Abstract
BackgroundThis study cephalometrically compared the dentoskeletal and soft tissue changes consequent to one and three-premolar extraction protocols of class II subdivision malocclusion treatment.MethodsA sample of 126 lateral cephalometric radiographs from 63 patients was selected and divided into two groups. Group 1 consisted of 31 type 1 class II subdivision malocclusion patients treated with asymmetric extractions of two maxillary premolars and one mandibular premolar on the class I side, with an initial mean age of 13.58 years. Group 2 consisted of 32 type 2 class II subdivision malocclusion patients treated with asymmetric extraction of one maxillary first premolar on the class II side, with an initial mean age of 13.98 years. t test was used for intergroup comparison at the pre- and posttreatment stages and to compare the treatment changes.ResultsGroup 1 had greater maxillomandibular sagittal discrepancy reduction and greater maxillary first molar extrusion. Group 2 had mandibular incisor labial inclination and protrusion, and group 1 had mandibular incisor lingual inclination and retraction. Maxillary molar asymmetry increased in group 2, while mandibular molar asymmetry increased in group 1.ConclusionsThe treatment changes produced by these two class II subdivision protocols are different to adequately satisfy the different needs for types 1 and 2 class II subdivision malocclusions.
Highlights
This study cephalometrically compared the dentoskeletal and soft tissue changes consequent to one and three-premolar extraction protocols of class II subdivision malocclusion treatment
Type 2 class II subdivision malocclusions are characterized by mesial positioning of the maxillary first molar on the class II side, deviation of the maxillary dental midline to the class I side and coincidence of the mandibular dental midline with the midfacial plane [4, 5]
One of the treatment options for type 1 class II subdivision malocclusions consists in extractions of two maxillary premolars and one mandibular premolar on the class I side, as long as the facial profile and/or the amount of crowding allow extractions to be performed [1, 6,7,8,9,10,11,12]
Summary
This study cephalometrically compared the dentoskeletal and soft tissue changes consequent to one and three-premolar extraction protocols of class II subdivision malocclusion treatment. Type 1 class II subdivision malocclusions are characterized by distal positioning of the mandibular first molar on the class II side, coincidence of the maxillary dental midline with the midfacial plane and deviation of the mandibular dental midline to the class II side, in a frontal clinical view [1,2,3,4,5]. Type 2 class II subdivision malocclusions are characterized by mesial positioning of the maxillary first molar on the class II side, deviation of the maxillary dental midline to the class I side and coincidence of the mandibular dental midline with the midfacial plane [4, 5].
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