This case report describes the treatment of a Class II malocclusion with upper lateral incisors agenesis in an adult patient, performed by an invisible preadjusted lingual appliance, monolateral space opening and dental Class II correction. The patient had previously been treated by clear aligners with the insertion of an implant in upper right canine position in order to close the remaining space. With the twofold aim of obtaining ideal occlusal relationship and smile aesthetic improvement, it highlights how a fixed orthodontic technique is needed to achieve the planned results, when anterior torque, bodily translations and deep-bite correction are necessary. On the other hand, it underlines how the treatment plan should not be adapted to the limits of the employed appliance, but should aim for the best clinical result for the patient. A prosthetic finalisation was in the end performed in order to obtain the best aesthetic result.