[001] The present patent application claims priority from U.S. provisional patent application No. 62/492,595 filed on May 1, 2017, the specification of which is incorporated herein by reference in its entirety. Technical Field

[002] This application relates to the field of dental restoration, namely matrices used to restore a tooth that has a cavity, involving removal of a part of a non-occlusal surface during the tooth preparation.

Background [003] Cavity removal usually results adding a filling to the gap created in the tooth. The filling of the cavity is commonly known as tooth restoration. The direct restoration of a tooth, that is restoration that does not involve an intermediary step performed outside of the mouth, is usually done with two materials, that is by using a metal mixture called a dental amalgam, or by using a composite resin formed from a mixture of monomers and filler particles that polymerize when exposed to a polymerization activator such as a LED curing lamp, producing light in the visible spectrum.

[004] The composite resins have become popular during the last couple of decades due to their esthetic quality and their relatively low toxicity when compared to the amalgams. However, the use of composite resins for the restoration of the rear teeth is limited as a result of the reduced longevity of the material when compared to the amalgams. Some of the reasons for this is that the composites are more sensitive depending on the conditions tied to the restoration, such as with respect to the humidity found in the cavity to be restored, access to the polymerization curing lamp, the uniformity of the layers sequentially added, and so forth. In fact, the restoration procedure using composite resin is often long-winded and requires several critical steps in order to arrive at a successful result.

[005] The composite has to adhere to the enamel and the dentin. This is usually performed by subjecting the tooth to phosphoric acid creating porosities in which a resin adhesive may penetrate that afterwards also binds to the restorative material. During this procedure, no liquid (such as saliva or blood) must contaminate the cavity that is to be restored, where the liquid may prevent adhesion. Moreover, the polymerization done by using a polymerization curing LED lamp is possible usually when polymerizing a layer that has a thickness of 2 millimeters or less. Therefore, a cavity with a greater depth usually requires the insertion of successive layers of composite, which may lead to imperfection with respect to the layers, stretching out the procedure and increasing the risk of contamination as a result of liquid trapped between each layer.

[006] Furthermore, an important challenge for those that perform the dental procedure (herein defined as the "practitioner") is to repair the proximal surface of a tooth, the surface facing a mesial or distal adjacent tooth. The cavities made are usually deep and create an opening in the surrounding environment that is exposed to liquids. In order to seal off this opening, the dentist usually inserts a band with a thickness of around 20 to 100 microns, called a matrix, a stripe or a band, between the teeth and pushes this matrix on the tooth to be restored using a wooden or plastic wedge that is inserted between the two teeth. The positioned matrix acts as the cavity's wall, and the dentist inserts the composite that remains trapped between the cavity walls and the matrix. Once the composite hardened, the dentist removes the matrix and carries out the final adjustments with respect to the restoration.

[007] The first matrices are derived from and for amalgam insertion techniques, such as using the well-known Tofflemire™ device. Matrices that are made in metal do not allow light to penetrate and it is therefore [nearly] impossible to polymerize the composite by placing a lamp on the sides of the tooth when the matrix is in place. Some plastic matrices allow for polymerization on the sides, but they yield an imperfect seal of the cavity and there may be leakage of liquid produced by the mouth via the gingival margin of the cavity.

[008] An important aspect to consider when adding a composite to fill an interproximal cavity is to obtain a good contact point between the restored tooth and the adjacent tooth. A weak contact point or an opening between the teeth leads, for instance, to food entrapment, a new cavity, or periodontal disease. Composite resins do not compact, and the matrix's thickness leaves the same space as that which is taken up by the matrix once the matrix has been removed. Systems based on sectional matrices, where the matrix only covers the proximal surface instead of surrounding the entire tooth, coupled with a ring system to exert pressure upon the teeth in order to push them apart, results in allowing the composite to fill a greater space in the cavity, but only partially addresses this spacing problem. However, dental practitioners, employing currently available techniques, still have difficulty achieving a good contact point between both teeth. [009] Another problem is to have to adjust and polish off the inter-proximal surface using rotary and/or manual instruments where access is limited or unobtainable.

[0010] Usually, composite resins are more easily used when their insertion is done inside a cavity or by applying it to a desired surface. In cases where the tooth is entirely covered to protect it against fractures, such as in the case of making an indirect crown (indirect because the restoration is done outside of the patient's mouth using a mold of the tooth on which the crown is built), it is difficult to use actual composite insertion techniques to perform this kind of restoration. In fact, little to no alternatives exist with respect to techniques for making indirect crowns that are, in addition, very costly when compared to "direct" restoration techniques, using either composites or amalgams.

[0011] A solution to the aforementioned problems was to create a matrix made out of similar composite resin to the one used for restoration, where the composite matrix is made to integrate the tooth after restoration instead of being removed. As the removal of a matrix may be long and difficult, leaving it in place simplifies the procedure.

