Table 9 Summary of inter-orifices distances results of the mandibular first molar

Gu et al. [12]

Whole tooth/ (25)

length of a line between centre points of two orifices

Pulp chamber floor

MBO-MLO = 2.35

Harris et al. [52]

Whole tooth

(22)

1. The shortest linear distance between canals' orifices

2. The longest linear distance between canals' orifices

1.5 mm coronal to the furcation

Longest MB-ML = 3.09

Shortest MB-ML = 1.43

Longest DB-DL = 1.98

Longest M-D = 4.35

Versiani et al. [56]

MR

(258)

Distance between the mesial canals' orifices

1.5 mm coronal to the furcation

MMC-MLC 1.34 ± 0.74 (0.45–3.92), and

MMC-MBC 1.35 ± 0.74 (0.35–3.38)

Moe et al. [60]

MR

(75)

Distance between the centres of the MB and ML canals

at 1.5 mm coronal to the furcation

2.60 ± 0.41 (1.69–3.48 mm)

De-Deus et al. [11]

MR (28)

The linear distance between (MB) and (ML) canal orifices' centres

At the lowest level of the CEJ on the buccal aspect of the crown

MB-ML

3.76 ± 0.89 (2.36–5.58) in grp I

4.49 ± 0.75 (3.28–6.08) in grp II