Table 2 Log of endodontic treatment time and variables in the final ANCOVA model

Study site Hong Kong Beijing^a

3.09

21.86

6.15 – 77.69

<0.001

Root canal multiple single^a

0.62

1.85

1.72 – 2.00

<0.001

Preoperative pain presence absence^a

0.09

1.09

1.01 – 1.18

0.028

Visit multiple visits single visit^a

0.28

1.32

1.22 – 1.43

<0.001

Use of magnifying loupe Yes No^a

−0.22

0.80

0.73 – 0.88

<0.001

Experience of the operator

−0.27

0.76

0.66 – 0.88

<0.001