### I. Introduction

### II. Materials and Methods

^{®}OP100 (Instrumentarium Imaging Ind. Co. Ltd., Tuusula, Finland), and cephalograms were taken by CX-90SP (Asahi Roentgen Ind. Co. Ltd., Kyoto, Japan). Each radiograph was taken with the same digital machine. Cephalometric data including SNA (Sella-Nasion-A point angle), SNB (Sella-Nasion-B point angle), ANB (A point-Nasion-B point angle), and APDI (Anterior Posterior Dysplasia Indicator) of selected patients, were measured by V-ceph 5.5 (Osstem Implant Co. LTD., Seoul, Korea), to confirm the Angle classification.

*™*5.0 (INFINITT Healthcare Co. LTD., Seoul, Korea).

*t*-test, Pearson’s correlation test and regression analysis. In regards to difference in genders, each value was compared by independent

*t*-test, and the homogeneity of variance was checked with Levene’s test. These analyses were performed using the SPSS 21 (SPSS Inc., Chicago, IL, USA).

### III. Results

*p*= 0.611). In the panoramic radiograph, there was no significant difference between right and left gonial angles (

*p*= 0.214). The gonial angle of each gender in panoramic radiographs also showed no statistically significant difference (

*p*= 0.843).

*ρ*) between average values of gonial angle in panoramic radiographs and lateral cephalograms was 0.945 (

*p*< 0.001), which means that there is a strongly positive relationship between each gonial angle. Also, the coefficient of determination (

*ρ*

^{2}) was 0.893. Fig. 3 presents regression analysis between gonial angles. The relationship between the gonial angle measurements obtained from each radiograph was represented in the linear function (GoA (C) : The value of gonial angle (lateral cephalograms), AGoA (P) : The average value of gonial angle (panormic radiographs)).

*p*< 0.001). The Pearson’s correlation coefficients of each value were 0.816 and 0.835, portraying a weaker correlation than gonial angles (Fig. 4, Fig. 5). Relationships between each value from panoramic radiographs and lateral cephalograms could be represented in the following linear equation (MnH (C) = Mandibular height (lateral cephalograms), AMnH (P) = Average mandibular height (panoramic radiographs), IMn (C) = The distance between lower incisors and mandibular symphysis (lateral cephalograms), IMn (P) = The distance between lower incisors and mandibular symphysis (panoaic radiographs)).

### IV. Discussion

*p*= 0.406). When Oksayan [7] also compared the gonial angle, the differences were found to be 0.04° on the right side and 0.02° on the left side with no statistically significant differences. These disparities in results could be results of unspecified samples and study designs. While this study’ s sample age was between 4 and 12 years, Shahabi [6] and Oksayan [7] focused on adult and adolescent (each with age range of 12-29 and 15-30 years). Ghosh [10] concluded that the gonial angle tended to increase with age in the panoramic radiographs. Children’s mandibular body is short, and they have more round mandible than adults, because eruption of the permanent dentition is correlated with an anteroposterior increase in mandibular body length [11]. The corpus divergence of children’s mandible is larger than adults. The direction of an x-ray beam in a panoramic radiograph is perpendicular to a horseshoe shaped focal trough, but the x-ray beam of a lateral cephalogram irradiates perpendicular to the sagittal plane of the head. Therefore, in this study, each gonial angle of children shows statistically significant differences, whereas others did not.

*ρ*) between the average values of gonial angle in panoramic radiographs and lateral cephalograms was 0.945 (

*p*value < 0.001). It means each value shows a strong positive relationship. As a result, the gonial angle obtained from a panoramic radiograph can help to predict the angle from a lateral cephalogram.

*p*= 0.843), and there was no significant difference between right and left angles (Right = 125.71°, Left = 125.28°,

*p*= 0.214). These findings coincided with the results of previous studies [6,7,13,16]. Akcam [16] stated that there was no statistically significant difference between male and female subjects. Larheim [13] stated that no statistically significant differences were observed between the reproducibility of the right and left gonial angle.