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The future of orthodontic materials: The long-term view

1998; Elsevier BV; Volume: 113; Issue: 1 Linguagem: Inglês

10.1016/s0889-5406(98)70280-x

1097-6752

Robert P. Kusy,

Dental Implant Techniques and Outcomes

Today orthodontists move teeth using fixed appliances fashioned from metals, ceramics, and polymers. Stainless steel, cobalt-chromium, nickel-titanium, and β-titanium are the main alloys used to fashion arch wires. 1 Kusy RP A review of contemporary archwires: their properties and characteristics. Angle Orthod. 1997; 67: 197-208 PubMed Google Scholar Stainless steel has been the workhorse for generations; despite its heat-treatment capabilities, cobalt-chromium has remained a distant competitor. The two titanium-based alloys have found their market niches as well: nickel-titanium in the early stages of treatment and β-titanium in the intermediate stages of treatment. None of these materials is ideal, however. The first three alloys contain nickel, which is regarded by some as an allergen. 2 Al-Waheidi EMH Allergic reaction to nickel orthodontic wires: a case report. Quintessence International. 1995; 26: 385-387 PubMed Google Scholar Anecdotal reports ranging from edema of the tongue, lips, and mouth lining to anaphylaxis reach this laboratory some half-dozen times a year. Although β-titanium contains no nickel, this alloy tends to cause galling, fretting, 3 Williams DF Corrosion of implant materials. Annu Rev Mater Sci. 1976; 6: 237-265 Crossref Google Scholar and high friction, 4 Kusy RP Whitley JQ Effects of sliding velocity on the coefficients of friction in a model orthodontic system. Dent Mater. 1989; 5: 235-240 Abstract Full Text PDF PubMed Scopus (45) Google Scholar thereby making sliding mechanics more problematic. Ligatures are manufactured as 0.010 inch (0.25 mm) stainless-steel wires or as O-rings from polyester or polyether urethanes. Although stainless steel is quite serviceable, all polymeric O-rings, unfortunately, undergo force degradation, 5 Hershey HG Reynolds WG. The plastic module as an orthodontic tooth-moving mechanism. Am J Orthod. 1975; 67: 554-562 Abstract Full Text PDF PubMed Scopus (60) Google Scholar are prone to staining, and host odor-forming bacteria. 6 Stevenson JS Kusy RP Structural degradation of polyurethane-based elastomeric modules. J Mater Sci Mater Med. 1995; 6: 377-384 Crossref Scopus (21) Google Scholar Brackets have been manufactured from metals such as stainless steel and titanium; 7 Kusy RP, Whitley JQ, Ambrose WW, Newman JG. Evaluation of titanium brackets for orthodontic treatment. I. The passive configuration. Am J Orthod Dentofac Orthop (submitted for publication). Google Scholar from ceramics such as single-crystal sapphire, 8 Saunders CR Kusy RP. Surface topography and frictional characteristics of ceramic brackets. Am J Orthod Dentofac Orthop. 1994; 106: 76-87 Abstract Full Text PDF PubMed Scopus (83) Google Scholar polycrystalline alumina, 9 Kusy RP Whitley JQ. Coefficients of friction for arch wires in stainless and polycrystalline alumina bracket slots. I. The dry state. Am J Orthod Dentofac Orthop. 1990; 98: 300-312 Abstract Full Text PDF PubMed Scopus (93) Google Scholar and zirconia; 10 Keith O Kusy RP Whitley JQ. Zirconia brackets: an evaluation of morphology and coefficients of friction. Am J Orthod Dentofac Orthop. 1994; 106: 605-614 Abstract Full Text Full Text PDF PubMed Scopus (89) Google Scholar and from polymers such as polycarbonate. 11 Dobrin RJ Kamel IL Musich DR. Load-deformation characteristics of polycarbonate orthodontic brackets. Am J Orthod. 1975; 67: 24-33 Abstract Full Text PDF PubMed Scopus (40) Google Scholar With regard to brackets, stainless steel and titanium are comparable in the passive state, which includes the 0° pretorque, 0° preangulation condition. Although the transparent or translucent appearance of the single-crystal sapphire and polycrystalline alumina makes these materials esthetically pleasing, all three of the aforementioned ceramics are abrasive when they bear against opposing enamel. Polymers are esthetically pleasing as well, but they lack strength and rigidity—problems common to all unreinforced polymers.