WO2019224614A1

WO2019224614A1 - Dental matrix

Info

Publication number: WO2019224614A1
Application number: PCT/IB2019/051329
Authority: WO
Inventors: Jordi Pérez Casas
Original assignee: Polydentia Sa
Priority date: 2018-05-24
Filing date: 2019-02-19
Publication date: 2019-11-28
Also published as: CH716341B1; IT201800005690A1

Abstract

Dental matrix band (1 ), in particular for the restoration of front teeth, comprising: a central collar (2) and two wings (3, 4); an inner side (5) intended to face a tooth during application of the matrix, and an opposite outer side (6); wherein on both sides the matrix comprises a proximal zone between the collar and the respective right wing or left wing, and said proximal zone comprises a rounded surface (10), such that in the proximal zone the outer side (6) of the matrix is convex and the inner side (5) is concave.

Description

Dental matrix

DESCRIPTION

Field of application

The invention relates to the field of dental matrices. Prior art

A dental matrix ("matrix band") is a well known item used by dentists during restoration work carried out on the front and rear teeth in the context of treating dental caries or for aesthetic modification in conservative dentistry.

A dental matrix is essentially a thin and flexible strip which is positioned around the tooth during the procedure in order to create an artificial wall for containing the restoration material while it is being applied. In other words, the function of the matrix is to replace a missing wall of the tooth around a cavity which may be formed following removal of damaged tissue, for example by the caries. The matrix, depending on type (circumferential or sectional), is held in place by means of suitable accessories, such as tensioners, pincers or clips, or plastic and/or wooden wedges. At the end of the procedure, once the restoration material has hardened, the matrix is removed.

The materials used for the manufacture of dental matrices include stainless steel, other metals or metal alloys, or polymers. In some embodiments, the dental matrix has a lining which prevents the restoration material from adhering to the matrix and, consequently, facilitates removal thereof.

A dental matrix according to the prior art essentially is in the form of a strip or band which has a rectangular shape, in the simplest cases, or a shaped form. For example a known type of dental matrix (called "Tofflemire") has a boomerang shape comprising two sections which are more or less inclined and which join together to form a vertex. Shaped matrices have been developed with the aim of improving approximation of the natural shape of the tooth and facilitating the introduction and the correct arrangement of the restoration material. However, the shaped matrices according to the prior art have been developed essentially for approximating the rear teeth, i.e. the molars and premolars, which historically are most affected by caries and consequently most frequently require restoration in conservative dentistry.

For this reason, the solutions provided by the prior art for restoration of the front teeth, wherein this term denoted the incisors and canine teeth, are limited in terms of choice and suitability of performance. More specifically, the available matrices are unable to precisely approximate both the interproximal walls and the cervical zone, making the restoration procedure more laborious and complex. The quality of the result is not always satisfactory and in any case depends greatly on the dentist's skill. The need for reconstruction of the front teeth is increasing, not only in order to repair a carious damage or trauma, but also in order to correct defects in form. There is an increasing demand from patients to correct, for aesthetic reasons, defects in form of the front teeth, which are more visible. For these reasons reconstruction operations, which previously were limited basically to the rear teeth, are now becoming increasingly frequent for the front teeth as well. The dental matrices according to the prior art, however, are unable to provide a satisfactory solution for this need.

Summary of the invention

The invention aims to provide a dental matrix with a shaped form which is optimized for reconstruction procedures involving the front teeth. In greater detail, an object of the invention is to provide an anatomical dental matrix which is able to approximate in a satisfactory manner the form of the side walls (proximal walls) and cervical walls of the front teeth, so as to facilitate the work of the dentist and improve the precision in application of reconstructive material. The objects are achieved with a matrix which comprises a central collar and two wings respectively left and right which project from said collar; an inner side intended to face a tooth during application of the matrix and an opposite outer side; on both sides the matrix comprises a proximal zone for connecting and joining together the collar and the respective wing, and said proximal zone comprises a rounded surface, such that on said rounded surface the outer side of the matrix is convex and the inner side is concave.

The applicant has found that a convex form of the proximal zones, which are situated between the collar and the wings, is anatomically optimal for use in the restoration or reconstruction of the front teeth. With this rounded form, the matrix approximates in an optimum manner the anatomy of the tooth, optimizes the positioning of the restoration material and facilitates the dentist's work.

Some preferred features are described in the dependent claims.

In one embodiment for example said rounded surface comprises, or is formed by, a cylindrical surface. In another embodiment, said rounded surface comprises, or is formed by, a spherical surface. In another embodiment, said rounded surface comprises, or is formed by, an anatomical surface having multiple radii of curvature.

Preferably the matrix is symmetrical with respect to a central axis passing through a middle point of the collar. A longitudinal direction of the matrix can be defined, substantially corresponding to said axis of symmetry, and a radial direction extending away from said axis.

