Table 6. Frequency distribution of the available bone thickness parameters.
| Range | IRB2 | IRB4 | IRBA | |||
|---|---|---|---|---|---|---|
| N | Ratio (%) | N | Ratio (%) | N | Ratio (%) | |
| ≤ 2.0 | 6 | 4.29 | 0 | 0 | 1 | 0.71 |
| 2.1 ‒ 3.0 | 87 | 62.14 | 55 | 39.29 | 9 | 6.43 |
| 3.1 ‒ 4.0 | 47 | 33.57 | 66 | 47.14 | 40 | 28.57 |
| 4.1 ‒ 5.0 | 0 | 0 | 17 | 12.14 | 50 | 35.71 |
| 5.1 ‒ 6.0 | 0 | 0 | 2 | 1.43 | 33 | 23.57 |
| > 6.0 | 0 | 0 | 0 | 0 | 7 | 5.00 |
| Total | 140 | 100 | 140 | 100 | 140 | 100 |
IRB2/IRB4: the interradicular alveolar bone thickness at 2 mm, 4 mm apical from the furcation fornix; IRBA: the interradicular alveolar bone thickness between the mesial and distal root apex.