This study aimed to investigate the dental effects of a three-dimensional (3D) bimetric maxillary distalizing arch. The Wilson rapid molar distalization appliance for Class II molar correction was used in 14 patients (10 girls and four boys with a mean age of 12.18 years). The open coil springs were activated with bent Omega stops and Class II intermaxillary elastics. The mandibular anchorage was gained by a 0.016 x 0.016 utility arch with a 3D lingual arch or a lip bumper with a standard lingual arch. The lateral cephalograms taken before and after treatment formed the material of the research. A Wilcoxon test was used to statistically evaluate the treatment effects. The results showed that the distal tipping of the maxillary first and second molars, and first and second premolars and canines were statistically significant. Significant distal movement occurred in all posterior and canine teeth. The maxillary first molar distalization was found to be 3.5 mm. The maxillary incisor showed significant proclination and protrusion. The decrease in overbite was found to be statistically significant. The mandibular plane angle significantly increased by a mean of 0.5 mm. In addition, significant soft tissue changes were observed.
The purpose of this study was to evaluate the effects of bilateral upper premolar extraction on mandibular growth. Twenty-six subjects (eight males, 18 females) in maximum pubertal growth with an Angle Class II molar relationship, normal to mild overjet increase, mild or no lower arch length discrepancy but severe upper arch discrepancy and no severe skeletal discrepancy were divided into two groups equal in number and gender, as extraction and control groups. The median chronological age was 11.2 years in the extraction group and 12.6 years in the controls. The subjects were observed for a median period of 1.1 years in the extraction group after bilateral extraction of the upper premolars and 1.2 years in the controls until termination of pubertal growth (DP3u) without any orthodontic treatment. Twenty-nine linear and angular measurements were made on 52 lateral cephalograms and hand-wrist radiographs taken before and after the study period. The increase in SNB measured on the total superimposition was significantly greater in the controls than in the extraction group (P < 0.05). In addition, anterior mandibular (counter-clockwise) rotation was only significant (P < 0.05) in the control group. Thus, it might be suggested that bilateral upper premolar extractions might affect the mandibular rotation tendency.
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