WO1995018579A1 - Method and apparatus for providing a number of dental aids on a series of teeth - Google Patents

Abstract

A method for providing on a series of teeth a number of dental aids, wherein a dental model (9) is manufactured, whereupon the aids (8) are temporarily mounted on the dental model and fixed relative to each other by means of a mold (18) which is subsequently removed from the dental model together with the aids, whereupon the aids are each provided, on a bonding surface thereof, with a bonding agent and the mold with the aids is mounted on the teeth, in such a manner that after curing of the bonding agent and removal of the mold, the aids are fixedly connnected to the teeth via the bonding surface. Each aid (8) is mounted on the dental model (9) by means of a securing apparatus (26), the securing apparatus being fixedly connected to the dental model and the aid being detachably retained in the securing apparatus, such that the bonding surface is clean and free of binding agent.

Description

  
 



  Title: Method and apparatus for providing a number of dental aids on a series of teeth.



   The invention relates to a method for providing on a series of teeth a number of dental aids, such as a series of brackets for use in an orthodontic apparatus, wherein, by means of a dental cast and a counter cast, a dental model is manufactured, whereupon the aids are successively temporarily mounted on the dental model and fixed relative to each other by means of a mold, whereupon the mold together with the aids is subsequently removed from the dental model, the aids are each provided, on a bonding surface thereof, with a bonding agent and the mold with the aids is mounted on the teeth, in such a manner that after curing of the bonding agent and removal of the mold, the aids are fixedly connected to the teeth via the bonding surface. Such a method is known from
U.S. Patent 3,738,005.



   Within the field of technology of orthodontics, it is known to carry out tooth regulation by means of a brace built up from a series of brackets mounted on the tooth faces of a number of teeth to be aligned, which brackets are interconnected by a relatively rigid, wire-shaped element.



  Because forces are transmitted to the teeth by the brace in a predetermined magnitude and direction, the position of the teeth is influenced by the brace.



   In the known method, a model is made, by means of a cast and a counter cast, of the series of teeth to be regulated, to which model the brackets are temporarily bonded at the desired locations by means of a bonding agent provided on the bonding surface. Over the model a mold is manufactured wherein the brackets are received. When the mold is removed, the temporary bond of the brackets gives way, and the brackets can be removed together with the mold, the brackets being positionally fixed relative to one another by the mold. After removal of the mold, the bonding surface of each bracket is thoroughly cleaned to enable a proper definitive bond to the teeth. Subsequently, each bonding surface is provided with a bonding agent, after which the brackets are placed on the  series of teeth by means of the mold.

  After the bonding agent has cured, the brackets are fixed on the teeth and the mold can be removed, while the brackets remain behind on the teeth.



  Such a method for providing brackets on teeth is commonly referred to as the "indirect bonding system".



   The advantage of using this known method is that the proper position of the brackets relative to the teeth can be determined and fixed outside the patient's mouth, and even in the patient's absence, while the positioning of the series of brackets takes place in a quick and accurately determined manner. This minimizes the inconvenience to the patient, because his or her presence is only required for making the cast for the dental model and the eventual bonding of the aids. Moreover, the time that the orthodontist needs to spend on the patient is considerably shortened and, accordingly, the costs are reduced.



   In the known method, each aid is temporarily fixed on the dental model by means of a relatively weak bonding agent provided between the bonding surface and the dental model.



  After the mold has been manufactured and the aids have thereby been removed from the model, the bonding surfaces should first be cleaned in a thorough and very careful manner before the aids can be bonded to the patient's teeth. After all, a contamination of the bonding surface yields an improper bond between the aid and the tooth, and moreover, a contamination possibly results in the occurrence of dental caries due to the aid, which dental caries will only be detected after the removal of the aid. Further, because of the necessary thoroughness and accuracy, the cleaning of the bonding surface is a time-consuming and hence relatively costly affair.



   Therefore, the object of the invention is to provide a method of the type described in the opening paragraph, wherein the drawbacks mentioned are avoided and the advantages are maintained. To that end, the method according to the invention is characterized in that each aid is mounted on the dental model by means of a securing apparatus, the securing apparatus being fixedly connected to the dental model and the aid being  detachably retained in the securing apparatus such that the bonding surface is clean and free of bonding agent.



