GB2505164A - Orthodontic appliance with piston, cylinder and spring force generator - Google Patents

Abstract

An orthodontic appliance has a first body adapted to exert a force on the lingual surface of the anterior teeth of a wearer of the appliance, attachment to the posterior teeth and in fixed relationship with a force generator 1 mounted to a second body, the force generator having a piston rod attached to the first body, a piston head which is slidably mounted in a cylinder, and a resilient spring located inside the cylinder between the piston head and a retaining means which may be a flattened end, a removable end or a threaded adjuster to avoid exposing springs of the appliance. The piston head may be spherical.

Description

Orthodontic Appliance

Field of the Invention

The present invention relates to orthodontic applicances. and more specifically to sprung applicances for correction of problems specific to the anterior teeth.

Background of the Invention

Orthodontic appliances have been used for many years to correct the position and orientation of teeth.

One type of appliance uses springs to generate a force that is applied to the teeth to push or pull them into a desired position and orientation.

One type of device is described in US 6,435,871, Ibis device comprises hardened acrylic bodies having Adams clamps attached thereto, the bodies connected to each other by a support wire the ends of which are encapsulated in the two acrylic bodies. Lach acrylic body encapsulates a tube which receives one end of a lingual rod, the rod supporting a lingual body which contects the lingual surface of the teeth. Two springs are journaled on the lingual rod between the tube and the lingual bodU Hence, the springs push the lingual rod and the lingual body mounted thereon away from the acrylic bodies, to exert a correcting force on the teeth.

The apparatus of US 6,435.871 also exerl 5 an opposing torce on he eelh, A labial body of hardened acrylic is mounted on a labial rod formed of wire. The free ends of die labial rod pass through sleeves mounted on the Adams clamps. The free ends of the rod each have a hooked end. A spring is journaled on the rod and lies between the rear end of the sleeve and the hooked end of the labial rod. Hence, the springs pull the labial body against the labial face of the teeth, exerting a correcting forc on the teeth.

Another type of the device is described in LS parent tic 8,062.031. This device comprises a pair of metal bands which attach to posterior teeth. These hands are attached to each other liv a wire xvhich in use sits in the dental arch. A lingual body having eel h con acing surfaces is also all ached 10 I he pair of bands, T'h is body includes open coil springs which exert a force on the teeth contact surfaces and hence the teeth, to correct the position of the teeth. The device also includes a labial body having teeth contacting surfaces which is also attached to the pair of hands. The labial body also includes open coil springs which exert a force on the teeth contacting surfaces and hence the teeth, to correct the postion of the teeth.

The devices described in TJS 6,435.871 and US 8,062,031 suffer from Ihe disadvuniage i'nai he labia] body is visible when the wearer smiles, speaks and eats.

Another tlevice is described iii U52007/0087300, This tlevice seeks to overcome the problem of the labial body being visible when Ihe wearer smiles, speaks and eals. Whereas in TJS 6,435,871 Adams clamps are niilised as attach the appliance to the teeth, in TJS2007/0087300, the acrylic bodies are attached to clear plastic supports, each it' the form of a cap that fits on to the posterior teeth. The acrylic bodies are bonded to the clear plastic supports. The clear plastic hotly provitles a labial component which extends over the labial surfaces of the teeth resisting the force exerled on he I ingual surflces of he leelh, hereby assisi ing in ceirreci ing he posil ion and orienlal ie,n of he leeih.

US2007/0087300 "iso discusss the use of a plastic chain in addition to or in place of the labial component formed of clear plastic, Ihere nevertheless remai us room for improvement to the above-mentioned appliances. All of the above-mentioned appliances have exposed springs. These exposed springs are not pleasant for the user of the appliance. Food becomes lodged in hem ant] he users own flesh caugh I up in hem. Al so, where a, labial rod is moun ed in sleeves, he free end of die rod can also catch the flesh, causing the user of the appliance discomfort Further, the plastic lingual bodies in which the sleeves that receive the lingual rod are mounted is bulky, intl therefore uncomfortable for the user of he appliance.

