FIELD OF THE INVENTION

The present invention relates to an improved teeth realignment system, and in particular to an improved substantially damage-free clear orthodontic teeth aligner system for use in removable attachment and force transfer to realign a patient ̆s teeth.

In particular, the present invention relates to a substantially damage—free teeth aligner system which maintains an orthodontic teeth-aligning device in an attachment position for effective teeth alignment substantially without affecting aesthetics, oral environment including hygiene and teeth enamel.

The invention has been developed primarily for use with removable thermoplastic orthodontic aligners and will be described hereinafter with reference to this application.

BACKGROUND OF THE INVENTION

The desire for teeth that follow a conforming aesthetic and useful functional alignment dates back to ancient times as archaeology finds have revealed human remains including metal bands wrapped around teeth. As orthodontics has evolved over the centuries there has seen the development and evolution of orthodontic treatments for remedying various misalignments, malocclusions and other maxillo-facial related issues.

One approach used early in the 20th century to assist correcting crowded teeth was to selectively extract teeth in order to provide remaining teeth sufficient space to move into a desired position. While the movement of teeth to new positions was always subject to scientific debate, orthodontists aiming to correct misalignments of teeth progressively introduced the use of metal braces in place of extraction.

Metal brace systems generally comprise an arch wire which is wrapped around the arch of treatment, and attached to a posterior molar on each side of the mouth. The arch wires are held to the teeth by brackets attached (bonded) to the enamel of the crown of each tooth. A specific load is applied to the arch wire which is controlled by its engagement with a bracket slot. The purpose of the arch wire/bonded brackets arrangement of metal braces is to impart force to the teeth to correct any misalignments which exist. Conventionally, such an arrangement required stainless steel bands placed on each individual tooth. Once a normal, balanced occlusion is restored, braces are removed. These are fixed for the duration of treatment and such fixed appliances require regular bracket and wire adjustment or tightening as well as wearing of tight elastics which generate greater sense of pain as well as papillary bleeding sores.

While conventional metal braces have shown to be a functional success, there are numerous clinical limitations. Limitations include time taken for installing the braces, significant patient discomfort, poor access to teeth surfaces for cleaning and flossing, and the braces are fixed on the teeth for the duration of treatment degrading the enamel. Metal bracket attachments and the arch wire often retain food particles. This can easily result in increasing the patient ̆s chances of developing a diseased legion in the gingiva affecting the supporting tissues.

Further limitations arise when metal braces are removed from teeth. For example, it is often the case that adhesive used for bonding brackets to teeth remain on the teeth after removal of the brackets. Adhesive remaining on the teeth surface needs to be removed, which can cause damage to the tooth enamel.

A further and important consideration of patients using metal braces is aesthetics. While individuals desire to have aesthetic and functionally conforming teeth general acceptance of metal braces, aesthetics and self-esteem is an increasingly important factor in consideration of treatments for broader community and particularly critical for young adults and adolescents.

One approach which has been used to address the importance of maintaining aesthetics while undergoing teeth realignment has been the introduction of ceramic brackets as an alternative to metal braces. A so-called advantage of ceramic braces is the ability to color match. However, the problems of ceramic braces are exacerbated by the extent of treatment, and the staining by elastomeric bands used to secure wires to slots of the braces. A further drawback of ceramic brackets as with metal braces is that they are not removed from the teeth until treatment is concluded. This fixed treatment again complicates regular tooth care resulting in exposure of teeth to high acid decay environment observed with use of metal braces.

In addition, fixed orthodontic treatments can only apply forces on the labial or lingual surfaces of teeth leading to its controversy surrounding its ability to achieve precision in tooth placement, correction of tooth rotation and effective bodily translation.

A recent advance is the introduction of the so-called :clear or invisible  ̆ aligner system. Removable Thermoplastic Aligners (RTA  ̆s) are an area of preference for improved oral hygiene and aesthetics compared to traditional fixed metal or ceramic bracket systems.

These systems provide orthodontic tooth movement (OTM) using RTA  ̆s based on an intentional mis-fit between the aligner and the entire initial dental position. Positioning of the aligner over the teeth produces a force system of stresses and strains in specific locations to gradually move the teeth into the new required configuration.

Patients are given a successive set of custom designed aligners every one to four weeks (depending on specific type of appliance) over a period of up to 1.5 to 2 years. Each successive set comprises new configurations that eventually move the teeth through a series of intermediate configurations to a final desired configuration. The RTA  ̆s are usually worn at least 20 hours per day and the patient removes them to eat, floss and brush.

Primarily these systems do not use adhesives but a close misfit between the aligner and the entire initial dental position. The result is that there is a tight grip on the teeth and each time there is removal there is difficulty in detaching that can be painful and can cause damage to the enamel of the teeth.

