NZ524323A - A dental contact matrix system - Google Patents

Abstract

A wedge for use with a dental contact matrix system is described for the placement of dental fillings. The wedge comprises a one piece member of elastic material having an elongated narrow section and an elongated tapered section with a triangular cross section. The elongated narrow section extending directly or indirectly from the narrow end of said tapered section. A wedge having two elongated tapered sections is also described. (62) Divided out of 515528

Description

524 3 NEW ZEALAND PATENTS ACT 1953 No: 524323/524324/524325/524326 Date: 19 November 2001 6 December 2001 7 December 2002 3 January 2003 COMPLETE SPECIFICATION DENTAL WEDGE I, SIMON PAUL MCDONALD, a New Zealand citizen of 18 Giles Way, Tanners Point Road, Katikati, Bay of Plenty, New Zealand, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: Intellectual P.operty Office of N.Z. 2E SEP 200"i RECEIVED FIELD OF THE INVENTION 'rtoltertua I T\3pertJ Office of N.z. 2 2 C'cP 2004 received The present invention relates to an apparatus for use with dental matrixes in the placement of dental fillings and in particular light curable dental fillings. SUMMARY OF THE PRIOR ART The dental profession has moved over the last two or so decades from the use of mercury based fillings to the use of composite resins that are used to provide natural looking fillings. Composite resin is cured by the application of concentrated light. To enable the dental professional to place composite resin fillings matrixes are used. A matrix which is a device which wraps around the tooth and acts as a mould to contain the composite resins before they are cured. Matrices are generally formed of plastic or stainless steel and are either circumferential or sectional. Sectional matrices fit only in one proximal area of the tooth while circumferential matrix bands fit around the entire circumference of the tooth. Matrixes are secured in place by the use of wedges and/or clamps. Wedges are generally made of wood or plastic and are placed between the matrix and an adjacent tooth. Wedges are used to hold the matrix against the tooth being filled and to temporarily separate the tooth being filled and the adjacent tooth. In the prior art wedges have a sharp point which may cause punctures to the soft tissues and so are traumatic. Local anesthetics are often required. Additionally prior art wedges offer no assistance in constricting the blood vessels in the inter-proximal gingival tissues and therefore do not provide any assistance in keeping the field of work dry.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a wedge for securing dental matrices which is an improvement on the prior art systems and devices or which will at least provide the industry with a useful choice.

The present invention may broadly be said to consist in a wedge for use in a dental contact matrix system, said wedge comprising a one piece member of elastic material, and having: an elongate narrow section, largely of a uniform cross section, with a low aspect ratio or perimeterA2-to-area ratio, said elongate narrow section including an intermediate flattened section of higher aspect ratio or perimeterA2-to-area ratio, and an elongate tapered section with a triangular cross section, a narrow and a broad end, said elongate narrow section extending directly or indirectly from the narrow end of said tapered section.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

BRIEF DESCRIPTION OF THE DRAWINGS One preferred form of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 is a three dimensional view of the wedge of the present invention.

Figure 2 is an end view of the wedge of the present invention.

Figure 3 is a side view of the wedge of the present invention.

Figure 4 is an alternative side view of the wedge of the present invention.

Figure 5 is a three dimensional view of an alternative embodiment of the wedge of the present invention.

Figure 6 is a side view of an alternative embodiment of the wedge of the present invention.

Figure 7 is an alternative side view of an alternative embodiment of the wedge of the present invention.

Figure 8 is a side view of another alternative embodiment of the wedge of the present invention.

Figure 9 is a side view of another alternative embodiment of the wedge of the present invention.

Figure 10 is a three-dimensional view of the wedge of the present invention assembled with a matrix system.

Figure 11 is a three-dimensional view of an alternative embodiment wedge of the present invention assembled with a matrix system.

Figure 12 shows the wedge of the present invention in place with a contact matrix dental system.

DETAILED DESCRIPTION OF THE PRESENT INVENTION Referring to Figures 1 to 4 there is shown the most preferred embodiment of the wedge 101 of the present invention. The wedge 101 comprises a one piece member of elastic material such as rubber, polyurethane or other suitable material. In the preferred embodiment polyurethane is used as it has suitable elasticity properties but any other material that has like elasticity properties would be suitable. Suitable elasticity properties require the wedge to stretch approximately 40%. The elastic wedge 101 has an elongate narrow section marked 102 and an elongate tapered section marked 103. The narrow section 102 is a cylindrical section 111 as seen in Figure 2. The narrow section 102 has a diameter of 0.5 to 1.5 and a length of 10 to 15 millimetres. In an alternative embodiment an oval, triangular or other cross sectional shape could be used. For example in the preferred circular form it has an aspect ratio of 1, and the minimum perimeter squared to area ratio of 4n.

