The deviations and misalignments of teeth and jaw can lead to Angle's Class I malocclusion (division 3 and 4 according to Anderson) and Angle's Class III malocclusion. It causes cross-bite in front incisor, premolar or molar teeth with relatively high proportion. The proportion of patients with Angle's Class I malocclusion (division 3 and 4 according to Anderson) and Angle's Class III malocclusion due to the combination of maxillarvlaterallv deficiency and mandibular prognathism vaties in ethnicity and area residents. In clinical practice, the authors conducted treatments for 86 patients with Angle's Class I malocclusion (division 3 and 4 according to Anderson) and Angle's Class III malocclusion to the following objectives: - Evaluate dentofacial phenotypes, X-ray images of patients having Angle's Class I malocclusion (division 3 and 4 according to Anderson.) and Angle's Class III malocclusion. - Analyze the results of treatments using MBT straight wires in patients with Angle's Class I malocclusion (division 3 and 4 according to Anderson) and Angle's Class III malocclusion. Treatment results are shown as followings: 1. The prevalence of Angle's Class I malocclusion (division 3 and 4 according to Anderson) is quite high with 79.06 percent and that of Angle's Class III malocclusion is 20.93 percent. The collected data on Cephalometric films before and after of Class III malocclusion treatments showed improvements in prognosis, especially with a good correspondence in sagittal plane (anterior to posterior relationship). 2. Results of treatments have been achieved in accordance with the standard functionality, aesthetics, X - ray and PAR scores in both pre and post treatments. The percent of good results is 90.69 percent and that of mediocre result is 9.30 percent. The average duration of the treatments is 2,366 + or - 24.68 months.