These RTA systems can have limited control over precise tooth movements; hence the use of an RTA is complicated by use of additional attachment composites that are used as force transfer mediums for better localized tooth control. The attachments are often tooth coloured Food and Drug Authority (FDA) approved composite adhesive resins that are usually cured using light activated polymerization.

However, while claiming to be ‘invisible_, the aligners still use visible attachment composites as a method of force delivery. These attachments visibly bulge out and if they are knocked off will also result in loss of enamel from the tooth, requiring the patient to make premature visits to the orthodontist. Also these attachments require complementary concavities in the aligner which result with the aligner more tightly hanging onto the teeth and making regular removal difficult, painful and likely to cause damage.

Several problems also arise with use of the conventional adhesive, including:i. Hygiene;ii. Discoloration; andiii. Detachment of, particularly posterior portion of, the braces occurs in relation to rear/molar teeth Andiv. damage to tooth enamel when removing.

A major commercial disadvantage of RTA  ̆s ironically is the visibility of the attachment composites while the RTA  ̆s are advertised to be a ‘clear’ system, leading to patient dissatisfaction. In clinical reports, “blobs” of attachment composites are described as “crude” and in need of refinement and improvement. It is also suggested that these attachments are prone to discolouration and can remove enamel from the tooth's surface. Further, it is observed that chemical and physical changes occur to the RTA  ̆s over two weeks of wear to an extent that retrieved aligners at the end of two weeks are noticeably more opaque than at commencement of use.

The placement of attachments, their polishing, removal and reinsertion during refinement procedures and ultimately removal at the completion of treatment is also time consuming. As most cases require the placement of multiple attachments, it is costly to a clinician in terms of material as well as time costs.

At the removal of the attachments (either for refinements or completion), the attachments are usually ground away layer by layer judiciously and a final polish done to high shine the enamel and remove any trimming scratch marks. However careful the clinician may be, there is an inevitable chance of enamel removal during this procedure.

The appearance of these attachments, especially on the anterior teeth may be aesthetically unacceptable to some patients. These clear aligner systems are designed to be aesthetic alternatives to conventional braces. In situations where the clinician is not able to place attachments on the patients  ̆ teeth due to aesthetic demands by the patient, the clinical predictability of teeth movement decreases markedly. RTA systems that currently do not include attachments are usually deemed highly inaccurate and do not move teeth as well as the systems with attachments.

Attachments are also horizontal projections on the patients  ̆teeth. Patient often complain that they stick into the surrounding perioral soft tissues, causing pain, discomfort and ulceration at the initial part of the treatment. They usually get accustomed to them after about a week.

It can therefore be seen that the use of an RTA in the prior art systems have the problems of:a) Tight fit to retain in locationb) Painful to removec) Difficult to remove due to tight fit that can cause tearing of the surface of the teethd) Use of adhesives that come in contact with teeth and is likely to damage teeth enamel on removal or accidental dislodgement.

The deficiencies and drawbacks suffered by the prior art systems needs to be solved or at least approached in one form or another to provide an improved teeth aligner system and in particular a substantially damage—free clear teeth aligner system.

While the prior art therefore goes some way to addressing issues associated with orthodontic aesthetics by RTA  ̆s, there remains a need for an alternative means for anchoring an aligner system, improving its mechanical and retentive properties, that overcomes one or more of the deficiencies of the prior art in a practical and effective way.

An alternative force transfer system is needed to attach and maintain RTA  ̆s in place over teeth to apply an orthodontic aligning force to teeth while addressing problems of the prior art systems.

It is therefore an object of the present invention to address one or more of the foregoing problems. It is a further object to provide a useful alternative means for mounting an orthodontic aligner to teeth.

The present invention seeks to provide an oral adhesive, which will overcome or substantially ameliorate at least one or more of the deficiencies of the prior art, or to at least provide an alternative.

It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method of providing orthodontic tooth movement (OTM) using a removable aligner, the method including the steps of providing a shaped removable aligner formed of a thermoplastic and moulded to an OTM fitting shape relative to the teeth of a patient; applying a layer of a gel to an inner surface of a teeth-receiving cavity of the thermoplastic aligner; and locating the shaped removable aligner with the applied gel layer in a required OTM fitting position on the teeth of the patient to provide an effective OTM force on the teeth.

In this way, the gel layer substantially separates and spaces the aligner from the teeth while providing a force transfer mechanism from the aligner to the teeth.

The gel can be a heat curable material providing a comparative stronger adhesion to the thermoplastic aligner than to the teeth of the patient. The comparative stronger adhesion to the thermoplastic aligner than to the teeth of the patient allows ready removal of the aligner.

The gel can be a heat curable material able to set in a shaped form to correspond with the aligner and/or teeth of the patient to provide a minimalist thickness gel layer. The gel layer are formed from an amount of gel substantially in the range of 0.7 to 1.5 grams.

