Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not applicable. 
       BACKGROUND 
       [0003]    1. Field of the Invention 
         [0004]    The present disclosure generally relates to dental appliances and methods involved in dental restorations. In particular it relates to matrix bands used during the filling of tooth cavities. The disclosure demonstrates a new system for ensuring tight proximal contacts between teeth after the dental matrix band has been removed following a dental restoration. 
         [0005]    2. Description of the Related Art 
         [0006]    One of the most common practices of dentists is the treatment of dental cavities, or caries that grow in teeth. The mammalian tooth is a structure comprising an enameled crown supported by one or more roots embedded in the mandible or maxilla, bones of the upper and lower jaw. The enamel is the highly mineralized hard tissue on the outside of the tooth. The calcium phosphate rich enamel is secreted, supported and nourished by the hard tissue, dentin, of the tooth body, with a soft pulp core, supplied by blood. A layer of cementum and the periodontal membrane anchor the tooth in the underlying bone structure of the jaw, in conjunction with the gums, or gingiva Enamel, when healthy, is one of the hardest natural substances, but is susceptible to decay and the formation of cavities. 
         [0007]    Cavities are holes in teeth caused by the acids present in dental plaque. Bacteria in the mouth produce acids when in the presence of sugars such as sucrose, fructose and glucose. Food debris remaining in the teeth of an individual can cause the production of these acids. The acids demineralize the tooth&#39;s hard tissues: enamel, dentin and cementum. Lactic acid produced by oral bacteria when they consume sugars. The acid causes demineralization of crystals in the enamel, which can allow the acids to penetrate deeper into the tooth, causing cavities. Cavities, if left untreated, can penetrate the enamel and affect the cementum, the calcified substance covering the root of the tooth, and the dentin, the calcified body that makes up the majority of the tooth&#39;s structure, of the tooth. 
         [0008]    Dentists can treat cavities by removing decayed tissue. Dentist then insert a dental restoration, or filling, into the prepared cavity in the tooth. Fillings can be made of several different materials including silver alloy, gold, porcelain, or composite resin. When performing a dental restoration, a dentist generally numbs the area around the tooth to be restored with a local anesthetic. He or she then uses an instrument, often a high-speed dental drill to remove the decayed portion of the tooth. After the decay is removed, the dentist shapes the targeted area using burs to prepare the area receiving the restoration to receive the filling. The dentist may place a base or liner in the space to protect the pulp of the tooth. The dentist then places the unhardened restoration into the area of the tooth that has been prepared. After the filling is placed, the dentist will shape the filled area using burs to restore the tooth&#39;s proper anatomic contours. The process of hardening and shaping the tooth and restoration after the restoration has been placed in the prepared area varies based on the type of filling that is used in the procedure, established practice, and the preference of the dentist. 
         [0009]    The particular dental restoration procedure used is dependent on the affected tooth, where on the tooth the cavity has developed, and where the restoration is to be placed. For cavities that have developed on the occlusal, or biting, surfaces of teeth in the rear of the patient&#39;s mouth, the restorative material may be able to be held in place by the remaining material of the teeth. When cavities have developed along the sides or edges of a tooth, however, there may not be sufficient dental material remaining to hold the restorative material in place until it has hardened sufficiently. A particular type of restoration, a type II interproximal cavity preparation involves a cavity between the adjacent surfaces of two teeth. 
         [0010]    In such a situation dentists often employ a matrix band to serve as a barrier to hold the restorative material in its proper place on the tooth until the material has sufficiently hardened. The bands are made to mimic the proximal contours of the patient&#39;s tooth so that, once the procedure is completed, the patient&#39;s tooth with the restorative material added will be as close to natural as possible. Matrix bands are very thin flexible pieces of metal, often made of stainless steel, but can also be made of brass or copper. Typical thickness of the band body is 30 to 50 micrometers. Certain types of matrix bands are made of plastic or similar flexible materials with high tensile strength. The main function of the matrix is to restore proper anatomic proximal contours and contact areas to the tooth or teeth involved in the dental restoration procedure and their adjacent teeth. 
         [0011]    The bands are very thin because they are placed between the tooth receiving the restoration and an adjacent tooth. The occlusal edge of the band is placed towards the occlusal surface of the tooth, while the gingival edge is placed towards the gingiva, or gums. Bands are available for use with specific teeth (premolar or molar), and universal bands are also available. Before inserting the matrix band in between the tooth structure of the damaged tooth and the adjacent tooth the matrix band must be shaped, or burnished, to give the band a contour that is properly adapted to the structure of the tooth. A dentist may burnish the band by rubbing a blunt dental instrument along the length of the band to introduce a curvature to the matrix band. 