[0012] Therefore, from the time that a first layer of composite seals off the space between the tooth and the matrix, no more liquid originating from the mouth can seep into the cavity space created by the matrix. Moreover, as the matrix is not removed after restoration, the space resulting from its removal is no longer an issue, where a more intimate contact is made with the adjacent tooth, the matrix already in contact with the adjacent tooth and forming the interproximal wall following the restoration.

[0013] Furthermore, the matrix has a smooth surface, uniform and completely polymerized, reducing the need for adjustments of the surface using rotary and/or manual instruments.

[0014] Also, the composite resin is transparent or semi-transparent with thin layers, which would allow the curing LED lamp to polymerize the composite mixture by penetrating through the matrix, not possible with a metal matrix, increasing the chances that the filling is sufficiently hardened during restoration.

[0015] However, the above referenced inventions have certain problems. A first problem is that the matrix must be larger and deeper than the cavity that is to be sealed in order to rest on the remaining wall of the tooth. If the matrix joins the restoration during filling, the excess material must be removed, which is located on the proximal surface of the tooth and therefore difficult to access. [0016] Also, another problem is tied to the very nature of composite resins, usually lacking flexibility and resistance. This is a problem as the composite resin in the form of the matrix undergoes intensive manipulation and is usually very thin. In addition, a matrix must be resistant when inserted between two teeth in partial contact. The matrix must also withstand torsion caused when pushed by a wedge that is placed between both teeth. For the above reasons, the preferred material for a matrix is stainless steel, biaxially-oriented polyethylene terephthalate (BoPET) or celluloid.

[0017] Patent document DEI 02004031427 suggests a conventional matrix with an injection opening located at the proximal contact region of the matrix for insertion of a body. The body, made in ceramic or plastic, becomes part of the restored portion of the tooth and forms a contact point. However, the teachings of this reference fail to resolve the issue of having a complete and uniform proximal wall. The composite, following the teachings of this reference, would also not be used at the gingival margin to properly seal off the cavity space.

[0018] Problems associated with current matrices are, but not limited to, an imperfect seal between the tooth and the matrix, which can lead to contamination from the liquid produced in the mouth in the cavity to be restored, which can prevent proper adhesion between the adhesive restorative material and the tooth or between the different layers of material; difficulty in obtaining a good contact point; difficulty in obtaining a polished and uniform surface; difficulty in polymerizing a composite resin in a deep cavity; difficulty in removing the matrix; and lack of a direct restoration technique that is easily applicable allowing for the building of a crown to completely cover the tooth, in order to protect the weakened tooth from fractures, but at a lesser cost. Moreover, some additional problems exist with respect to matrices that are composed of a composite resin that is similar to the material used to restore the tooth such as difficulty in removing the excess matrix; the material of the matrix is not optimal for manipulating the matrix; and the absence of a more efficient method for inserting the matrix into the mouth.

Summary

[0019] A first broad aspect is a dental matrix strip having a first portion for fusing with a dental restorative material and a separable second portion for releasing from a dental restorative material, the strip being suitable to cover a surface of a tooth preparation to receive a dental restorative material with the first portion adapted to fuse with the dental restorative material and the second portion adapted to seal a cavity of the tooth preparation near a floor thereof so as to retain the dental restorative material within the tooth preparation and to prevent body fluids from entering the tooth preparation until curing is completed.

[0020] A second broad aspect is a dental matrix strip having a first portion for fusing with a dental restorative material and a second portion, wherein second portion adapted to seal a cavity of the tooth preparation near a floor thereof so as to retain the dental restorative material within the tooth preparation and to prevent body fluids from entering the tooth preparation until curing is completed, and also have extensions helping tighten the matrix either when wrap around or insert in a section of the tooth to be restored, offering the possibility of being used with a variety of different tightening systems.

[0021] In some embodiments, the second portion may be attached to and detachable from the first portion. In some embodiments, a series of perforations may separate the first portion and the second portion, and the second portion may be detachable from the first portion along the series of perforations. In some embodiments, the second portion may have openings on both extremities of the second portion to facilitate at least one of the positioning of the second portion on and removal of the second portion from the tooth preparation. The first portion may be made of a polymerized composite material. The second portion may have elongated extremities adapted to be twisted together to assist with fastening the dental restoration matrix to the tooth preparation.

[0022] In some embodiments, the first portion may have a first side and a second side opposite to the first side, the first side may be porous and may be adapted to take part in adhering to the received dental restorative material, and the second side may be smooth and may be adapted to face away from the tooth preparation when the dental restoration matrix is positioned to cover the surface of the tooth preparation.

[0023] In some embodiments, the composition of the first portion may include a different type of material than the filling material, chosen for its tenacity, flexibility, or other advantage absent in the filling material.

