Functional asymmetry is often accompanied by a shift in the dental midline and a one-sided crossbite. In this context, occlusal disorders, such as malposition teeth or premature contact, can cause deviation. Therefore, a comprehensive evaluation is required to determine the etiology of asymmetry, distinguishing between dental and skeletal origin. This case report presented a 23-year-old woman with Class I malocclusion, mandibular dental arch midline shift, left-sided scissors bite, and transposition of upper left canine and first premolar (UL3–UL4). Based on observations, upper right lateral incisor (UR2) teeth were peg-shaped. The treatment was administered using the Damon self-ligating system with asymmetric and one-sided cross-elastic. The results showed that the midline shift was corrected and the UR2 peg-shape was reshaped. However, the transposition teeth were not corrected purposely. Asymmetric mechanotherapy was applied, utilizing asymmetric elastic from the initial to the high wire phase, alongside one-sided cross-elastic. In this case, intermaxillary elastic often used symmetrically was formulated asymmetrically, marking a novel aspect of the treatment method. © 2025 Journal of Orthodontic Science.