| Total examined | Normal | TF | TF | Pearson Chi square | P value | |
| No. | No. | % | ||||
| Boys | 528 | 451 | 77 | 14.6 | 4.4798 | 0.034 |
| Girls | 567 | 457 | 110 | 19.4 | ||
| Total | 1095 | 908 | 187 | 17.1 |