Ni-Ti orthodontic palatal expansion arch and method of imparting forces on teeth

Abstract

A removable orthodontic palatal expansion arch having a generally "M"-shaped configuration, the arch having a center segment composed of a near-stoichiometric alloy of nickel and titanium which possesses memory-retaining characteristics to simultaneously expand the bicuspids and expand, rotate, intrude and/or torque the maxillary molars, and end segments composed of an alloy of stainless steel or another biocompatible material configured for securing the archwire to lingual sheaths attached to molar bands.

What is claimed is: 
     
       1. A method for adjusting the forces imparted on a patient's palatal arch by a temperature-affected archwire comprising: removing the archwire from the patient's mouth heating the archwire at 1200° Fahrenheit while under 6% strain,   deforming the archwire in its martensitic state to the specific configuration of the patient's pre-treated arch, and re-inserting the archwire into the patient's mouth.   
     
     
       2. A method for treatment of a malaligned palatal arch using an archwire composed of a temperature-affected material having a transition temperature below mouth temperature which comprises: step one: deforming the archwire in its austenitic phase to the specific configuration of a desired post-treatment palatal arch,   step two: deforming the archwire in its martensitic state to the specific configuration of a patient's pre-treated malaligned palatal arch,   step three: inserting the archwire into the patient's mouth and attaching the ends of the archwire into lingually projecting sheaths,   readjusting the forces imparted on the palate by removing the archwire from the patient's mouth, adjusting the archwire spread dimensions and heating the archwire at 1200° Fahrenheit while under 6% strain,   repeating steps two and three. .Iadd.   
     
     
       3.  A method for uprighting, rotating, and distalizing molars and expanding the mandibular or maxillary dental arch of a patient comprising: providing a generally mishaped archwire composed of a temperature-affected material having a martensitic phase to austenitic phase transition temperature below mouth temperature.   forming said archwire to present a configuration of a desired post-treatment palatal arch when said archwire achieves its austenitic phase configuration,   deforming the formed archwire while in its martensitic state to the configuration of a patient's pre-treated malaligned palatal arch, and   attaching the ends of the archwire into lingually projecting molar sheaths to impart a corrective force to said dental arch and molars as said archwire achieves its austenitic phase configuration. .Iaddend. .Iadd.4. the method as claimed in claim 3, wherein said temperature-affected material is a metal alloy is composed of a near-stoichiometric alloy of nickel and titanium. .Iaddend. .Iadd.5. The method as claimed in claim 4, wherein the composition of the nickel-titanium alloy is at least 50.5   
     
     
        atomic percent nickel. .Iaddend. .Iadd.6.  A method of expanding the mandibular or maxillary dental arch and correcting molar malalignment comprising the steps of: forming a generally M-shaped archwire composed of a near-stoichiometric alloy of nickel and titanium and having a transition temperature below normal mouth temperature to provide an austenitic phase configuration that is larger than the unexpanded shape of the selected dental arch,   attaching said archwire to the lingual surfaces of opposed molars,   allowing said archwire to achieve an austenitic state, and   exerting with said archwire a continuous low-pressure corrective force against said molars to expand the dental arch and adjust the rotation, and   
     
     
        malalignment of said molars. .Iaddend. .Iadd.7.  A method of expanding the distance between opposing molars of the mandibular or maxillary dental arch comprising the steps of: spanning the interior cavity of a dental arch with an archwire composed of a temperature-affected material having a transition temperature below mouth temperature, said archwire having for its austenitic state configuration the orientation desired to be imparted to malaligned molars,   cooling said archwire to an martensitic state,   connecting said archwire to a lingual surface of each of two opposed molars,   permitting said archwire to achieve its austenitic state, and   exerting through the return of said archwire to its austenitic configuration a substantially continuous low-pressure force against said molars to provide corrective adjustments to said malaligned teeth and to expand the distance between opposing sides of the selected dental arch. .Iaddend. .Iadd.8. The method as claimed in claim 7, wherein said temperature-affected material is a metal alloy is composed of a near-stoichiometric alloy of nickel and titanium. .Iaddend. .Iadd.9. The method as claimed in claim 8, wherein the composition of the nickel-titanium alloy is at least 50.5 atomic percent nickel. .Iaddend.   
     
     
        .Iadd.10.  A method of uprighting, rotating and distalizing the molars of a dental arch comprising the steps of: selecting a generally M-shaped archwire composed of a near-stoichiometric alloy of nickel and titanium with shape memory-retaining characteristics and a transition temperature below mouth temperature, said archwire being of a configuration to impart corrective uprighting, rotating and distalizing forces to malaligned molars as said archwire shifts from its martensitic state configuration to its austenitic state configuration,   attaching said archwire to the lingual surface of opposed malaligned molars, and   applying a substantially continuous low-pressure corrective force to upright, rotate and distalize the molars of a dental arch through said transition of said archwire from its martensitic state configuration to its austenitic state configuration. .Iaddend.