RELIABILITY OF PANORAMIC RADIOGRAPHS TO DETERMINE GONIAL AND FRANKFURT MANDIBULAR HORIZONTAL ANGLES IN DIFFERENT SKELETAL PATTERNS
Figure 2. Gonial and Farnakfort mandibular plane angles shown on panoramic radiograph |
Table 1. Mean and standard deviation of Go and FMA on lateral cephalograms and OPGs |
Gonial Angle |
FMA Angle |
Lateral Ceph. |
OPG |
Lateral Ceph. |
OPG |
|
Mean |
SD |
Mean |
SD |
Mean |
SD |
Mean |
SD |
Horizontal |
115.5 |
3.3 |
113.8 |
4.3 |
21.3 |
3.9 |
20.5 |
3.9 |
Normal |
123.3 |
2 |
121.1 |
2.4 |
25.8 |
3.1 |
25 |
3.2 |
Vertical |
132.7 |
2.9 |
128 |
4 |
31 |
4.2 |
29 |
3.7 |
Total |
123.8 |
7.6 |
121 |
6.9 |
26 |
5.5 |
24.9 |
5 |
Table 2. Correlation coefficient between lateral and OPG for Go angle |
|
Pearson’ s Correlation
Coefficient
|
p Value |
Horizontal |
0.733 |
0.01 |
Normal |
0.399 |
0.05 |
Vertical |
0.425 |
0.05 |
Total |
0.896 |
0.01 |
The mean value of the gonial angle in lateral cephalograms and OPGs were 123.8 ° ± 7.6 ° and 121 ° ± 6.9 °, respectively. The same value for FMA was 26 ° ± 5.5 ° and 24.9 ° ± 5 °, respectively.( Table 1) Pearson’ s correlation coefficient showed a significant correlation between the means of the gonial angle in the lateral cephalogram and OPG for all three groups of horizontal, normal and vertical growers. In horizontal growers r was 0.733( P < 0.01), in normal growers it was 0.399( P < 0.05) and in vertical growers it was 0.425( P < 0.05).( Table 2) According to Table 3 there were significant correlations between the means of FMA determined by OPG and Lateral cephalograms( P < 0.01).
4. Discussion
The current study was performed to evaluate the measurements of gonial and FMA angles in panoramic radiographs and lateral cephalograms. The analysis of the two techniques suggests that
Go and FMA can be reliably determined from the panoramic radiograph. The finding of the current study corresponds with the results of the studies done conducted by Larheim and Svanaes 4 and Oksayan et al. 5 Panoramic radiography is frequently used in orthodontic practice to provide important information about the teeth and their axial inclinations. Thus, this technique would allow a reduction in the patient radiation doses before or during orthodontic treatment. Go and FMA have important roles in predicting growth direction and are good indicators for mandibular steepness. Go and FMA also act as a valuable diagnostic landmarks to determine a patient’ s growth pattern. 6, 7 Since OPGs are routinely requested by dentists and orthodontists during clinical examination, being able to determine Go and FMA from OPGs would omit the need for further radiographic images such as lateral cephalograms. Matilla et al. 2 reported that the accuracy of the measurement of the gonial angle on panoramic radiograph is
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