         [0012]    Dental wedges are usually used along with matrix bands in dental restoration procedures. Wedges have traditionally been wooden but are also available in a variety of plastic materials. Specialized wedges are available that are suited to particular areas of the mouth, or a dentist can personally contour a wedge so that it properly fits the mouth of the patient. The dentist places the dental wedge along the gingiva between the tooth to be restored and the adjacent tooth. A proper-fitting wedge should cover the entire gingival proximal surface between the teeth. Wedges are used to slightly separate the adjacent teeth to compensate for the thickness of the matrix band, helping to create a tight contact between the finished restoration and the adjacent tooth. If a wedge is not used with the band, a space equal to the thickness of the band can remain between the proximal surface of the teeth receiving the restoration and the adjacent tooth when the band is removed following the procedure. The dental wedge also compresses the matrix band against the tooth to create a tighter seal. Wedges also prevent gingival overhang. 
         [0013]    While the matrix band is the operative element in a dental restoration procedure, the band must be held in place by a matrix retainer. Two types of matrix band systems are commonly used by dentists. The Universal matrix system uses a device with a U-shaped head with three slots into which the band is positioned. A locking vise with a sliding body is used to hold the band. A knob at the middle of the device can be turned to change the diameter of the loop in the band based on the size of the tooth. A knob on the outside of the device locks the band in place, and can also be used to tighten the spindle. A matrix band is placed into the guides of the device and is then placed around the circumference of the tooth receiving the restoration. The knob at the middle of the device is turned to properly position the band around the tooth. The outer knob can be used to tighten the band to the sides of the tooth to create a tight contact with the tooth. The Universal system is also referred to as a Tofflemire matrix system. U.S. Pat. No. 3,517,444 to Tofflemire discloses an example of such as system. 
         [0014]    The other common matrix band system is a sectional matrix band system. The sectional system consists of a contoured matrix band, or shim, and a “BiTine” ring. The shim is a smaller piece of metal than used in the Tofflemire system, and the BiTine Ring is an open ring with legs extending downwards from the curvature towards the gums of the patient. The BiTine ring is applied interproximally between the tooth to be restored and the adjacent tooth. The BiTine ring applies a wedging force that enhances contact formation and aids in the proximal contouring of the dental restoration. The BiTine ring is applied by first using dental pliers to separate the legs of the ring, which are then positioned to straddle the interproximal area adjacent to the dental wedge and the matrix band. The force of the legs creates a slight separation between the decayed tooth and the adjacent tooth. U.S. Pat. No. 5,788,487 to Meyer and U.S. Pat. App. No. 2002/0155410 to Bills provide examples of the elements of the sectional matrix band system. BiTine rings and related matrix bands and accessories are available under the Palodent brand of Dentsply Caulk of Milford, Del. 
         [0015]    Though the two above matrix band systems are the most popular systems currently employed by dentists, the systems have shown several shortcomings in their ability to create tight proximal contacts between the tooth receiving the dental restoration and the adjacent tooth following the procedure. Because the matrix band must remain in place during the dental restoration procedure and until the restoration has hardened the proximal contact between the restored tooth and the adjacent tooth can be compromised. The width of the matrix band, though slight, is still enough to result in dental problems associated with loose proximal contacts or physical gaps between teeth. 
         [0016]    Research has suggested that the lack of a tight proximal contact can cause several dental problems for the patient. Loose proximal contacts can be a factor in food impaction and retention. Impaction and retention of food between teeth can result in further damage to the tooth and its enamel. Loose proximal contacts can also lead to dental migration, periodontal complications and carious lesions. 
         [0017]    To alleviate such problems created by current matrix band systems, there is an unmet need for a matrix band system that provides for the function of the band, but which also provides for the maintenance of tight proximal contact during the dental restoration procedure, more thoroughly replaces or restores the proximal contacts after the procedure is completed, or that provides a replacement for the natural proximal contact to help avoid issues resulting from loose proximal contacts. The present disclosure is directed to providing such a system that minimizes the interproximal tooth gap, and improves the dental quality of interproximal tooth restorations. 
       BRIEF SUMMARY 
       [0018]    The disclosure includes embodiments of an apparatus, namely a dental restoration contact matrix band comprising: an elongated strap formed of impervious material with high tensile strength, said strap having a first and a second opposing ends, a body adapted to wrap around a tooth to be restored, said body having continuous upper and lower edges which extend between said first and second opposing ends, and an aperture retaining a contact matrix 
         [0019]    A further embodiment is a method for repairing an inter-proximal cavity during restoration of a tooth comprising: (a) inserting a contact matrix band in the interproximal gap adjacent to the inter-proximal cavity, said contact matrix band having a contact matrix approximating the form of the preexisting inter-proximal contact, said contact matrix compatible with the filling matrix and removeable from the contact matrix band; (b) clamping the contact matrix band to close apposition with the borders of the inter-proximal cavity and desired inter-proximal contact; (c) placing filling matrix in the cavity of the tooth in close contact with the walls of the cavity and the mesial surface of the contact matrix; (d) allowing the filling matrix to cure and to bond with the contact matrix; and (e) displacing the contact matrix band from the inter-proximal gap without displacing the contact matrix, wherein the contact matrix is permanently bound to the filling matrix and provides a close contact with the adjacent tooth, while minimizing the inter-proximal gap. The method disclosed provides a matrix band compatible with a Tofflemire clamp, a Bitine clamp, or a ring clamp. 