It would therefore be desirable to provide an improved orthodontic appliance.

SLinimaty of the Invention According o he inveni ion here is provided all orihodoni ic appliance comprising a body adapied as even a force on the lingual surface of the anterior teeth of a wearer of the appliance, the appliance further comprising attachment means for attaching die appliance to the posterior teeth of the wearer, and a body mounting a force generation means in fixed relationship with the attachment means, wherein the force generation means includes a spring and a piston and cylinder assembly, wherein the piston includes a piston rod and a piston head, the piston head slidably mounted in the cylinder and die piston rod attached to die body adapted to exert a force on the lingual surface of the anterior teeth, wherein the spring is located inside the cylinder between the piston head and the closed end of the cylinder.

The appliance may comprise two attachment means and two bodies each mounting a force generation means, wherei ii he pis Ion rod of each force general on means is ndepen ira ached o I he fits I body.

The piston rod may he formed of wire.

lhc piston rod may include a protrusion extending radially with respect to the lontudinal axis of the rod, the protursion being situated in the part of the rod embedded in the said body.

Ihe resilient member is preferably a coil spring and more prefereably a coil spring formed of a nickel/titanium alloy.

Advatitageouisy. the resilient member retaining means is formo] by a collapsed portion of the cylinder.

Ihe retaining means may comprise a removable element configured to engage with the resilent member.

The relaining means may comprise a breaded eetrenl configured 10 engage corresponding hreads in he cylinder, The appliance may further comprise an adjustment means adapted to adjust the degree of compression of the resilien member, The adjus men means is provided by I he hreaded elemen and he corresponding I breads in he cylinder, The appliance may further comprise a protrusion extending in a direction having a radial component with respect to the lorigitudi na I a xis of the cy Ii nder, Advantageo ly, the collapsed portion of the cyli ntler provides the said protrusion.

The cylinder may comprise an outer sleeve and an inner sleeve, wherein the external dimension of the inner sleeve corresponds substantially to the internal dimension of the outer sleeve, wherein the inner sleeve is shorter than the outer sleeve, arid wherein the inner sleeve is mounted in the outer sleeve at one end thereof, The ph ion rod may he sI id ably moun led in he inner sleeve, a rid wherein he pin ion head 5 local ed in side he outer sleeve between an end face of the inner sleeve and the closed end of the outer sleeve.

Ihe piston head may include edges that are: curved, rounded or chamfered. The piston head may be spherical, The appliance may further comprise a stahilisation connector attached to each of the two attachment means.

The slahilisal ion conneclor may he at ached 10 each of the bodies mount ing the force general ion means, Preferably, the stabilisaflon connector is shaped and dimensional and mounted in the said bodies so as to locate in use in the dental arch of the wearer.

Il-ic attachment means for attaching the appliance to the posterior teeth of the wearer may be selected from the group comprising: a gil ill, a band, and a clamp.

Advantageously, the appliance further comprises engagement means fbr engaging the labial surfaces of the anterior teeth of the wearer, Preferably, the engagement means comprises a resilient elongate flexible element. More preferably, the resilient elongate flexible elemenl is an elastic chain.

Preferably, the Butt body adapted to exert a force on the lingual surface of die anterior teeth of a wearer of the appliance and/or die body mounting the force geneation means are formed of a hard theranoplasitc material.

Preferably, the attachment means is in the form of a splint, said splint formed of a obable thermoplastic ma tcth al. The body adapted to exert-a force on the lingual surface of the anterior teeth of a wearer of the appliance imay be attached to the body mounting the force generation means by an adhesive,

Brief Description of the Drawings

In the Drawings, which illustrate exemplary embodiments of an orthodontic appliance according to the invention: figure 1 is a schematic representation of an orthodontic appliance according to a first cniboclinicnt of the invention; figure 2 is a schematic representation of the appliance illustrated in Figure 1 from another direction; I igure 3a is a cross-sectional elevation of a first embodiment of a force generator; Figure 31i is a cross-sectional elevation of a second embodiment of a force generator; Figure 4 is a schematic representation of an orthodontic appliance according to a second embodiment of the invention; figure 5 is an orthodontic appliance according to a third embodiment of the invention; and figure 6 is an orthodontic appliance according to a fourth embodiment of the invention.

