CA1219475A - Orthodontic bracket - Google Patents
Orthodontic bracketInfo
- Publication number
- CA1219475A CA1219475A CA000411428A CA411428A CA1219475A CA 1219475 A CA1219475 A CA 1219475A CA 000411428 A CA000411428 A CA 000411428A CA 411428 A CA411428 A CA 411428A CA 1219475 A CA1219475 A CA 1219475A
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- CA
- Canada
- Prior art keywords
- bracket
- metal powder
- layer
- thickness
- metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
ABSTRACT OF THE DISCLOSURE
An orthodontic bracket of the type intended for cementing directly to a previously etched surface of the tooth enamel is made by applying to the lingual face thereof that contacts the tooth enamel surface a thin porous layer of sintered metal powder which is arranged to have a porosity such that it has keying characteristics close to that of the etched enamel and thereby facilitates the cementing adhesion of the bracket to the tooth. A particularly suitable metal powder consists of particles of the same alloy as the bracket metal and of size in the range about 10 to about 150 microns (-100 mesh), preferably from about 10 to about 50 microns (-300 mesh) applied in a thickness of about 0.05 to 0.2 mm, by means of a sintering operation that fuses the particles to the lingual face and to one another. The porous layer preferably is pre-filled with a polymer material compatible with the bonding cement, such as the sealant employed with the cement, so as to protect the layer against mechanical damage caused by bending of the bracket by the orthodontist to conform the bracket surface more closely to the tooth surface to which it is to be applied.
An orthodontic bracket of the type intended for cementing directly to a previously etched surface of the tooth enamel is made by applying to the lingual face thereof that contacts the tooth enamel surface a thin porous layer of sintered metal powder which is arranged to have a porosity such that it has keying characteristics close to that of the etched enamel and thereby facilitates the cementing adhesion of the bracket to the tooth. A particularly suitable metal powder consists of particles of the same alloy as the bracket metal and of size in the range about 10 to about 150 microns (-100 mesh), preferably from about 10 to about 50 microns (-300 mesh) applied in a thickness of about 0.05 to 0.2 mm, by means of a sintering operation that fuses the particles to the lingual face and to one another. The porous layer preferably is pre-filled with a polymer material compatible with the bonding cement, such as the sealant employed with the cement, so as to protect the layer against mechanical damage caused by bending of the bracket by the orthodontist to conform the bracket surface more closely to the tooth surface to which it is to be applied.
Description
~219 ~75 ORTHODONTIC BRACKET
Field of the Invention The present invention is concerned with improvements in or relating to orthodontic brackets and especially to such brackets of the type which in use are bonded to the teeth.
Review of the Prior Art In the early days of orthodontic practice the brackets were fastened to respective metal bands which were then placed around the teeth, but this procedure is now rapidly being replaced by systems in which the brackets are bonded by a cement directly to the teeth surfaces. In one such known system the bracket lingual face to which the cement is applied is provided by a thin sheet of fine metal mesh supported by a thin metal foil attached (e.g. welded) to the bracket body. The tooth surface enamel is lS first etched to a depth of about 0.01 mm., so as to improve the mechanical bonding of the cement thereto, and a thin layer or un~illed cement is applied over the etched area. A relatively thick layer of filled cement is applied to the lingual face of the metal mesh and pressed firmly into the interstices thereof, so as to maximise the mechanical bonding; the bracket is then pressed firmly into place on the t~oth until the excess cement squeezes from the edges, the surplus "flash" being removed after the cement has hardened su~ficiently for the bracket to be held securely in place.
The filling of the cement, usually with very finely ground silica, is necessary to provide it with adequate anti-abrasion resistance in the highly hostile environment of the I .
~Z~L99t~5 human mouth, unfilled cement being eroded relatively quickly. The use of a surplus. of cement is necessary since the tooth surface usually is not particularly smooth and the foil is too stiff to be ab.le to deform enough to follow the tooth contours. It is important to ensure that there are no voids or crevices between the bracket and the tooth.surfaces in which food particles, bacteria, etc., can lodge, since these could promote the formation of decay and could in an extreme cas.e result in a cavity or cavities. A
good peripheral s.eal is also des.irable to avoid edges against ~hich.the patient ' 5 tongue could snag ~ith consequent discomfort.