         [0020]    In a further embodiment, a contact matrix band is provided with a channel, a perforation strip, or a perforation strip and a channel. Said matrix bands can be provided as a collection of matrix bands with 3 or more shapes of contact matrices. 
         [0021]    Another embodiment of the apparatus and system is a dental restoration contact matrix band comprising a) an elongated band portion formed of impervious material with high tensile strength, said band portion having a first and a second opposing ends, and a body with a cross section thin enough to be inserted into the interproximal gap between two teeth; b) a contact matrix formed of contact matrix material with a contact matrix area approximating the form of the preexisting inter-proximal contact; c) said contact matrix material being sufficiently compatible with an expected filling matrix to form a permanent bond between the contact matrix material and the filling matrix; d) an association between the band portion and the contact matrix that allows the contact matrix band to be separated from the contact matrix band during a dental restoration procedure; whereby when a dental restoration is performed, the contact matrix band is placed in a position occupying the interproximal gap between the teeth, and filling matrix is used to fill a cavity said filling matrix bonds with a proximal surface of the contact matrix so that the association between the band portion and the contact matrix can be broken, without displacing the contact matrix, allowing the band portion to be removed, and allowing the contact matrix to remain in the interproximal gap between the teeth, so that the contact matrix is permanently bound to the filling matrix and provides a close contact with the adjacent tooth, while minimizing the inter-proximal gap. 
         [0022]    The contact matrix band is further embodied in a contact matrix that is a rectangular, square, circular, dumbbell, dog bone, or irregularly shaped area and wherein the width to length ratio of the matrix band body is one or more of approximately 1 to 20, approximately 1 to 10, approximately 1 to 5, approximately 2 to 1, or approximately 1 to 1. 
         [0023]    Yet another embodiment is a contact matrix band further comprising the proximal surface of the contact matrix that has been abraded, roughened with a number of irregularly shaped protrusions, formed to have channels, or formed to have irregularly shaped surfaces and cavities wherein the proximal face exhibits enhanced bonding to a filling matrix. 
         [0024]    In yet another embodiment, the system and apparatus for use with the claimed method are comprised of a kit providing components necessary for implementing a contact matrix band system comprising a series of contact matrix bands of variable sizes; a selection of several sizes of contact matrix affixed to the contact matrix band said contact matrix being proportional to an interproximal contact area; a selection of several shapes of contact matrices for filling interproximal gaps; 
         [0025]    The system shown in the accompanying figures merely illustrates the various components of the contact matrix band system and is not a limitation of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    For a fuller understanding of the nature and advantages of the present assembly and components thereof, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which: 
           [0027]      FIG. 1  is an overhead view of a matrix band that utilizes the various components disclosed herein; 
           [0028]      FIG. 2  is an overhead view of a typical bi-tine ring used for restoration; 
           [0029]      FIG. 3  is a side view of a contact matrix band; 
           [0030]      FIG. 4  is a perspective view of two teeth with a restoration contemplated in the interproximal gap between the teeth; 
           [0031]      FIG. 5  is a top view of two teeth with a contact matrix band inserted in the interproximal gap between the teeth during the process of dental restoration; 
           [0032]      FIG. 6  is a side view of two teeth with a partial cross section, during dental restoration prior to the placement of filling matrix in the prepared cavity; 
           [0033]      FIG. 7  is a side view of two teeth with a partial cross section, during dental restoration after the placement of filling matrix in the prepared cavity; 
           [0034]      FIG. 8  is a side view of two teeth with a partial cross section, during dental restoration after removal of the contact matrix band body following restoration of the cavity; 
           [0035]      FIG. 9  is a top view of a contact matrix emplaced in the interproximal gap between two teeth, using the embodied system; 
           [0036]      FIG. 10A-C  are front views of alternative embodiments of the contact matrix band; 
           [0037]      FIG. 11A-C  are front views of embodiments of the contact matrix band with a contact matrix channel; 
           [0038]      FIG. 12  is a top view of a contact matrix band similar to the embodiment shown in  FIG. 11A ; 
           [0039]      FIG. 13  is a side view of a contact matrix band shown as it may be placed on a molar; 
           [0040]      FIG. 14  are several views of various contact matrices; and 
           [0041]      FIG. 15A-C  are top views of contact matrix bands were the contact matrices are embodied for enhanced bonding to filling matrix. 
       
    
    
       [0000]    
       
         The drawings will be described in further detail below. 
       
     
       DETAILED DESCRIPTION 
       [0043]    The contact matrix band of the presently disclosed embodiments is adaptable for use with a number of matrix band apparatuses that are widely used in dentistry. The contact matrix band solves a continuing problem of the inability to maintain tight interproximal contacts following a Type II dental restoration. 
