Abstract:
A lingual dental matrix tensioner comprising two posts maintained parallel by two parallel rods through the posts at a right angle to the post axes One rod is threaded and has an end knob for adjusting the spacing between the posts, the other rod is a guide rod. Both ends of a matrix band are clamped to one post and the doubled matrix is guided through one of several slots in the other to form a retainer loop at any location. Rotating the threaded rod to separate the posts reduces the size of the loop.

Description:
BRIEF SUMMARY OF THE INVENTION 
     This invention relates to dental tools and particularly to a matrix band holder and tensioner that is used from a position on the lingual side of the teeth. 
     The matrix tensioners have been used by dentists for many years for encircling and tightening a very thin metal matrix band around teeth in preparation for tooth filling procedures. These matrix tensioners are small devices that rests of the labial side of the teeth and which clamp the ends of a matrix band to form a loop which may be tightened to form a metal retainer around a tooth so that the dentist can compress filling material into the tooth. 
     Heretofore, matrix tensioners have been applied on and labial side of the tooth between the gums and the lips so that, when working with the rear molars, the dentist&#39;s working space was restricted and the patient suffered discomfort. The matrix tensioner to be described is designed for retaining on the lingual side of the teeth, thus providing the dentist with ample working space and causing less discomfort for the patient. 
     Briefly described the lingual matrix tensioner includes two parallel, spaced posts, each less than one centimeter in diameter and about two centimeters in length. Both ends of a metal matrix band are clamped to one of the posts and the doubled matrix passes through various slots in the lower third of each post so that a matrix loop is produced at various locations at the other post. The spacing between the two posts is adjusted by a rotatable rod which is anchored to one post and threaded through the other so that rotation of the rod causes separation of two posts and a reduction in the size of the matrix loop. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate a preferred embodiment of the dental matrix tensioner 
     FIG. 1 is a side elevational view of the tensioner with matrix installed; 
     FIG. 2 is a bottom plan view thereof; 
     FIG. 3 is a sectional side elevational view thereof; 
     FIGS. 4 and 5 are bottom plan views thereof showing the matrix being tightened around a tooth shown by broken lines; and 
     FIG. 6 is a sectional side elevational view of the tensioner showing is being tightened around a tooth shown by broken lines. 
    
    
     DETAILED DESCRIPTION 
     A matrix is a tissue-thin stainless steel band that tightened around a tooth or group of teeth so that the dentist can compress material into the tooth without it squeezing out. There are numerous types of matrix holders or matrix tensioners that tighten a matrix band around a tooth but these are labial matrix holders designed to be operated from the front of the jaw where they become a working obstacle for the dentist. The matrix holder of the invention is a lingual matrix holder or tensioner so that, in its position behind the teeth, it is out of the dentist&#39;s way and is not a working obstacle. 
     FIG. 1 is a side elevational view of the lingual matrix tensioner  10  which comprises two identical parallel posts  12 ,  14  radially connected by two parallel rods at a right angle through the diameters of the posts: a guide rod  16  having one end anchored in post  12  and slideable through post  14 , and a threaded rod  18  having one end rotatably anchored in post  12  and threaded through threads in post  14 . A knurled handle  20  is on the end of the threaded rod  18  opposite the post  12 . 
     The posts are preferable solid stainless steel cylinders approximately one inch long and ¼ inch in diameter. The guide rod  16  is approximately centered and the threaded rod  18  is near the top of the posts. Approximately one third up from the bottom of each post  12 ,  14  is slotted for the passage of a double thickness of the matrix band  22  which is formed into a loop that passes through selected slots in the bottom of the posts and has its free ends attached to the post  12  by a locking screw  24  as shown in FIG.  1 . 
