ABSTRACT
To determine the best-fit arch wires using the 3M MBT arch wire system Cross-sectional analytical Setting: Orthodontic department, Karachi Medical and Dental College. Best-fit arch wire was determined by superimposing scanned image of the occlusal surface of the patients casts and the three different arch wires [orthoform I, II and III]. Two hundred patients were enrolled. In the maxillary arch, none of the arch wires fits best by both cuspid and maximum number of teeth methods [69% and 81%] [P<.001]. In the mandibular arch, arch wire fits best by cuspid method is Orthoform I [35%] and Orthoform III [53%] according to maximum number of teeth method [P<.001]. It was concluded that when treating Pakistani patients, one should expect to use tapered arch forms in a significant percentage of patients. The current preformed NiTi wires are too wide for many patients and should be modified when these patients are being treated