         [0044]      FIG. 1  shows a typical dental restoration  100  utilizing existing matrix band systems on a posterior mandibular tooth, a molar of the lower jaw, at  110 . Teeth  126 - 131  (representing mandibular teeth 26-31) are in close contact with one another. Tooth  130  is in need of restoration, with shaded area  140  representing the location of a dental carie that has been removed to leave a cavity in need of dental restoration. The restoration shown in  FIG. 1  illustrates an interproximal Class 2 cavity preparation, known to those skilled in the art of dentistry. The restoration of tooth  130  extends to the proximal border of tooth  130 , so that following the removal of tooth material during restoration of tooth  130 , the contact between the posterior surface of tooth  130  and the anterior surface of tooth  131  is removed. The proper restoration of tooth  130  relies on the re-establishment of the close contact between the posterior surface of tooth  130  and the anterior surface of tooth  131 . 
         [0045]    Proper dental restoration procedure utilizes a matrix band, as at matrix band  144 , to provide a border for the creation of a restoration filling. Matrix band  144 , when properly implemented is preferably in a position where the insertion of a filling fills the space between the cavity  140  and matrix band  144 , and following removal of matrix band  144 , recreates the close contact between tooth  130  and tooth  131 . Existing practices often rely on a Tofflemire clamp  150 , with clamp jaws  152  and  254  to tighten matrix band  144  around tooth  130 . As described above, the thickness of the matrix band  144  introduces a difficulty in forming a close contact between the posterior surface of tooth  130  and the anterior surface of tooth  131 . Following restoration, removal of matrix band  144  leaves a gap approximating the thickness of matrix band  144 . 
         [0046]      FIG. 2  illustrates an alternative system in current use, replacing the Tofflemire clamp and extended matrix band with a “Bitine” ring clamp and leaf-like matrix bands. The embodiments of the present disclosure are adaptable for use with existing systems of matrix bands, including those utilizing the Tofflemire system and the Bitine ring clamp system. In  FIG. 2 , dental restoration  200  utilizing existing Bitine sectional matrix band systems on a molar of the lower jaw  210 . Teeth  226 - 231  are in close contact with one another. Tooth  230  is in need of restoration, with a dental carie that has been removed to leave a cavity  240  in need of dental restoration. The restoration of tooth  230  extends to the proximal border of tooth  230 , so that following drilling of material during restoration, the contact between tooth  230  and the anterior surface of tooth  131  is removed. Matrix band  244 , when properly implemented is preferably in a position where the insertion of a filling fills the space between the cavity  240  and matrix band  244 , and following removal of matrix band  144 , recreates the close contact between tooth  130  and tooth  131 . The Bitine system utilizes a spring-loaded ring  242  with appended jaws  246  and  248  to maintain the position of the sectional matrix band  244  around tooth  230 . Following restoration, release of Bitine ring  242  and removal of matrix band  244  leaves an interproximal gap approximating the thickness of matrix band  244 . 
         [0047]      FIG. 3  is a side view of one embodiment of the new contact matrix band. Matrix band  300  is a dental restoration contact matrix band suited for use with a Tofellmire clamp. Contact matrix band  300  is shown with an elongated body portion  306 , formed of impervious material with high tensile strength, such as stainless steel. The band portion  306  has a first and second opposing ends ( 308 ,  310 ), and a body with a cross section thin enough to be inserted into the interproximal gap between two teeth. Typically, an angle is formed in the longitude of the body, between a first end  311  and a second end  312 . Between the first and second ends is a contract matrix area  320 . In a preferred embodiment, the contact matrix is an elliptical area. The contact matrix area can be shaped to conform with a variety of interproximal contacts. Therefore, in alternative embodiments, the contact matrix is a rectangular, square, circular or irregularly shaped area, such as a dumbbell or dog bone shape. As shown in  FIG. 3 , the width to length ratio of the matrix band body is approximately 1 to 20. Other typical ratios may be 1 to 10 or 1 to 5. As discussed below in relation to  FIG. 5 , matrix bands for use with the Bitine system will typically have a width to length ratio of 2 to 1, 1 to 1 or less. 
         [0048]    Affixed to the contact matrix area  320  is a contact matrix formed of contact matrix material with a contact matrix area approximating the form of the preexisting inter-proximal contact. According to the system of the invention the contact matrix is affixed to the contact matrix area with a bond of moderate strength, sufficient to retain the contact matrix to the contact matrix band during insertion of the matrix band into the interproximal space, but a weak enough attachment that the attachment to the matrix band can be separated at the conclusion of the dental restoration. As described below, a number of mechanisms for retaining the contact matrix to the contact matrix area are available as disclosed herein. Thus, the association between the band portion and the contact matrix allows the contact matrix band to be separated from the contact matrix band during a dental restoration procedure. 