It is of cours.e fun~amental that there be an excellent bond between each tooth and the-bracket of sufficient strength to withstand the relatiYely high forces that are applied by normal everyday activities, extending o~er a period of up to about three years, while permitt-ing the bond to be broken relatively easily at the conclusion ofthe procedure.
The use of the above-described fine metal mesh has proven to be relatively satisfactory, the interwoven wires providing a large number of re~entrant crevices, and the like into which the ~onding cement can penetrate to provide the desired mechanical keying. Studies of ~racket failures show that predominantly (90~) they result from breaking of the bond between the cement and the bracket, and any improvement in such keying that can be obtained is therefore highly desirable. The production of the brackets involves the secure fastening of the mesh to the foil, and of the foil to the bracket, without damaging. any of the components and any improvements in cost, speed of manufacture, scrap rate
Field of the Invention The present invention is concerned with improvements in or relating to orthodontic brackets and especially to such brackets of the type which in use are bonded to the teeth.
Review of the Prior Art In the early days of orthodontic practice the brackets were fastened to respective metal bands which were then placed around the teeth, but this procedure is now rapidly being replaced by systems in which the brackets are bonded by a cement directly to the teeth surfaces. In one such known system the bracket lingual face to which the cement is applied is provided by a thin sheet of fine metal mesh supported by a thin metal foil attached (e.g. welded) to the bracket body. The tooth surface enamel is lS first etched to a depth of about 0.01 mm., so as to improve the mechanical bonding of the cement thereto, and a thin layer or un~illed cement is applied over the etched area. A relatively thick layer of filled cement is applied to the lingual face of the metal mesh and pressed firmly into the interstices thereof, so as to maximise the mechanical bonding; the bracket is then pressed firmly into place on the t~oth until the excess cement squeezes from the edges, the surplus "flash" being removed after the cement has hardened su~ficiently for the bracket to be held securely in place.
The filling of the cement, usually with very finely ground silica, is necessary to provide it with adequate anti-abrasion resistance in the highly hostile environment of the I .
~Z~L99t~5 human mouth, unfilled cement being eroded relatively quickly. The use of a surplus. of cement is necessary since the tooth surface usually is not particularly smooth and the foil is too stiff to be ab.le to deform enough to follow the tooth contours. It is important to ensure that there are no voids or crevices between the bracket and the tooth.surfaces in which food particles, bacteria, etc., can lodge, since these could promote the formation of decay and could in an extreme cas.e result in a cavity or cavities. A
good peripheral s.eal is also des.irable to avoid edges against ~hich.the patient ' 5 tongue could snag ~ith consequent discomfort.
It is of cours.e fun~amental that there be an excellent bond between each tooth and the-bracket of sufficient strength to withstand the relatiYely high forces that are applied by normal everyday activities, extending o~er a period of up to about three years, while permitt-ing the bond to be broken relatively easily at the conclusion ofthe procedure.
The use of the above-described fine metal mesh has proven to be relatively satisfactory, the interwoven wires providing a large number of re~entrant crevices, and the like into which the ~onding cement can penetrate to provide the desired mechanical keying. Studies of ~racket failures show that predominantly (90~) they result from breaking of the bond between the cement and the bracket, and any improvement in such keying that can be obtained is therefore highly desirable. The production of the brackets involves the secure fastening of the mesh to the foil, and of the foil to the bracket, without damaging. any of the components and any improvements in cost, speed of manufacture, scrap rate
- 2 - a 34~
reduction, etc., that can be obtained is of course desirable.
There is moveover a constant endeavour to reduce the size of the brackets, not only from the point of view of patient comfort because of the reduced bulk and protrusion, but also to give the orthodontist greater flexibility in the positioning of the brackets on the teeth, so that the required tooth movements can be obtained more readily and without the need to move the position of the brackets on the teeth during the procedure.
Therefore any reduction in thickness of the bracket element that is interposed between the bracket body and the tooth is highly desirable. However, such miniaturization reduces the area of mesh available for bonding to the tooth.
Definition of the Invention It is therefore an object of the invention to provide an orthodontic bracket having a new kind of lingual surface for facilitating the bonding of the bracket to a tooth.
In accordance with the present invention there is provided an orthodontic bracket comprising a bracket body having on the lingual face thereof a thin porous layer of metal powder for reception of a bonding material for fixing the bracket to a respective tooth surface.
Preferably the said particles are adhered to the bracket and to one another by sintering.
The material of the metal powder layer may be the same as that of the bracket lingual face to which it is applied, and the said layer may be of thickness about 0.05 to 0.2 mm.
The said layer of metal powder may be carried by a separate thin metal foil constituting part of the bracket and 9'~75 fixed to the re~ainder of the bracket body, and preferably the said metal foil is of thickness about 0.15 to 0.45 mm.
The metal powder may be of particle size about 10 to 150 microns and preferably is of particle size about 30 to 50 microns.
The particles may be of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
The thin layer may be filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
Description of the Drawings Particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-EIGURES 1 and 2 are respectively back and frontperspective views of an orthodontic bracket of the invention,
reduction, etc., that can be obtained is of course desirable.
There is moveover a constant endeavour to reduce the size of the brackets, not only from the point of view of patient comfort because of the reduced bulk and protrusion, but also to give the orthodontist greater flexibility in the positioning of the brackets on the teeth, so that the required tooth movements can be obtained more readily and without the need to move the position of the brackets on the teeth during the procedure.
Therefore any reduction in thickness of the bracket element that is interposed between the bracket body and the tooth is highly desirable. However, such miniaturization reduces the area of mesh available for bonding to the tooth.
Definition of the Invention It is therefore an object of the invention to provide an orthodontic bracket having a new kind of lingual surface for facilitating the bonding of the bracket to a tooth.
In accordance with the present invention there is provided an orthodontic bracket comprising a bracket body having on the lingual face thereof a thin porous layer of metal powder for reception of a bonding material for fixing the bracket to a respective tooth surface.
Preferably the said particles are adhered to the bracket and to one another by sintering.
The material of the metal powder layer may be the same as that of the bracket lingual face to which it is applied, and the said layer may be of thickness about 0.05 to 0.2 mm.
The said layer of metal powder may be carried by a separate thin metal foil constituting part of the bracket and 9'~75 fixed to the re~ainder of the bracket body, and preferably the said metal foil is of thickness about 0.15 to 0.45 mm.
The metal powder may be of particle size about 10 to 150 microns and preferably is of particle size about 30 to 50 microns.
The particles may be of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
The thin layer may be filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
Description of the Drawings Particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-EIGURES 1 and 2 are respectively back and frontperspective views of an orthodontic bracket of the invention,
- 3~ -~'~19 ~75 FIGURE 3 is a top plan view of another orthodontic bracket embodying the invention, and FIGURE 4 is a photograph of a microscopic view of a small portion of the lingual surface of the brackets of Figures 1 and 2 to a magnification of 300 times, in order to show the nature of the surface obtained by the application of the invention.
Description of the Preferred Embodiments -The bracket illustrated in Figures 1 and 2 is that descri~ed and claimed in Patent Serial NoO 4,248,588 issued to Herbert G. Hanson. Briefly, the bracket consists of a body 10 of stainless steel having therein a mesial-distal extending slot 12 that receives an arch wire 14. The labial side of the slot is opened and closed as required, respectively for the insertion and retention of the arch wire, by respective movem~nts of a generally V-shaped spring member 16 that embraces the brac~et body and has an end that in the slot-closed position is urged by its inherent spring action to protrude into the slot 12 for engagement with the arch wire therein. The bracket has many other features that adapt it for its special task, but the exact structure of the bracket is not crucial to a complete disclosure of the present invention, and further description thereo~ is believed not be necessary. One of the advantages of the Hanson bracket is the possibility of making it of very small dimensions and a current series has an occlusal-gingival height of 2.49 mm (0.098 in), a mesial-distal width of 2.50 mm (0.1 in) and a lingual-labial thickness of 1.52 mm (0.060 in).
The bracket body 10 has fastened to the lingual face thereof by accurate laser welding a thin piece 17 of a thin stainless steel ~9 ~ 5 metal foil of 0.15 mm (0.006 in) thickness and about 3 mm by 4 mm (0.12 to 0.16 in) dimensions with the longer edges extending mesially-distally.
