US2790238A - Dental matrix - Google Patents

Description

April 30, 1957 F. M. TRANGMAR DENTAL MATRIX Filed Sept. 10, 1954' United States Paten fi This invention relates to a dental matrix, and more particularly to a preformed malleable matrix which can be readily applied to a tooth without the use'of special tools, kept in place for an extended period of time without discomfort to the patient, and easily removed after it has served its purpose.

The matrix of this invention is of the same general type as the dental matrix covered by United States Letters Patent No. 2,674,801 issued to me on April "13, 1954.

The matrix covered by that patent is primarily adapted for use as a mold in connection with the making of wax impressions for gold inlay work on teeth of the bicuspid or molar type. Although useful in the application of amalgam, porcelain and other similar dental fillings, it is not primarily designed for that purpose since the thickness of the band of which the matrix is formed is in most cases too great for interproximal work with those types of fillings. In making gold inlay patterns, contact points may be soldered on the gold inlay casting to make up for the thickness of the matrix which was used for making the impression. However, this may not be done in the case of amalgam, porcelain or plastic fillings because in these cases extra material can not be added in this way.

The matrix of my present invention is formed in such a way that the portions of the band which must be inserted between the tooth being worked upon the adjacent teeth are of very slight thickness. As a result, it is relatively easy to push the matrix between contact. points of the tooth with the adjacent teeth, even when the contact is tight. Thus when the matrix is removed a large space is not left at the contact points, which would permit food to pack between the teeth and create an undesirable gum condition and perhaps also produce or accelerate tooth decay in nearby areas. v

It is obvious that the matrix of this invention, producing a negligible spread, if any, between the contact points of adjacent teeth, will result in much greater comfort on the part of the patient, both during the filling operation and during the hardening period, because it has no protruding parts to give the patient an awkward or uncomfortable feeling by reason of the presence of the matrix in his mouth.

The matrix commonly used for forming and hardening amalgam, porcelain and plastic fillings is comprised of a steel strip and a combination tightening and holding tool. In order to keep the steel strip tightly in place while the filling hardens, the dentist must stand at the chair and keep tension on the steel strip with the matrix holder. It is obvious that this is awkard and uncomfortable for both the patient and the dentist. In fact, it simply is not feasible to attempt to keep the matrix in place for more than 15 or 20 minutes at the outside. Usually the time is even shorter. 7 Unfortunately, this is not long enough to produce a truly reliable hardening of the dental filling. Depending 7 upon all the circumstances, final hardening of thefilling may not occur for many hours after the filli'rig put in tooth.

With the matrix of this invention, the dentist need not spend any time at all holding the matrix with a cumbersome matrix holder while the, filling is inserted and hardens in the patients tooth. In effect, the matrix of this invention contains 'within itself its own 'matrix holder.

Thus the annoyance, discomfort and fatigue caused both the dentist and patientby use of the conventional matrix holder described above are avoided. In addition, there. is vvirtually no limit to the period of time the matrixmay be leftin place while the fillin g hardens. Moreovenboth the dentists hands are free for working on the tooth; for example, itpermits easy insertion of a wedge or separator if desired, at either interproximal surface of the tooth. Y 4 I The overall result with the use of the matrix of the present invention is an improved amalgam, porcelain or. plastic filling operation carried outfaster, more eflicient ly, painlessly, and more reliably. The matrix may be. used not only with molar andbicuspid teeth, but also cuspids and lateral and central incisors.

,In, the accompanying drawing several embodiments of this invention have been shown. In these drawings:

Figure'l is a perspective view of one embodiment of the matrix of this invention;

Figure 2 is an end elevation of the matrix shown in Figure 1;

Figure 3 is a perspective view of a jaw fragment showing the embodiment of Figures 1. and 2 being applied to a molar having a mesial-occlusal-distal cavity therein;

Figure 4 shows. theembodiment of Figure 3 'installed'in place about the tooth;

Figures 5 and 6 ar'ejplan views of other embodiments of this invention; v

Figure 7 is a plan view of a flattened tubular blank from which another embodiment of this invention may be formed;

Figure 8 is a plan view of another embodiment of'the matrix of this invention; and

Figure 9 is a perspective view of a. series of units of the dental matrix ;of this invention fabricated for convenient storage and availability for use. i I

Embodiment formed A of two materials.Figure 1 shows an embodiment of the matrix of this invention which is formed of two difierent materials. One of the materials. is very thin and has relatively high tensile strength. The other is thicker and has sufficient malleability that it may be permanently deformed upon being first pinched. when the matrix is tightened snugly about the tooth as shown in Figure 3, and then folded over as shown, for example, in Figure 4.