The method can have prior to the applying the gel into a gel layer on the inner surface of a teeth-receiving cavity of the thermoplastic aligner, the step of undertaking a pretreatment of the surface with a pretreatment composition that alters the surface texture. The pretreatment can include scoring the inner surface of the teeth-receiving cavity of the thermoplastic aligner.

The gel can be a heat curable material which enables the setting of the gel is undertaken for a predetermined time on the aligner external of the patient and the remaining setting of the gel in location in the OTM fitting position in the patient to provide the shaped form to correspond with the aligner and/or teeth of the patient to provide a minimalist thickness gel layer.

Depending on whether it is anterior or posterior teeth, cusp tips or side contours, varying undercuts of dental anatomy, during the vacuum formation process, the plastic forms deferentially over the casts. the thickness of the plastic that forms the aligners (different brands) also affects the final potential space. The range of the gel layer filling the space can be between 100 to 800 micrometers

The curing for the predetermined time on the aligner external of the patient during the setting period is preferably greater than 50% but less than 85%.

The shaping and spacing of the aligner from the teeth by the gel layer and the resilient nature of the gel layer allows for ready cyclic removal and insertion daily with effective replacement into OTM fitting position on the teeth of the patient.

The force transfer mechanism from the aligner to the teeth is cushioned by the gel layer to an extent while still allowing an effective OTM force on the teeth by the aligner which allows for ready cyclic removal and insertion daily with effective replacement into OTM fitting position on the teeth of the patient.

The gel is preferably a polysiloxane base material. The gel can be a heat curing polysiloxane base material.

The gel preferably is a heat curing two-part room temperature vulcanizable polysiloxane wherein the polysiloxane base material is heat curable by addition with use of a catalyst.

The curing can include a heat-generating method to speed up the heat affected gel curing rate. The heat-generating method to speed up the heat affected gel curing rate can use one or more of:a) Dissolution of calcium chloride. wherein the use of 1 to 3 grams of calcium chloride provides a significant amount of heat when a 1:1 mass ratio to water is used.b) uses a hot water bath.c) uses a heat plate.

In one preferred form, the heat-generating method is used to increase to a raised curing temperature to speed up the heat affected gel curing rate out of location of the patient until gel is cured to a predetermined percentage cure then removed from the heat-generating method and inserted in the aligner into patient to finalise curing at a temperature lower than the raised curing temperature. The raised curing temperature is preferably greater than 37ł C. and the raised curing temperature could be about 55ł C.

The predetermined percentage cure during the heat-generating method is preferably greater than 50% but less than 85%.

The predetermined percentage cure during the heat-generating method is about 80%.

The invention also provides a teeth aligner system providing orthodontic tooth movement (OTM) for use in assisting corrective realignment of a patient ̆s teeth, the aligner system including: a removable thermoplastic aligner having a teeth-receiving cavity with a teeth-aligning surface formed as an inner surface of the teeth-receiving cavity; a substantially transparent force transfer layer formed on the teeth aligning surface comprising a curable gel engaging between the teeth aligning surface and the patient ̆s teeth, enabling substantially a separation and spacing of the aligner from the teeth while providing a force transfer mechanism from the aligner to the teeth when in located in a required OTM fitting position on the teeth of the patient to provide an effective OTM force on the teeth. wherein the curable gel and the thermoplastic of the aligner are selected to provide a comparative difference of adhesion bond between the cured gel and thermoplastic aligner and the cured gel and the patient ̆s teeth allowing ready removal of the aligner without damage to the teeth and ready repositioning to the OTM fitting position.

The gel, upon completed curing of the gel, forms a first bond with the thermoplastic of the teeth aligning surface of the aligner and a second bond with the enamel surface of the teeth of the patient.

The transfer layer conforms to the teeth location configuration of the aligner and provides effective cushioning of initial orthodontic realignment force while substantially able to maintain a minimal force over time and multiple removal cycles effective for realignment of teeth.

A teeth aligner system according to any one of claims1to14wherein a heat curing two-part room temperature vulcanizable polysiloxane wherein the polysiloxane base material is heat curable by addition with use of a catalyst;

The system further including an applicator for providing a substantially constant thickness layer of gel over the teeth-aligning surface formed as the inner surface of the teeth-receiving cavity.

The teeth aligner system can further include a heat generating system for providing heat source to increase to the heat affected gel curing rate.

The heat generating system can be incorporated in the applicator.

The applicator can include a scoring means and a delivery means; wherein the scoring means affects a top surface of the aligner to forma textured surface in advance of the gel and wherein the delivery means stores and delivers a quantity of the gel to the inner surface of the teeth-receiving cavity.