Prior to its attachment to the bracket body this foil piece has applied to the lingual face thereof by a sintering operation one or more layers 18 of stainless steel metal particles in the size range of about 37 to 44 microns, the layer or layers 18 being of thickness 0.05 mm (0.002 in), so that the total thick-ness of the foil plus metal layer/s is 0.20 mm (0.008 in). The particles are of the same material as the foil, and the sintering operation is such that they are not only fused to the foil but they are fused to one another to form a resultant integral porous layer or porous layers with excellent mechanical keying properties when the cement is applied to the lingual face of the layer or outermost layer for attachment of the bracket to a tooth. It is preferred to use the same metal for the foil 16 and the metal powder layer 18 since ready adhesion by the sintering operation is thereby assured, but different metals can of course be used A typical relatively simple test of the adhesion capability of a particular cement/metal powder layer combination involves supporting a newly extracted tooth in some suitable manner, e.g. by burying ik in a cement in a holder with the labial face exposed, cementing a bracket to the exposed tooth face and, after the cement has set, applying a progressively increasing tensile force to the bracket until it separates from the tooth. A
minimum acceptable figure for the applied force is about 6 kg.
Tests performed with brackets of the invention, employing the 7~
cement sold by 3M Corporation under the trade mark "CONCISE", showd that the brackets did not separate when a force of about 6.7 kg was applied, failure occurring at the laser weld.
The embodiment of Figure 2 is a bracket of the type which is attached to an arch wire (not shown) by means of one or more tie wires ~also not shown). In this embodiment the metal powder layer 18 is applied directly to the lingual face of the body 10 instead of to a separate foil. When an intermediate foil is used this preferably will be of thickness from about 0.11 mm to 1.25 mm, (0.004 to 0.010 in); the thickness of the metal powder layer preferably is from about 0.5 mm to 0.2 mm, (0.002 to 0.008 in) so that the thickness of the resultant sandwich is from about 0.15 mm to 0.45 mm, (0.006 to 0.018 in).
The minimum satisfactory thickness of a prior art foil/metal mesh sandwich is about 0.2 mm (0.008 in).
~ It is believed that the excellent bonding obtained with the brackets of the invention is due to the fact that the sintered metal porous layer or layers corresponds at least approximately in its keying characteristics to the etched enamel tooth surface, so that the cement employed is able to provide a satisfactory bond both to the tooth surface and the bracket surface.
The size of the metal powder particles should be within the range 10 to 150 microns, but preferably are within the range 30 to 50 microns. It is preferred that the particles be of size such that the difference between the smaller and the larger particles is not more than about S0 microns, this uniformity in size ensuring that they will not paclc too densely, so as to '7~;
leave a large number of voids into which the cement can penetrate for mechanical keying thereto. It will be understood by those skilled in the art that when dealing with particles of this size there is no abrupt cut-off in size and although the difference between the statistically smaller and larger particles is 50 microns there will in fact be present a much wider range of sizes, but of numbers too small to be significant. It will also be appreciated that the range of particle size for a particular metal powder will be chosen predominantly to ensure a satisfactory bond of the cement to the layer 18; adequate bonding of the metal particles to one another will usually be less critical in such choice since the required strength is more easily obtained and, as indicated above, the majority of failures have previously occurred in the cement/foil interface and not the bracket/foil junction.
The particle size employed is readily determined by the size of mesh through which the powdered material will pass.
Thus, a 100 mesh sieve will pass particles of size less than 149 microns but retain any larger, while a 300 mesh sieve will pass particles less than 50 micron size; the preferred material is that which will pass through the 300 mesh sieve.
It is also well known to those skilled in the art that the shapes of the particles are affected substantially by the conditions under which they are prepared. The usual method of preparation is to finely divide the molten metal and then to cool it, and the shapes are affected by the cooling procedure;
thus, it is known that gas cooling tends to result in particles of regular spherical shape, while liquid cooling tends to result ,~ .
S
in particles of irregular shape.
In other embodiments it may be preferred to apply the metal powder layer 18 in more than one stage. For example, a first sub-layer can be applied directly to the foil or bracket lingual face can be of smaller size particles and/or of a wide range to achieve denser packing, the layer 18 being completed by the application of one or more other sub-layers of particle size and distribution preferred to provide the desired mechanical characteristics for adequate keying of the cement thereto.
A very satisfactory procedure for fastening the particles of the metal powder layer to the remainder of the bracket, and to one another, is by sintering at about three quarters of the melting temperature. As a specific example, when the material of the foil 16 and the layer 18 is 17/4 stainless steel with a melting point of about 1480C (2700F) the sintering will be carried out at about 1100C to 1250C
(2012F to 2282F) for about one half hour in a vacuum or hydrogen atmosphere. The coated foil may subsequently be heat treated to restore its hardness to its former value, if the material used will permit such treatment.