Matrix 10 includes stainless steel band 11, which is about 0.0015 or v0.00.2 inch thick and extends throughout about /a'of the perimeter of the matrix. The remainder 12 of the matrix is formed of copper having a thickness of about 0.005 inch. The two strips'may be soldered or brazed together or otherwise securely attached at areas 13.

Thicker portion may be provided with horizontal slit 14, as shown in Figure 1; This permits a double folding of thicker portion 12, if. desired, as in the installed matrix shown in Figure 4. 1 r v Tubular band 11 generally has a height somewhat largerthan-that 'of .the exposed portion. of the tooth with' whichit 'is to.bef=u's'ed. This permits the band to cover the exposed'portion of'thetooth-and to extend above it so as to provide a surface entirely "adequate to deedestrians-3. 57..

thicknessofthinportions 'tive embodiments shownirsfabout 0.002 inch :This di-f' mension will produce a negligible spread, if -any,-between the tooth being filled and adjacent teeth. At thesarne tion 12 to be pinched by pliers and folded over against itself.

Because of the thickness and malleability of portion 12 of the band, this portion may be forced .open by the dentist if necessary when the blank is -being distended before application to the tooth to be filled, without danger of weakening or breaking the metal strip at the bend. Likewise, the thickened portion may be again pinched together with safety when the matrix is being fitted snugly around the tooth as shown in Figure 3.

Thicker portion 12 may be characterized as being permanently deformable because it is so for all practical purposes and for all forces likely to be applied. which tend to open the band up after it has been folded ,over against itself, except a deliberate opening by the dentist or. patient to remove theband after its purpose has been served. "The terms permanently deformable and permanently deformed are used in this sense throughout this specification and in the claims. Figure 2 gives a view of the matrix of Figure 1 from the righthand side of the latter. figure, and shows the further features of boiled sides 15 and downwardly extending lips 16 which will be discussed in 'more detail below. i

Figure 5 gives a plan view of another embodiment of the matrix of this invention in which stainless steel band 11 is a thin cylindrical band of uniform height throughout. embodiment of Figure 1' but has neither belied sides nor lips 16. V

Figure 6 shows a plan view' of another embodiment of this invention. In this embodiment dental matrix 10 is formed from a complete tube 17 made of stainless steel having a thickness of about 0.0015 or 0.002 inch. Brazed upon about /3 of the perimeter of this band is copper sheathing 18 having a thickness of about 0.005 inch. In use, portion 18 and the part of tube 17 to which In other words, this embodiment is similar to the time, it is a feasible dimension to be specified for many materials of which this matrix may be fabricated.

A desirable thickness for thick portions 12, 18, and 19 is about 0.005 inch. This does not produce too bulky a matrix, yet provides the necessary ability to retain a deformed shape after being pinched and folded over.

The thick portion of the matrix should be extensive enough to provide sufficient material to be conveniently pinched together and folded over in installation of the matrix. On the other hand, it should never under any circumstances extend so far around the perimeter of the matrix that it will intrude between the interproximal surfaces of the tooth being worked upon and the adjacent teeth. 7

Thus if it is desired to provide a longer portion for the pinching and folding operations, the thick portion may extend around somewhat more than one-third of the perimeterof the matrix before installation, butthe extra length of the thicker portion must be taken up by the Vshaped member (element 12 in Figure l, for example), rather than by extending after installation beyond areas 13 (in Figure 1) to the mesial and distal sides of the tooth. However, no advantage results if the V shaped member is made very much longer than one-third of the total perimeter, as more than this tends to produce too much bulk for convenient handling by the dentist. s v V With all the embodiments of this invention, the dimensions of the thick and thin portions of the matrix may be varied depending upon the materials used and other relevant factors.

Other dimensions of thetdental matrix of this invention may also be varied within quite wide limits. This it is attached are bent into a V shape similar to that of r A portion. 12 of the embodimentof Figure 5.

Figure 8 shows an embodiment similar to the embodiment of Figure 5, except that thick portion 12 is joined to thinner portion 11 at areas 13 by lock sealing and, if desired, electric welding.

Embodiment formed of single materiaL-Figurd 7 shows a plan view of a flattened tubulai' blank formed 0" a single material, from which another embodiment'of the matrix of this invention may be made This embodiment may, for example, be formed of a metal, such as steel, which is hard enough to provide the necessary strength in the thinner portion and yet may be treated in its thicker portions to provide the necessary malleability there. i j

In this embodiment, thicker portion 19 performs the same function as portion 12 of the embodiment of Figures 1 and 5 and portion 18 of theembodiment of Figure 6. It is the part of the matrix which is pinched and then folded overto clamp the rest of the device tightly about the tooth. Although portion 19 is shown as being integrally "formed, this couldbe built up in two pieces of the same metal, if desired for convenience of fabrication. Y

When thematrix is installed in place about the tooth,

portions 20 form the side walls of the device.