The applicator preferably has a sponge tip on or adjacent the delivery end of the barrel, the sponge tip being movable relative to or over the delivery end during egress of the gel composition, wherein during delivery of the gel composition onto a surface of the aligner, the sponge tip applies microscopic score lines or textured surface to a surface of the dental straightening device, and wherein the scored or textured surface is adapted to allow preferential mechanical adherence of the gel layer to the dental straightening device. The sponge tip is selected from a range of polymeric materials including polyether, polyvinyl alcohol, or polyester, and a collection of bioglass particles.

The present invention in a further aspect is directed to a substantially damage—free clear teeth aligner system for use in assisting realignment of a wearer ̆s teeth substantially without use of teeth attachments, the aligner system including:a. a removable thermoplastic aligner having a teeth-contacting surface with predetermined teeth location configuration for mounting on or over a patient ̆s teeth to urge orthodontic teeth realignment movement;b. a substantially transparent force transfer layer comprising a curable gel of predetermined thickness on the teeth contacting surface of the removable thermoplastic aligner, wherein the gel forms a first bond with the teeth contacting surface of the aligner and a second bond with the teeth of the wearer upon completed curing of the gel;c. wherein the transfer layer conforms to the teeth location configuration of the aligner and provides effective cushioning of initial orthodontic realignment force while substantially maintaining a minimal force over time and multiple removal cycles effective for realignment of teeth; andd. wherein the first and second bond formed between (i) the transfer layer and aligner and (ii) the transfer layer and teeth, respectively, allows retention of the aligner system on the wearer ̆s teeth and removal of the aligner substantially without damage to tooth enamel following removal of the aligner.e. an upper surface of the gel layer opposite the lower surface provides an attachment surface for frictional attachment to the teeth and allowing easy removal of the appliance from the wearer ̆s teeth without detaching the gel from the appliance while substantially minimising damage to tooth enamel during the removal process.

The aligner system of the invention allows effective adherence of the force transfer layer to the dental straightening aligner and to the teeth of a wearer such that the aligner can be mounted on the teeth and remain on the teeth to apply an orthodontic alignment force without attachment devices of the prior art, and be readily ‘peelably_ removed from contact with the teeth of a wearer being preferentially retained in the aligner, while substantially minimizing removal of tooth enamel.

Further advantages of the present invention is no requirement for attachments, and there is substantially no disclororation of the aligner as this is protected by the force transfer layer hence aesthetics are improved.

Throughout this document and the claims defining the invention:The term ‘aligner_ is to include orthodontic temporary wrap-around aligners or smaller arch aligners and including braces, plates or bridges formed of plastic, synthetic or other mouldable material to be inserted and place over teeth and connected to the teeth.The term ‘oral adhesive_ is to include temporary adhesive for holding aligners over teeth and connected to the teeth in a reversible manner.The term ‘adhesive teeth alignment system_ is to include temporary braces, aligners, plates or bridges formed of plastic, synthetic or other mouldable material to be inserted and place over teeth and connected to the teeth, and temporary adhesive for holding aligners over teeth and connected to the teeth in a reversible manner.

Preferably, the force transfer layer comprises a pourable, curable polysiloxane composition, wherein the polysiloxane composition is applied onto the teeth contacting surface of the removable thermoplastic aligner and allowed to cure so as to form a mechanical or chemical bond with the teeth engaging surface of the aligner, and wherein a surface of the polysiloxane composition, opposite the teeth engaging surface of the aligner, provides a temporary bond with the teeth, the difference between the first and second bonds allows preferential fitment and removing of the aligner system from the teeth substantially without removing tooth enamel.

In one embodiment, a surface texture is provided on the teeth contacting surface of the removable thermoplastic aligner to enhance the first bond between the aligner and force transfer layer.

Preferably the surface texture is formed on the teeth contacting surface of the aligner by an applicator. In one aspect, the surface texture is applied by the applicator before the polysiloxane composition is applied onto the teeth-engaging surface of the aligner. Preferably the applicator is adapted to microscopically etch the teeth engaging surface of the aligner to assist increasing the bond formed between the force transfer layer and the aligner and thereby improve preferential retention of the force transfer layer to the removable thermoplastic aligner. In addition, the second bond formed between the force transfer layer and teeth provides sufficient mechanicalgrippability—to the teeth to effectively transfer an effective orthodontic force of the aligner to allow dental straightening and maintained on the teeth in a tooth straightening position, and the differential bond strength allows preferential removal of the aligner and force transfer layer from the teeth substantially without damaging removal of enamel from teeth surface. In essence, the force transfer layer is retained preferentially in the aligner when the aligner system is removed from the teeth for replacement or cleaning.

The surface texture of the aligner can be formed by a series of grooves wherein the grooves are effective for improving adherence of the force transfer layer to the teeth when the dental straightening aligner is worn by a patient.