The elongated tapered section 103 has a maximum thickness of 3 to 5 millimetres and an approximate length of 10 to 15 millimetres. In the preferred embodiment the cross section 112 shown in Figure 2 is an equilateral triangle but any triangular or other shape would be also be suitable. In the preferred embodiment the faces 110 of the tapered section are concave.

At the end of the elongated taper section 103 at the point where it joins the elongated narrow section 102 there is an integrated bead 106 which is wider than the elongated narrow section 102. At the free end of the elongated tapered section 103 there is a small elongated narrow section 105 and intrinsic bead 104. The integrated bead 104 is wider in cross section than the narrow section 105.

The elongated narrow section 102 has at the free end a bead 109 which is wider in cross section than the elongated narrow section. A short distance from the free end of the elongated narrow section 102 and from bead 109 there is an additional bead 108 which is wider in cross section than the elongate narrow section 102. In the preferred Intellectual P.ocerty Office of N.Z. 2 8 SEP 2004 embodiment this bead is 3 to 5 millimetres from the bead 109 at the end of the narrow section 102.

In approximately the middle of the elongate narrow section 102 there is a flattened section 107. In its narrowest orientation flat section 107 shown in Figure 3 has a thickness smaller than the thickness of the elongate narrow section 102. In the broadest orientation of the flat section 107 shown in Figure 4 the flat section 107 is wider than the thickness of the elongated narrow section 102. In the preferred embodiment the flat section 107 of the elongated narrow section 102 is 3 to 8 millimetres long. The flat section 107 makes it easier for the dental professional to use the wedge of the present invention as it passes more easily between two teeth.

To use the wedge 101 of the present invention the dental professional would position their preferred matrix band or sectional matrix on the tooth to be filled in the usual manner using fingers and/or tweezers.

The dental professional would then elongate the narrow elongated section 102 of the wedge 101 by stretching it and placing the wedge between the matrix band and the adjacent tooth. The wedge is placed in a similar fashion to the use of dental floss. The dental professional then releases both ends and pulls on the narrow elongated section 102 to pull the elongated tapered section 103 through the gap so that the tapered section passes inter-proximally until the space is tight.

The present invention has the advantage that when the tension on the wedge 101 is released the elastic wedge 101 expands further increasing the pressure on the matrix band and on the adjacent teeth, thereby causing them to separate. The elastic wedge of the present invention, because it does not have a point and is pulled or threaded into the inter-proximal space, is gentler on the gingival tissue and thereby less traumatic for dental patients.

In an alternative embodiment referring to Figures 5 to 8 the wedge 101 has two elongated tapered sections marked 501 and 503 respectively and an elongated narrow section 502. In approximately the middle of the elongate narrow section 502 there is a flattened section 506. In its narrowest orientation flat section 506 shown in Figure 5 has a thickness smaller than the thickness of the elongate narrow section 503. In the broadest orientation of the flat section 506 shown in Figure 6 the flat section 506 is wider than the thickness of the elongated narrow section 502. In the preferred embodiment the flat section 506 of the elongated narrow section 502 is 3 to 8 millimetres long. The flat section 506 makes it easier for the dental professional to use as it passes more easily between two teeth.

Since the wedge has tapered sections 501 and 503 either side of the elongated narrow section 502 the dental professional can pull the wedge from either the buccal or lingual side depending on the clinical situation.

In a further alternative embodiment show in Figure 8 the wedge 801 comprises two elongated tapered sections marked 802 and 803 respectively and a flattened section 804 in the between the two elongated tapered sections. In this embodiment the narrow section that passes into the space between the teeth during insertion is the flattened section 804. This embodiment is advantageous when the inter-proximal space between two teeth is small. A further alternative embodiment shown in Figure 9 has a wedge 901 comprising two elongated tapered sections 902 and 903 joined together, in approximately the middle there is a narrow tapered section 904. As the wedge is stretched the wedge narrows allowing the wedge and in particular the narrow tapered section to pass between two teeth.

Referring to Figures 10 and 11 there is shown the dental contact matrix system suitable for us with the wedge of the present invention. The dental contact matrix system includes a retainer with a spring 1 lOland two lugs 1110 attached to the spring 1101. A matrix 1130 is held in place by lugs 1110 and the wedge 1120 is wrapped under the two lugs 1110 and the spring 1101.

