes, the shape of each element in accompanying drawing Shape, size, relative size and relative position etc. are only easy for explanation, and should not be taken to limit the scope of the claims of the present invention.This Outside, the present invention can be embodied with many different forms, when explaining the present invention, should not be limited only to what this specification was proposed Embodiment aspect.

For convenience of description, some narrations relevant with the relative position in space may be used in specification, The relative space relation between function or the element and other elements to certain element in accompanying drawing is described.For example, " in ... On ", " in ... top ", " in ... under ", " in ... lower section ", " being higher than ... ", " being less than ... ", " upward ", " downward " etc..Affiliated skill The technical staff in art field is, it is to be appreciated that these narrations relevant with the relative position in space, not only comprising described member The points relationship (orientation) of part in the accompanying drawings, it is also each when using, operating or assembling comprising described element Plant and be differently directed relation.If for example, accompanying drawing is turned upside down, it is original with " in ... on " come the element that describes, Jiu Huibian Into " in ... under ".Therefore, in the description it is used " in ... on " describing mode, contain in explanation " in ... under " with And " in ... on " two kinds of different points relationships.Similarly, contained in " upward " one word used herein, explanation " upward " with And " downward " two kinds of different points relationships.

In specification and claims, if the first element of description is located on the second element, above the second element, company Connect, engage, being coupled to the second element or connect with the second element, then it represents that the first element can directly position on the second element, it is straight Connect in succession, directly engage, be coupled directly to the second element, can also represent that the first element and the second interelement have other elements. Under relative, if the direct position of the first element of description on the second element, be directly connected to, directly engagement, directly coupling or direct phase The second element is connected to, then represents the first element and other elements is not present in the second interelement.

It these are only presently preferred embodiments of the present invention, all equivalent changes and modifications done according to the claims in the present invention, all The covering scope of the present invention should be belonged to.

Claims

1. a kind of detachable dental prosthesis system, it is characterised in that include：

One bearing, for connecting a dental implant, and comprising an abutment interface and a hollow cavity, wherein, the hollow cavity With a perforate and an outer surface, and there is a screw hole on the seating wall of the hollow cavity；

One superstructure, is provided with an accommodating area and the medial surface around the accommodating area；And

One screw, comprising a screw terminal and a screw rod, the screw terminal is included to be provided with a contact site and a guidance part, the screw rod Screw thread, the contact site has a top surface, and the guidance part is located between the contact site and the screw rod, and when the screw is arranged at the spiral shell When in silk hole, local this from the hollow cavity of the screw terminal is outwardly protruded；

Wherein, groove corresponding with the screw terminal or perforate need not be pre-set on the medial surface of the superstructure, and when on this When cage structure entangles the bearing, the part of the regional area of the outer surface of the hollow cavity and the medial surface of the superstructure Region is in contact, and the screw terminal props up the opposite side of the medial surface, to apply a positive force to the medial surface, thereby makes this Superstructure with can detachable manner be fastened on the bearing, but the screw and not through the superstructure, to avoid damage on this The structure and integrality of cage structure.

2. detachable dental prosthesis system as claimed in claim 1, it is characterised in that shape and the guidance part phase are provided with the screw hole The guiding area coordinated, and when the screw is arranged in the screw hole, the guidance part is located in the guiding area, and the contact site This from the hollow cavity is outwardly protruded, and when the regional area and the superstructure of the outer surface of the hollow cavity The regional area of medial surface when being in contact, the contact site props up the opposite side of the medial surface, to apply the positive force to should On medial surface.

3. detachable dental prosthesis system as claimed in claim 2, it is characterised in that the side view of the contact site is rectangle.

4. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the length of the screw rod is less than the internal diameter of the hollow cavity Half.

5. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the length of the screw rod is less than the branch of the hollow cavity The thickness of seat wall.

6. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the length of the screw rod is less than the branch of the hollow cavity The 150% of the thickness of seat wall.

7. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the length of the screw rod is between 0.5 millimeter to 3.5 millimeters Between.

8. dental prosthesis system as claimed in claim 1 detachable, it is characterised in that thread turns on the screw rod between 1.5 to 6 it Between.

9. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the pitch of the screw rod is between 0.1 millimeter to 1.0 millimeters Between.

10. detachable dental prosthesis system as claimed in claim 1, it is characterised in that the diameter of the screw terminal is between 0.5 millimeter to 3.0 Between millimeter.

11. a kind of screw being used in a detachable dental prosthesis system, it is characterised in that the detachable dental prosthesis system includes a bearing And a superstructure, the bearing is used to connect a dental implant, and comprising an abutment interface and a hollow cavity, cavity in this Body has a perforate and an outer surface, and has a screw hole on the seating wall of the hollow cavity, and the superstructure is provided with an appearance Area and the medial surface around the accommodating area are put, the screw is included：

One screw terminal, includes a contact site and a guidance part；And

One screw rod, is provided with screw thread；

Wherein, the contact site has a top surface, and the guidance part is located between the contact site and the screw rod, and when the screw is arranged at When in the screw hole, local this from the hollow cavity of the screw terminal is outwardly protruded；

12. such as the screw of claim 11, it is characterised in that be provided with shape is engaged with the guidance part one in the screw hole Guiding area, and when the screw is arranged in the screw hole, the guidance part is located in the guiding area, and the contact site is hollow from this This of cavity is outwardly protruded, and the inner side of the regional area and the superstructure when the outer surface of the hollow cavity When the regional area in face is in contact, the contact site props up the opposite side of the medial surface, to apply the positive force to the medial surface.

13. such as the screw of claim 12, it is characterised in that the side view of the contact site is rectangle.

14. such as the screw of claim 11, it is characterised in that the length of the screw rod is less than the half of the internal diameter of the hollow cavity.

15. such as the screw of claim 11, it is characterised in that the length of the screw rod is less than the thickness of the seating wall of the hollow cavity Degree.

16. such as the screw of claim 11, it is characterised in that the length of the screw rod is less than the thickness of the seating wall of the hollow cavity The 150% of degree.

17. such as the screw of claim 11, it is characterised in that the length of the screw rod is between 0.5 millimeter to 3.5 millimeters.

18. such as the screw of claim 11, it is characterised in that the thread turns on the screw rod is between 1.5 to 6.

19. such as the screw of claim 11, it is characterised in that the pitch of the screw rod is between 0.1 millimeter to 1.0 millimeters.

20. such as the screw of claim 11, it is characterised in that the diameter of the screw terminal is between 0.5 millimeter to 3.0 millimeters.