Leveling the curve of Spee with a continuous archwire technique: A long term cephalometric study

Introduction: The orthodontic technique favored by a clinician frequently determines how a deep curve of Spee (COS) is leveled. The primary purpose of this investigation was to confirm radiographically the long-term effectiveness of a continuous archwire technique—the Alexander discipline—in leveling the COS in patients with Class II Division 1 deep-bite malocclusions treated without extractions. Methods: The sample for this retrospective cephalometric study consisted of the randomly selected orthodontic records of 31 subjects (22 female, 9 male) treated with the continuous archwire technique in the private practice of Dr R.G. “Wick” Alexander in Arlington, Texas. Results: The mean pretreatment COS for this sample was 2.47 mm, and the corresponding mean posttreatment COS was 0.19 mm. The COS was completely level in 21 patients after treatment, and the rest had slight residual COS at the end of this phase. Ten of the 31 subjects remained level from 5 to 25 years after orthodontic treatment. Conclusions: The results indicate that most leveling was accomplished by the extrusion of the premolars. The continuous archwire technique is effective in leveling the COS in patients with Class II Division 1 deep-bite malocclusions treated without extractions when the initial COS is 2 to 4 mm. The leveling of the COS with the continuous archwire technique takes place by a combination of premolar extrusion and, to a lesser extent, incisor intrusion.