     FIG. 2 is a bottom plan view of the tensioner showing the slot detail in the bottom of each post  12 ,  14 . The locking screw  24  is threaded into the post  12  near the bottom surface and on an axis parallel with the axis of the adjustment screw  18  and guide rod  16 . The screw  24  is threaded into a hole that is drilled and tapped through the post at a point approximately half way between the bottom surface of the post and the top of the slots cut in the post for the passage of the matrix band. The slot  26  in the bottom of the post  12  is in the form of a “V”. The locking screw  24  is positioned midway between the legs of the “V” with its end in the apex of the “V”, clamping the matrix band. The width of each leg of the V slot must be adequate to pass two thicknesses of the matrix band. 
     The bottom of post  14  is also slotted but with an axial cross, the first leg  28  of which is on an axis parallel with the adjustment screw  18 , the second leg  29  being transverse at a right angle to the first leg  28 . The width of both legs  28 ,  29  of the slot must be adequate to easily pass a double thickness of the matrix band. It is recommended that the interior intersection of the legs  29 ,  29  are rounded, as shown, to further reduce friction as the matrix is being tightened if the dentist elects to guide the matrix band through both the first leg  28  and the transverse leg  29 . 
     FIG. 3 is a sectional elevational view of the matrix tensioner  10  showing the construction of the preferred embodiment. The two posts  12 ,  14  which may be solid cylinders have the slots  26 ,  28 ,  29  and the locking screw  24  in the approximate lower third, the guide rod  16  through the diameter of the posts at the center, and the adjustment screw  18  through the diameter of the posts as near as possible to the top surface. The matrix is at the lowest part of the tensioner  10  and the guide rod  16 , located above the matrix, must be sufficiently above the matrix so it will not contact the top surface of the teeth. Therefore the length of the posts from their bottom ends to the guide rod  16  must be greater than the length of the patient&#39;s teeth. 
     The guide rod  16  is tightly attached in hole  30  through the post  12  and is slideably engaged in hole  32  through the post  14  so that post  14  may be moved toward and away from post  12 . The adjustment screw  18  has a hub  34  within the post  12  which is locked against all lateral movement but which permits rotational movement of the screw by the strong washers  36 ,  38  that screw or are tightly pressed into the post  12 . 
     To use the matrix tensioner, the dentist first rotates the adjustment screw  18  to bring the post  14  close to the post  12 . The matrix band material is doubled and may be passed through the desired half of the transverse slot  29 , then turning the band into the slot  28  on the bottom of the post  14  and the free ends are passed through a convenient leg of the V slot  26  on the bottom of post  12  and attached to the post by the locking screw  24 . Alternatively, if it is too difficult to pass the doubled matrix band through half of the transverse slot  29  and then turn it and pass it through the half of slot  28 , it may be passed completely through a transverse slot  28  and then passed into the “V” slot  26  in the bottom of post  12 , as shown. The large loop in the matrix band produced from the slot  28  in the post  14  encircles a tooth and the adjustment screw  18  is then rotated to separate the two posts  12 ,  14  whereby the loop diameter is reduced to tighten the matrix around the tooth. 
     FIGS. 4 and 5 are bottom plan views of the matrix tensioner positioned adjacent teeth, such as molars. FIG. 4 illustrates the matrix tensioner  10  retaining a tooth on one side of the jaw and FIG. 5 illustrates the tensioner  10  retaining an adjacent tooth on the opposite side of the jaw. When the post  14  is positioned close to the post  12 , the matrix band is loose and can easily be slipped over a tooth. After the dentist had encircled the tooth with the matrix band the adjustment screw is rotated to separate the post  14  from the post  12  thereby tightening the matrix around the tooth thus permitting the dentist to proceed. 
     FIG. 6 is an elevational view showing the use of the matrix tensioner retaining an “in-line” tooth. 
     Thus the matrix tensioner is very versatile and is able to apply a matrix to nearly every tooth with little movement of the tensioner. It is easily adjustable extra-orally and its position on the lingual side of the tooth won&#39;t interfere with the dentist&#39;s procedure. Furthermore, the tensioner is easy to sterilize and is safe for use by both the dentist and patient