Patent Publication Number: US-2005118554-A1

Title: Device and system for separation and matrix retention and adaptation during dental restoration and method for preparing tooth using system

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/725,295 filed Dec. 1, 2003 and entitled DEVICE AND SYSTEM FOR SEPARATION AND MATRIX RETENTION AND ADAPTATION DURING DENTAL RESTORATION AND METHOD FOR PREPARING TOOTH USING SYSTEM, which is incorporated herein by reference in its entirety as if completely set forth herein below. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to a matrix band retention device for separating adjacent teeth and holding a matrix band in proper placement during a dental restoration procedure, a system that includes the device, and a method of preparing a tooth for restoration using the system.  
     BACKGROUND OF THE INVENTION  
      When a patient develops caries in a tooth, the dental practitioner removes the infected portion of the tooth, prepares the tooth for restoration, and then restores the tooth by depositing a filling material into the tooth cavity preparation. To prepare the tooth for the filling, a matrix band is typically placed against the side of the tooth to approximately define the desired shape for the restored tooth, and as a means to prevent overflow of the filling material beyond the tooth boundary. The matrix band typically comprises a flexible metallic or plastic strip that can be bent around the tooth being restored. If the matrix band is not properly adapted to the tooth contour, and if it is not retained properly in place throughout the restoration procedure, then too much or too little filling material may be deposited in the tooth cavity preparation, and the filling material may flow out of the tooth cavity preparation, thereby distorting the configuration of the restored tooth and creating costly finishing and polishing procedures to correct the distorted restoration.  
      To place the matrix band into the desired position, particularly for proximal restorations, it is often necessary to separate the teeth by placing small dental wedges in the interproximal space between the teeth, and while the wedges press the matrix band to the proximal surface of the tooth, they are not effective in pressing the matrix band to the other tooth surfaces where the matrix band bends around the tooth, i.e., to the facial and lingual surfaces close to the line angle. In addition, the wedges are subject to slipping from their position, which causes movement of the matrix band. Matrix band retainers have also been used, with or without additional dental wedges. These conventional matrix band retainers have a generally ring-shaped body with a pair of tines extending perpendicularly downward from the ends of the ring-shaped body such that the tines are adjacent the interproximal space for adapting the ends of the matrix band to the tooth surfaces and retaining the matrix band in that position during the restoration procedure. However, many of these retainers do not provide a firm and complete adaptation of the matrix band and many are subject to slipping out of position. Also, tensioning instruments, such as forceps, are generally used to engage the ends of the ring-shaped body to place the tines in the desired position. While numerous matrix band retainers have been developed, many require a special pair of forceps designed specifically for that matrix band retainer, and many are difficult to manipulate. There is currently no matrix band retaining device or system that is easy to manipulate, that is effective to both separate adjacent teeth and adapt and retain the matrix band in an efficient and reliable manner, and that may be operated using any of the many forceps available on the market.  
     SUMMARY OF THE INVENTION  
      The present invention provides a device that achieves interproximal separation as well as matrix retention and adaptation during a dental restoration. To this end, a body member having a pair of spaced apart ends is provided with a pair of tines that extend downwardly from the ends to be positioned adjacent the interproximal space between the tooth to be restored and an adjacent tooth. A wedge element is integral with each tine and extends inwardly toward the wedge element of the other tine, such that upon placement of the body member in the oral cavity, the wedge elements are capable of being wedged between the adjacent teeth in the interproximal space, thereby achieving separation. Additionally, the wedge elements adapt the matrix band to the proximal surface of the tooth to be restored. A cushion element is positioned about and engageable with each of the tines between the wedge element and the end of the body member. When the body member is placed in the oral cavity, with the wedge elements wedged into the interproximal space, the cushion elements adapt the ends of the matrix band to the tooth contour, i.e., from the proximal tooth surface to the facial and lingual tooth surfaces and retain the band in place softly, yet firmly, such that the matrix band is held in a stable position throughout the restoration procedure. In an exemplary embodiment, the device includes U-shaped grooves formed in the top surface of the ends of the body member and extending downwardly into the tines in general alignment with the wedge elements. The grooves are compatible with numerous available tensioning instruments, and upon manipulation of the body member, torque is avoided during placement of the device in the oral cavity, thereby making the device easy to use and manipulate.  