[0024] In some embodiments, the composition of the first portion may include polyether ether ketone.

[0025] In some embodiments, the second portion may include at least one of a first wing located at a first end of the second portion and a second wing located at a second end of the second portion. [0026] In some embodiments, the second side of the first portion may be coated with a substance or material to improve its interaction with the surrounding environment and nearby tooth surface, such as elements with bioactive properties or antibacterial agents.

In some embodiments, the coating may include fluoroaluminosilicate, well known to act as a fluoride reservoir, calcium aluminate, known to induce hydroxyhapatite formation, and/or calcium silicates, known to induce remineralisation on a nearby tooth surface.

[0027] In some embodiments, the first portion may have a first side and a second side opposite to the first side, the first side and the second side may be porous and wherein each of the first side and the second side may be adapted to take part in adhering to one of the received dental restorative material and the porous surface of another dental restoration matrix.

[0028] In some embodiments, the second portion may be made of a dissolvable material.

[0029] In some embodiments, the first and the second portions may be provided separately and the operator may choose a preferred first portion which may then be fitted to a preferred second portion. In some embodiments, there may be a kit of second portions with different shapes, sizes and types of material adapted for different clinical situations. Similarly, the same kit, or a different kit may comprise a variety of different first portions with a variety of shapes, shades, thickness or formula adapted for the clinical situation or the specific restoration. A sticky layer on the first portion and/or the second portion may be present to help the operator attach both portions prior to use.

[0030] In some embodiments, the dental restorative material may have a filling material for filling a tooth preparation, and an adhesive material configured to assist with fusing the first portion to at least one of the filling material and the surface of the tooth preparation. The first portion may be adapted to receive the adhesive material and to fuse to the restorative material following the receiving of the adhesive material.

[0031] A third broad aspect is a method of dental restoration in a tooth preparation located in an interproximal region using a dental matrix strip for sealing the tooth preparation from infiltration of body fluids and having a first portion for fusing with a dental restorative material and a second portion for releasing from a dental restorative material. The method involves removing the second portion once the first portion has fused to the dental restorative material received in the tooth preparation in an interproximal region to contact an adjacent tooth while providing the second portion at the same level or slightly above the gingival margin of the tooth preparation.

[0032] In some embodiments, prior to the step of fusing the first portion, the method may include filling the tooth preparation with the dental restorative material. Once the tooth preparation is filled with the dental restorative material, the method may call for curing the dental restorative material.

[0033] In some embodiments, where the first portion has a first side and a second side opposite to the first side, and the first side is porous, and where the dental restorative kit includes a filling material and an adhesive material, the filling material is configured to fill a tooth preparation, and the adhesive material is configured to assist with fusing the first portion to at least one of the filling material and the surface of the tooth preparation, where the fusing of the first portion to the dental filling material occurs after the first side comes into contact with the adhesive material.

[0034] In some embodiments, the method may include removing an excess amount of the first portion combined with the tooth restorative material. In some embodiments, where the dental matrix strip further has a pair of malleable extensions located at the second portion to provide a tourniquet by twisting together to apply tension to at least the second portion when wrapped around the tooth preparation, the method may call for twisting together the malleable extensions to apply tension to at least the second portion wrapped around the tooth preparation. Prior to the step of fusing the first portion, the method may include positioning the dental matrix strip around at least a portion of the tooth preparation, where the second portion may be positioned to seal a cavity of the tooth preparation near a floor thereof.

[0035] In some embodiments, the method may include adding a thin layer of dental filling material to the corner formed by the first portion of the dental matrix strip and the inner margin of the tooth preparation to fix the first portion to the tooth preparation and create a seal between the tooth preparation and the first portion prior to fill the tooth preparation with the filling material. All further steps may be performed without having concerns about contamination of the tooth preparation by body fluids from the gingival aspect.

[0036] In some embodiments, the method may include adding a thin layer of a first dental filling material to the corner formed by the first portion of the dental matrix strip and the inner margin of the tooth preparation to fix the first portion to the tooth preparation and create a seal between the tooth preparation and the first portion prior to fill the tooth preparation with the filling material. After that the filling material has hardened, the method may include filling the tooth preparation with a second dental filling material that is compatible with the first dental filling material and the first portion.

[0037] In some embodiments, the tooth preparation may first be layered with a glass ionomer in the deeper part of the proximal box , and then filled with a composite resin. A person of ordinary skill in the art will recognize this technique as the sandwich technique, both materials adhering to the tooth and the first portion.

[0038] In some embodiments, the method may include adding a thin layer of a first dental filling material to the corner formed by the first portion of the dental matrix strip and the inner margin of the tooth preparation to fix the first portion to the tooth preparation and create a seal between the tooth preparation and the first portion prior to fill the tooth preparation with a second filling material. The tooth preparation may then be filled with the second filling material, for example a glass ionomer. The first portion of the dental matrix strip may then form an outside wall to protect the second filling material. It will be understood that, in some examples, the second filling material may be too weak, on its own, to resist mastication forces.