   Because the aid is not directly bonded to the dental model via the bonding surface. but is received in a securing apparatus that is fixedly connected to the dental model, the bonding surface of the aid remains clean, allowing it to be directly provided on a patient's tooth without prior cleaning.



  Hence, the bond between the aid and the tooth is correct at once. As a result, the method according to the invention saves labor and costs, while, moreover, the inconvenience to at least the patient and the orthodontist is further reduced, because repositioning of poorly bonding aids is dispensed with.



   Preferably, the securing apparatus is glued on to the dental model, because a proper bond can thus be obtained in a simple and inexpensive manner.



   The securing apparatus can be mounted on the dental model prior to the aid being placed in the securing apparatus, but it is preferred that the aid be first placed in the securing apparatus before the securing apparatus is mounted on the dental model, because in that manner a proper positioning of the aid can simply be realized.



   In different embodiments of the method according to the invention, the aid can be slid into the securing apparatus in a direction substantially parallel to the bonding surface or pressed into the securing apparatus in a direction that is substantially at right angles to the bonding surface, and the aid can be slid or drawn out of the securing apparatus.



   In an alternative embodiment of the method according to the invention, the aid is cut loose or torn loose from the securing apparatus when the mold is being removed from the dental model. This embodiment has the advantage that also in the case of a series of aids received in securing apparatuses and in a rotated or tilted position relative to each other the aids can readily be released from the securing apparatuses without their relative positions being negatively influenced.  



   The invention further relates to a securing apparatus for use in a method according to the invention, comprising retaining means for receiving the dental aid so as to be at least restrained from rotation, which securing apparatus defines an abutting face for the tooth face or dental model face, and the aid being engageable, in the condition wherein it is received inside the retaining means, from outside the retaining means from at least one side, other than the side that forms the bonding surface.



   Because the aid is engageable, in the condition wherein it is received in the retaining means, from outside the retaining means, other than via the bonding surface, the aids can be relatively fixedly received in a mold formed over the aids, the securing apparatuses and the dental model, and for instance a wire connecting the   aidsr    without the bonding surface being contaminated.



   The securing apparatus is preferably manufactured from synthetic material. Hence, the securing apparatus can be of an inexpensive and slightly elastic construction, which allows a proper bond to the dental model, while, moreover, there is a relatively great freedom of design of the securing apparatus.

 

   In a preferred embodiment of the securing apparatus according to the invention, the bonding surface of the aid, in the condition wherein it is received in the retaining means, is covered by a face of the securing apparatus, preferably by the abutting face. Because typically, a dental model is manufactured from plaster, contact between the aid and the dental model would cause contamination to the bonding surface, which is prevented by the face that covers the bonding surface. By constructing the abutting face as a glueing face, the securing apparatus can readily be fixedly connected to the dental model.



   In a further preferred embodiment of the securing apparatus according to the invention, the retaining means comprise two walls extending from the abutting face and substantially parallel in longitudinal direction, between  which the aid can be received so as to be slidable in only one direction and restrained from rotation.



   In a first structural variant of this preferred embodiment, the walls on their facing sides comprise projections or longitudinal edges, and the aid can be retained between the longitudinal edges and the abutting face. This embodiment has the advantage that the position of the aid is univocally fixed and the aid can readily be slid in and out between the walls and the abutting face, parallel to the walls and the abutting face.



   In a second structural variant of this preferred embodiment, the walls enclose a space converging in a direction away from the abutting face, and the aid can be retained between the walls and the abutting face. This structural variant has the advantage that the aid can be slightly clamped, without the measurement of the aid having to be delicately adjusted to the securing apparatus.



   Preferably, in the securing apparatus according to the invention, near a plane defined by two opposite ends of the walls, a stop is provided as limitation of the slidability of an aid between the walls, which stop is preferably formed by an edge that connects the walls and is lower than the walls.