         [0049]    When a dental restoration is performed, the contact matrix band is placed in a position occupying the interproximal gap between the tooth being restored and the adjacent tooth. Filling matrix is used to fill a prepared tooth cavity, and is contained by the contact matrix band. The contact matrix material is formed of dentally compatible materials sufficiently compatible the material to be used to fill the cavity, i.e. the expected filling matrix, so that the contact matrix and the filling matrix will form a permanent bond between the contact matrix material and the filling matrix. The filling matrix bonds with the contact matrix so that the association between the band portion and the contact matrix can be broken without displacing the contact matrix. This allows the band portion to be removed, and the contact matrix to remain in the interproximal gap between the two teeth. 
         [0050]    In a preferred embodiment the contact matrix is permanently bound to the filling matrix and provides a close contact with the adjacent tooth, while minimizing the inter-proximal gap. The bond between the materials need too be sufficiently permanent to be maintained through the life of the dental restoration. Dental restorations may be temporary, for instance a few weeks during an implant procedure, or for decades in certain restoration in otherwise healthy permanent molars. 
         [0051]      FIG. 4  is a perspective view of two teeth with a restoration contemplated in the interproximal gap between the teeth. Dentition portion  400  shows a lower left jaw,  410  carrying two teeth,  418  and  419 . Tooth  418  is shown with a crown  420  with embedded roots  422 , and several cusps, as at  423 , on the occlusal surface. A cavity  430  (dental cane) is present on the interproximal surface of tooth  418 . During the restoration procedure, a typical Type II restoration will require removal of the decayed tooth material. In order to completely remove the decayed material and allow for implanting filling matrix, removes the tooth structure up to the occlusal surface of the crown. 
         [0052]      FIG. 5  shows a top view of teeth, such as shown in  FIG. 4 , with a cavity prepared for implantation of filling matrix. Restoration  500  shows teeth  518  and  519 , with a prepared cavity  531  in tooth  518  that extends into the interproximal region  534  between teeth  518  and  519 . As shown in  FIG. 5 , a sectional contact matrix band  536  is in place between the teeth, and is held in place by clamp arms  538  and  539 .  FIG. 5  also shows contact matrix  540  located at the interproximal gap between teeth  518  and  519 . 
         [0053]      FIGS. 6 through 8  show partial cross sections of a tooth with an interproximal dental carie, such as shown in  FIG. 4 . The tooth is shown undergoing restoration utilizing the contact matrix bands disclosed herein. Restoration  500  shows teeth  518  and  519 , with a prepared cavity  531  in tooth  518  that extends into the interproximal region  534  between teeth  518  and  519 . Tooth  518  is shown as a cross section to reveal the internal structure of the region being restored. The gingival margin is shown at  560 , with the roots of tooth  519  shown at  562 . As shown in  FIGS. 6-8 , a contact matrix band  536  is in place between the teeth. With respect to contact matrix band  536 , the band  536  could be a sectional contact matrix band as shown in  FIG. 5 , or it could alternatively be a Tofflemire compatible matrix band as shown in  FIG. 1 . Also in  FIGS. 6-8 , the contact matrix  540  is located at the interproximal gap between teeth  518  and  519 . The contact matrix band  536  has a lingual margin  568  and a gingival margin  566 . 
         [0054]    Prior to undertaking the restoration shown in  FIG. 6 , interproximal contact, shown generally at  580 , was created by physical contact between contact region  582  of tooth  519  and contact region  584  of tooth  518 . Preparation of cavity  531  opened the cavity to the occlusal surface  538  of tooth  518 . The cavity preparation also removed tooth structure in the region of the interproximal contact  580 . In order to restore the tooth by the placement of filling matrix in the prepared cavity, the tooth margin  534  needs to be recreated in order to recreate the contact region  584  of tooth  518 . The contact matrix band is inserted into the interproximal gap, and clamped in place. One or more wedges, as at wedge  564  are forced between teeth  518  and  519  to force the gingival margin of matrix band  536  into close contact with tooth  518  thereby containing the filling matrix within cavity  531 . Contact matrix  540  is placed against the cavity margin  534 , and is held in place by clamps or wedges. Once the filling matrix is compacted into the prepared cavity  531 , the contact matrix  540  will recreate the contact region  584 . 
         [0055]    As shown in  FIG. 7 , following the cavity preparation and emplacement of the contact matrix band, restoration proceeds with the placement of filling matrix in the prepared cavity. Due to the presence of contact matrix band  540 , the tooth margin  534  is recreated by the bonding of the filling matrix to the contact matrix. Thus, the contact between tooth  519  at region  582  is recreated with the contact region  584  of tooth  518 . The contact matrix band is inserted into the interproximal gap, and clamped in place. As shown in  FIG. 8 , once the filling matrix  586  has cured within the prepared cavity  531 , wedge  564  is removed, and contact matrix band  536  is shifted to disrupt the connection between contact matrix  540  and contact matrix band  536 . The separation of the contact matrix from the contact matrix band allows the contact matrix band to be removed. As will be further described in the following description, the formation of a bond between the filling matrix and the contact matrix allows for a stronger connection between the filling matrix and the contact matrix than between the contact matrix and the contact matrix band. Thus, the system allows the contact matrix to stay securely in place in the restoration, while the contact matrix band can be readily removed without damaging the restoration or injuring the patient. 
         [0056]    The completed restoration, shown in  FIG. 8 , leaves teeth  518  and  519  with tight interproximal contacts. This contact is further maintained because the teeth were not forcibly displaced during restoration in an attempt to leave space for a contact matrix band while seeking tight interproximal contact. Thus the permanent emplacement of the contact matrix  540  will recreate the contact region  584  of tooth  518 , allowing tight contact with contact region  582  of tooth  519 . The contact region  584  is finally polished to create a smooth and ledge free interproximal restoration using standard polishing techniques. 
         [0057]    After completion of the restoration, the contact matrix band system provides for the restoration to have the look, feel and structure of the teeth prior to undertaking the restoration.  FIG. 9  shows a top view of the completed restoration with a contact matrix  540  emplaced in the interproximal gap, using the embodied system. As shown in  FIG. 9  teeth  518  and  519  have maintained, or regained tight interproximal contacts in regions  582  and  584 . In an alternative embodiment, as described in connection with  FIG. 14  below, along with the other figures, a selection of contact matrix size and shapes can be provided. While the contact matrix  540  shown in  FIGS. 8 and 9  occupies the gap, the contact matrix could be sized to fit within the border of the cavity preparation. With a contact matrix occupying space  540 ′, shown in phantom, the contact matrix band system provides a margin for the restoration, and cavity filling, while leaving no lasting change to the configuration of the tooth contacts. 
         [0058]    The contact matrix bands can be made available in a number of configurations.  FIG. 10A-C  show several front views of alternative embodiments of the contact matrix band. It should be recognized that each of these views shows a relative area for the contact matrix, but the illustrations in  FIG. 10  are not exhaustive. Those skilled in the art will recognize other contact matrix forms that may be useful for a particular restoration. In  FIG. 10A , dental restoration contact matrix band  600  is comprised of an elongated band portion  602  formed of impervious material with high tensile strength. The band portion has a first and second opposing ends,  608 , and  609 , and a body with a cross section thin enough to be inserted into the interproximal gap between two teeth. Band  602  has a top margin  604  and a bottom margin  606 . As shown in  FIG. 10 , the top margin and the bottom margin are continuous, without interruption by gaps or intervening contact matrix. Area  610  is shown as an oval hole in band  602 , and will provide a location for the contact matrix to reside. Contact matrix area  612  is bordered by edge  612 . The size and shape of area  610  are adaptable to the needs of the dental surgeon. In general, the contact matrix formed of contact matrix material compatible with filling matrix material has a contact matrix area approximating the form of the preexisting inter-proximal contact, or with the desired post-restoration inter-proximal contact. It is expected that the contact matrix material will be sufficiently compatible with the chosen filling matrix for a particular restoration to form a permanent bond between the contact matrix material and the filling matrix. 
         [0059]    A number of implementations are available to form the desired association between the band portion and the contact matrix to allow the contact matrix band to be separated from the contact matrix during the final stages of a dental restoration procedure. As shown in  FIG. 10A , the contact matrix could have a physical position surrounded by the band  602 . Alternatively, a stainless steel matrix band could be chemically etched to allow the contact matrix to displaceably bind to the surface of the matrix band.  FIG. 10B  shows contact matrix band  620 , with a chemically etched matrix band  622 , where the etched area is represented by contact matrix area  624 . Etched area  624  does not completely penetrate band  622 , therefore allowing the contact matrix to be removeably attached to the surface of band  622  in area  624 . It should be recognized that a contact matrix of a polymerizing liquid could be spotted on the contact matrix area  624 , and following completion of polymerization, the etched area  624  would form relatively secure bond with the polymerized contact matrix, or at least a stronger bond than with the un-etched band. As shown in  FIG. 10C , rather than chemical milling, abrasion or physical milling could be used on contact matrix band  640 , so that band  642  provides a bonding area  644  for the adhesion of contact matrix to all or part of bonding area  644 . 
         [0060]    In another alternative embodiment, referring to area  624  of  FIG. 10C  (shaded) (and similarly area  644  of  FIG. 10C ) is either milled or chemically etched, to a greater extent than to simply provide a bonding surface, i.e. to thin the original thickness of the matrix band to a greater extent. In this alternative embodiment, the thinning of the cross section of the matrix band is less than as shown in  FIG. 12 , i.e., without perforating the band. In essence a hollow, or matrix material pocket is formed. By doing so, the availability of the contact matrix material pocket simplifies the manufacturing process of the band and provides for greater surface area or space for the restorative material to fill between the teeth. The end result is variable thickness contact matrix band that produces a filling with a better contact than one provided by a band of a single thickness. As is apparent, in conjunction with the following figures, the various configurations of a contact matrix pocket may be combined with other iterations of the contact matrix band, in particular the addition of a scoring or perforated fracture line. 