Derailed Description of the Preferred Embodiments

Referring first to Figure 3a, there is shown a force generator 1, in the form of a spring biased piston and cylinder. The piston is formed by ll1 piston rod 2 having a piston head 3 at one end thereof. The cylinder 4 comprises an outer sleeve 5 which is suhstantialiy circular in cross-section and is closed at its end 6. In the illustrated example, the outer sleeve 5 is closed by being flattened. However, the sleeve could he closed by inserteing a plug into the end of the sleeve.

In the end of the cylinder which mounts the Piston an inner sleeve 7 of smaller diameter is inserted into the end of the outer sleeve 5. As can be seen from Figure 3, the piston head 3 may slide in the cylinder, between the closed end 6 and the inner sleeve 7, The hit ernal diameter of I he in ncr sleeve 7 is sigh I great er han I he ext enial d iamet er oF the piston rod 2, For example 0,1mm greater. Similarly, the internal diameter of outer sleeve S is slightly greater than the external diameter of the pistun head 3, for example 0.1mm greater. This proxides some play to take up off parallel location of the force generators in an appliance.

A spring S is located inside the outer sleeve 5 between the closed end 6 and the piston head 3. As the piston head 3 moves towards the closed end 6, so the spring S is compressed.

Ihe piston rod 2 is formex] of an elongate piece of wire (typical iy 7 mm diameter, The piston head 3 has an external diameter corresponding to the internal diameter of the outer sleeve 5, to a allow a sliding ft therebetween. The end 6 oF the outer sleeve 5 is closed, For example by flattening the wails of the sleeve 5,/\ spring 8, preFer'abiv Formed oF a nickel titanium alloy, is position inside the sleeve S. Fhe inner sleeve 7 is mounted on the piston rod 2, and is slid along the rod until one end of the inner sleeve 7 engages with a face of the piston head 3. l'he assembly comprising the piston and inner sleeve are then inserted into the open end of the outer sleeve 5 until the end of the inner sleeve distal From the pist ion head 3 is substantially flush with the free end of the outer sleeve 5. The inner sieeve 7 and outer sleeve 3 are then attached together, for example by spot welding or another suitable method. For example, the outer surface of the inner sleeve 7 arid the inner surface of the end portion of the outer sleeve 5 may he correspondingly threadeil to Fasten the inner sieeve 7 to the outer sieeve 5.

The flattened end (i serves two ftincdons. First, flattening the end (i closes the outer sleeve 5 providing a surface for the spring S to react against. Second, the 11 attened end is utiiised in attaching the cyiinder 4 to another part of the appl alice, as is described in greater detail heiow with reference to Figures 1 and 2.

Referring now to Figures 1 and 2, there is shown a removable orthodontic appliance 10 comprising lefthand and righthand splints 11 configured to mount on the posterior teeth of a user. the txvo splints 11 are attached to one another by a stahilisat.ion connector 12, which in the illustrated embodiment is a wire fonned into an arch. The connector 12 is shaped arid dimensioned and attached to the splints 11 such that in use the connector 12 sits in the dental arch of the user. The free ends of the connector are turned to form an eyelet 12a, lhc formation of an eyelet 12a increases the intergily of the connecnon between the connector 12 and the splint 11 and also resists forces acting to rotate the splints II with respect to the connector 12.

