Disturbed passive eruption of teeth is associated with aesthetic problems due to abnormal tooth proportions. Crown lengthening treatment can only be carried out once the final position of the incisal edges has been determined. In the case presented here, orthodontic treatment was carried out as a first step to realign the teeth. The surgical procedure was carried out using a set of instruments designed by Chu (Chu's Aesthetic Gauges, Hu Friedy). The desired length of the crowns of the teeth was visualised using a proportion gauge, followed by a gingivectomy. After dissection of the mucoperiosteal flap, the extent of osteoplasty and osteotomy required was assessed using the crown lengthening gauge. The distance from the bone edge to the enamel-cement junction should be approximately 2 mm. In the final step, the surgical flap was recomposed and stabilised. The last photo shows the clinical situation immediately after the procedure.