      The present invention further provides a system for separation and matrix band retention for use during a dental restoration, the system including at least one matrix band, a matrix retention device having the body member with tines and inwardly extending wedge elements, and at least one pair of cushion elements for positioning on the tines of the retention device. The present invention further provides a method for preparing a tooth for a restoration, the method including providing a device having the body member with tines and inwardly extending wedges, and having the cushion elements placed on the tines, then placing a matrix band in the interproximal space between the tooth to be restored and an adjacent tooth. The tines of a tensioning instrument are then inserted into the grooves of the retention device and the tensioning instrument is manipulated to push the spaced apart ends further apart. When the body member is positioned in an appropriate place in the oral cavity, the tensioning instrument is released to bring the spaced apart ends back toward each other to insert the wedge elements into the interproximal space between the matrix band and the adjacent tooth to press the matrix band to the proximal surface of the tooth to be restored, and also to press the cushion elements against the ends of the matrix band to adapt them around the tooth toward and against the facial and lingual surfaces. In another exemplary embodiment, the cushion elements comprise a microporous plastic that is capable of absorbing fluids around the tooth to be restored, and the cushion elements are removable and replaceable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.  
       FIG. 1  is a perspective view of a portion of an oral cavity including a tooth to be restored and an adjacent tooth.  
       FIG. 2  is a perspective view of a portion of the oral cavity of  FIG. 1  depicting placement of a matrix band.  
       FIG. 3  is a perspective view of a device of the present invention.  
       FIG. 4  is a perspective view of the device of the present invention depicted in  FIG. 3  being manipulated by a tensioning instrument.  
       FIG. 5  is a perspective view depicting placement of the device of  FIG. 3  in the oral cavity of  FIG. 2 .  
       FIG. 6  is a top view depicting the device of  FIG. 3  placed in the oral cavity of  FIG. 2  after release by the tensioning instrument and prior to restoring the tooth to be treated.  
       FIG. 7  is a top view depicting the retention of the matrix band by the device of  FIG. 3  during restoration of the tooth.  
       FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 6  depicting the intended placement for the device of the present invention in the oral cavity.  
       FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 7  depicting the placement of the device of the present invention in the oral cavity.  
       FIG. 10  is a cross-sectional view depicting removal of the matrix band after restoration of the tooth.  
       FIG. 11  is a perspective view of an alternative embodiment of the device of the present invention.  
       FIG. 11A  is a perspective view of an alternative embodiment of a cushion element for the device of the present invention.  
       FIG. 12  is a top view of the alternative embodiment of the device shown in  FIG. 11  in the oral cavity.  
       FIG. 13  is a side view the device of the present invention depicted in  FIG. 3 .  
       FIG. 14  is a side view of an alternative embodiment of a device of the present invention.  
       FIG. 15  is a side view of another alternative embodiment of a device of the present invention. 
    
    
     DETAILED DESCRIPTION  
      The present invention provides a separation and matrix band retention device that is simultaneously effective to both separate a tooth to be restored from its adjacent tooth and to adapt and retain a matrix band against the tooth contour throughout the restoration procedure in a manner that is comfortable to the patient and yet firm so as to prevent slipping of the device and the matrix band during the procedure. The device of the present invention is easy to manipulate and may be used with many of the currently available tensioning instruments on the market. The present invention further provides a system that includes the device, as well as a method of preparing a tooth to be restored utilizing the system. The present invention may be best understood with reference to the drawings, in which like numerals are used to refer to like parts throughout.  