Each splint ii includes labial and lingual side walls ii a, 1 lb and a connecting surface 1 Ic. Each splint sits on the crowns of the posterior teeth of the user. The splints are formed of a thermoplastic material of the same type as commonly used to form retainers. An acrylic body lid is attached to the lingual side wall of each splint ii. The con ned or 12 and he Force general or I are embedded i 110 ih is acrylic body lid. hal is he acrylic body lid is mouldec] around them, The acrylic body lId must be attached to the lingual wall I lb of the splint. The hard acrylic of the body lid does no I bond easily I 0 I he I hertnopla 51 ic oF he sp I in Is. There fore, a bond i rig mcii erial is applied 0 one or ho I h OF I he surfaces of lingual wali 1 lb and the body lid. One suitable bonding material is known as "Pearly Bond".

As can be seen from Figures 1 and 2, the force generator 1 is located between the connecting surface iic and the connector 12, the piston rod 2 of each force generator -l isatttached to a body 2111 which iii the illustrated embodiment is formed of an acrylic, typically the same acrylic as the acrylic body in which the connector and the force generalor are embedded, Tn he illusI raied example, he Free end of each pislon rod 2a is urned jo form an eyelel 2a.

the acrylic body 20 is formed around the eyelets 2a and the ends of the rods 2. The eyelet 2a lies substantially parallel with the plane of the connecting surfaces lie. By so forming the eyelets 2a, turning forces exerted on the body 21) generated by reaction of the said body with the lingual surfaces of the teeth are better resisted than might he the case if no eyelel s were Formed in I he ends of I he roe] s 2, or indeed if he evelel 5 2a were 0 lie in I he pla ic ci F I he lingual surfaces of the teeth.

In the same way that the eyelets 2a assist in resisting reaction forces causing the body 20 to turn with respect to the rods 2, the flattened end 6 of the outer sleeve 3 of the cylinder 4 assists in attaching the force generator I to thc body 12, and again resists tnrning forces on the cylinder 4 that might cause the cylinder 4 to tnrn with respect to the body 12.

The labial side walls ha at their anterior ends each mount a button lid to which an elastic orthodontic chain 13 is attached, The appliance is manufactured such that the elastic chain applies a desired amount of force to the labial surtaces of the front teeth. Further, the chain 13 works with the body 20 to apply the desired corrective forces to the labial and lingual surfaces of the front teeth.

figure 4 illustrates another enthodiment of the invention which is an orthodontic appliance which is fixed in the mouth of die user hr anterior and posterior hands 30, 31. The anterior bands 30 each mount a button 30a to winch an elastic orthodontic chain 32 is attached. The bands 30, 31 are attached to the teeth of the wearer in a manner well known in the an, Other than being fixed in I he wearers mouth, I here are few differences beiween lie appliances shown in figures 1 and 2 and the appliances shown in figure 4. The bodies lId arc bondcxl to the bands 30, 31. The force generators I function in the same manner it) each of the embodiments, Figure 5 H lus Ira I es ancit her embotl iment of he invent ion, which is a removal,] e appliance and is held in place with Adams clamps 411 rather than the splints ii. The Adams clamps are embedded into the acrylic of the bodies lid.

figure 3b illustrates an altemative embodiment of the force generator 100 in the form of a spring biased piston 101 and cylinder 104, I'he piston 101 is formed ha at) piston rod 11112 having a piston head 103 at one end thereof. l'he cylinder 104 comprises an outer sleeve 105 which is substantially circular in cross-section and is closed at its end 106. In this embocl iment, the outer sleeve 105 is closed by a screw 110, The entl port ion 109 of the sleeve 105 is ml ernally threaded 109' and the external threads 110' of the screw 110 co-operate sdth the internal threads 109' to close the end of the cylinder 1 (i4, By closing the end of the cylinder 104 with a screw 109 it is possible to adjust the extent to which the spring 108 is compressed and hence adjust the appliance to which it is fitted, The cylinder 104 mounts the piston an inner sleeve 107 of smaller diameter is inserted into the end of die outer sleeve 1055, As can be seen from Figure 3b, the piston head 103 may slide in the cylinder 104. between the closed end 106 and the inner sleeve 107.

