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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