The present study analyzed the utilitary arch of Ricketts made with TMA and Elgiloy alloys, evaluating the forces that each one presented at different activation lengths. METHODS: A total of 30 arches (15 per alloy) 17x25 caliber were assessed. An acrylic model that simulated the jaw was used with tubes welded to the bands located on the first molars where the arches were attached and brackets were bonded to the lower incisors. The Ricketts arches had a total length of 100 mm and were activated in their distal branch, obtaining the lengths of 5, 10 and 15 mm measured from the slot of the anterior brackets in the midline. A Digital Universal Testing Machine CMT-5L was used to measure the bending force and the statistical analysis was carried out with the Student's T and Mann-Whitney U test. RESULTS: The TMA alloys had a significantly lower strength in each of the activations 5, 10, 15 mm (13,53; 31,61 and 42,01grams respectively) compared to Elgiloy (31.41; 62,61 y 93,00 grams respectively). While increasing the activation length, the flexural forces increased significantly for both alloys. CONCLUSION: The suggested forces for the intrusion of lower incisors were reached by the Elgiloy arches.

Keywords: Dental intrusion; Alloys; Flexural resistance.