[0039] In some embodiments, the method may include treating the tooth preparation with acid prior to filling the tooth preparation with the dental restorative material.

[0040] In some embodiments, the removing of the second portion may include pulling on a wing of the second portion located at an end of the second portion.

[0041] In some embodiments, the removing of the second portion may include separating the first portion from the second portion along a series of perforations delimiting the first portion and the second portion.

[0042] A fourth broad aspect is a dental matrix strip for containing a dental restorative material having a pair of malleable extensions located at a bottom of the strip suitable to provide a tourniquet by twisting together to apply tension to at least the bottom of the strip when wrapped around a tooth preparation to retain a dental restorative material within the tooth preparation and to prevent body fluids from entering the tooth preparation until curing is completed.

[0043] In some embodiments, the dental matrix strip may also have a tube in which the malleable extensions are passed, where the tube may have a transversal bar extending across the tube, where each of the malleable extensions may be passing on either side of the transversal bar and out of the tube. The dental restoration matrix trip may also have a twistable handle configured to receive the malleable extensions and twist together the extensions as the handle is twisted. The malleable extensions may be welded to the strip.

[0044] In some embodiments, the strip may have a first portion for fusing with a dental restorative material and a separable second portion for releasing from a dental restorative material. The first portion may be configured to fuse with the dental restorative material and the second portion to seal a cavity of the tooth preparation near a floor thereof so as to retain the dental restorative material within the tooth preparation and to prevent body fluids from entering the tooth preparation until curing is completed. The malleable extensions may be located at the second portion.

[0045] The malleable extensions may be made out of stainless steel.

[0046] A fifth broad aspect is a method of fastening a dental matrix strip to a tooth preparation for containing a dental restorative material within the tooth preparation and for preventing body fluids from entering the tooth preparation until curing of the dental restorative material is complete, wherein the dental matrix strip has a pair of malleable extensions located at a bottom of the strip suitable to provide a tourniquet by twisting together the malleable extensions, including twisting together the malleable extensions in order to apply tension to at least the bottom portion of the strip when wrapped around the tooth preparation.

[0047] In some embodiments, where the dental matrix strip further includes a twistable handle configured to receive the malleable extensions and twist together the extensions as the handle is twisted, the twisting together of the malleable extensions may be initiated by turning the twistable handle. In some embodiments, where the dental restoration matrix has a tube in which the malleable extensions are passed, the tube having a transversal bar extending across the tube, wherein each of the malleable extensions passes on either side of the transversal bar and out of the tube, wherein the bar is adapted to separate the portions of the malleable extensions that are twisted together from the rest of the malleable extensions, the twisting together of the malleable extensions may cause the tube to move up closer to the point where the malleable extremities are in contact with the strip and to increase tension applied to the strip wrapped around the tooth preparation.

[0048] A sixth broad aspect is a method for insuring a minimal thickness of dental restorative material applied to form a crown around a tooth preparation using a dental matrix strip with a designated length to surround at least a portion of the tooth preparation, having spacers of the desired minimal thickness spaced along the length of the dental matrix strip, including surrounding the tooth preparation with at least one of the dental matrix strip such that the spacers are touching the surface of the tooth preparation and creating a space between the surface of the tooth preparation and the dental matrix strip prior to adding the dental restorative material to the tooth preparation to shape the crown directly on the tooth preparation.

[0049] Another broad aspect is a method of dental restoration using a dental matrix strip for sealing a tooth preparation of a tooth from infiltration of body fluids and having a first portion for fusing with a dental restorative material and a second portion for releasing from a dental restorative material. The method includes placing the dental matrix strip on the tooth, filling the tooth preparation with the dental restorative material, hardening the dental restorative material, removing the second portion once at least a portion of the first portion has fused to the dental restorative material received in the tooth preparation, and removing an excess amount of the first portion combined with the tooth restorative material.

Brief Description of the Drawings

[0050] The invention will be better understood by way of the following detailed description of embodiments of the invention with reference to the appended drawings, in which:

[0051] Figure 1 is a drawing of a front view of an exemplary two-section matrix.

[0052] Figure 2 is a drawing of a front and rear view of an exemplary first section of a two- section matrix, showing the front side and the rear side of the first section.

[0053] Figure 3 is a drawing of a rear perspective view of a rounded out exemplary two- section matrix.

[0054] Figure 4 is a drawing of a rear view of an exemplary two-section matrix, illustrating a line of protrusions separating the first section and the second section of the matrix.

[0055] Figure 5 is a drawing of a front view of a tooth to be restored, showing its cavity floor, and an exemplary two-sectioned matrix band, where the second section is protruding slightly above the cavity floor.