A spring 108 is located inside the outer sleeve 105 hetween the closed end 106 and the piston head 103. As the piston head 103 moves towards the closed end 106, so the spring 108 is ccmpressed.

The piston rod 102 is formed of an elongate piece of wire (typically 7mm diameter). The piston head 103 has an external diameter corresponding to the internal diameter of the outer sleeve 105, to a allow a sliding fit therebetween.

A spring 108. preferably fonned of a nickel dianiwn alloy, is positioned inside the sleeve 105. The inner sleeve 107 is mounted on the piston rod 102, and is slid along the rod un-il one end of the inner sleeve 107 engages with a face of the piston head 103. The assembly comprising the piston and inner sleeve are then inserted into the open end of the outer sleeve 105 until the end of the inner sleeve distal from the pistion head 103 is substantially flush with the free end of the outer sleeve 105. The inner sleeve 107 and outer sleeve 105 are then attached together. for example by spot welding or another suitable method. For example. the outer surface of the inner sleeve 107 and the inner surface of the end portion of he other sleeve 105 may be correspondingly breaded lo fasien lie nner sleeve 107 to the ouler sleeve 1 05.

Figure 3c illustrates a force generator 100 which differs from the force generator 100 iliustrated in Figure 3h in that the piston head 103' is a spherical in shape rather than cylindrical. The advantage of providing a spherical piston head is ihai such a shape 01 pislon head is likely lo slide more easily in ihe cylinder 104 when he Iwo force genetalcirs of an appliance do not lie exactly parallel.

l'he piston head 3 in force generator I may equally be spherical ri shape rather than cylindrical. Further, where the piston head 3. 103 is cylindrical in shape, the edges thereof may be rounded, Figure 6 illusirai es a' appliance according o a burl h embod imen of he inven lion, The appliance is similar I that shown in Figures 1 and 2, the difference being that the force generators arc force generators 100 of the type illustrated in Figure Sb. The main difference between the appliance illustrated in Figures I and 2 and that of Figure 6 is that in the Figure 6 embodiment, the screw 110 remains accessible with the cylinder 104 moulded into the lingual side wall 11 lb of thc splint Ill.

The appliances illustrated iii Figures 4 to 6 would typically include a connector 12, which is not shown for the sake of clarily.

The appliance of the invention provides the advantage that the springs 8 are contained, whereas in the prior art appliances the springs arc open, which makes them less comfortable for the user than is the case for the appliance of the invention. By enclosing the springs further advantages. For instance, food is not able to accumulate in die spring in the way it can with an expose sprthg. Further, the flattened end of the cylinder which extends into the lingual wall lib assists ir anchoring the cylinder therein. Still further, the force generator may be mass produced in a factory setdng, with that component then being used in a dental laboratory for the custom manufacture of an orthodontic appliance.

Suhsee1uent assembly of the appliance in the dental laboratory is simpler.

Claims (3)

1. Claims 1. An orthodontic appliance comprising a first body adapted to exert a force on the lingual surface of die anterior teeth of a wearer of the appliance, the appliance further comprising attachment means for attaching the appliance In die poslerior leei}i of he wearer, and a second body mounhing a ftrce generalion means in fixed relationship with the attachment means, wherein the force generation means includes a resilient member and a piston and cylinder assembly, wherein the piston includes a piston rod and a piston head, the piston head slidably mountcd in the cylinder and thc piston rod attached to the first body, wherein the resilient member is localed inside he cylinder beiween I lie pislon hem] and a resil ienl member relain ing aieans.
2. 2, An orthodontic appliance ac cording to Claim 1. comprising two attachment means and two bodies each mounting a force generation means, wherein die piston rod of each force generation means is independy attached to the first body.
3. 3. An orihodoniic appliance according 0 Claim 2, wherein Ilie pislon rod is formed of wire.