A small portion 21 diametrically opposite area 19 is also thicker than the remainder of the band. 'It has sufficient malleability and strength so that-when the blank. is distended before use the matrix will not be.

weakened in this area by the unbending accompanying the straightening ofthe' bend in lhis portion of the blank. I 1.

, Dimensions of V 17, and 20 0f gthe respecmalrim-flhe -preferred fmaximum matrix may be manufactured, for instance, in a dozen or more cross-sectional sizes and in full or fractional height, depending uppon the particular use it is desired to make of the matrix.

Matrix shape when applied to t00th.Figure 3 indicates how the various embodiments of the dental matrix of this invention may be pulled tightly around the patients tooth and cause to assume in quite accurate form the exact shape of the tooth. The dental matrix shown a in Figure 3 is of the type shown in Figures 1 and 2. When portion 12 of the matrix is pinched 'togetherand folded over against itself, this will bring the tubular band tightly around the tooth, and the band 'will retain its shape permanently until pried apart by the dentist or the patient. 7 t

In the condition shown in Figure 3, the thick portion of the dental matrix is seen to extend beyond pinched area 22 by a short distance along the sides of the matrix in the vicinity of areas 13. This provides additional strength to cause the matrix to retain its deformed shape after being pinched and folded over. it also provides some adjustability in the size of the tooth to which this dental matrix may be fitted.

The thickened portion of the matrix does not, however, extend so far beyond areas 13 that it \villinterfere with the positioning of the dental matrix in the interproximal areas ofthe tooth. As band 11 is very thin and as the material used (stainless steel) is a smooth surfaced material, the matrix can be pressed down with a minimum of friction or othermcchanical difiiculty between the toothbeing filled and the adja ent teeth,

7 even if these teeth press fairly tightly against the tooth beingworked upon.

'As already mentioned, the 'embodimentdof, Figures 1 and 2 includes two other features of this invention, belledsides-ls and lips'lfi which extend downward from the main body of the matrix and are curved inward at their bottom areas; when it is dejsiredto extend the matrix into the lower interproxirnalfareaof the tooth on the rnesial and distal sides of the tooth.

These are of. special advantage amazes Application of matrix to .toozfh;Figure.3 shows the? application of the dental matrix of Figure 1 to molar.

24 which has a mesi'al-occlusal-distal cavity 25. A suitable tool such as pliers 26 is used to tighten the dental.

however, the matrix may be applied so that this pinched portion extends in a lingual direction.

Lip 16 is shown in Figure?) as extending into. the mesial interproxirnal space below gun line 27. The opposite lip also extends below the gum line, into the distal interproximal space below that "lin'eJThe inward belling of these lips permits them to follow closely the contour of the lower mesial and distal regions of the tooth when the matrix is drawn tightly about the tooth.

As the matrix is pressed 'about' the tooth, it will assume the general shape of the tooth wherever the outside surface of the tooth takes a convex shape. If the tooth has an indentation such as lingual indentation 28,

a portion of the matrix will of course bridge this indentation in spaced relation to it. ()therwise, the matrix will conform quite closely to the contour of the tooth and provide an accurate mold for the filling which to be placed in cavity 25. l 6

After the matrix has been pinched tightly around the tooth as shown in Figure 3, the next step in its installa tion is to fold pinched portion 22 over upon itself firmly to secure the matrix in place. a

This folding may be accomplished, as shown in Fig-; ure 3, by bending in opposite directions the two segments of pinched portion 22 for-med by slit-1 4. This has the advantage of permitting greater tension to be placed on the lower part of the matrix wall, for instance, if it is desired to tighten one part of the band more firmly around the tooth than the other. Other slits may even be provided if still more variations in tension between one vertical part of the matrix and another is desired.

In its simplest form, however, matrix 10 has no slits in the thick portion at all. It has been found entirely satisfactory for most purposes to have but one fold when pinched portion 22 is pressed into its final, permanently deformed position.

If the tooth to which the matrix of this invention is being installed has opposite side walls which are not substantially parallel but instead are at a rather marked angle, as in wedge-shaped teeth such as cuspids and incisors, it may be desirable to form the matrix of this in'- vention with a second thick portion diametrically opposite the first. If this second thick portion is pinched and folded over, additional adaptability to various shaped teeth will be provided.

