Photo-elastic stress analysis of initial alignment archwires.
Photo-elastic models replicating a lower arch with a moderate degree of lower incisor crowding and a palatally displaced maxillary canine were used to evaluate the stresses transmitted to the roots of the teeth by initial alignment archwires. Six initial alignment archwires were compared, two multi-strand stainless steel wires, two non-super-elastic (stabilized martensitic form) nickel titanium wires, and two stress-induced super-elastic (austenitic active) nickel titanium wires. Three specimens of each archwire type were tested. Analysis of the photo-elastic fringe patterns, in the medium supporting the teeth, revealed that the non-super-elastic nickel titanium archwires produced the highest shear stresses (P = 0.001). However, the shear stresses generated by the super-elastic alignment archwires and the multi-strand stainless steel archwires were very similar (P = 1.00). These results show that even in situations where large deflections of initial alignment archwires are required, super-elastic archwires do not appear to have any marked advantage over multi-strand stainless steel alignment archwires in terms of the stresses transferred to the roots of the teeth.
Orthodontic Division, School of Clinical Dentistry, Queen's University Belfast, Northern Ireland.
Serene A
SA
Badran
John F
JF
Orr
Mike
M
Stevenson
Donald J
DJ
Burden
D000704:Analysis of Variance; D003481:Cuspid / Q000503:physiopathology; D003722:Dental Alloys / Q000737:chemistry; D006801:Humans; D007180:Incisor / Q000503:physiopathology; D008310:Malocclusion / Q000628:therapy; D008334:Mandible; D008437:Maxilla; D008954:Models, Biological; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D019228:Tooth Crown / Q000503:physiopathology; D014079:Tooth Eruption, Ectopic / Q000628:therapy; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D014092:Tooth Root / Q000503:physiopathology
D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium