|
| Author | Country | Age | Sex | Tooth number | Root canals | Christies’s radicular type [12, 13] | Versiani’s pulpal floor type [14] | Additional information |
| MB | DB | MP | DP |
|
| Thews et al. 1979 [11] | USA | 21 | M | n.m. | 1 | 1 | 1 | 1 | n.m. (I) | — | Single, enlarged lingual cusp |
| Stabholz and Friedman 1983 [69] | Israel | 13 | F | 16 | 2 | 1 | 1 | 1 | n.m. (III) | B | Unusual configuration of the crown |
| Wong et al. 1991 [70] | USA | 22 | M | 26 | 2 | 1 | 2 | 1 | n.m. (III) | — | |
| Christie et al. 1991 [12] | Canada | n.m. | F | 16 | 1 | 1 | 1 | 1 | I | B | |
| Jacobsen and Nii 1994 [71] | USA | 25 | M | 26 | 2 | 1 | 1 | 1 | n.m. (III) | | Presented case 3 |
| Di Fiore 1999 [72] | USA | 31 | M | 16 | 1 | 1 | 1 | 1 | II | B | |
| Baratto-Filho et al. 2002 [13] | Japan | 38 | F | 16 | 1 | 1 | 1 | 1 | I | — | Presented case 1 |
| Maggiore et al. 2002 [73] | USA | 19 | M | 26 | 2 | 1 | 2 | 1 | n.m. (III) | — | Third palatal canal |
| Barbizam et al. 2004 [5] | Brazil | 35 | M | 26 | 1 | 1 | 1 | 1 | I | — | Presented case 1 |
| Nahmias and Bery 2006 [74] | Canada | 58 | F | 26 | 1 | 1 | 1 | 1 | n.m. (I) | — | |
| Adanir 2007 [75] | Turkey | 31 | M | 16 | 2 | 2 | 1 | 1 | n.m. (II) | A | |
| Ravishanker and Prashanthi 2008 [76] | India | 25 | F | 26 | 1 | 1 | 1 | 1 | n.m. (I) | — | |
| Gandhi and Madan 2009 [77] | India | 50 | M | 26 | 1 | 1 | 1 | 1 | n.m. (II) | B | |
| Tomazinho et al. 2010 [78] | Brazil | 32 | M | 26 | 2 | 2 | 1 | 1 | I | B | MB and DB RC : Vertucci Class II |
| Salapoor and Mollashahi 2010 [79] | Iran | 40 | F | n.m. | 1 | 1 | 1 | 1 | n.m. (II) | — | |
| He et al. 2010 [80] | China | 35 | M | 16 | 1 | 1 | 1 | 1 | n.m. (II) | A | |
| Chakradhar Raju et al. 2010 [81] | India | 24 | M | 26 | 1 | 1 | 1 | 1 | I | B | |
| | India | 21 | M | 16 | 1 | 1 | 1 | 1 | I | — | |
| Moghaddas and Tabari 2010 [82] | Iran | 41 | F | 26 | 1 | 1 | 1 | 1 | n.m. (I) | — | Enamel pearl, hemisection |
| Kottoor et al. 2011 [83] | India | 42 | M | 16 | 1 | 1 | 1 | 1 | n.m. (III) | A | 2 fused palatal roots |
| Singh et al. 2011 [84] | India | 21 | F | 16 | 1 | 1 | 1 | 1 | n.m. (I) | A | Presented case 1 |
| Reddy et al. 2011 [85] | India | 45 | M | 16 | 1 | 1 | 1 | 1 | n.m. (I) | B | |
| Du et al. 2011 [86] | China | 21 | F | 26 | 2 | 1 | 1 | 1 | n.m. (III) | B | |
| Madhuram et al. 2012 [87] | India | 27 | F | n.m. | 1 | 1 | 1 | 1 | n.m. (III) | — | Pronounced Carabelli tubercle |
| Kottoor et al. 2012 [88] | India | 23 | M | 26 | 1 | 1 | 1 | 1 | n.d. | A | Second mesiobuccal root, 16 with identical morphology |
| | India | 23 | M | 16 | n.m | n.m. | n.m. | n.m. | n.d. | — | |