It is to be understood that the thickness of thin por tion 11 of the matrix is exaggerated in Figures 3 and 4. If adjacent bicuspid 29 is very close to molar 24 or fits snugly against it, insertion of thin wall -11 will not as a practical matter decrease the mesial-distal dimension of the filling to any significant extent. Pressing this thin Wall between the two teeth will displace them so'little, if any, that the displacement may be discounted in forming a filling for cavity 25.

It isseen that with the dental matrix of this invention, the dentist can achieve nearly perfect adaptation to the floor of a mesial or distal cavity without permitting the filling to extend into the tissue area. In addition, he can attain accurate contouring of the filling in conformity with the general outline of the particular tooth being treated, despite the inaccessibility of the region of the cavity.

Furthermore, the filling so formed will not leave a large space at the contact point between the tooth being filled and the adjoining tooth which would permit rete'ntion' of food particles between the-teeth. Finally, the

matrix may be very easily andquickly installed in place around the tooth, and may be left in place as longas is desired without any discomfort to the patient or danger of its working loose fromthe tooth.-

Fabricazion of matrix.Figure 9 shows how a series of blanks for the matrix may be manufactured in quantity' in a form easily available-for use by the dentist.

The matrix blanks are of the type shown in Figure 6 having an outside sheath of a thickmalleable metal portion 18 soldered, brazed, or otherwise joined to a portion ofra thin stainless-steel tubular band 17.

Thin connecting segments 30 provide ameans of keep-- ing -a quantity of the dental matrices of this invention,

together for shipment and-storage; When the. dentist wishes to use one of these matrices, connection 30 may be very easily and'conveniently c1ippedoff.-

The above detailed description ,of this invention is somewhat largerthan that of the exposed portion of the tooth with which it is to be used, a portion of said band extending no farther than about one-third of the perimeter thereof being of sufficient thickness andmalleability to be permanently-deformed upon being first pinched to tighten the matrix snugly. about the tooth and then folded over against itself, and the portions of. the band on either side of said first portion and in ap proximately relationship to each other being of ver much smaller thickness than said first portion.

2. The dental matrix'of claim 1 .in which said thinner;-

portions have a thickness not more than about two thousandths of one inch."

3. The dental matrix of claim 1' in which said thicker portion has a horizontal-slit through the major portion of its width, whereby one segment ofsaid thickerportion can be folded in onedire'ction and another'segment in'the other. H

4. A dental matrix which comprisesz'a unitary seamless deformable tubular band having a cross-sectional area when distended somewhat larger than that of the exposed portion of the tooth with which it is to be used, a portion ofsaid band extending no farther than about onethird of the perimeter thereof being of sufiicient thickness and malleability to be permanently deformed upon being first pinched to tighten the matrix snugly aboutthe tooth and then folded over against itself, and the portions ofthe band on. either side of said first portion and in approximately 180 relationship to each other being of very much smaller thickness than said first portion.

5. The dental matrix of claim 4 in which a portion of the band approximately diametrically opposed to said first portionhas sufiicient malleability that after being bent and unbent in fabrication and preparation for'application of the matrix said diametrically opposed por- =tion still retains sufficient tensile strength to oppose the tubular band. having a cross-sectional area when distended somewhatlarger than that of the exposed portion' of the tooth with which it is to beused, a portion of said band extending no farther than about one-third of the perimeterthereof being of sufficient thickness and: malleability to I be permanently deformed upon; being.

first pinched to tighten the matrix snugly about the tooth and thenfolded over against itself, the remainder of the V band comprising alength of a second material .of higher tensile strength and of very much smaller thickness.

7. A dental matrix which comprises: a deformable tubular band having a cross-sectional area when distended somewhat greater than that of the exposed portion of the tooth with which it is to be used, said band including a tube of material of relatively high tensile strength and very small thickness in relation to the usual distance of a tooth from the teeth on either side thereof, a portion of the band extending no farther than about one-third of the perimeter thereof having joined securely thereto a sheath of material of sufficient thickness and malleability to be permanently deformable and adapted upon being first pinched when the matrix is in place to tighten the matrix snugly about the tooth and then folded over against itself to fasten the matrix securely in place.

8. A dental matrix'which comprises: a deformable tubular band having a cross-sectional area when distended somewhat larger than that of the exposed portion of the tooth with which it is to be used, the lower rim of said band being formed with a pair of spaced downwardlyextending, inwardly-bowed lips adapted to be projected into the interproximal area of the tooth onthe mesial and distal sides thereof, a portion of the band between said lips being of suificient thickness and malleability to be permanently deformed upon being first pinched to tighten the matrix snugly about the tooth and then folded over against itself, and the portions of the band in the vicinity of the lips being of very much smaller thickness than said first portion.