Without being bound by theory, the force transfer layer composition of the invention provides a differential adhesion strength between a first interface formed between the textured surface of the dental straightening appliance and the gel layer, and a second interface between the gel layer and the patient ̆s teeth.

In a further related aspect of the present invention there is described a force transfer layer applicator for applying a layer of a curable gel composition of predetermined thickness to a teeth-engaging surface of a dental aligner including:a. a reservoir including one or more chambers for receiving a predetermined amount of a curable gel composition base and a catalyst,b. a mixing chamber at or close to a dispensing end of the reservoir;c. an applicator tip for dispensing a curable gel composition aft of the mixing chamber;d. a drive mechanism upstream of the reservoir for driving the curable gel composition base and a catalyst towards the mixing chamber;e. a sponge tip containing a scoring means allowing for the mechanical etching of the aligner upon application; andf. wherein in use, the drive mechanism promotes displacement of the gel and catalyst towards the mixing chamber for combining, and combined gel/catalyst is urged through the sponge tip for dispensing; andg. wherein the applicator is moved over the straightening/aligner appliance as the gel is liberated such that the scoring means contacts the surface of the dental straightening appliance in advance of gel front to form a textured surface for adherence of the gel.

The gel when applied sits in the microscopically etched grooves on the teeth engaging surface of the straightener/aligner appliance. The gel would push tightly into these grooves coupling it to the surface of the aligner appliance.

The aligner system of the invention represents an advance over the prior art as a result of preferential bonding of the cured gel composition to the textured surface of the dental straightening appliance compared with frictional bonding between the gel layer surface and a wearers teeth. To date there has been no ability to provide differential bonding other than by use of dental adhesive cement or attachment wiring, which adversely affect tooth enamel when an aligner device is removed and/or cause patient discomfort.

In one embodiment, the surface texture on the appliance is formed by an applicator which scores the surface in advance of delivery of the gel layer. Preferably the applicator is adapted to etch the teeth engaging surface of the appliance, wherein the surface texture is formed by a series of microscopic grooves effective for mechanical bonding between the gel layer and appliance.

The mechanical grippability of the liner allows the dental straightening appliance to be maintained in a tooth straightening position, and also allows peeling removal from the teeth substantially without damaging removal of enamel from teeth surface.

Preferably the sponge tip can be selected from a range of polymeric materials including polyether, polyvinyl alcohol, or polyester, and a collection of bioglass particles

Without being bound by theory, the system of the invention provides a differential adhesion strength between a first interface formed between the dental straightening appliance and the gel layer, and a second interface between the liner and the patient ̆s teeth.

Preferably the force transfer layer can be a polysiloxane selected from compounds having the general formula below:

wherein R1, R2 and R5 and R6 can be an alkyl or an alkyl group or a phenyl group;wherein R3 and R4 can be selected from alkyl groups and vinyl groups; andwherein R7 and R8 can be selected from alkyl groups and vinyl groups

The polysiloxane composition can include one form which is provided under the trademark Silpuran™ of Wacker Chemie AG.

Preferably the gel layer comprises a polysiloxane gel composition of two-part catalyst wherein the polysiloxane gel composition and catalyst are present in a ratio of 50:50 to 20:80, wherein the gel composition and catalyst are combined to form a film of predetermined thickness on a surface of the dental straightening appliance, and wherein one surface of the appliance is scored to form a surface texture effective for adhesion of the gel layer to the scored surface of the straightening appliance.

The polysiloxane gel composition can include a source of calcium such as hydroxyl apatite. Calcium can be therefore applied directly to the teeth by diffusion through the S1 matrix, to maintain teeth and sufficient lubrication while wearing the dental appliance.

The polysiloxane gel composition can include additional agents selected from an antibacterial agent, probacterial agent, calcium salts and bioactive glass.

The present invention is directed to a multi-functional liner for adhering to a dental brace appliance, the liner comprising at least one component formed of a curable polysiloxane composition applied to a modified teeth-engaging surface of the appliance to form an effective differential adhesion bond strength between a first interface formed between the aligner and the gel layer and a second interface between the gel layer and the patient ̆s teeth.

The effective differential adhesion bond strength can be such that the first interface formed between the aligner and the liner/gel is greater than second interface between the oral adhesive and the patient ̆s teeth wherein the aligner is more readily removed with the gel layer from the patient ̆s teeth.

The effective differential adhesion bond strength can have the ratio of bond strength formed at the first interface formed between the aligner and the liner/gel and the second interface between the liner/gel and the patient ̆s teeth of between about 3:1 to 10:1.

The effective differential adhesion bond strength can have the bond strength at the second interface between the gel layer and the patient ̆s teeth allowing the aligner to be fitted to and effective for realignment of teeth, and removed from teeth substantially without damaging teeth enamel.