         [0061]    An objective of the contact matrix band system, as embodied particularly in  FIGS. 10 and 11  is that when a dental restoration is performed, the contact matrix band is placed in a position occupying the interproximal gap between the teeth, and filling matrix bonds with the contact matrix, but the association between the band portion and the contact matrix can be broken without displacing the contact matrix. Thus, this allows the band portion to be removed, and allows the contact matrix to remain in the interproximal gap between the teeth. Turning to  FIG. 11 , panels  11 A-C are front views of embodiments of the contact matrix band with a contact matrix channel. As shown in  FIG. 11 , the contact matrix area as a channel differs from the contact matrix areas in  FIG. 10 , so that the contact area edge is not fully surrounded by contact matrix band, but is contiguous in part with the band margin.  FIG. 11A  shows a contact matrix band  660 , with a band body  662 , bottom edge  663 , top edge  664 , and ends  665  and  666 . The contact matrix area  668  is shown as a channel cut through matrix band  662 . Thus contact matrix edge  667  extends to top margin  664 , so that upper contact matrix margin  672  forms part of the top margin  664 . Also shown in  FIG. 11A  is an alternative embodiment, comprising the contact matrix extending beyond the contact matrix area edge  667  to retaining lip  670 , so that the contact matrix is retained more securely on the matrix band  662 . Similar overlap of the contact matrix could be provided in combination with the embodiments shown in  FIG. 10-15 . Refer also to the top view of the system shown in  FIG. 12 .  FIG. 11B  shows a nearly identical contact matrix band system  676 , but the alternative embodiment is that the contact matrix area  678  is contiguous with bottom edge  679 , rather than top edge  680 . It should be recognized that although the matrix band  677  is shown as a simple rectangular strap, the matrix band could alternatively be any of the various sectional matrix bands, or a matrix band with asymmetry between the top and bottom edge conformations. Those skilled in the art of dental surgery will recognize the need for a variety of matrix band shapes. 
         [0062]      FIG. 11C  shows another alternative embodiment of a matrix band with a channel contact matrix area. The contact matrix band  684 , with a band body  686 , end margins  686  and  687  and bottom margin  689 . The contact matrix area  688  is shown as a channel cut into top margin  690 , top edge  664 , and through matrix band  686 . The contact matrix extends beyond the contact matrix area edge  692  to secure the contact matrix on the matrix band  662 . An additional embodiment is a stress fracture region  694 . Lateral or torsion stress about the ends of the contact matrix band will cause the matrix band  686  to fracture or tear along fracture region  694 , allowing the two ends  686  and  687  to be readily extracted from the interproximal region following restoration without displacing the filling or the contact matrix. As shown in  FIG. 11C , the stress fracture region  694  could be perforations through the matrix band  686 , indentations, a score line, or other weak zone along the matrix band. Thus, a fracture line allows the contact matrix band to fracture or tear at a predictable location.  FIG. 12  shows a top view of the contact matrix band  700  similar to the embodiment shown in  FIG. 11C . Matrix band  736 , has a channel occupied by contact matrix  740 , with the contact matrix having a proximal face  748  and a distal face  749 . Distal face  749  of the contact matrix is shown extending over the contact matrix edge  742 , while the proximal face of contact matrix  740  protrudes from the face of contact matrix band  736 . Stress fracture region  744  is positioned along about the centerline of the contact matrix. Alternatively, the edge zone could be etched to foster better adhesion, the contact matrix could protrude from both, or neither face, and the edge could overlap the matrix band on either face. 
         [0063]      FIG. 13  is a side view of a contact matrix band  700  as shown in  FIG. 12  with the contact matrix band shown as it would be placed on a molar. Contact matrix band  736  is shown in front of molar  718 . Contact matrix  740  has an edge overlap  742 . Stress fracture region  744  is approximately equidistant from the two sides of the molar. Fracture of region  744 , frees contact region  744  from matrix band  736 , and the ends of the matrix band can be withdrawn from between two adjacent molars or other teeth. Top edge  750  of contact matrix  740  is narrower than the maximum width of the contact matrix region. This conformation serves to better retain the contact matrix upon the matrix band, and alternatively could be adapted to the shape of the dental restoration or interproximal contact. 
         [0064]      FIG. 14  displays several views of various contact matrices, demonstrating that the actual size and shape can be varied to fit particular applications and needs. The contact matrices shown in  FIG. 14  would be removeably attached to a matrix band utilizing the Tofflemire, sectional matrix, or other system.  FIG. 14A  shows a circular form contact matrix  760  about 5 mm in diameter.  FIG. 14B  shows an ovoid form contact matrix  762  about 2 mm by 3 mm, while.  FIGS. 14C and 14D  show ovoid forms of contact matrix  764  and  766  about 1.5 mm by 2.5 mm and 1.5 mm×2 mm respectively.  FIG. 14E  shows a circular form contact matrix  768  about 1 mm diameter. Although not shown in detail in  FIG. 14 , the contact matrix will typically be used in an oblate, or flattened three-dimensional conformation. Thus, a variety of overall circular or ovoid cross sections from one axis may be utilized, with the thickness and relative height to width ratio being similarly varied along the opposing axis. In a particularly preferred embodiment, a contact matrix with an ovoid contact face, is combined with a flattened cross section. 
