**Table 3.** *Number of roots and root canals of maxillary third molars in different populations.*

**129**

**Author(s)** Weng et al. [41]

China (2009) (HAN)

MB DB

P

Sert et al.

Turkey

Single

63.1

12.3

7

12.2

3.5

–

–

–

–

–

–

–

1.75

(2011)

MB DB

P

Ahmad

Jordan

Single

66.8

–

8.3

–

8.3

8.3

–

–

8.3

–

–

–

–

(2016)

MB DB

P

Zhang et al.

China

Single

51.4

12.8

5.7

1.4

12.8

–

–

–

1.4

5.7

1.4

1.4

1.4

(2018)

MB DB

P

**Table 4.**

*Root canal configuration of maxillary third molar in different populations.*

93.9

–

–

6.1

–

–

–

–

–

–

–

–

–

100

–

–

–

–

–

–

–

–

–

–

–

–

72.7

–

–

12.1

12.1

–

3

–

–

–

–

–

–

[50]

100

–

–

–

–

–

–

–

–

–

–

–

–

100

–

–

–

–

–

–

–

–

–

–

–

–

55

5

–

20

15

–

–

5

–

–

–

–

–

et al. [46]

100

–

–

–

–

–

–

–

–

–

–

–

–

100

–

–

–

–

–

–

–

–

–

–

–

–

77.8

13.1

–

5.1

4

–

–

–

–

–

–

–

–

[49]

91.6

–

4.2

–

4.2

–

–

–

–

–

–

–

–

87.5

–

4.2

–

8.3

–

–

–

–

–

–

–

–

62.5

20.8

4.2

8.3

4.2

–

–

–

–

–

–

–

Single

63.2

21

–

–

–

5.3

10.5

–

–

–

–

–

–

**Country (year)**

**Root**

**Type (1-1)**

**Type (2-1)**

**Type (1-2-1)**

**Type (2-2)**

**Type (1-2)**

**Type (2-1-2)**

**Type (3-3)**

**Type (1-2-3)**

**Type (1-3)**

**Type (3-2-1)**

**Type (1-3-2)**

**Type (3-2)**

**Type (3-1)**

*Morphology of Root Canal System of Maxillary and Mandibular Molars*

*DOI: http://dx.doi.org/10.5772/intechopen.84151*

–


#### *Morphology of Root Canal System of Maxillary and Mandibular Molars DOI: http://dx.doi.org/10.5772/intechopen.84151*

*Human Teeth - Key Skills and Clinical Illustrations*

**Number of canals**

**128**

**Author(s)** Sidow et al. [44]

Ng et al. [48] Alavi et al. [45]

Weng et al. [41]

Sert et al. [49] Cosić et al. [47]

Ahmad et al. [46]

Zhang et al. [50]

Razumova et al. [40]

**Table 3.**

*Number of roots and root canals of maxillary third molars in different populations.*

Russia (2018)

CBCT

238

47.9

–

52.1

–

13.8

11.8

72.3

2.1

–

–

Jordan (2016) China (2018)

Micro KT

130

51.5

19.2

25.4

3.8

–

–

–

–

–

–

Clearing

89

13.5

5.6

74.2

6.7

9

6.7

55.1

27

2.2

–

USA (2000) Burmese (2001)

Thai (2002) China (2009) Turkey (2011) Croatia (2013)

Sectioning

56

8.9

5.4

83.9

1.8

7.1

7.1

75

10.8

–

–

Clearing

290

35.5

28.6

34.1

1.7

12.4

29.7

46.9

11

–

–

Clearing

43

–

–

–

–

27.9

11.6

44.2

16.3

–

–

Clearing

151

1.3

6.6

88.1

4

9.9

11.3

48.3

29.1

1.3

–

Clearing

72

19.4

19.4

55.6

5.6

5.6

25

47.2

22.2

–

–

Clearing

150

15

32

45

7

7.4

3.3

57.3

27.3

2.7

0.7

**Country (year)**

**Type of** 

**Number of** 

**Number of roots**

**teeth**

**1**

**2**

**3**

**4**

**1**

**2**

**3**

**4**

**5**

**6**

**study**

**Table 4.**

*Root canal configuration of maxillary third molar in different populations.*

#### **Figure 13.**

*Maxillary third molar with one root and one long oval canal (A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*

#### **Figure 14.**

*Maxillary third molar with one root and two canals (A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*

(2-1) and type IV (2-2) (**Table 6**). The distal root has one straight canal with type I (1-1), and the incidence of two canals is less and ranged from 3.5 to 20% [61]. The incidence of C-shaped root canals is higher in this tooth than the other teeth

**131**

mandibular second molars.