       FIG. 1  depicts in perspective view a relevant portion of an oral cavity  10  that includes adjacent teeth  12  and  14 , specifically tooth to be restored  12  and its adjacent tooth  14 . The tooth to be restored  12  has been prepared by removing infected material to thereby create a cavity, or small hole, to be filled with restorative material (not shown). As shown, the prepared cavity to be filled  16  is located so as to be exposed to the interproximal space  18  between tooth  12  and adjacent tooth  14 . The prepared cavity shown may also be referred to as a proximal box. The tooth to be restored  12  includes a proximal surface  20  facing the interproximal space  18 , a facial surface  22  and a lingual surface  24 . Facial surface  22  may be a buccal surface, which refers to a tooth surface that faces the cheek, and thus this term is used in reference to posterior teeth, i.e., the teeth in the back of the mouth. Tooth  12  in  FIG. 1  is a molar, which is a posterior tooth, and thus, facial surface  22  is a buccal surface. Similarly, the facial surface  22  may be a labial surface (not shown), which refers to a tooth surface that faces the lip, and thus this term is used in reference to anterior teeth, i.e., the teeth in the front of the mouth. The lingual surface  24  refers to a tooth surface that faces the tongue  11 , and thus this term is used in reference to both anterior and posterior teeth. It may therefore be understood that although the figures are depicting a mesial proximal surface restoration on the second molar, the present invention is applicable to restorations for any tooth surface, and in particular, any proximal surface, for any tooth in the mouth.  
       FIG. 1  further depicts a matrix band  20 , which typically comprises a flexible metallic or plastic strip, that is used to form a tooth boundary where a portion of a tooth surface has been removed during removal of the infected portion of the tooth  12 . Thus, as indicated by the arrow in  FIG. 1 , matrix band  30  is intended to be placed in the interproximal space  18  to form a boundary at the proximal surface  20  to close off the prepared cavity  16 . After filling the prepared cavity  16  with a restorative material, the proximal surface  20  of tooth  12  will be restored, such that the matrix band  30  can then be removed. In order for the tooth boundary to be properly restored, it is important that the matrix band  30  be held firmly in place in the interproximal space  18  against the tooth contour without slipping therefrom to ensure that the restored boundary is not distorted.  
       FIG. 2  further depicts the relevant portion of the oral cavity  10  of  FIG. 1  with the matrix band  30  inserted into the interproximal space  18 . The majority of the matrix band  30  resides in the interproximal space  18 , but end  32  extends outwardly from the interproximal space  18  in the facial, i.e., buccal/labial, direction and end  34  extends outwardly from the interproximal space  18  in the lingual direction. As shown in  FIG. 2 , matrix band  30  is not firmly retained against the proximal surface  20  such that a distorted restoration would likely result. Advantageously, the ends  32 ,  34  should be wrapped around the tooth contour such that end  32  is adapted toward and against the facial surface  22  of the tooth to be restored  12  and end  34  is adapted toward and against the lingual surface  24  of tooth  12 . When adapted to surround the tooth contour in a manner that presses the matrix band  30  firmly against the proximal surface  20 , facial surface  22  and lingual surface  24 , a properly shaped restoration may be achieved.  
       FIG. 3  depicts in perspective view a device  40  of the present invention suitable for use in adapting and retaining matrix band  30  around and against the tooth to be restored  12 . Device  40  also simultaneously achieves separation between the tooth to be restored  12  and adjacent tooth  14 . Device  40  has a body member  42  terminating in a pair of spaced part ends  44 ,  46 . Advantageously, body member  42  is flexible and generally ring-shaped, as depicted. However, the present invention contemplates non-ring-shaped body members as well as non-flexible body members. While the ring-shape is shown as generally circular, it may be understood that a more square or rectangular ring-shape would also be suitable. In one embodiment, the body member  42  is made of plastic material or metal or any other suitable material that has sufficient flexibility to allow the body member  42  to be manipulated, such as by forceps or other tensioning instrument  50 , so as to spread the spaced apart ends  44 ,  46  further apart, as indicated by the arrows, to allow placement of the device  40  in the oral cavity  10  of  FIG. 2 . Exemplary materials include polyetheretherketone, polyetherimide, polyphenylsulfone and carbon fiber-reinforced polyetheretherketone. In another embodiment, the body member  42  is a flexible metal or long fiber-reinforced flexible plastic, in order to reduce the dimensions of the body member and to be less cumbersome, while the spaced apart ends  44 ,  46  are made of a different and/or rigid plastic material. Upon release of device  40  by the tensioning instrument  50 , the flexibility of the body member  42  will result in the spaced apart ends  44 ,  46  returning to their original spaced apart position, thereby tightening the body member  42 . Thus, as shown in  FIG. 3 , when not manipulated by the tensioning instrument, spaced apart ends  44 ,  46  are in a first position that is a tightened resting position.  