| Mathew et al. 2013 [89] | India | 35 | M | 16 | 1 | 1 | 1 | 1 | I | — | |
| Rajalbandi et al. 2013 [90] | India | 42 | M | 26 | 1 | 1 | 1 | 1 | I | B | |
| Yesidal Yeter et al. 2013 [91] | Turkey | 28 | M | 16 | 2 | 2 | 1 | 1 | n.d. | A | Second mesiobuccal root |
| Aggarwal et al. 2013 [92] | India | 24 | M | 26 | 1 | 1 | 1 | 1 | I | A | |
| Ghani et al. 2013 [93] | India | 34 | F | 16 | 1 | 1 | 1 | 1 | I | B | End. retreatment, both teeth fused MB&MP roots |
| | India | 34 | F | 26 | 1 | 1 | 1 | 1 | I | B | |
| Sharma et al. 2014 [94] | India | 31 | F | 16 | 1 | 2 | 1 | 1 | n.d. | D | Fused MB&MP and DB&DP roots |
| Kararia et al. 2014 [95] | India | 20 | F | 26 | 1 | 2 | 1 | 1 | I | B | Endodontic retreatment, DB canal:Vertucci Class II |
| Shah and Jadhav 2014 [96] | India | 38 | F | 16 | 1 | 1 | 1 | 1 | n.m. (II) | B | Crown with four palatal cusps |
| Sánchez-Salas et al. 2014 [97] | Mexico | 31 | M | 26 | 1 | 1 | 1 | 1 | I | B | |
| Shrestha 2015 [98] | Nepal | 58 | F | 26 | 2 | 1 | 1 | 1 | II | A | Presented case 1, End. Retreatment |
| Asghari et al. 2015 [99] | Iran | 21 | F | 16 | 1 | 1 | 1 | 1 | I | B | |
| Wu and Wu 2015 [100] | China | 29 | M | 26 | 1 | 1 | 1 | 1 | n.m. (II) | B | |
| | China | 37 | M | 16 | 1 | 1 | 1 | 1 | n.m. (I) | v | Enamel pearl, pronounced cusp of Carabelli |
| Gu et al. 2015 [31] | China | n.a. | n.a. | 16 | 1 | 2 | 1 | 2 | n.m. (IV) | — | Fused MB&MP roots |
| Deepa et al. 2016 [101] | India | 41 | F | 16 | 1 | 1 | 1 | 1 | n.m. (I) | — | CBCT after extraction |
| | India | n.m. | n.m. | n.m. | 1 | 1 | 1 | 1 | I | A | End. Retreatment, DB canal: Vertucci II |
| Tao et al. 2016 [102] | China | 10 | F | 16 | 1 | 1 | 1 | 1 | n.m. (II) | A | Three well-developed lobulated palatal cusps |
| Nayak et al. 2016 [103] | India | 24 | M | 16 | 1 | 1 | 1 | 1 | I | A | |
| Barreto and Lins 2016 [104] | Brazil | 28 | M | 26 | 1 | 1 | 1 | 1 | n.m. (I) | — | MB canal: Vertucci Type II |
| Vázquez and Llácer 2016 [105] | Spain | 46 | M | 16 | 2 | 1 | 1 | 1 | n.m. (I) | A | |
| Rodrigues et al. 2016 [106] | Brazil | 23 | F | 16 | 3 | 2 | 1 | 1 | n.m. (III) | A | |
| Cao et al. 2017 [107] | China | 30 | M | 16 | 2 | 1 | 1 | 1 | n.m. (II) | B | |
| Magnucki et al. 2018 [108] | Germany | 51 | M | 26 | 2 | 1 | 1 | 1 | I | A | 2 enamel pearls, MB RC : Vertucci II |
| Meena and Hasija 2018 [109] | India | 27 | F | 16 | 1 | 1 | 1 | 1 | n.m. (III) | — | |
| Schryvers et al. 2018 [110] | Belgium | 44 | M | 26 | 1 | 1 | 1 | 1 | I | A | |
| Sriganesh and Priyan 2019 [111] | India | 18 | F | 26 | 2 | 1 | 1 | 1 | n.m. (III) | — | |
|