   4, An orthodontic appliance according to Claim 2 or 3, wherein the piston rod includes a protrusion extending radially with respect to the longitudinal axis of the rod, the protursion being situated in die part of die rod embedded in the said hod 5. An on hodon lie appliance according o any preceding cIa liii, wherein he res il ien member s a spring.6. An orthodontic appliance according to any preceding claim, wherein the resilient member retaining means is formed by a coliapsed pordon of the cylinder.7. An orthodonuc appliance according to any of Claims 1 to 5, wherein the retaining means comprises a removable elemeni configured to engage wilh he resileni member.8. An orthodontic appliance according to any of Claims I to 5 or 7, wherein the retaining means comprises a threaded element configured to engage corresponding threads in the cylinder.9. An orthodontic appliance according to any preceding claim, further eompflsing an adiustment means adapted 0 adjusi he degree of compression of he resilieni member, 10. An orthodonde appliance according to Claim 9 when dependent on Claim 8, wherien the adjustment means is provided by I he I breaded elemeni and I he corresponding I hreads in he cyl i id er.11. An orthodontic appliance according to any preceding claim, further eomprsing a protrusa)n extending in a direction having a rat] ial component with respect to the longitudinal axis of the eyl hider.12. An orthodontic appliance accoreling to Claim 11, wherein the collapsed portion of the cylinder provides the said protrusion.13. An orthodontic appliance according to any preceding claim, wherein the cylinder comprises an outer sleeve and an inner sleeve, wherein the external dimension of the inner slee'e corresponds substantially to the internal dimension of the outer sleeve, wherein the inner sleeve is shorter than the outer sleeve, and wherein the inner sleeve is mounted in the outer sleeve at one end thereof.14. An orthodontic appliance acccrding to Claim 13, wherein the piston rod is slidably mounted in the inner sleeve, and wherein the pistion head is located inside the outer sleeve between an end face of the inner sleeve and the closed end of the outer sleeve.15. An orthodontic appliance according to any preceding claim, wherein the piston head includes edges that are: curved, rounded or chair feted.16. An orthodontic appliance according to Chuirn 15, wherein the piston head is spherical.17. An orthodontic appliance according to any of (:laims 2 to 16, further comprising a stahilisation connector attached to each of the rtvo attachment means.1 8. An on}ioelon ic appliance acccrd ing o Claim 1 7, wherein I he siab isal ion conned or is al [a c}ied 0 each oF he bodics mounting thc forcc gcncration mcans.19. An orthodontic appliance according to Claim 1 H or 19, wherein the stahilisation connector is shaped and dimensioned and mounted in the said bodies so as to locate in use in the dental arch of the vearer.20. An onihodoni ic appliance according to any preceding claim, wherein he all achrneni means fbr al aching he appliancc to thc postcrior tccth of thc wcarcr is sclcctcd from thc group comprising: a splint, a band, and a clamp.21. An orthodontic appllance according to any preceding claim, further comprising engagement means for eligagilig he labial suraices of the anienior cdli of he wearer, 22. An orthodontic appllancc according to Claim 21, whcrcin thc cngagcmcnt mcans comprises a rcsilicnt clongatc flexible element.23. An orthodontic appliance according to Claim 22, wherein the resilient elongate flexible element is an elastic chain.24. An orthodontic appliance according to any preceding claim, wherein the body adapted to exert a force on the lingual surface of the anterior teeth of a wearer of the appliance and/or the body mounting the force geneation means are fanned of a hard thennoplasitc material.25. An orthodontic appliance according to any preceding claim, wherein the attachment means is in the form of a splint, said splint formed of a pliable thermoplastic material.26. An orthodontic appliance according to any preceding claim, wherein the body adapted to exert a force on the lingual surface of the anterior teeth of a wearer of the appliance is attached to the body mounting the force generation means by an adhesive, 27. An on hodon ic appliance subsi an a I ft as shown in, and as described wil H reference ci, I he drawings.