<![CDATA[Background: Bimaxillary and bidental protrusion Class I Angle malocclusions have a characteristic convex facial profile and protrusion lips due to the labial inclination of the anterior teeth. Extraction of the first four premolars is the most common choice for orthodontic treatment of these cases when all the permanent teeth are complete and in good condition. Orthodontic treatment can be performed using the Begg or Straightwire techniques. Purpose: This study aims to investigate the difference in the effect of orthodontic treatment with Begg and Straightwire appliances on molar position, occlusal plane, and anterior and posterior facial height. Methods: Sixty pairs of lateral cephalograms before and after the treatment of patients with bimaxillary and bidental protrusive Angle malocclusion Class I, aged 18–35 years old, who underwent orthodontic treatment using the Begg and Straightwire techniques with the extraction of all first premolars that met the inclusion criteria. Data analysis was performed using two-way repeated analysis of variance (p<0.05) and Pearson correlation (p<0.05). Results: Molar position, occlusal plane angle, and anterior and posterior facial heights increased significantly after the Begg technique treatment and decreased significantly after the Straightwire technique treatment (p<0.05), but there were no significant differences between the four variables in the two techniques (p>0.05). Medium correlation was found between variables in both the Begg and Straightwire techniques. Conclusion: Molars were extruded and mesialized and the occlusal plane angle and height of the anterior and posterior faces increased after the Begg appliances treatment. The molars moved mesially and occlusally and there was a decrease in the occlusal plane angle, as well as the height of the anterior and posterior faces, after treatment with the Straightwire appliances. However, there was no difference between the two techniques.]]>