      Extending downwardly from the spaced apart ends  44 ,  46  are a pair of tines  60 ,  62 . The tines  60 ,  62  may extend perpendicularly from the body member  42  or may be angled, as desired. The tines  60 ,  62  are integral with the body member  42 , including a single-piece construction or mechanical attachment, such as screws or an adhesive bond. The tines  60 ,  62  may be the same or a different material than the body member  42 . For example, body member  42  may be made of a flexible metal or long fiber-reinforced flexible plastic, while the spaced apart ends  44 ,  46  and tines  60 ,  62  are made of a different and/or rigid plastic material. In one embodiment, the spaced apart ends  44 ,  46  and tines  60 ,  62  are of single-piece construction and made from a rigid plastic material, and are mechanically or adhesively attached to body member  42 , which comprises a flexible material. Extending inwardly from the tines  60 ,  62  are a pair of wedge elements  64 ,  66 . The wedge elements  64 ,  66  are integral with the tines  60 ,  62 , and as a result, the use of separate wedges is eliminated. The separate wedges of the prior art were subject to slipping out of place, whereas the integral wedge elements  64 ,  66  of the present invention are not subject to slippage. Again, the term “integral” contemplates single-piece construction or mechanical attachment, though single-piece construction is preferred due to the stress placed upon the elements that could cause failure in a mechanical bond, such as an adhesive bond. Thus, in one embodiment, the spaced apart ends  44 ,  46 , the tines  60 ,  62 , and the wedge elements  64 ,  66  are of single-piece construction and made from a rigid plastic material, and are mechanically or adhesively attached to body member  42 , which comprises a flexible material.  
      In one embodiment, shown most clearly in side view in  FIG. 13 , the center axis of wedge element  64  lies in the same plane and is coaxial with the center axis of wedge element  66 . These wedge elements  64 ,  66  are adapted to be wedged between, and thereby separate, the tooth to be restored  12  and adjacent tooth  14 . In another embodiment, when the spaced apart ends  44 ,  46  are in the first position, the respective tips  65 ,  67  of wedge elements  64 ,  66  are in contact or near contact.  
      In another embodiment, depicted in side view in  FIG. 14 , wedge elements  64 ′,  66 ′ of device  40 ′ each include a concave cut  68  on their underside, i.e., on the bottom surface that faces or contacts the gums. The concave cuts  68  extend from adjacent the respective tines  60 ,  62  to the respective tips  65 ,  67 . The concave cuts  68  allow better universal proximal access. In other words, the concave cuts better approximate the shape of the gumline to allow the device  40 ′ to be placed adjacent the gumline with the wedge elements  64 ′,  66 ′ being placed to the side of the gums and extending over the gums to meet between the tooth to be restored  12  and adjacent tooth  14 .  
      In yet another embodiment, depicted in side view in  FIG. 15 , wedge elements  64 ″,  66 ″ of device  40 ″ are slanted such that the center axis of wedge element  64 ″ does not lie in the same plane with the center axis of wedge element  66 ″, but rather, are angled downward, i.e., toward the gumline, from the horizontal plane H. Horizontal plane H is parallel to the plane of the gumline. In one embodiment, the center axis of each wedge element  64 ″,  66 ″ is angled downward at an angle α of 2-25°. In another embodiment, the center axis of each wedge element  64 ″,  66 ″ is angled downward at an angle α of 2-150°. The downward orientation of the wedges  64 ″,  66 ″ enables the device  40 ″ to be positioned above the gumline, with the wedges  64 ″,  66 ″ extending toward the gumline.  
      Device  40  further includes a pair of cushion elements  70 ,  72  positioned about and engageable with tines  60 ,  62 , respectively. Cushion element  70  is positioned on tine  60  between the spaced apart end  44  and the wedge element  64 . Similarly, cushion element  72  is positioned on tine  62  between spaced apart end  46  and wedge element  66 . Cushion elements  70  and  72  each have an outer surface  70   a ,  72   a,  respectively, and in inner surface  70   b,    72   b,  respectively. Inner surfaces  70   b ,  72   b  engage the outer surfaces  61 ,  63  of tines  60 ,  62 , respectively. The outer surfaces  70   a,    72   a  of cushion elements  70 ,  72  will engage the ends  32 ,  34 , respectively, of matrix band  30  upon placement of the device  40  in the oral cavity  10 . Advantageously, the outer surfaces  70   a,    72   a  of the cushion elements  70 ,  72  are such that a portion of each cushion element extends over its respective wedge element  64 ,  66  one-third to two-thirds the length of the wedge element  64 ,  66 , wherein the length is defined as the distance from the outer surface  61 ,  63 , respectively, of the tines  60 ,  62  to the respective tip  65 ,  67 . As shown in  FIG. 3 , the cushion elements  70 ,  72  are generally ring-shaped for engagement with cylindrically-shaped tines  60 ,  62 .  
