Laser shaping of green metal body used in manufacturing an orthodontic bracket

Abstract

A green metal body is comprised of metal particles and a binder in the shape of an orthodontic bracket and/or base plate. The green metal body is fabricated by being laser-cut with a laser to shape the green metal body into the shape of an orthodontic bracket and/or or to carve recesses and/or undercuts into the bonding surface of the bracket. The green metal body is sintered to shrink its volume into a denser and less porous sintered metal body configured to be an orthodontic bracket. The resultant sintered orthodontic bracket includes recesses and/or undercuts in the bonding surface to provide a mechanical aspect when bonded to a tooth.

1 . A laser-shaped green metal body for use in making an orthodontic bracket, comprising: 
 a plurality of metal particles;    a binder in an amount so as to hold the metal particles together as a green metal body during laser-shaping of at least a portion of the green metal body; and    at least one laser-shaped portion formed by removing metal particles from green metal body,    wherein the green metal body at least approximates the shape of an orthodontic bracket that is comprised of a base for attachment to a person's teeth and at least one archwire slot for receiving an archwire therein.    
   
   
       2 . A laser-shaped green metal body as in  claim 1 , wherein the metal particles are comprised of a metal selected from the group consisting of aluminum, nickel, titanium, copper, cobalt, and stainless steel.  
   
   
       3 . A laser-shaped green metal body as in  claim 1 , wherein the binder is an organic binder.  
   
   
       4 . A laser-shaped green metal body as in  claim 3 , the organic binder including at least one member selected from the group consisting of wax, polypropylene, polyethylene, acrylic polymers, polystyrene, polyethylene-vinyl acetate, polyethylene vinyl alcohol, polyethylene acetate, chlorinated polyethylene, polyisoprene, polybutadiene, styrene-butadiene di- and tri-block polymers, polychloroprenes, polyethylene-propylene copolymers, chlorosulfonated polyethylenes, polyurethanes, styrene-isoprene copolymers, styrene ethylbutylene copolymers, styrene-butadiene rubber latex, polychloroprene latex, polymethylmethacrylate, polyethylmethacrylate, and polydimethylsiloxanes.  
   
   
       5 . A laser-shaped green metal body as in  claim 1 , at least a portion of the laser-shaped portion comprising a bonding surface having at least one of recesses, protrusions, or undercuts.  
   
   
       6 . A laser-shaped green metal body as in  claim 1 , wherein that portion of metal particles located on a surface of the laser-shaped portion are at least partially fused together as a result of laser shaping prior to sintering the green metal body.  
   
   
       7 . A laser-shaped green metal body as in  claim 1 , wherein that portion of metal particles located on a surface of the laser-shaped portion are not fused together as a result of laser shaping prior to sintering the green metal body.  
   
   
       8 . An orthodontic bracket formed by sintering the laser-shaped green metal body of  claim 1 .  
   
   
       9 . An orthodontic bracket comprising: 
 a sintered metal body formed by sintering a green metal body comprised of a plurality of metal particles held together with a binder, 
 the sintered metal body including a base for attachment of the bracket to a person's teeth and at least one archwire slot for receiving an archwire therein; and  
   at least one laser-shaped portion formed by removing metal particles from the green metal body using a laser and prior to sintering, 
 the laser-shaped portion being substantially devoid of charring as otherwise occurs when laser shaping a solid metal body.  
   
   
   
       10 . An orthodontic bracket as in  claim 9 , at least a portion of the laser-shaped portion comprising a bonding surface having at least one of recesses, protrusions, or undercuts.  
   
   
       11 . An orthodontic bracket as in  claim 9 , wherein the laser-shaped portion has a smoother topology compared to a corresponding laser-cut portion of the green metal body that existed prior to sintering to form the sintered metal body.  
   
   
       12 . An orthodontic bracket as in  claim 9 , at least the laser-shaped portion of the sintered body having an oxidized surface resulting from sintering the green metal body.  
   
   
       13 . A method of manufacturing a laser-shaped green metal body for use in manufacturing an orthodontic bracket, comprising: 
 providing an initial green metal body comprising a plurality of metal particles and a binder in an amount so as to hold the metal particles together as a green metal body during laser-shaping of at least a portion of the green metal body; and    removing a portion of the metal particles from the initial green metal body using a laser to in order to yield a laser-shaped green metal body that at least approximates the shape of at least a portion of an orthodontic bracket.    
   
   
       14 . A method as in  claim 13 , wherein the initial green metal body is formed by introducing the metal particles and binder into a mold and applying pressure thereto.  
   
   
       15 . A method as in  claim 14 , wherein the particles and binder are subjected to a pressure in a range of about 100 MPa to about 200 MPa.  
   
   
       16 . A method in accordance with  claim 14 , further comprising increasing the temperature within the mold to within a range of about 120° C. to about 340° C.  
   
   
       17 . A method in accordance with  claim 13 , wherein removing a portion of the metal particles from the green metal body using a laser yields a bonding surface including at least one of protrusions, recesses or undercuts.  
   
   
       18 . A green metal body formed according to method of  claim 13 .  
   
   
       19 . A method of manufacturing an orthodontic bracket comprising sintering the laser-shaped green metal body formed according to the method of  claim 13  to yield a sintered body.  
   
   
       20 . A method of manufacturing at least a portion of an orthodontic bracket, comprising: 
 introducing metal particles and a binder into a mold;    forming the metal particles and binder into an initial green metal body;    removing a portion of the metal particles from initial green metal body using a laser to yield a laser-shaped green metal body; and    sintering the laser-shaped green metal body to yield a sintered body that comprises at least a portion of an orthodontic bracket.    
   
   
       21 . A method in accordance with  claim 20 , wherein removing a portion of the metal particles from the initial green metal body using a laser yields a bonding surface including at least one of protrusions, recesses or undercuts.  
   
   
       22 . A method in accordance with  claim 20 , wherein any charring that may occur while removing a portion of the metal particles from the initial green metal body using a laser is substantially removed during sintering.  
   
   
       23 . A method in accordance with  claim 20 , wherein at least the portion of the sintered body has a smoother topology than the laser-shaped green body.  
   
   
       24 . A method in accordance with  claim 20 , wherein substantially all of the sintered body has an oxidized surface.  
   
   
       25 . A method in accordance with  claim 20 , wherein the sintered body has a volume that is about 10% to about 30% smaller than the volume of the laser-shaped green metal body as a result of sintering.  
   
   
       26 . A method as in  claim 20 , wherein the sintered body is an orthodontic bracket.  
   
   
       27 . A method as in  claim 20 , wherein the sintered body is a base plate of an orthodontic bracket.