It can be seen that the teeth aligner system of the present invention is found to be effective in allowing fitting of a clear orthodontic aligner onto teeth for the purpose of realigning a patient ̆s teeth, and upon removal of the aligner teeth enamel is substantially free from adhesive residue. Further, it is found that the gel layer of the present invention retains the aligner system in a desired position without adverse structural effects of the aligner, and the gel layer is substantially transparent hence aesthetics of a clear orthodontic aligner is improved over mounting systems of the prior art.

The curable polysiloxane composition can be selected from compounds having the general formula below:

wherein R1, R2 and R5 and R6 can be an alkyl group or a phenyl group;wherein R3 and R4 can be selected from alkyl groups and vinyl groups; andwherein R7 and R8 can be selected from alkyl groups and vinyl groups

The curable polysiloxane composition can be of one form such as known under the trade mark Silpuran 2430.

The gel layer can be provided in a form which can be cured from a one pack form.

The gel can include a catalyst.

The catalyst can primarily include Platinum (Pt). The catalyst might comprise organometallic complexes.

The ratio of the curable polysiloxane composition to the catalyst can be in the range of 60/40 to 70/30 in order to provide a compression malleability providing a deformable viscoelastic.

The gel can be activated by an activator for initiating RTV (room temperature vulcanization) addition curing.

The activator can be selected from a heat source, a UV source, or an IR source.

It can be seen that the crosslinking is effective for producing an adhesive having preferential bond strength whereby minimal residual adhesive remains on a patient  ̆s teeth after removal of the aligner.

The polysiloxane component can include an inorganic filler, wherein polysiloxane can be present in an amount of up to about 95 percent by weight.

The polysiloxane component can further include a minor amount of a diluent such as methacrylate esters, dimethacrylate esters, trimethacrylate esters, wherein the polysiloxane can be present in an amount of up to about 95 percent by weight.

Throughout the body of the specification, the term :adhesion ̆ refers to preferential bonding of the gel to one surface such as teeth over another surface such as orthodontic aligner.

The gel preferably includes a calcium fortifier to assist in the protection at the second interface of gel to teeth to protect enamel surface.

The gel preferably includes an antibacterial agent to assist in the general protection at the first interface between the gel and the aligner and the second interface of gel to teeth to decrease growth of bacteria due to the increased amount of rough enclosed surface areas and decrease of saliva washing which otherwise enhances bacteria growth.

The gel preferably includes a probiotic agent to assist in the protection at the second interface of gel to teeth to encourage growth of essential bacteria which are important for the overall health of the mouth, and to replenish any essential bacteria which may have been perturbed by the antibacterial agent and/or any other component of the gel.

The present invention in a further related aspect is directed to a substantially damage—free dental brace gel for releasable coupling of a substantially transparent dental straightening appliance to a patient  ̆s teeth, the dental brace gel comprising a pourable, curable polysiloxane composition, wherein the polysiloxane composition is poured onto a teeth engaging surface of the dental straightening appliance and allowed to cure so as to form a chemical bond with the teeth engaging surface, and wherein the teeth engaging surface of the appliance has applied thereon a surface texture which allows mechanical bonding engagement of the textured surface with the gel, wherein in use the gel layer is effective to maintain the dental straightening appliance in a desired position, and wherein the mechanical engagement allows preferential removing of the appliance from the teeth substantially without removing tooth enamel.

In a related aspect of the present invention, there is a teeth alignment system including: a removable thermoplastic aligner for orthodontic treatment of teeth alignment; a force transfer layer on the removable thermoplastic aligner adapted to form a first bond between the aligner and force transfer layer, and a second bond between the force transfer layer and the teeth of a wearer, wherein the first bond strength is greater than the second bond strength effective for retaining the aligner on teeth, transferring orthodontic force, and providing preferential removal of the force transfer layer from the teeth; the force transfer layer having a composition including:a two-part room temperature vulcanizable polysiloxane wherein the polysiloxane is selected from compounds having the general formula 1 below

where R1, R2and R5and R6can be an alky group or a phenyl groupwhere R3 and R4 can be selected from alkyl groups and vinyl groups, and where R7 and R8 can be selected from alkyl groups and vinyl groupsand a catalyst comprising a metal such as Pt or organometallic complexes; and an activator for initiating RTV addition curing;wherein the gel composition is applied as a gel film to an internal surface(s) of the aligner, and wherein the adhesion composition when cured has adhesion determined by preferential bond strength analysis such that preferential bonding occurs at the gel aligner interface and a probiotic agent for maintaining the healthy bacteria around the teeth.

The aligner can be a substantially transparent plastic teeth alignment aligner.

The inorganic filler can be present in an amount of about 60 to about 75 weight percent of the gel.

Preferably the finely divided inorganic filler is selected from the group consisting of silanized quartz, silica, fumed silica, zirconium, barium or strontium glass and silanized glass.