In one embodiment, said rounded surface forms a strip comprised between an outer top edge of the matrix and a bottom demarcation line, below which the respective wing of the matrix extends. Preferably, the rounded strip extends in the aforementioned radial direction while the wing extends mainly in the longitudinal direction, in some cases with a certain inclination with respect to the axis of symmetry. Preferably said strip has a width greater than the wing. For example, in one embodiment, said strip is delimited externally by an edge which forms an indentation joining to an outer edge of the wing, so that the width of the wing is smaller than the width of the curved strip. The two wings extend from the same side of the collar so that the matrix has an essentially U-shaped or V-shaped form.

In an embodiment, the two wings extend from the collar in diverging directions. For example, in preferred embodiments, each of the two wings extends in a direction which, with respect to a central axis of the matrix, forms an angle ranging from 5° to 30°, and preferably equal to 15° or about 15°. Said central axis preferably is also an axis of symmetry.

Preferably, the collar has a central zone with a minimum width. In one embodiment, the collar has a concave double profile which defines said central zone with a minimum width. In one embodiment, said concave double profile is defined by the edges of the curvilinear collar, with centres of curvature on opposite sides of the said collar.

The collar, since it is bounded by at least partially curvilinear edges with centres of curvature on opposite sides of said collar, has the form of a concave double profile which is thinner towards the centre and assumes a greater width towards the sides, that it towards the said proximal connecting zones.

In an embodiment, the collar is bounded by a bottom edge, which is located in the space between the two wings, and by a top edge, which is situated on the opposite side to the two wings. At least one portion of the bottom edge follows a circumferential arc with a first centre which is located at a point between the wings, and at least one portion of the top edge follows a circumferential arc with a second centre which is located on the opposite side of the collar with respect to the first centre. In a preferred embodiment, said top edge comprises two circumferential arc lateral portions and a straight central portion in the zone of minimum width of the collar.

The wings have preferably a section with a constant width and terminate with a curved end edge, preferably in the form of a circumferential arc and even more preferably in the form of a semicircle.

The matrix may be made of metallic or polymer material. Preferred materials for making the matrix according to the invention comprise: stainless steel, titanium and alloys thereof, and polyester. In a preferred embodiment the material is AISI 304 stainless steel.

In a preferred embodiment, the matrix is made of stainless steel which has undergone a surface treatment. Said surface treatment may comprise colouring so that the operating field is more clearly visible to the specialist during the restoration work. The thickness of the matrix is preferably equal to a few hundredths of a millimetre, for example 3/100 mm.

The matrix is preferably disposable.

The matrix may be obtained by means of a die cutting process, which gives a flat matrix with the desired shape, and a subsequent forming (rounding) step which defines the convex zones.

The shape features of the matrix, which have been described, are to be understood as referring to the flat development of the matrix. During use, owing to its flexibility, the matrix is arranged in a condition where the two wings are folded towards each other, bringing the two rounded interproximal surfaces to face each other. Another aspect of the invention relates to a kit for restoration of front teeth comprising at least one matrix according to any one of the preceding claims. In addition to a certain number of matrices, the kit may comprise, for example, wedges and/or pincers for positioning the matrix around a tooth. The matrix according to the invention allows to properly copy both the geometry of the tooth in the interproximal zone and the cervical zone of the tooth. The advantages of the invention will be more evident with the aid of the following description relating to a preferred embodiment.

Brief description of the figures Fig. 1 shows the development on a plane of a matrix according to an embodiment of the invention.

Fig. 2 shows, in a perspective view, the matrix of Fig.1 in a position folded for use.

Fig. 3 shows the matrix according to Fig. 1 during its use, positioned around a front tooth.

Detailed description

Fig. 1 shows the development of a shaped dental matrix for use in the reconstruction of front teeth, denoted generally by the reference number 1.

The matrix 1 has a symmetrical form with respect to an axis A-A and comprises essentially a collar 2 and two wings 3, 4 respectively left and right.

The matrix 1 in addition has an inner side 5 intended to face a tooth during application of the matrix, and an opposite outer side 6.

On both sides (left-hand side and right-hand side in Fig. 1 ) the matrix comprises a first proximal zone 7 and a second proximal zone 8 which represent zones of connection and junction between the collar 2 and the respective left wing 3 or right wing 4.

Each of said proximal zones 7 and 8 comprises a rounded surface, i.e. having a curved form, such that in the proximal zones 7 and 8, the outer side 6 of the matrix is convex, while the inner side 5 is concave. The outer side 6 corresponds to the plane of the drawing in Fig. 1 ; the two sides 5 and 6 are better visible in the view of Fig. 2 in which the matrix 1 is folded ready for use.

Said rounded surface, in the zones 7 and 8, may be for example cylindrical or spherical or have variable radii of curvature in different embodiments of the invention.

The rounded surface, in the example shown, forms essentially a strip 10 which is comprised between a top edge 1 1 and a bottom edge 12. The top edge 1 1 is also an edge of the matrix 1 , while the bottom edge 12 essentially marks off the rounded strip 10 from the respective wing 3 or 4, which extends underneath said bottom edge 12. The edge 12 may be formed during step for rounding of the matrix 1.

