Allen et al – J Endod 1987
| No. of Years | % of cases | Cum. % |
|---|---|---|
| < 1 | 21.9 % | 21.9 % |
| 1 - 2 | 37.3 | 59.2 |
| 2 - 5 | 13.7 | 72.9 |
| > 5 | 27.1 | 100.0 |
No. of cases examined: 1300
Time Since Previous Endodontic Treatment until Re-Treatment Required[^13]
Abbott 1998
| No. of Years | % of cases | Cum. % |
|---|---|---|
| < 1 | 21.2 % | 21.2 % |
| 1 - 2 | 15.8 | 37.0 |
| 2 - 5 | 24.0 | 61.0 |
| > 5 | 39.0 | 100.0 |
No. of cases examined: 575