It is found to be advantageous to apply to the sintered metal powder layer a coating of a cement-compatible sealant that will completely fill the pores of the layer. This is found to protect the layer against compaction and consequent loss of porosity during mechanical manipulation in applying a coated foil to the bracket body, and also as the orthodontist applies the bracket to a tooth. A suitable material is the filler-free sealant used to coat the etched portion of a tooth prior to the ' A
7~
application of the bracket, such as the unfilled material sold by 3M Company under the trade mark ~licence~, or that sold by ~eliance Orthodontic Products of Itasco, Illinois under the trade mark "Phase II~.
About one half of the brackets must be manipulated in this manner. It has been found that even if this bending manipulation is of such severity that cracks appear in the polymer these appear to be repaired by usual application of sealant by the orthodontist just prior to the application of the beacket to the teeth, so that the orthodontist is given much more freedom of operation in this regard. The unfilled sealant material is used since it is of course inherently compatible with the paste material of the system, but any other compatible material can be employed.
The porous layer is found to be inherently somewhat easily crushed by the type of mechanical handling and deformation required to conform the foil to the tooth shape.
Visual inspection of such a crushed portion shows the surface to have a burnished, compacted appearance contrasting clearly with the characteristic porous appearance of the remainder of the surface, and the crushed portion no longer exhibits the required excellent keying characteristics it possessed prior to the handling and deformation. A bracket of the invention with the porous layer pre-filled as described is found to be capable of manipulation and deformation without this loss of keying characteristic, and is preferred by the orthodontist because of the ease of operation that it provides.
- 8a -
Description of the Preferred Embodiments -The bracket illustrated in Figures 1 and 2 is that descri~ed and claimed in Patent Serial NoO 4,248,588 issued to Herbert G. Hanson. Briefly, the bracket consists of a body 10 of stainless steel having therein a mesial-distal extending slot 12 that receives an arch wire 14. The labial side of the slot is opened and closed as required, respectively for the insertion and retention of the arch wire, by respective movem~nts of a generally V-shaped spring member 16 that embraces the brac~et body and has an end that in the slot-closed position is urged by its inherent spring action to protrude into the slot 12 for engagement with the arch wire therein. The bracket has many other features that adapt it for its special task, but the exact structure of the bracket is not crucial to a complete disclosure of the present invention, and further description thereo~ is believed not be necessary. One of the advantages of the Hanson bracket is the possibility of making it of very small dimensions and a current series has an occlusal-gingival height of 2.49 mm (0.098 in), a mesial-distal width of 2.50 mm (0.1 in) and a lingual-labial thickness of 1.52 mm (0.060 in).
The bracket body 10 has fastened to the lingual face thereof by accurate laser welding a thin piece 17 of a thin stainless steel ~9 ~ 5 metal foil of 0.15 mm (0.006 in) thickness and about 3 mm by 4 mm (0.12 to 0.16 in) dimensions with the longer edges extending mesially-distally.
Prior to its attachment to the bracket body this foil piece has applied to the lingual face thereof by a sintering operation one or more layers 18 of stainless steel metal particles in the size range of about 37 to 44 microns, the layer or layers 18 being of thickness 0.05 mm (0.002 in), so that the total thick-ness of the foil plus metal layer/s is 0.20 mm (0.008 in). The particles are of the same material as the foil, and the sintering operation is such that they are not only fused to the foil but they are fused to one another to form a resultant integral porous layer or porous layers with excellent mechanical keying properties when the cement is applied to the lingual face of the layer or outermost layer for attachment of the bracket to a tooth. It is preferred to use the same metal for the foil 16 and the metal powder layer 18 since ready adhesion by the sintering operation is thereby assured, but different metals can of course be used A typical relatively simple test of the adhesion capability of a particular cement/metal powder layer combination involves supporting a newly extracted tooth in some suitable manner, e.g. by burying ik in a cement in a holder with the labial face exposed, cementing a bracket to the exposed tooth face and, after the cement has set, applying a progressively increasing tensile force to the bracket until it separates from the tooth. A
minimum acceptable figure for the applied force is about 6 kg.
