Alleviation of mandibular anterior crowding with copper-nickel-titanium vs nickel-titanium wires: a double-blind randomized control trial.
BACKGROUND
The purpose of this study was to investigate the efficiency of copper-nickel-titanium (CuNiTi) vs nickel-titanium (NiTi) archwires in resolving crowding of the anterior mandibular dentition.


METHODS
Sixty patients were included in this single-center, single-operator, double-blind randomized trial. All patients were bonded with the In Ovation-R self-ligating bracket (GAC, Central Islip, NY) with a 0.022-in slot, and the amount of crowding of the mandibular anterior dentition was assessed by using the irregularity index. The patients were randomly allocated into 2 groups of 30 patients, each receiving a 0.016-in CuNiTi 35 degrees C (Ormco, Glendora, Calif) or a 0.016-in NiTi (ModernArch, Wyomissing, Pa) wire. The type of wire selected for each patient was not disclosed to the provider or the patient. The date that each patient received a wire was recorded, and all patients were followed monthly for a maximum of 6 months. Demographic and clinical characteristics between the 2 wire groups were compared with the t test or the chi-square test and the Fisher exact test. Time to resolve crowding was explored with statistical methods for survival analysis, and alignment rate ratios for wire type and crowding level were calculated with Cox proportional hazards multivariate modeling.


RESULTS
The type of wire (CuNiTi vs NiTi) had no significant effect on crowding alleviation (129.4 vs 121.4 days; hazard ratio, 1.3; P >0.05). Severe crowding (>5 on the irregularity index) showed a significantly higher probability of crowding alleviation duration relative to dental arches with a score of <5 (138.5 vs 113.1 days; hazard ratio, 2.2; P=0.02).


CONCLUSIONS
The difference of the loading pattern of wires in laboratory and clinical conditions might effectively eliminate the laboratory-derived advantage of CuNiTi wires.
Pandis
Nikolaos
N
Department of Community and Preventive Dentistry, School of Dentistry, University of Athens, Athens, Greece
Polychronopoulou
Argy
A
Eliades
Theodore
T
D000293:Adolescent; D002648:Child; D003300:Copper; D003722:Dental Alloys; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible; D009532:Nickel; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D009971:Orthodontics, Corrective / Q000295:instrumentation*; D016016:Proportional Hazards Models; D013997:Time Factors; D014025:Titanium
D003722:Dental Alloys; C062136:nickel copper alloy; C040654:titanium nickelide; D003300:Copper; D009532:Nickel; D014025:Titanium