      In an exemplary embodiment of the present invention, the cushion elements  70 ,  72  comprise a microporous plastic that has the mechanical stiffness necessary for adapting the ends  32 ,  34  of the matrix band  30  as well as elasticity to provide a soft cushion that is gentle to soft tissue, yet firm enough to hold the matrix band against the tooth contour. The microporous plastic may be high density polyethylene, polytetrafluoroethylene, ultra-high molecular weight polyethylene, nylon-6, polypropylene, polyvinylidene fluoride, polyethersulfone, and combinations thereof. The Porex Porous Products Group, Fairburn, Ga., offers a line of commercially available porous plastics suitable for the cushion elements  70 ,  72  in the device  40  of the present invention. The microporous plastic may also be a foamed polyurethane elastomer, such as that provided by GTK Timex Group SA, Rivera, Switzerland. The cushion elements  70 ,  72  may also comprise a silicone or thermoplastic elastomer having a Shore A hardness in the range of about 20-60. Advantageously, the cushion elements  70 ,  72 , for example, the microporous plastic, are capable of fluid absorption in the oral cavity, such that the cushion elements  70 ,  72  will absorb saliva and/or blood during the restoration procedure. The foamed polyurethane elastomer from GTK Timex Group SA, for example, has a 300-400% water absorption capability with a 25% volume expansion. The cushion elements  70 ,  72  may also be removable and replaceable, such that device  40  may be used for multiple patients with the cushion elements  70 ,  72  being replaced for each patient.  
      The vast majority of the force acting on the tines  60 ,  62  is distributed to the wedge elements  64 ,  66 , with a much smaller force being distributed to the cushion elements  70 ,  72 . Thus, advantageously, the wedge elements  64 ,  66  have a significantly higher stiffness than the cushion elements  70 ,  72 . For example, the resiliency ratio of the wedge elements to the cushion elements may be on the order of 1:100 to 1:1000.  
      In an exemplary embodiment of the present invention, device  40  includes a pair of open grooves  76 ,  78  formed in spaced apart ends  44 ,  46 , respectively. Advantageously, the open grooves  76 ,  78  may be V-shaped or U-shaped. The V- or U-shaped open grooves  76 ,  78  are formed from the top surfaces  45 ,  47  of the spaced apart ends  44 ,  46  extending downwardly into the tines  60 ,  62 . The V- or U-shaped grooves are positioned to open inwardly at the outer surfaces  61 ,  63  of tines  60 ,  62  in opposition to one another, and are advantageously in alignment with wedge elements  64 ,  66 . When the open grooves  76 ,  78  are in alignment with the wedge elements  64 ,  66 , torque between the cushion elements  70 ,  72  and the wedge elements  64 ,  66  is reduced during manipulation of the body member  42  by a tensioning instrument  50 , thereby providing more stability to the device during its insertion into the oral cavity  10 . The open grooves are adapted to receive a pair of tines  52 ,  54  of a tensioning instrument  50  to permit manipulation of the body member  42 . By virtue of being an inwardly open V- or U-shape, the grooves  76 ,  78  are compatible with numerous different tensioning instruments  50  currently available on the market, thereby eliminating the need for a specially designed tensioning instrument.  
       FIG. 4  depicts in perspective view the manipulation of device  40  by tensioning instrument  50 . After placement of tines  52 ,  54  of tensioning instrument  50  into respective V- or U-shaped open grooves  76 ,  78 , the spaced apart ends  44 ,  46  are pushed further apart, as indicated by the arrows, to a second spaced position greater than the first position, such that the tips  65 ,  67  of respective wedge elements  64 ,  66  are not in contact or near contact. The second spaced apart position depicted in  FIG. 4  is an unnatural position for the body member  42 , such that upon release of the tensioning instrument  50 , the body member  42  and spaced apart ends  44 ,  46  will tend to return to or toward the first position depicted in  FIG. 3 .  
