Comparison of some cephalometric indices in skeletal class III with skeletal class I patients

ABSTRACT

The individual variations in patients with skeletal class III malocclusions affect the cephalometric indices e.g., the curve of cranial base and anteroposterior displacement of nasion and the SN inclination can affect the cephalometric indices such as the ANB angle. The aim of this study was to compare some cephalometric indices in skeletal class III with skeletal class I patients as control group. Samples in this Case-control study were 65 lateral cephalometric radiographs randomly selected before the orthodontic treatment. The samples were divided into two study and control groups with skeletal class III relationship [ANB<1] and skeletal class I relationship [2Wits, Jaraback index, GOGn-SN, IMPA, overbite, lower facial height, and Mandibular length were indicative of significant differences between two skeletal class I and III groups. The Wits appraisal showed a significant positive relation with ANB [P<0.001, r= 0.71] and a significant negative relation with FMA [P=0.01, r= -0.41], lower facial height [P=0.02, r= -0.37], anterior facial height [P<0.001, r= -0.47], and the mandibular length [P=0.02, r= -0.37]. According to the data found in the present study, the Wits appraisal is a valuable diagnostic index for evaluating the intensity or anteroposterior jaw discrepancy in skeletal class III patients. From the jaw position and size point of view, the maxillary retrognathism and the mandibular length are the main determining factors for maxilomandibular relationship, respectively. The dental compensation for skeletal class III patients is more associated with the mandibular incisor retrusion rather that the maxillary incisors protrusion