© 2006 - The Charles H. Tweed International Foundation

Fig. 2B. Pretreatment dental castsmeasurement of 6mm reflects alveolar imbalance.The cephalogram and itstracing (Figs. 4A, 4B) illustrate anANB angle of 3 o . The SNA angleof 77 o confirms a slight maxillarydeficiency. The FMA is 8 o . The.86 facial height index of Horn 1 isa confirmation of an imbalance ofanterior and posterior facial height.The IMPA angle of 92 o reflectsan acceptable inclination of themandibular incisors. The Z angle 2of 88 o confirms a retruded softtissue overlay, however, Wits 3,4TREATMENT OBJECTIVES1. Maintain a normal profile line to nose relationship and a normal Z angle 22. Reduce overbite and overjet3. Obtain normal canine and incisal guidance4. Increase lower anterior facial heightTREATMENT ALTERNATIVES1. Extract the maxillary 1 st premolars andmandibular 2 nd premolars to correct the overjet andoverbite. This option could have a deleterious effect onthe facial profile.2. Extraction of only the maxillary right and left 1 stpremolars to correct the overbite and overjet. This optioncould collapse the upper lip.3. Non extraction 10-2 orthodontic treatment. Thisoption was considered but the amount of cooperationrequired was not appealing to the patient.Fig. 3. Pretreatment panoramic radiograph4. Non extraction treatment and a mandibular advancement with a genioplasty to increase lower facial height.This option would provide an ideal result.Fig. 4A. Pretreatment cephalometricradiographFig. 4B. Pretreatment cephalometric tracingTREATMENT PLANWhen orthodontictreatment withoutsurgical correction isplanned, the diagnosisis predicated on thepretreatment positionand the desired finalposition of themandibular incisors.Merrifield’s totalspace analysis 5, 6 wasused to determinespace requirements.13