       FIG. 5  depicts in perspective view the placement of the device  40  in the oral cavity  10  by tensioning instrument  50 .  FIG. 6  depicts in top view the position of the device  40  in the oral cavity after the tensioning instrument is released. With the spaced apart ends  44 ,  46  in the second position, the device  40  may be inserted into the oral cavity  10  so as to place the tines  60 ,  62  of device  40  adjacent respective opposing sides of the interproximal space  18 . Tine  44 , wedge  64  and cushion element  70  are positioned adjacent the facial surface  22  of the tooth  12  to be restored with wedge element  64  in alignment with the interproximal space  18  and cushion element  70  contacting end  32  of matrix band  30  to push it toward the facial surface  22 . Similarly, tine  62 , wedge element  66  and cushion element  72  are positioned adjacent lingual surface  24  with wedge element  66  in alignment with the interproximal space  18  and cushion element  72  in contact with end  34  to push it toward the lingual surface  24 . The flexibility of cushion elements  70 ,  72  allow them to adapt to the tooth contour, thereby causing the matrix band  30  to adapt to the tooth contour. Simultaneously, the integral wedge elements  64 ,  66  separate the tooth to be prepared  12  and adjacent tooth  14  and hold the matrix band  30  in place at the proximal surface  20  of tooth  12 . When the tensioning instrument  50  is released from the device  40 , the spaced apart ends  44 ,  46  are naturally urged inward toward the first resting position, as indicated by the arrows in  FIG. 5 , thereby firmly pressing the wedge elements  64 ,  66  into the interproximal space  18  and the cushion elements  70 ,  72  against the ends  32 ,  34  of matrix band  30  to press them against the tooth contour. The cushion element  70 ,  72  likewise press against the tooth contour of adjacent tooth  14 , providing a very stable retention of the device  40  and matrix band  30  in position throughout the restoration procedure.  
       FIG. 7  depicts in top view a portion of device  40  placed in a portion of oral cavity  10  following filling of the prepared cavity  16  with a restorative material  80 . The restorative material  80  is confined by the matrix band  30 , which is held firmly in place by device  40 .  
      While the figures depict a flexible, generally ring-shaped body member  42 , it may be understood that the device  40  of the present invention is not so limited. A non-flexible body member could be utilized that is manipulated by other means to move the spaced apart end  44 ,  46  toward or away from each other. For example, a screw-adjusted clamp-type body member could be used. Therefore, while a flexible, generally ring-shaped body member is exemplary and is indicative of the current trend in matrix retention devices, the present invention should not be limited regarding the shape or flexibility of the body member.  
       FIGS. 8-9  further depict in cross-section the method of the present invention. The cross-section of  FIG. 8  is taken along line  8 - 8  of  FIG. 6 , but with the device  40  not yet positioned. As shown in  FIG. 8 , a matrix band  30  is placed in the interproximal space  18  between the proximal surface  20  of the tooth to be restored  12  and an adjacent tooth  14 . The retention device  40  is placed in the oral cavity  10  such that tine  62  and wedge element  66  are generally aligned with the interproximal space  18 , as shown generally by the phantom line, and are placed adjacent the lingual surface  24  of tooth  12 . The cross-section of  FIG. 9  is taken along line  9 - 9  of  FIG. 7 .  FIG. 9  depicts the proper placement of the device  40  in the oral cavity  10  after removal of the tensioning instrument  50  as cavity  16  is being filled with restorative material  80 . Wedge element  66  is wedged in the interproximal space  18  adjacent the gums  82  of the patient. The wedge element  66  is also pressing the matrix band  30  against the proximal surface  20  of tooth  12  while achieving and maintaining separation between tooth  12  and adjacent tooth  14 . Above wedge element  66  is the cushion element  72 , which is pressing end  34  of matrix band  30  against the lingual surface  24  of tooth  12 .  
       FIG. 10  depicts removal of the matrix band  30  leaving the restored tooth  12 ′ that includes a restoration  80 ′ that accurately defines the tooth boundary at the proximal surface  20 .  