  This stop, together with the walls and the abutting face, enables a univocal, locationally and positionally fixed positioning of the aid within the securing apparatus, and the aid can be gripped above and along the stop.



   In the securing apparatus according to the invention, it is particularly advantageous if the retaining means are provided, on the side facing away from the abutting face, with recesses for at least partly receiving or letting through a wire-shaped element that connects a series of aids and/or bonding elements that connect this wire-shaped element with the aid. This securing apparatus enables a complete brace or a like orthodontic means to be made on the dental model by means of the "indirect bonding system", and, subsequently, the brace to be integrally positioned on the patient's teeth by means of  the mold made. This minimizes the inconvenience to the patient and the required time for the orthodontist.



   To explain the invention, a number of exemplary embodiments of the securing apparatus will be described hereinafter, with reference to the accompanying drawings. In these drawings:
 Fig. 1 is a top plan view of a securing apparatus according to the invention;
 Fig. 2 is a perspective view of a securing apparatus according to the invention having a bracket received therein;
 Fig. 3 is a front view, partly cut, of a securing apparatus having a bracket received therein, received in a mold;
 Fig. 4 is a top plan view of an alternative embodiment of the securing apparatus according to the invention;
 Fig. 5 is a perspective view of an alternative embodiment of a series of securing apparatuses according to Fig. 4, mounted on a dental model; and
 Fig. 6 is a front view of a further embodiment of the securing apparatus according to the invention.



   The securing apparatus according to Figs 1-5 comprises a contact face 1, two walls 2 extending parallel in longitudinal direction from the contact face 1 on one side thereof, and a stop 3. The stop 3 extends transversely between two opposite ends 4 of the walls 2. On their facing sides, the walls 2 are provided with a surface 5, inclined from the contact face 1 toward the center plane of the securing apparatus, such that the inclined faces 5 and the contact face 1 bound a space 6 converging in the direction away from the contact face, which space, moreover, is partly bounded on one side thereof by the stop 3, which is preferably lower than the walls 2.



   As shown in Figs 2 and 3, the base 7 of an aid, for instance a bracket 8, can be slid into the coverging space 6 from the side located opposite the stop 3 such that it is received therein so as to be restrained from rotation, stopped by the stop 3 in the direction of insertion and retained by the longitudinal walls 2 and the contact face 1 against  lateral displacement and against movement transversely to the contact face. Hence, the bracket 8 cannot, i.e. not without the bracket and/or the securing apparatus being damaged, be moved into and out of the securing apparatus other than through sliding along the contact face and between the walls.



   Because the stop 3 is lower than the walls 2, the bracket can readily be gripped between the two ends 4 of the walls 2 and over the stop 3, which minimizes the chances of tilting and hence for instance misalignment of the bracket 8 tilts when it is slid out of the securing apparatus.



   By means of the securing apparatus as shown in the drawing, a brace may for instance be formed in the following manner.



   By means of a dental cast and a counter cast, a dental model 9 is made of one or more teeth, and preferably of all top and/or bottom teeth, which model is used by the orthodontist for determining and fixing the positions and shapes of the brackets 8 that are to be provided on the patient's teeth to form a teeth-regulating brace 10. By means of glue, a securing apparatus is subsequently mounted on each location where, in the opinion of the orthodontist, a bracket should be positioned, with the side 11 of the contact face 1 that faces away from the walls 2 against the dental model 9, so as to enable the bracket 8 intended for that location to be slid into the space 6 from the side of the incisal face 12 of the relevant tooth 13 and to be slid out of it in the direction of that incisal face 12. 

  The stop 3 generally extends approximately parrallel to the incisal face 12, on the side of the gums (i.e. of the cast thereof), as a result of which the position of the bracket 8 relative to the dental model is univocally determined. When the securing apparatus is being glued, the bracket 8 may aleady be received therein, but it may also be provided therein afterwards.