Tests performed with brackets of the invention, employing the 7~
cement sold by 3M Corporation under the trade mark "CONCISE", showd that the brackets did not separate when a force of about 6.7 kg was applied, failure occurring at the laser weld.
The embodiment of Figure 2 is a bracket of the type which is attached to an arch wire (not shown) by means of one or more tie wires ~also not shown). In this embodiment the metal powder layer 18 is applied directly to the lingual face of the body 10 instead of to a separate foil. When an intermediate foil is used this preferably will be of thickness from about 0.11 mm to 1.25 mm, (0.004 to 0.010 in); the thickness of the metal powder layer preferably is from about 0.5 mm to 0.2 mm, (0.002 to 0.008 in) so that the thickness of the resultant sandwich is from about 0.15 mm to 0.45 mm, (0.006 to 0.018 in).
The minimum satisfactory thickness of a prior art foil/metal mesh sandwich is about 0.2 mm (0.008 in).
~ It is believed that the excellent bonding obtained with the brackets of the invention is due to the fact that the sintered metal porous layer or layers corresponds at least approximately in its keying characteristics to the etched enamel tooth surface, so that the cement employed is able to provide a satisfactory bond both to the tooth surface and the bracket surface.
The size of the metal powder particles should be within the range 10 to 150 microns, but preferably are within the range 30 to 50 microns. It is preferred that the particles be of size such that the difference between the smaller and the larger particles is not more than about S0 microns, this uniformity in size ensuring that they will not paclc too densely, so as to '7~;
leave a large number of voids into which the cement can penetrate for mechanical keying thereto. It will be understood by those skilled in the art that when dealing with particles of this size there is no abrupt cut-off in size and although the difference between the statistically smaller and larger particles is 50 microns there will in fact be present a much wider range of sizes, but of numbers too small to be significant. It will also be appreciated that the range of particle size for a particular metal powder will be chosen predominantly to ensure a satisfactory bond of the cement to the layer 18; adequate bonding of the metal particles to one another will usually be less critical in such choice since the required strength is more easily obtained and, as indicated above, the majority of failures have previously occurred in the cement/foil interface and not the bracket/foil junction.
The particle size employed is readily determined by the size of mesh through which the powdered material will pass.
Thus, a 100 mesh sieve will pass particles of size less than 149 microns but retain any larger, while a 300 mesh sieve will pass particles less than 50 micron size; the preferred material is that which will pass through the 300 mesh sieve.
It is also well known to those skilled in the art that the shapes of the particles are affected substantially by the conditions under which they are prepared. The usual method of preparation is to finely divide the molten metal and then to cool it, and the shapes are affected by the cooling procedure;
thus, it is known that gas cooling tends to result in particles of regular spherical shape, while liquid cooling tends to result ,~ .
S
in particles of irregular shape.
In other embodiments it may be preferred to apply the metal powder layer 18 in more than one stage. For example, a first sub-layer can be applied directly to the foil or bracket lingual face can be of smaller size particles and/or of a wide range to achieve denser packing, the layer 18 being completed by the application of one or more other sub-layers of particle size and distribution preferred to provide the desired mechanical characteristics for adequate keying of the cement thereto.
A very satisfactory procedure for fastening the particles of the metal powder layer to the remainder of the bracket, and to one another, is by sintering at about three quarters of the melting temperature. As a specific example, when the material of the foil 16 and the layer 18 is 17/4 stainless steel with a melting point of about 1480C (2700F) the sintering will be carried out at about 1100C to 1250C
(2012F to 2282F) for about one half hour in a vacuum or hydrogen atmosphere. The coated foil may subsequently be heat treated to restore its hardness to its former value, if the material used will permit such treatment.
It is found to be advantageous to apply to the sintered metal powder layer a coating of a cement-compatible sealant that will completely fill the pores of the layer. This is found to protect the layer against compaction and consequent loss of porosity during mechanical manipulation in applying a coated foil to the bracket body, and also as the orthodontist applies the bracket to a tooth. A suitable material is the filler-free sealant used to coat the etched portion of a tooth prior to the ' A
7~
application of the bracket, such as the unfilled material sold by 3M Company under the trade mark ~licence~, or that sold by ~eliance Orthodontic Products of Itasco, Illinois under the trade mark "Phase II~.