[0056] Figure 6 is a drawing of a front view of a tooth surrounded by an exemplary two- section matrix with the extremities of its second section twisted together to tighten the matrix around the tooth.

[0057] Figure 7 is a drawing of a top-down view of a system for tightening the two-sectioned matrix to the tooth. [0058] Figure 8 is a drawing of a front view of a tooth to be restored surrounded by an exemplary two-section matrix that is being tightened using a Tofflemire™ tightening apparatus.

[0059] Figure 9 is a drawing of a front perspective view of an exemplary tightening device of an exemplary matrix.

[0060] Figure 10 is a drawing of a top-down side view of an exemplary tightening device of an exemplary matrix;

[0061] Figure 11A is a drawing of a perspective view of an exemplary two-section matrix with side wings; and

[0062] Figure 1 IB is a drawing of a top-down view of an exemplary two-section matrix with side wings.

Detailed Description

[0063] In the present disclosure, it will be understood that the terms "section" and "portion" are used interchangeably to refer to the features of the flexible matrix.

[0064] In the present disclosure, it will be understood that by "fusing", it is meant the joining of one material to another such that the materials are affixed to one another, such as the joining of a portion or section of the matrix to a restorative material, the portion of section of the matrix affixed to the restorative material, including by using a bonding agent.

[0065] The present application relates to a flexible matrix made of two or more distinct sections. Reference is made to Figure 1 illustrating an exemplary two-section matrix 10 for covering a surface of a tooth preparation (i.e. the entire prepared tooth, ready for placement of dental restorative materials) to receive a dental restorative material. In some embodiments, the restorative material may include a filling material for filling a tooth preparation during the restorative process, and an adhesive material configured to assist with the bonding of the matrix to the filling material and/or surface of the tooth preparation. The adhesive material may be applied, for instance by using a brush, to the tooth preparation, and/or the matrix prior to filling the cavity with the filling material that has been added to the tooth preparation, and/or the surface of the tooth preparation (in some examples, prior to the applying of the adhesive material to the filling material). The adhesive material may also be applied within the cavity of the tooth preparation to assist with the binding of the filling material to the tooth itself as described herein. [0066] A first section 12 may be made of a material similar to the one used to restore a tooth preparation that is to be integrated in whole or in part to the tooth during the restoration, the composite material added to the tooth preparation. For instance, the material of the first section 12 of the matrix 10 may be made of the polymerized composite material similar to the composite resin used for tooth restoration.

[0067] In some examples, the first section 12 may be made out of a tenacious and flexible material suited to affix to the tooth and adhere to the filling material, namely a highly resistant polymer such as polyether ether ketone (PEEK). A bonding agent might be coated on the second side 14b of the first portion 12 to help bonding with the filling material.

[0068] The second section 11 is detachable from the first section 12. In some examples, there may be more than one additional detachable section with a same or similar function to that of the second section 11. The second section 11 is glued, joined or attached to the first section 12 and serves to facilitate the manipulation, the adaptation of the matrix 10 to the tooth and the tightening of the matrix 10 on and around the tooth. The second section 11 may be configured to be placed at the level of the gingival margin of the cavity to be restored, in most part below the cavity but slightly exceeding its floor so that the first section 12 does not extend below the cavity floor. In some examples, the second section 11 may transition to the first section 12 at the level, or slightly over the level, of the cavity floor. In some examples, as shown in Figures 11 A and 1 IB, the second section 11 may have side wings. The second section 11 may run along the bottom and the sides of the matrix 10 (i.e. in some cases, having substantially an ovoid shape). The side wings may facilitate the handling of the matrix 10, including the positioning of the tooth with respect to the tooth preparation.

[0069] In some embodiments, the first section 12 is a flexible band of a thickness of less than 500 micrometers, made of polymerized composite resin and having two sides. A first side 14a of the first section 12, facing the mouth, is smooth and is destined to form the outside surface of the restoration. This first side 14a is polished with a smooth surface that reduces the retention of dental plaque and of food on its surface. The second side 14b, facing the cavity of the tooth to be restored, is porous, the pores, such as exemplary pores 21 of Figure 2, are achieved by, for instance, laser etching, plasma, sand blasting and/or by another physical or chemical treatment of the surface. These pores are first wet by an adhesive material that can adhere to the rest of the restorative material or filling material and the tooth before placing the filling material on the first section 12. Moreover, the cavity side of the first section 12, or the entire first section 12, may be treated or manufactured so as to achieve a higher surface energy than that of the adhesives used so that the adhesives can optimally wet the porous side of the first section 12.

[0070] In some examples, the first side 14a may be treated or coated with a thin layer of material 41 for its effect on its environment. For instance, the thin layer of material 41 may reduce tooth decay or cavity formation, contain an anti -bacterial agent, etc. In one example, the thin layer 41 may include fluoroaluminosilicate particles, containing fluoride that can be released into the mouth when in contact with acidic saliva. It will be understood that fluoride is known for its anti- cariogenic, remineralizing and anti-demineralizing qualities. In some examples, the substance may contain calcium aluminate, suitable to cause hydroxyapatite to be deposited on nearby surfaces. In some examples, the substance may contain calcium silicate or a modified resin of calcium silicate, known for its remineralizing qualities. It will be appreciated that other substances may be contained in the coating over the first side 14a, such as those conferring antibacterial properties, anti-plaque properties, or any substance that improves dental health or periodontal health.

[0071] To optimize the adherence of the first section 12 and the adhesive, the same principles to those applied to adhering a composite resin to the enamel or dentin of a tooth may be used, such as the adherence of an adhering fluid to its solid substrate. Several factors may be considered, including: the substrate's surface energy must be slightly superior to the surface tension of the adhesive in order for the adhesive to properly wet and hug the substrate; the substrate's surface is preferably porous, which can be achieved by physically or chemically treating the surface providing it with porosities having optimal shape and size for the penetration of the adhesive; and the substrate's surface must in addition or alternatively have end terminals allowing for the formation of covalent bonds with the end terminals of the adhesive composite resin. Chemical and physical means of adhering an adhesive to a substrate, such as the ones known in the art to adhere the composite resin to the enamel or the dentin of a tooth, may be used.

[0072] When the application of the matrix 10 onto the tooth leads to a partially compromised stability of the matrix 10 onto the tooth, the first section 12 may be stabilized on the tooth by first placing a small amount of adhesive onto the first section 12 that may harden, then by placing the portion of the first section 12 with the adhesive on a part of the wall of the tooth that is not part of the cavity to be restored, and then by activating the hardening of the adhesive. This method of gluing the matrix 10 to the tooth may be important in a situation where it is difficult to stabilize a traditional matrix onto the tooth, such as when the cavity is extensive in size and/or depth, a significant portion of the sides of the tooth are missing, or that the adjacent tooth is located too far apart (i.e. too great a space) from the tooth that is to be restored, so the adjacent tooth cannot be used to fasten in the matrix using a wedge placed between the teeth.

[0073] In some embodiments, a second section 11 of the matrix 10 is attached to the first section 12 and is configured to be removed from the matrix 10 once the restoration procedure is complete. This second section 11 abuts the tooth to be restored at the cavity's gingival margin. As such, this section 11 is inserted at the cervical portion of the tooth that is next to or under the gums, and may be pressed against the tooth using a wedge 25 inserted between the defective tooth and its adjacent tooth. An example of a material used to make a matrix for posterior teeth is stainless steel, as it is flexible, without shape retention, and tear resistant even when thinned out. This material, stainless steel, may be an example of a material used to make the second section 11 of the present two-section matrix. A second section 11 made out of stainless steel may provide increased resistance to the part of the matrix 10 that undergoes the most strain during the procedure. However, the first section 12 is made in composite material, which usually offers less resistance when manipulated where this first section 12 is dimensioned and positioned on the tooth to be integrated to the restored portion of the tooth.

[0074] The second section 11 may be sufficiently long to fully circle the tooth and have both of its extremities joined using, for example, a tightening system such as the one developed by Tofflemire™, Automatrix™, or of any other suitable tightening system, where the practitioner may use any tightening system or technique that the practitioner is the most comfortable with. Moreover, the fact of tightening only the cervical portion of the matrix 10 provides an advantage over other methods by providing a splayed matrix form, widening as it nears the contact point between the first section 12 and the tooth, imitating the natural shape of the tooth. Unlike with current methods, where the conventional matrix must be loosened to allow for contact with the adjacent tooth, the present bi-sectional matrix 10 allows for a tighter fit to the cervical portion of the tooth while also allowing for occlusal contact.

[0075] When placing the matrix 10 on the tooth, it is important to position the second section 11 at the level of the cavity floor found at the proximal side of the cavity, or surpassing it slightly, as shown in Figure 5. In this way, the first section 12 of the matrix 10 will be located near the gingival margin of the tooth. This reduces the problem of removal, difficult as rotary and/or manual instruments have reduced access to this part of the tooth. However, the height of the second section

11 does not have to be restricted as it may be placed in deeply next to the gums surrounding the cavity. In contrast, a practitioner using a matrix entirely made from a composite material may be required to insert it so that it is leaning only slightly onto the axial side of the tooth, at the gingival margin, and near the floor of the cavity, in order to limit the excess material that needs to be removed.

[0076] In other embodiments, the matrix 10 may be sectional, covering the mesial or distal side of the tooth to be restored, while not surrounding it. The first section 12 may be curved so that it mimics the rounded shape of a tooth's interproximal, as shown in Figure 3. The second section 12 may have openings 22 to facilitate manipulation of the second section 11 as well as its removal. A ring adding pressure to the buccal and lingual portions of the tooth to be restored and its adjacent tooth, such as the ring 24 as illustrated in Figure 7, would allow the practitioner to not change his pressure-applying technique. In the examples where the first section 12 is made out of composite material that is prone to tearing while being manipulated, having a second section 11 made out of more resistive material is a real advantage as this section is first inserted between the teeth and receives the bulk of the pressure resulting from the tightening of the matrix 10 to the tooth.

[0077] In some embodiments, the second section 11 is made out of a material that can decompose in the mouth within a few hours or a few days, such as a non-toxic bioplastic, and can therefore be left in place once restoration complete, the second section 11 dissolving after the procedure, leaving only the first section 12 that is joined to the restored tooth. This may be advantageous if it is desired to incorporate a therapeutic agent, which is readily soluble in the region, such as fluoride, a re-calcifying biomaterial or an antibacterial agent.

[0078] In some examples, the second section 11 is made out of celluloid, biaxially-oriented polyethylene terephthalate, or of another flexible plastic material that is joined to the first section 12.

[0079] In some embodiments, the second section 11 is an extension of the first section 12, where a series of perforations 27 (e.g. a line of perforations), as shown in Figure 4, extend across and between the first and second sections 11 and 12, allowing for the detaching of the first section

12 from the second 11. The surface of the second section 11 that is meant to face the tooth is as smooth as its opposite surface so as to prevent the adhering of the second section 11 to the restored portion of the tooth. The second section 11 may be made out of the same composite material as the first section 12, or can be of a different material, including a modified formula of the composite resin. For instance, the second section 11 may be composed of a same polymer matrix to which is added charged particles for favoring such properties as increased flexibility and tear resistance over other properties that are more advantageous for the first portion 12 of the matrix, such as reduced water absorption.

[0080] In some embodiments, a visible color is added to the second section 11 so it may be distinguished from the first section 12 as well as properly identified following the insertion of the matrix 10 during a restoration procedure.

[0081] In some embodiments, the matrix 10 surrounds completely or nearly completely the tooth. The extremities of the second section 11, in the cervical region of the tooth, are joined together. These extremities 23 may be twisted together or intertwined using a tool, such as a pair of pliers. Exemplary extremities 23 are illustrated at Figure 6. In the example where the second section 11 is made out of a polymer or a material with a lower melting point, heated pliers may be used to fuse both extremities 23 together. Both extremities 23 may also be joined together using an adhesive placed on the surface of at least one of the two extremities 23. In other examples, the extremities 23 may be joined together using a rolling mechanism, where both extremities are rolled together, or joined together using clips, such as hair clips. The Tofflemire™ apparatus 26 may also be used as illustrated in Figure 8.

[0082] In some embodiments where the first section 12 of the matrix 10 is dimensioned to surround the tooth, the second section 11 of the matrix 10 may be inferior in length to the circumference of the tooth to be restored, and shorter than its first section 12. At the extremities of this second section 11, stainless steel wires without shape memory are welded or glued to both ends of the second section 11. The user may press the two filament ends together and may twist them together to tighten the matrix to the cervical portion of the tooth. This system allows for the precise regulation the tension applied when tightening the matrix without having to use a large and cumbersome tooth device such as a metallic arm for tightening a metallic band matrix around the entirety of the tooth as is known in the art.

[0083] In other embodiments, the second section 11 is of a greater length than the circumference of the tooth to be restored. As illustrated in Figures 9 and 10, the matrix 10 may have a tightening system 30 for fastening and tightening the matrix 10 to the tooth. Stainless steel wires 32 are glued or welded to the second section 11. As the second section 11 is too large so that the twisting of the wires would allow for the tightening of the matrix 10 to the tooth, the wires extend through a tube 28 having a transversal bar 33 at its end. The wire extremities are then inserted in a sleeve 31 that may be turned manually in order to twist the wires, as shown by the twisted wires 29, and tighten the matrix 10 around the tooth.

[0084] In some examples, the restorative material may be a composite resin with or without an acid that is applied to the tooth and to the second side 14b of the first portion 12. The tooth preparation may be rinsed, and an adhesive may then be applied to the surface of the tooth and to the second side 14b of the first portion 12 and hardened, the composite resin then added to the tooth cavity defined by the tooth and the first portion 12 and hardened.

[0085] In some examples, the restorative material may include a glass ionomer, inserted directly into the cavity or inserted after that the tooth preparation has been acid-treated, adhering to the tooth and to the second side 14b of the second section 12 (in some examples, after that an adhesive had been applied to the tooth and/or to the second side 14b).

