Evaluation of Different Bracket's Resistance to Torsional Forces from Archwire

Abstract

The present study was aimed to evaluate the resistance to deformation or fracture of brackets of various materials (ceramic, ceramic reinforced with metal slot, and stainless steel brackets) with archwires during application of torque. The sample size included 30 brackets of maxillary right central incisor with slot dimension of 0.022 × 0.028" and made of three materials (10 of each type): (1) Ceramic brackets (cer), (2) ceramic brackets reinforced with stainless steel slot (cer/ss), and (3) stainless steel brackets (metal). Thirty stainless steel archwire segments of 0.019 × 0.025" SS 5 cm in length were used. Elastomeric ties were also used in this study. Highest to lowest deformation or fracture torque found is as follows: Stainless steel brackets (5713.2 gfmm), metal ceramic reinforced with metal slot brackets (4080.8 gfmm), and ceramic brackets (3476 gfmm). Stainless steel brackets showed significantly higher values of torsional load than ceramic brackets reinforced with metal slot and ceramic brackets. Clinically orthodontic treatment is based on specific force applications to the dentition, the maxilla and the mandible. In order to obtain these forces, orthodontic brackets are attached to the teeth. Most commonly used brackets are metal (stainless steel), ceramic, and combination of metal reinforced ceramic brackets. For successful orthodontic treatment, it is necessary to maintain proper torque and avoid torque loss. Torque loss leads to deepening of bite. Torque loss occurs due to many reasons, one of them being bracket failure to withstand applied torque.