Atypical Orthodontic Extraction In The Treatment Of An Adult Patient With ClassⅠMalocclusion

Objective: The aim of this paper is to discuss the effect of upper unilateral extraction and lower incisor extraction in treating special Angle Class I cases.Method: A 20-year-old male patient was selected from Dr. Dalian dental clinic in July 2011.This patient was a borned unilateral cleft of lip with 3 times lip repaired operations.He presented as skeletal class III with retruded maxillary,and his profile was slightly concave.Permanent dentition with 21 erupted palatal inclined which resulted in crossbite of 31、32,and 42 lingual malpositioned. Maxillary midline shifted 4.5mm to the left side and mandible midline shifted 2.5mm to the right side. Both sides molar relationship were Class I, left side canine relationship was Class I and right side canine relationship was Class II. Overjet was 2mm and overbite was 4mm,the curve of spee was 2mm.Maxillary crowding was 4.5mm for alignment and adjusting the midline,madible crowding was 6.5mm with leveling the curve of spee. Considering of the results of X-ray and diagnostic setting-up of this patient,straight archwire technique was applied with extraction of 14,42,38,48. Then we compare and analysis the pre-treatment and pos-treatment casts and cephalometrics.Result: The treatment course was 22 months.Both dentitions were well aligned and leveled; overjet and overbite were normal. Maxillary midline was in the middle with correction of the palatal inclined incisor, both sides canine relationship were Class I, leftside molar relationship were Class I, right side molar relationship were Class II.By comparing the panoramic X-ray,there were no obvious resorptions in the root area or aveolar bone.Cephalometrics showed:(1)No obvious changes of SNA, SNB decreased1°,ANB increased 0.8° to-1.2°,NA-PA increased 0.7°,APDI decreased 4.5°,WITS decreased from-5.5mm to-1.7mm, above all,skeletal class III was slightly improved;FMA increased 1.5°,MP-SN increased 1.3°, indicated the clockwise rotation of mandible.(2) U1-SN decreased 3.5°,the angle of U1-NA decreased 2.8°,the distance of U1-NA decreased 2.5mm,for the position changed and slightly retruded of the central incisor;Axis of lower anterior teeth showed no obvious changes;OP-SN increased from17.5°to 21.5°,which resulted from the extrusion of upper incisors.(3)His profile was well kept,upper and lower lip retracted as the retraction of teeth.Conclusion:According to the analysis results and by the guidance of diagnostic setting-up, with foresights about any possible problems, atypical orthodontic extraction can be successful in treating special cases.