         [0065]    It is well known that a variety of shapes of contact faces may be desired, and the thickness of the interproximal gap is also variable. A kit of the most favored sizes of contact matrices may be provided. In yet another alternative embodiment, the contact matrix band as shown in  FIG. 12  or  13 , may be provided with a contact matrix foot, that snaps into place on a contact matrix band as shown in  FIGS. 12 and 13 . A contact matrix foot could be further provided with a contiguous contact matrix body of variable shape, so that a variety of contact matrices could be mated with a limited number of contact matrix bands, as conditions arise. 
         [0066]    The maintenance of the bond between filling matrix and contact matrix has been a difficult matter requiring experimentation. As previously described, in order to utilize the system most effectively the contact matrix must be more securely attached to the cured filling matrix than it is to the contact matrix band. The goal is for enhanced bond to filling matrix material for long term retention of the contact matrix to the restoration, and a detachable attachment of the contact matrix to the contact matrix band. The contact matrix-band retention may be a physical adhesion, using cement, glue or other enhancements discussed herein. It also could rely on structural retentions methods such as an overlapping contact matrix edge, or a contact matrix region shape that helps retain the contact matrix (See  FIG. 13 ).  FIG. 15A-C  are sectional views of contact matrix bands where the contact matrices are embodied for enhanced bonding to filling matrix. In  FIG. 15A , a protruding surface of a contact matrix is abraded to provide more bite to a bond between the contact matrix and filling matrix. Contact matrix band  770  is comprised of band portion  776  and contact matrix  780 , with overlapping lip  782 . Distal face  784  is opposed by proximal face  786 . Proximal face  786  has been abraded by common means to provide a rough surface with a number of irregularly shaped protrusions, such as  788 . Contacting filling matrix with proximal contact matrix surface  786  provides better adhesion, and a stronger filling matrix-contact matrix bond than the unabraded surface. Removal of the matrix band typically would involve lateral forces perpendicular to the tooth. Thus forces in the directions of force  790  and  792  are restrained by the invaginations in the contact matrix. These lateral forces are typically the forces that must be resisted to separate the contact matrix from the contact matrix band. 
         [0067]      FIG. 15B  shows a similar method of increasing filling matrix bond to the contact matrix. Contact matrix band  800  is comprised of band portion  836  and contact matrix  840 , with overlapping lip  842 . Distal face  846  is opposed by proximal face  844 . The proximal face  844  has been formed to have channels or fingers, forming lands  848  and grooves  850 . These structures could be formed by molding, milling or similar means that are generally available. When filling matrix is forced into close contact with proximal contact matrix surface  844 , it fills the grooves, and so long as the filling matrix has sufficient strength, the contact matrix is difficult to laterally displace along the filling matrix. 
         [0068]    Finally  FIG. 15C  shows a contact matrix created with a irregular surface configured to reduce the possibility that the contact matrix is separated from the cured filling matrix. Contact matrix band  900  is comprised of band portion  936  and contact matrix  940 , with overlapping lip  942 . Distal face  946  is opposed by proximal face  944 . During the process of forming the contact matrix, a number of bubbles  960  in the material of the contact matrix are formed. When the proximal surface is ground or milled away, variously shaped cavities are revealed. Proximal face  944  reveals a number of irregularly shaped surfaces  962  and cavities  964 . When filling matrix is extruded into close contact with proximal contact matrix surface  944  the cured filling matrix is tightly bound to the contact matrix. 
         [0069]    The system is further embodied in a kit comprising the components necessary to utilize the system in day-to-day dental practice. Such a kit would comprise a system utilizable with the typical Tofflemire clamp, while a separate kit would be generally utilizable with the Bitine sectional band system. The kit would contain a series of contact matrix bands of variable sizes; a selection of several sizes of contact matrix proportional to the interproximal contact area affixed to the contact matrix band, a selection of several shapes of interproximal gaps, in combination with the various contact matrix areas; and one or more clamps compatible with the contact matrix bands supplied. Thus, one kit would be expected to have elongated contact matrix bands, and a separate kit would be expected to provide a variety of contact matrix bands in a sectional matrix band conformation. 
         [0070]    As described, the system allows for maintaining or recreating close interproximal contacts between teeth following restoration. The system provides an improved system for use in dental surgery, and in the end produces a previously difficult-to-obtain result for dental patients. 
         [0071]    While the assembly and components thereof has been described with reference to various embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope and essence of the disclosure. Additionally, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure may not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims. In this application the US measurement system is used, unless otherwise expressly indicated. Also, all citations referred to herein are expressly incorporated herein by reference.

Technology Category: 1