   The brackets 8 are connected by a wire-shaped or barshaped element 14, the brace wire, secured to the brackets 8 by means of, for instance, elastic or wire 17. At the ends of the walls 2, recesses 26 are provided when the elastic or wire  17 can extend. The brace wire 14 ensures that when the brace has been fixedly arranged on the patient's teeth, the desired correcting forces can be exerted on the different teeth, realizing a change of position of the teeth. To enable a proper transmission of these forces to the teeth, it is important that the proper bond is obtained between a bonding surface 15 and the relevant tooth. For this purpose, it is of an essential importance that the bonding surface 15 is sufficiently clean prior to its securement.

  Because the bracket 8 is only slid into the securing apparatus and is not glued therein, nor to the dental model 9, while the bonding surface 15 within the securing apparatus is entirely covered by the contact face 1, contamination of the bonding surface 15 is prevented in a simple manner, as a consequence of which a proper bond can always be obtained without requiring additional cleaning measures or the like.



   After the brace wire 13 has been placed in the brackets 8, a slightly resilient cover 16 is provided over each bracket 8, which cover 16 substantially encloses the part of the bracket 8 that projects outside the securing apparatus, to form a spherical cap over the bracket 8 by which it can be gripped. A mold 18 is provided over the dental model 9, the brackets 8 covered by the caps, and the brace wire 13. Near the top side of the walls 2, an undercut is formed between the cap 16 and the walls 2, which undercut is filled with material of the mold 18. In this manner, the mold 18 is fixedly connected to the brackets 8 and the brace wire 13, and accordingly, the position of each bracket 8 relative to the other brackets 8 is fixed.



   After the mold has been applied and, possibly, after the curing thereof, the mold can be removed from the dental model, taking along the brackets 8 and the brace wire 13, through the simple displacement of the mold 18 in the direction away from the gums (i.e. the cast   thereof) .    This involves the base 7 of each bracket 8 sliding out of the space 6 wherein it was received, without permanently changing the position of the bracket 8 relative to the other brackets 8. After all, the  brackets are fixed in position not only by the brace wire 13, but also by the mold 18.



   As it is ensured that the bonding surfaces remain clean, the brace can be univocally and properly provided on the teeth in a relatively short time, without the degree of bonding being dependent on the accuracy of the cleaning of the bonding surfaces, as a consequence of which no repetition of operations occurs, due to poor bonding, when the brace is being applied. This minimizes the inconvenience both to the patient and to the orthodontist and his assistants. The bonding surfaces 15 are provided with a bonding agent suitable for a long-term bond, whereupon the brackets 8 are pressed down on the teeth, simultaneously or one at a time. Because the brackets 8 had each been received in a securing apparatus, the bonding surfaces 15 are slightly spaced from the tooth surface when the mold 18 is positioned on the teeth.

  After all, the bonding surfaces had been covered with a contact face 1 having a certain thickness, which contact face, after removal, leaves behind a cavity within the mold 18.



  Accordingly, when the mold 18 and brackets 8 are being mounted on the teeth, the bonding agent is prevented from being scraped off against the teeth or otherwise contacting a tooth at a wrong place and at a wrong moment. When a pressure is applied to the mold 18 near a bracket 8 and in the proper magnitude and direction, the mold 18 will be slightly deformed, and only then can the bonding surface 15 contact the tooth face, so that a proper bond will take place. Moreover, the rest of the tooth surface will accordingly remain free of bonding agent. Exertion of the proper pressure on the mold 18 can for instance be achieved with a covering mold, not shown in the drawing.



   As a matter of fact, it is also possible to mount the brackets 8 on the teeth in the above-described manner without the brace wire 14 having been priorly provided, because the brackets 8 are fixed in their relative positions by the mold.



  In that case, the brace wire 14 is secured to the brackets only after the removal of the mold 18 and the caps 16.  



   The securing apparatus is preferably manufactured from synthetic material that is to some degree flexible. This allows the brackets 8 to be slid out of the spaces 6 even when the securing apparatuses have been arranged in slightly tilted positions relative to each other, because the walls of the securing apparatuses will then be capable of deforming slightly, particularly if cuts have been made in the mold 18 between the brackets 8. In that case, a removable, relatively rigid covering mold is provided over the mold, which is relatively flexible because of the cuts, by means of which covering mold the mold 18 can be brought into its original shape.