About one half of the brackets must be manipulated in this manner. It has been found that even if this bending manipulation is of such severity that cracks appear in the polymer these appear to be repaired by usual application of sealant by the orthodontist just prior to the application of the beacket to the teeth, so that the orthodontist is given much more freedom of operation in this regard. The unfilled sealant material is used since it is of course inherently compatible with the paste material of the system, but any other compatible material can be employed.
The porous layer is found to be inherently somewhat easily crushed by the type of mechanical handling and deformation required to conform the foil to the tooth shape.
Visual inspection of such a crushed portion shows the surface to have a burnished, compacted appearance contrasting clearly with the characteristic porous appearance of the remainder of the surface, and the crushed portion no longer exhibits the required excellent keying characteristics it possessed prior to the handling and deformation. A bracket of the invention with the porous layer pre-filled as described is found to be capable of manipulation and deformation without this loss of keying characteristic, and is preferred by the orthodontist because of the ease of operation that it provides.
- 8a -
Claims (45)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An orthodontic bracket comprising a bracket body having at the lingual face thereof a thin layer of metal powder for reception of a bonding material for fixing the bracket to a respective tooth.
2. An orthodontic bracket as claimed in claim 1, wherein the said particles are adhered to the bracket and to one another by sintering.
3. An orthodontic bracket as claimed in claim 2, wherein the metal powder is of particle size about 10 to 150 microns.
4. An orthodontic bracket as claimed in claim 1, wherein the metal powder is of particle size about 10 to 150 microns.
5. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder layer is the same as that of the bracket lingual face to which it is applied.
6. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm.
7. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body.
8. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, and the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm.
9. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the metal powder is of particle size about 30 to 50 microns.
10. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
11. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
12. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, and wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm.
13. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, and wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body.
14. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, and wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm.
15. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, and wherein the metal powder is of particle size about 30 to 50 microns.
16. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
17. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
18. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the said layer of the metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body.
19. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the said metal foil is of thickness about 0.1 to 0.25 mm, and wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm.
20. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the metal powder is of particle size about 30 to 50 microns.
21. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
22. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
23. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the metal powder is of particle size about 30 to 50 microns.
24. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
25. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
26. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the metal powder is of particle size about 30 to 50 microns.
27. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
28. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
29. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the metal powder is of particle size about 30 to 50 microns, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
30. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the metal powder is of particle size about 30 to 50 microns, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
31. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
32. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body.
33. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, and wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm.
34. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the metal powder is of particle size about 30 to 50 microns.
35. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
36. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
37. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, and wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm.
38. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the metal powder is of particle size about 30 to 50 microns.
39. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
40. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
41. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the metal powder is of particle size about 30 to 50 microns.
42. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof.
43. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
44. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, wherein the metal powder is of particle size about 30 to 50 microns, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
45. An orthodontic bracket as claimed in any one of claims 1 to 3, wherein the material of the metal powder is the same as that of the bracket lingual face to which it is applied, wherein the said layer of metal powder is of thickness about 0.05 to 0.2 mm, wherein the said layer of metal powder is carried by a separate thin metal foil constituting part of the bracket and fixed to the remainder of the bracket body, wherein the said metal foil is of thickness about 0.1 to 0.25 mm, wherein the total thickness of the metal foil and the layer of the metal powder is about 0.15 to 0.45 mm, wherein the particles are of size within a range of about 50 microns from the smaller to the larger particles to avoid dense packing thereof, and wherein the thin layer is filled with a cement-compatible sealant material to protect it against compaction during mechanical handling thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30201181A | 1981-09-15 | 1981-09-15 | |
| US302,011 | 1981-09-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219475A true CA1219475A (en) | 1987-03-24 |
Family
ID=23165869
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000411428A Expired CA1219475A (en) | 1981-09-15 | 1982-09-15 | Orthodontic bracket |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS58126807U (en) |
| CA (1) | CA1219475A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1187727A (en) * | 1982-07-21 | 1985-05-28 | Dennis C. Smith | Orthodontic attachments |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5517063Y2 (en) * | 1973-05-26 | 1980-04-21 | ||
| CA1116895A (en) * | 1978-03-13 | 1982-01-26 | Gustaf H. Hanson | Orthodontic bracket |
-
1982
- 1982-09-15 CA CA000411428A patent/CA1219475A/en not_active Expired
- 1982-09-16 JP JP13901582U patent/JPS58126807U/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58126807U (en) | 1983-08-29 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |