Class III correction using an inter-arch spring loaded module Robert VanLaecken, D.D.S., D.M.D., Peter Ngan, D.M.D., Chris Martin, D.D.S., M.S., Thomas Razmus, D.D.S., M.S., Michael O. Williams, D.D.S. Objectives: To determine the skeletal and dental changes seen in the sagittal, vertical, and angular directions in a group of patients who had undergone treatment with an inter-arch spring loaded module, the CS2000® appliance. Methods: The treatment group consisted of 30 patients treated in the private practice office of Dr. Michael Williams in Gulfport, MS, (15 males, 15 females) with an average pre-treatment age of 9.6 and post-treatment age of 10.9. The average treatment time for the pooled group studied was 1.3 years. Lateral cephalometric films were collected from pre-treatment records before treatment began and from post-treatment records after CS2000® appliance removal. The two radiographs were then compared to allow a final calculation of average total effect seen by the CS2000® appliance in addition to normal growth of each patient during the treatment time prescribed. Results: Significant sagittal, vertical, and angular changes were seen between the pre-treatment and post-treatment. The maxillary base was found to move 1.5 mm forward, while the mandibular base moved 1.5 mm posterior. ANB and Wits measurements improved a significant level throughout treatment as well. The maxillary incisor moved forward 2.6 mm while the mandibular incisor only move 0.6 mm forward. The maxillary molar moved 1.2 mm forward while the mandibular molar moved 0.6 mm posterior. These sagittal, vertical, and angular changes contributed to the overjet and molar relationship correction. The average overjet correction found a skeletal contribution of 60 % and a 40% dental contribution. The molar relationship correction found a 62% skeletal influence a 38 % dental contribution. Conclusions: The CS 2000 appliance produces its correction by protraction of the maxillary base, proclination of the maxillary incisors, extrusion of the maxillary molars and mandibular incisors which rotates the occlusal plane in a counterclockwise direction, retraction of the mandibular base (partially coming from a downward and back rotation) mesialization of the maxillary molars, and distalization of the mandibular molars.