| Objective：Bimaxillary protrusion is a malocclusion which is characterized byincreased proclination of the upper and lower incisors, marked procumbency of the lips,increased facial convexity. It may be present on a Class I and Class II skeletal base. Theaim of this particular case report is to demonstrate the effectiveness of extraction of fourfirst bicuspids as an alternative treatment on a severe Class II skeletal bimaxillaryprotrusion case and the effectiveness will be evaluated qualitatively by using the PeerAssessment Rating Index (PAR Index).Methods and Diagnostics：In February2010, a12years old female patientattended the Orthodontic department of the Second Affiliated Hospital of DalianMedical University, chief complaints were crowding and protrusive lips. Cephalometricvalues showed, Class II skeletal base (ANB:5.5°), increased proclinations of the upperand lower incisors (┴SN:112°, IMPA:95°), convex profile and decreased esthetics (Zangle:53°, UL-E line:+4mm, LL-E line:+4mm). Patient was a high angle (FMA:40°), she presented with severe crowding in the lower arch. Initial PAR Index was28.The patient was treated with extraction of four first bicuspids and a fixedpreadjusted edgewise appliance. Reinforced anchorage in the form of lingual arch wereused during upper canine retraction.Results：Total treatment time was23months, post-cephalometric analysis showedupper and lower incisors uprighting (┴SN:101°, IMPA:91°). No posterior extrusionand increased facial esthetics was noticed. Facial convexity could not be fully beresolved due to the severity of the case initially and due to limited treatment options.Post treatment PAR Index obtained was2, which fell in the greatly improved area of thePAR nomogram. Conclusion Considering the severity of the case, since the results obtained arerelatively appreciable, we may conclude that the extraction of four first premolars totreat severe bimaxillary protrusion cases may be a feasible option. |
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