       FIGS. 11, 11A  and  12  depict in perspective views and top view, respectively, alternative embodiments of the present invention.  FIGS. 3-9  depicted ring-shaped cushion elements  70 ,  72 . However, the shape of the cushion elements is not so limited. Device  40  may include cushion elements  70 ′,  72 ′ that are anatomically shaped, for example, as shown in  FIGS. 11 and 12 . Cushion elements  70 ′,  72 ′ each include a wedge-shaped portion  71 ,  73 , respectively, that extends at least partially over its respective wedge element  64 ,  66 . Advantageously, the wedge-shaped portions  71 ,  73  extend about one-third to about two-thirds the length of the respective wedge element  64 ,  66 . These wedge-shaped portions  71 ,  73  are shaped so as to enter the interproximal space  18 , as depicted in  FIG. 12 . As a result, the outer surfaces  70   a ′,  72   a ′ at the wedge-shaped portions  71 ,  73  further adapt the matrix band  30  to the proximal surface  20  and the ends  32 ,  34  of the matrix band  30  around the tooth contour toward the facial surface  22  and the lingual surface  24 , respectively. Thus, the outer surfaces of the cushion elements may be of any shape desired that is effective in adapting the matrix band to the tooth contour and retaining it firmly in place. Similarly, the inner surfaces of the cushion elements and the outer surfaces of the tines may have any desired shape whereby the cushion elements may be positioned around the tines and in engagement therewith so as to provide a stable arrangement.  
       FIG. 11  further depicts a positioning hub  90  at the inner surface  70   b ′ of cushion element  70 ′. A positioning groove  92  is formed at the outer surface  61  of tine  60  and is configured to receive the positioning hub  90  to properly position and stabilize cushion element  70 ′ on tine  60 . In one exemplary embodiment, the positioning groove  92  is opposite the U-shaped groove element  76 , as depicted in  FIG. 11 . In another exemplary embodiment (not shown), the positioning groove is coaxial with the U-shaped groove element  76  and, optionally, the two grooves  76 ,  92  may form a single groove adapted to receive the tine  52  and the positioning hub  90 . Cushion elements  70 ,  72  and/or  72 ′ may each be provided with a positioning hub  90  that mates with a positioning groove  92 .  
       FIG. 11A  also depicts an anatomically-shaped cushion element  70 ″ to be positioned about and engageable with tine  60 . However, cushion element  70 ″ does not completely surround tine  60 , but rather, only partially surrounds tine  60 . Cushion element  70 ″ includes a pair of positioning hubs  94 ,  96  adapted to mate with positioning groove  92  and thereby secure the cushion element  70 ″ to the tine  60 . Thus, while the cushion elements  70 ,  72 ,  70 ′,  72 ′ are advantageously positioned completely about the tines  60 ,  62 , the present invention further contemplates cushion elements  70 ″ positioned partially about the tines  60 ,  62 . Moreover, though not shown, plural positioning grooves, holes or detents may be provided at the outer surfaces  61 ,  63  of tines  60 ,  62  to receive mating positioning hubs on the inner surfaces  70   b ,  72   b ,  70   b ′,  70   b ″ of cushion elements  70 ,  72 ,  70 ′,  72 ′,  70 ″, or vice versa.  
      Thus, the present invention includes a device  40  having an integral wedge element and a cushioning element for simultaneously separating a tooth to be restored and its adjacent tooth, and adapting and retaining a matrix band to the contour of the tooth to be restored. The present invention further provides a system for separation and matrix retention and adaptation that includes at least one flexible matrix band and the device of the present invention, with at least one pair of cushion elements. The system may further include additional pairs of cushion elements, such that the cushion elements are removable and replaceable after each patient. The system may also further include a tensioning instrument for manipulating the device. Finally, the present invention also includes a method of preparing a tooth to be restored, the method including providing the device of the present invention, inserting a matrix band into an interproximal space adjacent a tooth to be restored, manipulating the device of the present invention with a tensioning instrument to place the device in the oral cavity and then releasing the tensioning instrument to position the device in a manner that separates the tooth to be restored from its adjacent tooth and adapts and retains the matrix band to the tooth to be restored.  
      While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative device, system and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept.