Table 3 Peak maximum principal stress in normal root canal group, oversized root canal group and dumbbell-shaped root canal group within restored tooth components: root, post-core, crown, cement layer p, and cement layer c (MPa)

Root

305.49

307.5

299.3

90.162

90.284

89.6

116.38

117.86

109.51

Post-core

19.695

21.141

142.99

5.9645

7.2069

27.875

15.64

12.066

92.696

Crown

113.41

113.91

105.98

35.018

49.288

27.892

124.26

127.66

123.97

Cement layer p

6.1084

13.685

2.7704

1.0599

1.6532

0.56632

4.5313

23.4

1.707

Cement layer c

2.8624

2.7557

2.9279

2.281

2.9263

0.86601

3.7327

4.295

2.2453