   When using rigid securing apparatuses and/or strongly tilted positions thereof relative to each other, the brackets will have to be cut loose or torn loose from the securing apparatuses at least partly. For that purpose, each securing apparatus, as is clearly shown particularly in Figs 2 and 3, is on the outside provided with a groove 19 preferably approximately at the level of the transition between the walls 2 and, possibly, the stop 3 and the contact face 1. At the level of this groove 19, the relevant wall 2 or stop 3 can simply be cut through or torn loose by means of, for instance, a scalpel or another cutting tool, possibly after the mold 18 has been slightly lifted. 

  The retention of the bracket 8 in the space 6 is thus broken in a direction other than the inserting direction, and the bracket 8 can contiguously be removed for instance in a direction that is substantially at right angles to the contact face 1.



   In an alternative embodiment of the method according to the invention, the bracket 8 is moved into and out of the space 6 between the walls in a direction that is at right angles to the contact face 1, with the walls deflecting outwards. As the walls, after the mold has been formed, are completely confined thereby, they cannot deflect outwards within the mold, as a result of which the bracket is fixed in position. The bracket can be slid into and out of the securing apparatus, but only after the mold has been slightly lifted or  pulled away can the brackets be removed again from the securing apparatus in the direction at right angles to the contact face. This method has the advantage that when the mold and brackets are being removed, the securing apparatus need not be cut through, while the positioning and removal of the brackets can be carried out in a particularly simple manner.



  As a matter of fact, in this method, a stop 3 can also be provided at the two ends of the walls 2, thus precluding displacement of the bracket 8 within the securing apparatus, but in that case, the bracket 8 can no longer be slid into and out of the securing apparatus but can only be inserted therein through pressing and removed therefrom through pulling or cutting loose.



   Figs 4 and 5 show an advantageous embodiment of the securing apparatus according to the invention, wherein two locating lips 20, 21 are provided. The locating lips 20, 21 extend in the plane of the contact face 1 along the line M, centrally located between the walls 2. Moreover, the two locating lips 20, 21 can be visually connected by a line drawn in or across the contact face, thus marking the abovementioned line M.



   For positioning the securing apparatus and, accordingly, the bracket 8, or at least for fixing the position thereof, it is important that the position of the securing apparatus can be determined in a univocal and accurate manner, for instance relative to the center plane of the tooth. Because the securing apparatus comprises locating lips 20, 21, this positioning is simplified considerably, as positional deviations can directly and simply be detected because of the relatively long locating lips 20, 21 relative to the contact face 1.

  The locating lip 20 located close to the open side of the space 6 can moreover be provided, at its free end 22, with a downwardly pointing projection 23 that can be laid against the incisal face 12 of the tooth on which the securing apparatus is to be mounted, as a result of which the positioning in the direction at right angles to the incisal face 12 is univocally determined.  



   Fig. 6 shows an alternative embodiment of the securing apparatus according to the invention, wherein the walls 24 close to their free upper ends have been provided, on the facing sides, with projections or collars 25. In this embodiment of the securing apparatus, the bracket 8 is slid by its base 7 between the contact face 1 and the projections or collars 25 and accordingly fixed in position. This embodiment has as an advantage that the walls 24, the stop 3 and the projections or collars 25 are adapted to exactly connect to the base 7 of the bracket 8, as a result of which the bonding surface 15 is even better protected against contamination.

 

   The invention is by no means limited to the exemplary embodiments shown in the drawings. For instance, the securing apparatus can be designed with a partly open contact face, with the securing apparatus being glued to the dental model for instance only by the bottom sides of the walls, prior to the positioning of the bracket in the securing apparatus. This allows the bracket to be provided with its bonding surface closer to the surface of the dental model, while no glue needs to be provided on the bonding surface all the same.



   Moreover, the securing apparatus can be mounted on the dental model in various other manners, for instance by screwing or clamping, and securing apparatuses can be provided on the teeth or the dental model at widely different angles. 