Therefore, in one form the invention provides a teeth aligner system for use in assisting straightening a wearer ̆s teeth substantially without use of attachments, the dental brace comprising: a removable thermoplastic aligner appliance having a predetermined teeth location configuration for mounting on or over a patient ̆s teeth to urge teeth movement, the aligner including a teeth-contacting surface having at least a portion being textured; a force transfer layer on the textured portion of the teeth contacting surface of the aligner, wherein an inner surface of the force transfer layer and the textured surface portion of the aligner form a bond upon cross linking of the gel; wherein the aligner is effective for allowing receipt of and positioning of the teeth in the appliance to obtain a desired straightening effect; and wherein an outer surface of the gel layer opposite the inner surface provides an attachment surface to the teeth allowing easy removal of the appliance from the wearer ̆s teeth without detaching the gel from the appliance while substantially minimising damage to tooth enamel during the removal process.

The combination of the aligner and the force transfer layer can be substantially clear and allow substantially damage—free removal after use. The force transfer layer can be a polysiloxane gel curable composition.

Preferably the inner surface of the force transfer layer and the textured surface portion of the appliance forms a mechanical bond upon cross linking of the force transfer by curing of the gel.

The curved shaping and configuration of the dental straightening/aligner appliance can aid frictional attachment to the teeth.

Preferably the gel layer composition of the invention provides a differential adhesion strength between a first interface formed between the textured surface of the dental straightening appliance and the gel layer, and a second interface between the gel layer and the patient ̆s teeth.

The removable thermoplastic aligners are preferably selected from polypropylene, co-polyester of polyethylene terephthalate, hybrid copolyester.

The gel forming the force transfer layer is preferably partially cured by exposure to heat at about 55 degrees C. before dispensing onto the aligner, and the partially cured layer and aligner fitted to a wearers teeth where curing is completed at a lower temperature.

The predetermined thickness of the force transfer layer can be controlled by a combination of applicators.

The orthodontic force exerted by the aligner system of the invention is able to be maintained at a minimal level over a cycle period of 70 in a two week period.

The removal force of the aligner system of the invention is preferably.

Preferably the effective differential adhesion bond strength of the first interface formed between the aligner and the oral adhesive so as to be greater than second interface between the oral adhesive and the patient ̆s teeth wherein the aligner is more readily removed with the oral adhesive from the patient ̆s teeth.

The effective differential adhesion bond strength is such that the first interface formed between the aligner and the liner/gel is greater than second interface between the oral adhesive and the patient ̆s teeth wherein the aligner is more readily removed with the gel layer from the patient ̆s teeth.

In a particular form, the effective differential adhesion bond strength can have the ratio of bond strength formed at the first interface formed between the aligner and the liner/gel and the second interface between the liner/gel and the patient ̆s teeth of between about 3:1 to 10:1.

Preferably the effective differential adhesion bond strength is provided by scoring the textured portion of the teeth contacting surface of the dental straightening/aligner appliance to increase the adhesive bond of first interface of the gel layer to the dental straightening/aligner appliance and enable the lesser bond strength at the second interface between the gel layer and the patient ̆s teeth allowing the aligner to be fitted to and effective for realignment of teeth, and removed from teeth substantially without damaging teeth enamel.

In a related aspect of the present invention, there is a teeth alignment system including: a removable thermoplastic aligner for orthodontic treatment of teeth alignment; a force transfer layer on the removable thermoplastic aligner adapted to form a first bond between the aligner and force transfer layer, and a second bond between the force transfer layer and the teeth of a wearer, wherein the first bond strength is greater than the second bond strength effective for retaining the aligner on teeth, transferring orthodontic force, and providing preferential removal of the force transfer layer from the teeth;the force transfer layer having a composition including: a two-part room temperature vulcanizable polysiloxane wherein the polysiloxane is selected from compounds having the general formula 1 below

where R1, R2and R5and R6can be an alky group or a phenyl groupwhere R3 and R4 can be selected from alkyl groups and vinyl groups, andwhere R7 and R8 can be selected from alkyl groups and vinyl groupsand a catalyst comprising a metal such as Pt or organometallic complexes; andan activator for initiating RTV addition curing;wherein the gel composition is applied as a gel film to an internal surface(s) of the aligner, and wherein the adhesion composition when cured has adhesion determined by preferential bond strength analysis such that preferential bonding occurs at the gel aligner interface and a probiotic agent for maintaining the healthy bacteria around the teeth.

