Research Treatment effects of Forsus fatigue resistant device on class II malocclusion cases: A cephalometric evaluation Doa M. Dada a, * , Maria Therese Galang-Boquiren b , Grace Viana c , Ales Obrez d , Budi Kusnoto e a Clinical Assistant Professor, Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois b Assistant Professor, Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois c Statistician, Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois d Associate Professor, Department of Restorative Dentistry, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois e Clinic Director and Associate Professor, Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois article info Article history: Received 25 July 2014 Received in revised form 27 October 2014 Accepted 21 November 2014 Keywords: Cephalometrics Class II malocclusion Fixed functional appliances Forsus Forsus fatigue-resistant device abstract Background: This study was designed to evaluate dental and skeletal changes after a comprehensive orthodontic treatment protocol involving the use of Forsus fatigue-resistant device. Methods: Pre- and post-treatment cephalometric radiographs of 19 subjects (mean age 12  1.22 years) treated with the Forsus device were selected based on several criteria, including, but not limited to ANB and Angle molar classification. Treatment group records were evaluated, matched, and compared to an untreated control group. The control group’s lateral cephalometric radiographs were obtained from the archives of a longitudinal growth study. The Student’s t test was used, with a significance level of P < 0.05. Results: The treatment group showed a statistically significant reduction in ANB angle; SNA angle; and angle of convexity. Mandibular incisors showed significant proclination. The maxillary first molar showed no significant intrusion or distal movement. Conclusions: Based on the treatment protocol used in this study, Class II malocclusion correction was achieved mainly by dental changes in the mandible in the form of mandibular incisor proclination and some skeletal changes in the maxilla. Whether the changes in the maxilla were true skeletal changes remains to be verified. Ó 2015 World Federation of Orthodontists. 1. Introduction Class II malocclusion is a common problem encountered in the orthodontic population [1]. McNamara concluded that mandibular retrusion was the most common finding in Class II malocclusion cases [2]. Treatment modalities of Class II malocclusion include dentoal- veolar compensation, orthopedic correction, and/or orthognathic surgery. Headgear has been used in growing Class II malocclusion cases for applying extraoral forces and has proven to be reasonably effective [3e5]. The Herbst appliance is a fixed interarch appliance that has gained wide popularity, but findings from studies on its skeletal effects are inconsistent [6e11]. Vogt introduced a compliance-free fixed device called Forsus [12]. The nitinol flat-spring was the first Forsus device, followed by the fatigue-resistant device L pin and the Forsus fatigue-resistant device EZ2 module (or the Forsus EZ2 module). The Forsus EZ2 module is an interarch push-spring composed of a spring module that attaches to the headgear tube and a push-rod that attaches to the lower archwire either mesial or distal to the first bicuspid [12,13]. The Forsus device has been widely used for treating Class II malocclusion cases. In one study, the Forsus nitinol flat-spring produced dental effects that accounted for about two-thirds of Class II correction [14]. Vogt reported that the Forsus device introduced intrusive forces on maxillary molars [12]. Karacay et al. [15] concluded that the Forsus nitinol flat-spring inhibited maxil- lary growth and caused significant dentoalveolar changes. It has been reported that the Forsus device corrected the molar relationship mostly through mandibular mesial molar movement and that the device is an acceptable substitute for Class II elastics [16]. Recently, Franchi et al. [17] reported that the use of the Forsus * Corresponding author: Department of Orthodontics, College of Dentistry, Uni- versity of Illinois at Chicago, 801 South Paulina Street, Room 131, Chicago, IL 60612. E-mail address: ddada2@uic.edu (D.M. Dada). Contents lists available at ScienceDirect Journal of the World Federation of Orthodontists journal homepage: www.jwfo.org 2212-4438/$ e see front matter Ó 2015 World Federation of Orthodontists. http://dx.doi.org/10.1016/j.ejwf.2014.11.004 Journal of the World Federation of Orthodontists 4 (2015) 14e17