Angle Class II malocclusion is a common orthodontic condition characterised by a distal relationship between molars. This classification includes a high proportion of patients with protrusive facial profiles due to hypoplasia or mandibular retraction. In clinical practice, the twin block orthodontic appliance is frequently used for the correction of Angle Class II malocclusion in patients with mandibular retrognathism. The aim of the present study was to demonstrate the effective use of sagittal guidance twin block clear aligners (S8-SGTB), a product made by Smartee Denti-Technology (Shanghai, China), in the treatment of three patients aged from 23 to 30 years with different subtypes of Class II malocclusion. After 13 to 20 months of treatment, their Class II malocclusion had been corrected and an overall improvement in the occlusal relationship had been achieved. Acceptable two-dimensional changes were identified through cephalometric analysis. These results demonstrated that S8-SGTB clear aligners not only effectively corrected mandibular retrusion but also achieved balanced occlusal contact. In conclusion, the S8-SGTB clear aligner has shown promising clinical outcomes in treating adult patients with Class II malocclusion, deep horizontal and vertical overlap, and mandibular retrusion. Palabras clave: Class II malocclusion, clear aligner, sagittal-guidance twin block clear aligner (S8-SGTB), Smartee Denti-Technology