9. A dental matrix which comprises: a deformable tubular bandhaving a cross-sectional area when distended somewhat larger than that of the exposed portion of the tooth with which it is to be used, the lower rim of said band being formed with a pair of spaced downwardlyextending, inwardly-bowed lips adapted to be projected into the interproximal area of the tooth on the mesial and distal sides thereof, a portion of the hand between said lips having a horizontal slit therethrough and being of suflicient thickness and malleability to be permanently deformed upon being first pinched to tighten the matrix snugly about the tooth and then folded'over against itself with a first segment above said slit folded in one direction and a second segment below said slit folded in the other direction, the band in the vicinity of the lips having a very small thickness in relation to the usual distance of a tooth from the teeth on either side of: it and being of a smooth-surfaced material so that said two lips are adapted to slide with a minimum of friction or other mechanical difiiculty between said tooth and the adjacent teeth.

10. A dental matrix which comprises: a deformable tubular band having a cross-sectional area when distended somewhat larger than that of the exposed portion of the tooth with which it is to be used, a portion of said band extending no farther than about one-third of the perimeter thereof being of suificient thickness and malleability to be permanently deformed upon being first pinched to tighten the matrix snugly about the tooth and then folded over against itself, the portions of the band on either side of said first portion and in approximately 180 relationship to each other being of very much smaller thickness than said first portion, said band being integrally formed with a series of identical bands and attached to each of the adjacent bands in the series by a short, narrowconnecting strip extending from a portion of the band to the corresponding portion of each of said adjacent bands.

11. In a dental matrix, a strip of material having a relatively high tensile strength, said strip being of a generally rounded and tubular configuration for encirclement of a tooth, said strip having juxtaposed ends, and deformable 7 means joining the ends of said strip, said deformable.

means comprising a separate strip of material of suflicient malleability to be bent upon itself;

12. A dental matrix device in the form of a strip adapted to encircle a tooth and comprising a band meme bet portion for being received about a tooth and having flexible and high tensile strength characteristics, and a looped retaining element portion of deformable characteristics connected to said band member portion and being permanently deformable to contract said band member portion for clamping said band member portion about said tooth.

'13. A dental matrix device as set forth in claim 12 wherein at least a part of said retaining element portion is foldable upon itself generally in the direction of said band member portion.

14. A' dental matrix device as set forth in claim 12 wherein parts of the retaining element portion are fold able'in relatively opposite directions generally in the directionof said-band member portion.

15. A dental matrix device comprising a flexible band member section for being received about a tooth having top and bottom edges, the material of said band member being resilient and of high tensile strength, and a retaining element section of relatively. malleable material connected with said band member and substantially extending between the .top and bottom edges thereof and forming substantially a bight, said retaining element section being permanently deformable for contracting and clamping said band member section about said tooth.

16. A dental matrix device, comprising a flexible band section of high tensile strength for being received about a tooth, and a malleable, reentrant retaining element section having first and second legs with end portions respectively secured to said band section, said retaining element section being permanently deformable to bring said legs toward one another for contracting and clamping said band element about said tooth.

17. A dental matrix device comprising a flexible band I section of'predetermined material characteristics including a high tensile strength and in the form substantially of a cylindrical ring for being received about a tooth having top and bottom edges,and a retaining element section ofditferent, relatively malleable material characteristics, and having first and second legs with end portions respectively secured to said band member, said legs forming substantially a bight along said band section, and said retaining element section being permanently deformable for contracting and clamping said band section about said tooth. Y

18. A dental matrix device comprising a flexible band section of predetermined resilient and high tensile strength characteristics for being receivedabout a tooth and'having first'and second terminal portions and top and bottom edges, and a retaining element section having different and relatively malleable characteristics, said retaining element section having firstand second reentrant portions with the ends thereof secured to respective terminal portions of said band section, said retaining element section being permanently deformable to bring said reentrant portions substantially into proximity for contracting and clamping said .bandmember aboutsaid tooth.

19. A dental matrix which comprises: a deformable tubular band having a cross sectional area when distended somewhat larger than that of the exposed portion of the tooth with which itis to be used, a portion of said band being of sufficient thickness and malleability to be permanentlydeformed upon being first pinched to tighten the matrix snugly about the tooth and then folded over against itself, and the portions of the band on either side of said first portion being of very much smaller'thickness than said first portion.

7 References Cited in the file of this patent UNITED STATES PATENTS Johnson May-22, 1928 2,647,315 Dvorak Aug, 4, 1953 2,722,746

Brenner Nov. 8, 1955 x ",1. an

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