| Author (year) | Origin | No. of teeth | One root | Two roots | Three roots |
| Pineda & Kuttler (1972) [12] | Mexicans | 259 | 43.0 | 54.6 | 2.4 |
| Carns & Skidmore (1973) [10] | White Americans | 100 | 22.0 | 72.0 | 6.0 |
| Vertucci & Gegayff (1979) [6] | White Americans | 400 | 39.5 | 56.5 | 4.0 |
| Walker (1987) [9] | Chinese | 100 | 60.0 | 40.0 | 0 |
| Pecora et al. (1992) [4] | Brazilians | 240 | 55.8 | 41.7 | 2.5 |
| Loh (1998) [8] | Singaporeans | 957 | 49.4 | 50.6 | 0 |
| Chaparro et al. (1999) [14] | Spanish | 150 | 40.0 | 56.7 | 3.3 |
| Lipski et al. (2003) [5] | Polish | 142 | 15.5 | 75.3 | 9.2 |
| Awawdeh et al. (2008) [7] | Jordanians | 600 | 30.8 | 68.4 | 0.8 |
| Atieh (2008) [29] | Saudis | 246 | 17.9 | 80.9 | 1.2 |
| Özcan et al. (2012) [36] | Turkish | 653 | 45.2 | 53.7 | 1.1 |
| Rwenyonyi et al. (2011) [13] | Ugandans | 202 | 26.7 | 73.3 | 0 |
| Elkady et al. (2013) [35] | Saudis subpopulation | 120 | 28.3 | 71.7 | 0 |
| The present study | Kosovar | 221 | 21.72 | 70.14 | 8.14 |