[0086] In some examples, the restorative material may be a compomer, giomer, Orcomer ^® or any other material composed of polymers, and/or calcium silicate, glass, ceramic provided that the material may adhere directly, or with the aid of an adhesive, to the first side 14b of the first portion 12.

[0087] Interproximal Sealers and Contact Closure:

[0088] In some embodiments, an operator may perform a procedure to close up an opening left from a previous restoration procedure by only using one or several matrices (these matrices may be composed of a single section, or two or more sections as described herein) and an adhesive, such as dental cement (e.g. composite cement). In some instances, the operator may inject cement on the porous side of the matrix and, next, place it against the surface of the tooth to be thickened, polymerize the cement using a curing lamp, take off the second portion of the matrix if present and if it was not first taken off at the start, and remove the excess matrix found at the buccal and lingual sides. In some embodiments, a polymerized composite matrix has two porous sides in order to adhere on one of its sides to the side of the tooth or to a filling that needs to be thickened, and on the other of its sides to another two-sided porous matrix. Additional two-sided porous matrices may then be added to those matrices already joined to the tooth or restoration, where the number of matrix layers to be added by the practitioner depends on the desired increase in thickness that is to be made to the tooth or to the restoration. [0089] In some other embodiments, the operator may employ the matrix to create an interproximal sealant, where the matrix used is composed of a single section, or two or more sections as explained herein. A sealant may be, in some examples, a layer or superficial resin added to the region of the tooth that is more prone to cavities in order to prevent their development, as is known in the art.

[0090] Complete Recovery of the Tooth:

[0091] In some embodiments, the tooth is covered with a composite material in a similar manner to what is done when creating a crown using indirect restorative procedures. One of the purposes of adding a crown is to transform the force of tension that could lead to an increased risk of tooth fracture into a force of compression, when the tooth absorbs an occlusal impact. Therefore, this technique allows for extending the life of the tooth, such as one that has undergone a root canal and/or an extensive restoration. The operator may sculpt the tooth according to a crown preparation technique as is known in the art while ensuring that there is a minimal space on its surface to add the restorative material with a sufficient thickness, in some examples, around 0.5 to 1.5 mm. The operator then adds the matrix 10 as described herein where the first portion 12, made of a similar composition to that of the restorative materials, adapted to be integrated to the restorative material at least in part. The matrix 10 then completely surrounds the tooth. The operator may also ensure that the second portion 11 of the matrix 10 reaches or slightly surpasses the height of the gingival margin of the sculpted portion of the tooth at its proximal sides. The operator may then add the restorative material, after adding an adhesive material if needed. The operator then detaches the second portion 11 of the matrix 10 once the restorative material has hardened, and makes the final necessary adjustments.

[0092] In some embodiments directed to crown applications, the first section 12 of the matrix 10 made out of composite material has spacers of a minimal thickness corresponding to the desired thickness of the restorative material to be added to the tooth. After that the matrix 10 is put into place and the operator has injected the restoration material, the operator applies to a first section of the matrix 10 pressure using, for instance, his finger, or an instrument, on its buccal and lingual sides, allowing for the restoration material to harden. In this way, the spacers prevent having a restoration material that is too thin at certain portions of the tooth that are more prone to reduced thickness. Therefore, a method to prepare a crown over a tooth to be restored may first include sculpting the tooth so that there is sufficient space around and on top of the tooth to add a restorative material with a sufficient thickness that does not jeopardize the properties of the restorative materials. Then, a matrix may be added (e.g. the matrix has two portions described herein, where a second portion of the matrix is detachable from the first as described herein), the matrix having spacers of a desired minimal thickness, the matrix (or at least one matrix) to be positioned around the tooth preparation. Where the matrix has two portions, the second portion is positioned such that it is at or slightly above the gingival margin of the tooth preparation. The buccal and lingual sides of the matrix are positioned onto the surface of the tooth preparation so that the spacers are supported on the surface of the tooth preparation in order to maintain the desired minimal thickness of the filling material to be added between the matrix and the tooth preparation. An adhesive may be added to the tooth preparation and/or the surface of the matrix that will come into contact with the filling material of the restorative material. At least a thin layer of the filling material is added up to around the level of the spacers (interspersed along the length of the matrix, e.g. equi distantly). Then, the additional filling material is added to form the walls and the top of the crown. Optionally, the detachable second portion of the matrix may then be removed, and the excess restorative material, and/or matrix that is fused to the restorative material, may be removed.

[0093] Although the invention has been described with reference to preferred embodiments, it is to be understood that modifications may be resorted to as will be apparent to those skilled in the art. Such modifications and variations are to be considered within the purview and scope of the present invention.

[0094] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawing. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above and below may be utilized separately or in conjunction with other features and teachings.

[0095] Moreover, combinations of features and steps disclosed in the above detailed description, as well as in the experimental examples, may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.