Claims

1. A method for providing on a series of teeth a number of dental aids, such as a series of brackets for use in an orthodontic apparatus, wherein, by means of a dental cast and a counter cast, a dental model is manufactured, whereupon the aids are successively temporarily mounted on the dental model and fixed relative to each other by means of a mold, whereupon the mold together with the aids is subsequently removed from the dental model, the aids are each provided, on a bonding surface thereof, with a bonding agent and the mold with the aids is mounted on the teeth, in such a manner that after curing of the bonding agent and removal of the mold, the aids are fixedly connected to the teeth via the bonding surface, characterized in that each aid is mounted on the dental model by means of a securing apparatus,

the securing apparatus being fixedly connected to the dental model and the aid being detachably retained in the securing apparatus, such that the bonding surface is clean and free of bonding agent.

2. A method according to claim 1, characterized in that the securing apparatus is glued to the dental model.

3. A method according to claim 1 or 2, characterized in that the aid is placed in the securing apparatus prior to the securing apparatus being mounted on the dental model.

4. A method according to any one of the preceding claims, characterized in that the aid is slid into the securing apparatus in a direction that is substantially parallel to the bonding surface.

5. A method according to any one of the preceding claims, characterized in that the aid is pressed into the securing apparatus in a direction that is substantially at right angles to the bonding surface.

6. A method according to any one of the preceding claims, characterized in that the aid is taken from the securing apparatus when the mold is being removed from the dental model.

7. A method according to any one of the preceding claims, characterized in that the aid is cut loose or torn loose from the securing apparatus when the mold is being removed from the dental model.

8. A method according to any one of the preceding claims, characterized in that the aid is slid out of the securing apparatus in a direction that is substantially parallel to the bonding surface.

9. A securing apparatus for use in a method according to any one of the preceding claims, comprising retaining means for receiving the dental aid so as to be at least restrained from rotation, said securing apparatus defining an abutting face for the tooth face or dental model face, and the aid being engageable, in the condition wherein it is received inside the retaining means, from outside the retaining means from at least one side, other than the side that forms the bonding surface.

10. A securing apparatus according to claim 9, characterized in that the securing apparatus is manufactured from synthetic material.

11. A securing apparatus according to claim 9 or 10, characterized in that the bonding surface of the aid, in the condition wherein it is received inside the retaining means, is covered by a face of the securing apparatus.

12. A securing apparatus according to claim 11, characterized in that the bonding surface of the aid, in the condition wherein it is received inside the securing apparatus, is covered by a face that forms the abutting face.

13. A securing apparatus according to any one of claims 9-12, characterized in that the abutting face is a glueing face.

14. A securing apparatus according to any one of claims 9-13, characterized in that the retaining means comprise two walls extending from the abutting face and substantially parallel in longitudinal direction, between which the aid can be received so as to be slidable in only one direction and restrained from rotation.

15. A securing apparatus according to claim 14, characterized in that the walls on their facing sides comprise projections or longitudinal edges, and the aid can be retained between the longitudinal edges and the abutting face.

16. A securing apparatus according to claim 14, characterized in that the walls enclose a space converging in the direction away from the abutting face, and the aid can be retained between the walls and the abutting face.

17. A securing apparatus according to any one of claims 9-16, characterized in that the aid can be received inside the securing apparatus in only one or two positions.

18. A securing apparatus according to any one of claims 14-17, characterized in that near a plane defined by two opposite ends of the walls, a stop is provided as limitation of the slidability of an aid between the walls.

19. A securing apparatus according to claim 18, characterized in that the stop is formed by an edge connecting the walls.

20. A securing apparatus according to claim 18 or 19, characterized in that the stop is lower than the walls.

21. A securing apparatus according to any one of claims 9-20, characterized in that the retaining means are provided, on the side facing away from the abutting face, with recesses for at least partly receiving or letting through a wire-shaped element connecting a series of aids and/or bonding elements connecting said wire-shaped element with the aid.

22. A securing apparatus according to any one of claims 9-21, characterized in that it comprises recognition means for indicating the position thereof relative to a tooth face or dental model face.

23. A securing apparatus according to claim 22, characterized in that the recognition means comprise a straight line parallel to the longitudinal walls and/or at right angles thereto.