ORIGINAL ARTICLE Centrographic analysis of 1-phase versus 2-phase treatment for Class II malocclusion Calogero Dolce, a Randolph E. Schader, b Susan P. McGorray, c and Timothy T. Wheeler d Gainesville, Fla Introduction: Cephalometric analyses have been used by orthodontists to track growth and monitor treatment effects. Most of these analyses have normative values to which patients are compared, but some “normal” patients vary quite a bit from the normative values. The centrographic analysis is a visual analysis with no angles to measure or normative values to compare. After a reference plane is developed, the relative position of variable landmarks can be seen. Methods: We used the centroid centrographic analysis to study the effects of 1-phase and 2-phase orthodontic treatment. Phase 1 treatment consisted of bionator (n = 66), headgear/biteplane (n = 69), or observation (n = 65) until a Class I molar relationship was achieved or 2 years had elapsed. After 1 year, all subjects underwent full orthodontic treatment with fixed appliances. Results: Centrographic analysis showed that early treatment has effects on the mandible. However, the differences were not apparent by the end of fixed appliance treatment. Conclusions: The skeletal effects of phase 1 treatment disappear by the end of fixed appliance treatment. (Am J Orthod Dentofacial Orthop 2005;128: 195-200) L ateral cephalograms have been used by ortho- dontists for over 60 years to evaluate growth of the cranium and effects of treatment. Broad- bent 1 used the cephalometer, as it was called, to study growing children over time. He developed a method of superimposition of successive films whereby land- marks were identified and geometrically related. His sequential analysis of lateral radiographs was the first longitudinal perspective on cranial growth. Since then, many cephalometric analyses and their limitations have been described. 2-8 To establish reliability in cephalometric determina- tions, orthodontists have scrutinized the lateral ana- tomic representation by applying many analytical methods, including lines, angles, arcs, triangles, squares, and rectangles. There is much debate and research about which landmark to use as the fixed point of reference for measuring those that are deemed variable. All cranial structures are variable over time, some far more than others. 9 Nonnumerical analyses have been developed to avoid comparisons of patients with normative values. 4,10 The centroid analysis has received little attention after its introduction by Johnson 11 and later modifica- tion by Fishman. 12 In the original centrographic anal- ysis, 11 Johnson described the use of the center of gravity as a fixed reference point. He used a novel model that required cutouts of cephalometric tracings suspended twice in different locations on pins having a vertical line. The center of gravity was determined by the intersection of the 2 lines. When Johnson applied this method to 50 cephalograms of Chinese and English children, he concluded that these centers provided stable reference points generating a stable reference plane to which linear distances could be measured. When Johnson used the same technique for obtaining centers on a larger population of Chinese children “randomly” selected, the conclusions were the same, because he compared the sella (S)-nasion (N) reference plane with planes obtained with the above-described method. When a vastly simplified analysis was pub- lished, 13 Johnson compared lines representing mea- sures commonly identified in cephalometric analyses and coined the term centroid. In 1997, Fishman 12 published a centroid based analysis, using principles developed by Johnson and Hubbold. 13 This analysis reduces the task to the con- struction of 4 centroids with common and simple methods of tracing and landmark identification, with no angles to measure and no normative values to compare. The centrographic analysis is unique to each patient; it supplies independent identification of anteroposterior positions of the maxilla and the mandible, vertical From the University of Florida, Gainesville. a Associate professor, Department of Orthodontics. b Former resident, Department of Orthodontics. c Research assistant professor, Department of Statistics. d Professor and chair, Department of Orthodontics. Reprint requests to: Calogero Dolce, DDS, PhD, Department of Orthodontics, Box 100444, JHMHC, Gainesville, FL 32610-0444; e-mail, cdolce@dental. ufl.edu. Submitted, December 2003; revised and accepted, April 2004. 0889-5406/$30.00 Copyright © 2005 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2004.04.028 195