Abstract: This case systematically reports the process of invisible extraction orthodontic treatment with clear aligners for an adult patient with severe dentition crowding, lateral incisor crossbite, and generalized enamel hypoplasia. Based on the patient’s chief complaint, clinical examination, and imaging data, a comprehensive evaluation was conducted, leading to the final decision to implement an invisible orthodontic treatment plan involving the extraction of four first premolars. During the treatment, through scientifically design of molar anchorage, appropriate placement of auxiliary devices, refined controlled root movement, and anterior tooth retraction, the expected orthodontic goals were successfully achieved without the aid of mini-implant anchorage. Upon completion of the treatment, the upper and lower dental arches were neatly aligned, bilateral canines and molars achieved a Class Ⅰ occlusal relationship, the midlines of the upper and lower teeth aligned with the facial midline, and the overbite and overjet of the anterior teeth returned to normal. The occlusal relationship was stabilized, with significant improvements in the patient’s profile and oral function. This case suggests that for adult patients with severe crowding and lateral incisor crossbite, the clear aligner technology can effectively correct malocclusion through precise biomechanical design. It efficiently closes extraction spaces and completely resolves lateral incisor crossbite while maintaining aesthetic appeal and dental tissue health during treatment, providing a feasible clinical approach for such cases.

Key words: orthodontics, enamel hypoplasla, clear aligners, invisible extraction orthodontics, crowding