The invention also in one form provides a method of applying an aligner in a required temporary set position within the oral cavity of a patient the method including the steps of:a. providing an aligner for use with a patient, wherein the aligner has a modified textured teeth-engaging surface;b. applying an oral gel layer to a surface of polymeric material of the aligner comprising an interior surface to receive at least a portion of one or more teeth of the patient when the aligner is worn;c. curing the curable adhesive, the curing comprising after the applying to the curable adhesive of a light source sufficient to cause the curable adhesive to cure to form a cured product bonded to the surface of the polymer material;d. the curable adhesive comprising:e. a polysiloxane selected from compounds having the general formula 1 below

where R1, R2and R5and R6can be an alky group or a phenyl groupwhere R3 and R4 can be selected from alkyl groups and vinyl groups, andwhere R7 and R8 can be selected from alkyl groups and vinyl groups andf. an initiator.

According to a further aspect of the present invention, the aligner gel is preferably Silpuran 2430.

The aligner gel can include constituent components of calcium fortifier.

The aligner gel can further include constituent components of an antibacterial agent.

It can be seen that the invention of an aligner with gel layer provides the benefit of the gel being a mechanical-coupling interface between clear aligner systems and the teeth upon which they sit. The gel does not harbour unwanted bacteria is essential if the product is to be used safely in a patient  ̆s mouth. The gel does not promote anomalous growth of select organisms in the patients  ̆mouth.

The gel layer is biocompatible to the oral tissues. It is preferably a two-paste system that is mixed when extruded in a ‘gun-mixing tip’ system. From the softer gel state, it then sets over about a minute in a combined chemical reaction accelerated with intra oral temperatures, into a semi solid state.

The gel is thin enough to perpetuate the potential space and undercuts of the teeth between the teeth and the aligners. It is firm in order to withstand intra oral pressures and forces. The gel demonstrates minimal creep to allow an extended intra oral usage without constant replacement. It should not dampen the pressures and stresses that the original aligners have on the teeth prior the placement of the gel but may shrink slightly in dimension to enhance that force level. It should not be too porous or permeable to allow the blatant absorption of saliva and other liquids in the oral cavity. It should not ‘lock in’ the aligners and disallow simple removal of the aligners.

The gel layer of the invention is easily applied onto a clean and dry aligner appliance using the custom-made dispenser tip. After the insertion of the aligners, any excess gel can be easily cleaned out from the gums and surrounding soft tissues using a cotton bud or tissues before the initial set of the gel. The biogel adheres preferentially to the aligner and not the teeth when the aligners are removed. It is easily peeled off (from the aligners) and discarded at the end of its use, and can be biodegradable.

As the aligners are worn all the time except eating and brushing, the biogel should withstand an extended period of use. Ideally it is changed with every new aligner (2-4 weeks), but depending on dimensional changes and its ability to maintain consistent force levels over the test period, the biogel may need to be changed 2-3 times daily.

The gel layer of the invention allows a seamless connection between the aligners and the teeth, transferring the forces originally designed and intended by the manufacturers of the aligner systems.

It negates the need for attachment placement completely. This improves the aesthetics of clear aligner systems, improves the patient experience with any clear aligner systems, decreases the chair time and costs of the clinician and prevents the damage to the enamel when the attachments are removed.

The gel is tested for hypersensitivity and allergic reactions. With prolonged aligner wear, the buffering effect of saliva neutralising the oral acids is reduced. This increases carious incidences and leads to higher chances of enamel decalcification. The biogel may be incorporated with a Fluoride releasing and/or tooth mousse C PAP calcium phosphorous remineralisation agent to negate that effect.

The aligner gel can be applied using a syringe-type device that can accommodate a two-part gel component system that on mixing undergoes a cross linking-type reaction to yield a solid translucent film. This film functions to fill any gaps between aligner and teeth. Patient will typically wear aligner throughout the day and only require removing them for eating. The Aligner Gel is robust enough to withstand regular detachment/reattachment of the aligner/Aligner Gel composite device as required by the patient to follow their daily eating schedule.

Patients performs the Aligner Gel protocol each time a new aligner is fitted (currently˜every two weeks in accordance with the stepwise correction schedule dictated by the orthodontist/aligner manufacturer)

The aligners are preferably formed of a plastic material so as to enhance the effective differential adhesion bond strength of the first interface formed between the aligner and the oral adhesive so as to be greater than second interface between the oral adhesive and the patient ̆s teeth wherein the aligner is more readily removed with the oral adhesive from the patient ̆s teeth.

The ‘biogel’ system attempts to negate the need for the placement of attachments in any clear aligner systems (either digital or manually made ones). It should be a biocompatible material that is sufficiently thin that sits between the teeth and the plastic aligners. This interphase material allows the clear aligner system to function superiorly without the need for the placement of attachments on the patient ̆s teeth.

It can be seen that the system of the invention negates the need for attachment placement completely. This improves the aesthetics of clear aligner systems, improves the patient experience with any clear aligner systems, decreases the chair-time and costs of the clinician and prevents the damage to the enamel when the attachments are removed.