The rounded strip 10 extends in an essentially radial direction with respect to the axis A-A. On the outer side, the rounded strip 10 is bounded by an edge 13 which forms an indentation 14 or knee. Preferably, said indentation 14 is located underneath the bottom edge 12 of the rounded strip 10, i.e. on the opposite side to the collar 2 relative to said edge 12.

Some of the details in Fig. 1 are shown only with reference to the wing 3 for the sake of simplicity, the other wing 4 being symmetrical with the wing 3 relative to the axis A-A. The figures show a preferred embodiment, by way of example, in which the two wings 3, 4 extend with respect to the collar in diverging directions, each forming an axis of about 15° with respect to the axis A-A. The matrix 1 , when laid out in a plane, has an overall U-shaped or V-shaped form.

The wings 3, 4 have a zone with a constant width and an end 16 bounded by a rounded edge 17, which is preferably semi-circular. The collar 2 is bounded essentially by a bottom edge 18 and by a top edge 19.

The bottom edge 18 follows a circle arc with its centre at a point A on the axis A-A, between the two wings 3 and 4.

The top edge 19 has preferably two portions 19a and 19b in the form of a circumferential arc and a straight central zone 21. The portions 19a and 19b are joined continuously together with the edges 1 1 of the rounded strips 10, on both sides.

The portions 19a and 19b have centres 22, 23 respectively, on the opposite side to the centre 20, relative to the collar 2. Therefore the collar 2, as can be noted in the figure, has a double concave form which defines a thinner central part 24 (part with a minimum width).

The matrix 1 is made for example from stainless steel using a sheet with a small thickness (e.g. 0.03 mm) so as to be flexible. The matrix may thus be bent for fitting as shown in Fig. 2.

Figure 2 shows the matrix 1 in the fitted condition, in which the interproximal zones 7, 8 face each other and together with the collar 2 define walls for containing the reconstructive material around a front tooth.

In Fig. 3, which shows the matrix 1 during use on a front tooth T, it can be seen that, owing to the rounded form of the interproximal strips and the collar 2, the matrix 1 manages to approximate correctly the form of the tooth walls in a more efficient manner than the matrices of the prior art. In this way the restoration material may be supplied in a more precise manner and the end result is one of a better quality, while the specialist is able to work in a faster and more efficient manner.

Claims

1 ) Shaped dental matrix band (1 ), particularly for use in the restoration of front teeth, comprising: a central collar (2) and two wings respectively a left (3) wing and a right (4) wing which extend from said collar; an inner face (5) intended to face a tooth during application of the matrix, and an opposite outer face (6); wherein on both sides the matrix comprises a proximal zone (7, 8) of connection and joining of the collar (2) and the respective left or right wing, and said proximal zone (7, 8) comprises a curved surface (10), such that in correspondence of said curved surface the outer face (6) of the matrix is convex and the inner face (5) is concave.

2) Matrix band according to claim 1 , wherein said curved surface comprises, or consists of, at least one of the following: a cylindrical surface, a spherical surface or an anatomical surface having several radii of curvature. 3) Matrix band according to any one of the preceding claims, wherein said curved surface (10), on each side of the matrix, forms a band comprised between a top edge (1 1 ) of the matrix and a bottom demarcation edge (12), where the respective wing (3, 4) of the matrix extends below said edge. 4) Matrix band according to claim 3, wherein said band (10) has a width greater than the wing.

5) Matrix band according to claim 3 or 4, wherein said band (10) extends mainly in a radial direction relative to an axis of symmetry (A-A) of the matrix. 6) Matrix band according to any one of the preceding claims, wherein the two wings extend with respect to the collar in diverging directions. 7) Matrix band according to claim 6, wherein each of the two wings extends in a direction which, relative to a central axis (A-A) of the matrix, forms an angle of 5° to 30° and preferably 15° or about 15°.

8) Matrix band according to any one of the preceding claims, wherein the collar has a central zone of minimum width.

9) Matrix band according to claim 8, wherein the collar has a double concave profile bounded by edges being at least partly curvilinear and having centres of curvature on opposite sides of the collar.

10) Matrix band according to claim 8 or 9, wherein the collar has a bottom edge (18) in the space between the two wings and a top edge (19) opposite the two wings, and at least one portion of the bottom edge (18) follows an arc of a circumference with a first centre (20) which is located at a point between the wings, and at least one portion of the top edge (19) follows an arc of a circumference with a second centre (22, 23) which is located on the opposite side of the collar with respect to the first centre.

1 1 ) Matrix band according to claim 10, wherein the top edge (19) comprises two circumferential arc side portions (19a, 19b) and a straight central portion (21 ).

12) Matrix band according to any one of the preceding claims, made of metal or a metal alloy or a polymer material, preferably made of stainless steel.

13) Matrix band according to any one of the preceding claims, made of stainless steel which has received a treatment suitable to modify its surface characteristics.

14) A kit for restoration of front teeth, comprising at least one dental matrix band (1 ) according to any one of the preceding claims.