The spring 1101 is generally semi circular or U-shaped in plane view and has two arms 1102 under tension. The arms 1102 require force to push them apart. The dental professional pushes the arms 1102 apart using rubber dam forceps or another similar tool. Each arm 1102 has an oval shaped hole or socket 1104 to enable lugs 1110 to be attached to the spring 1101. The use of an oval shape hole 1104 prevents the lugs from rotating relative to the arms 1102. A channel 1105 in each arm allows for the elastic wedge 1120 to be attached to the spring 1101 and cleated. The channel 1105 includes a narrow neck through which narrow sections of the wedge can squeeze. Many alternative forms of connection for the ends of the wedge to the retainer can also be envisaged, including connection to the lugs rather than the spring member.

Lug faces 1112 in use abut the tooth being filled and the neighbouring tooth. The lug faces are in the preferred embodiment concave so as to adapt to the interproximal space between teeth. A ridge 1113 at the intersection of the faces projects into the inter-proximal space between the two teeth. In use one lug fits on the lingual side and the other lug on the buccal side.

Each lug 1110 has a matrix holder 1114 to hold the matrix 1130 in place. Referring to Figures 10 and 11 in use the wedge 1130 is threaded through channels of each lug to span across the gap between the lugs. Outward portions of the wedge 130 pass through channels 1105 of the spring arm 1102 and are cleated thereby. The channel of each lug is contoured in a "V" shape to enable the wedge to be inserted or threaded into the channel.

The matrix 1130 is formed of materials such as plastic or stainless steel. Matrix 1130 is formed such that an edge is shaped to conform to the contours of the interproximal gingival margin.

To use the assembled contact matrix system including the wedge of the present invention the dental professional expands the spring arms 1102. This also stretches the narrow section of the wedge 1120. In particular the narrow flat section of the wedge 1120 is stretched. The retainer is then manipulated to place the narrow section of the wedge 107 and the matrix 1130 into the inter-proximal space between two teeth. When the dental professional removes the rubber dam forceps the spring 1101 contracts and the lugs 1110 provide pressure to hold the matrix 1130 against the lingual and buccal sides of the tooth to be filled.

A dental contact matrix system and the wedge of the preferred embodiment of the present invention is shown in Figure 12 in place. The tooth to be filled 1201 and the adjacent tooth 1202 are shown. The matrix 1203 and narrow portion of the wedge are between the teeth in the inter-proximal space. The lugs 1206 are pressing the matrix 1203 (not visible) against the tooth surface 1207 thereby holding the matrix 1203 in place.

Once in place the dental professional can use tweezers or other suitable tools to detach the ends of the wedge from the cleats 1208 of the spring 1209. Beads 1208 and 1210 make this process easier by preventing the tweezers from slipping off the wedge 1204 Then using tweezers or other suitable tool, the dental professional pulls on either tapered section and in particular a bead. This pulls the other tapered section into the inter-proximal space between the two teeth to better secure the matrix 1130 against the tooth to be filled. The elastic wedge causes continuous lateral pressure. After restoring the tooth, the dentist can remove the wedge by cutting through the wedge with a sharp instrument such as scissors and then removing both ends Unlike a conventional wedge, which only presses the matrix band on the side where the wedge enters from, the wedge of the present invention presses against the matrix band on both the buccal and lingual sides. This occurs because of the elasticity of the wedge. The present invention has advantages over the prior art including being less traumatic for patients because there is no sharp point to puncture the soft tissues and local anesthetic is not required. The wedge of the present invention also acts like a tourniquet to constrict the blood vessels in the inter-proximal gingival tissues and helps maintain a dry field. Since the wedges of the present invention are elastic they continually put lateral pressure inter-proximally better forcing the matrix against the tooth being repaired In the preferred embodiment the lugs, wedge and matrix all transmit light enabling light used to cure the filling to reach the filling material. This has the advantage of enabling the filling to cure faster and to ensure a more complete cure.

Claims (23)

CLAIMS:

1. A wedge for use in a dental contact matrix system, said wedge comprising a one piece member of elastic material, and having: an elongate narrow section largely of a uniform cross section, with a low aspect ratio or perimeterA2-to-area ratio, said elongate narrow section including an intermediate flattened section of higher aspect ratio or perimeterA2-to-area ratio, and an elongate tapered section with a triangular cross section, a narrow and a broad end, said elongate narrow section extending directly or indirectly from the narrow end of said tapered section.

2. A wedge as claimed in claim 1 wherein said elongate narrow section has a thickness of from 0.5 to 1.5 millimetres.

3. A wedge as claimed in claim 1 or claim 2 wherein said elastic material has a percentage elongation of at least 40%.

4. A wedge as claimed in any one of claims 1 to 3 wherein said tapered section has a maximum thickness of from 3 millimetres to 5 millimetres.

5. A wedge as claimed in any one of claims 1 to 4 wherein each said elongate tapered section is from 10 millimetres to 15 millimetres in length.

6. A wedge as claimed in any one of claims 1 to 5 wherein said elongate narrow section is from 10 millimetres to 15 millimetres in length.

7. A wedge as claimed in anyone of claims 1 to 6 including an integral bead of expanded cross section at the transition between said elongate narrow section and said elongate tapered section, said integral bead having an expanded cross section relative to said elongate narrow section. Intelieutual P.ocerty Office of N.Z. 2 S SEP 2004 RECEIVED - 10-

8. A wedge as claimed in any one of claims 1 to 7 including a first integral bead of expanded cross section adjacent the free end of said elongate narrow section.

9. A wedge as claimed in claim 8 including an integral bead of expanded cross section near said free end of said elongate narrow section but spaced along said elongate narrow section from said first integral bead.

10. A wedge as claimed in anyone of claims 1 to 9 including a short narrow section extending from the broad end of said elongate tapered section, and an integral bead at the free end of said short narrow section, said bead being of expanded cross section relative to said short narrow section.

11. A wedge as claimed in any one of claims 1 to 10 wherein said wedge is formed from a light transmissive material.

12. A wedge for use in a dental contact matrix system as claimed in anyone of claims 1 to 7 and 10 to 11, said wedge further having a second elongate tapered section with a triangular cross section, a narrow end and a broad end, said elongate tapered section extending, by its narrow end, directly or indirectly from another end of said elongate narrow section.

13. A wedge as claimed in claim 12 wherein said second elongate tapered section is from 10 millimetres to 15 millimetres in length.

14. A wedge as claimed in claim 12 or claim 13 wherein each said elongate tapered section is from 10 millimetres to 15 millimetres in length.

15. A wedge as claimed in any one of claims 12 to 14 including an integral bead of expanded cross section at the transition between said elongate narrow section and said Intellectual P.ocerty Office of N.Z. 2 8 SEP 2004 D cr* C! I t / r -11 - second elongate tapered section, said integral bead having an expanded cross section relative to said elongate narrow section.

16. A method of using a dental wedge according to anyone of claims 1 to 15 said method comprising the steps of: stretching said narrow section of said wedge, passing the stretched narrow section of said wedge into the inter-proximal space between two teeth, and pulling on an end of said wedge, to draw a said elongate tapered section into said inter-proximal space.

17. A dental contact matrix system including a wedge as claimed in any one of claims 1 to 15, said dental contact matrix system including a matrix and a retainer for placing and retaining said matrix, said retainer comprising: a first lug, to fit on one side of a proximal contact between two teeth, a second lug to fit on the other side of said proximal contact, a spring member connecting between said first lug and said second lug, said spring member holding said lugs such that they must be separated to fit over said proximal contact, wherein the spring member applies a restorative force pressing said lugs against opposed sides of said proximal contact, and an adaptation for receiving and holding said wedge with said elongate narrow section spanning between said first lug and said second lug.

18. A dental contact matrix system as claimed in claim 17 wherein said adaptation comprises: a first wedge engagement associated with said first lug, a guide on said first lug to have said wedge exit from underneath said first lug, a second wedge engagement associated with said second lug, a guide on said second lug to have said wedge exit from underneath said second lug. Intelieaual P.ocerty Office of N.Z. 2 8 CZP 2004 r f n f i v f n Intellectual P.ocerty Office of M.Z. 21 SEP 2004 RECEIVED

19. A dental contact matrix system as claimed in claim 18 wherein said first and second wedge engagements each comprise a cleat formed in an end of said spring member adjacent the connection between said spring member and the respective said lug, said narrow section of said wedge engaging in each said cleat.

20. A method of using a dental contact matrix system as claimed in claim 18 or claim 19 comprising the steps of: placing a matrix against said lugs, to contact said first lug at a first location and said second lug at a second location, stretching said wedge and fitting same to said retainer to be held spanning between said lugs by said adaptions, expanding said retainer by flexing sad spring member into an open condition, with said retainer held open, positioning said lugs either side of a proximal contact between two teeth, releasing said retainer to allow said spring member to press said lugs against said teeth, and releasing said wedge from said retainer.

21. A method as claimed in claim 20 said method includes, after releasing said wedge: pulling on an end of said wedge, to draw a said elongate tapered section into said inter-proximal space.

22. A wedge as hereinbefore described in any of the embodiments with reference to any of the drawings.

23. A method of using a dental wedge as hereinbefore described in any of the embodiments with reference to any of the drawings. DATED THIS "1% DAY OF Sep^-rb^ 2006-AGENTS FOR THE APPLICANT