*middle third of root canal, (C) apical third of root canals.*

**Figure 15.**

**4.3 Mandibular third molar**

*Morphology of Root Canal System of Maxillary and Mandibular Molars*

(**Figure 18**). Several studies have reported the C-shaped canals among various populations: India (13.12%) [61], Korea (40%) [62], Brazil (3.5–15.3%) [63, 64], China (29–39%) [59, 65, 66], Russia (8.5%) [67], Saudi Arabia (9.1%) [60], and Jordan (21.6%) [16]. This variation could be related to ethnic groups. Regarding the root canal shape, mesial roots tend to have ribbon-shape type I or V by Kim et al., and the distal root canal in most cases has an oval shape and round in some cases (**Figure 19**). **Table 6** represents the root canal configurations of two-rooted

*Mandibular first molar with four canals (two mesial and two distal) (A) coronal third of root canals, (B)* 

This tooth erupts between the ages of 17 and 25 years old. It has morphologi-

cal radicular variations. Many dental treatment plans work on maintaining this tooth to use it as a strategic abutment when the first and second molars are missed, especially when there is sufficient room in the dental arch. Frequently, it has two roots (mesial and distal). A few studies in various populations found that mandibular third molar could have from one to four roots (**Figures 20** and **21**), which could be related to genetics and race differences; as in Croatia and China, one-rooted third molar was reported in 56% [47] and 48% [50] of cases, respectively (**Figure 22**) (**Table 7**). The root canal system of this tooth is unpredictable;

*DOI: http://dx.doi.org/10.5772/intechopen.84151*

*Morphology of Root Canal System of Maxillary and Mandibular Molars DOI: http://dx.doi.org/10.5772/intechopen.84151*

#### **Figure 15.**

*Human Teeth - Key Skills and Clinical Illustrations*

**130**

**Figure 13.**

**Figure 14.**

*third of root canal, (C) apical third of root canals.*

*canal, (C) apical third of root canals.*

(2-1) and type IV (2-2) (**Table 6**). The distal root has one straight canal with type I (1-1), and the incidence of two canals is less and ranged from 3.5 to 20% [61]. The incidence of C-shaped root canals is higher in this tooth than the other teeth

*Maxillary third molar with one root and two canals (A) coronal third of root canals, (B) middle third of root* 

*Maxillary third molar with one root and one long oval canal (A) coronal third of root canals, (B) middle* 

*Mandibular first molar with four canals (two mesial and two distal) (A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*

(**Figure 18**). Several studies have reported the C-shaped canals among various populations: India (13.12%) [61], Korea (40%) [62], Brazil (3.5–15.3%) [63, 64], China (29–39%) [59, 65, 66], Russia (8.5%) [67], Saudi Arabia (9.1%) [60], and Jordan (21.6%) [16]. This variation could be related to ethnic groups. Regarding the root canal shape, mesial roots tend to have ribbon-shape type I or V by Kim et al., and the distal root canal in most cases has an oval shape and round in some cases (**Figure 19**). **Table 6** represents the root canal configurations of two-rooted mandibular second molars.

#### **4.3 Mandibular third molar**

This tooth erupts between the ages of 17 and 25 years old. It has morphological radicular variations. Many dental treatment plans work on maintaining this tooth to use it as a strategic abutment when the first and second molars are missed, especially when there is sufficient room in the dental arch. Frequently, it has two roots (mesial and distal). A few studies in various populations found that mandibular third molar could have from one to four roots (**Figures 20** and **21**), which could be related to genetics and race differences; as in Croatia and China, one-rooted third molar was reported in 56% [47] and 48% [50] of cases, respectively (**Figure 22**) (**Table 7**). The root canal system of this tooth is unpredictable;

#### **Figure 16.**

*Mandibular first molar with three canals (two mesial and one distal) the mesial canals shape have the ribbon type I by Kim, while the distal canal shape is long oval (A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*

**Figure 17.**

*Mandibular second molar with three canals (two mesial + one distal) (A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*

it could have from one to six canals [44]. The most common form is to have three canals (two mesial canals and one distal canal). **Table 7** presents the root and canal number in different populations. Regarding root canal configurations, type (1-1) prevailed mostly in mesial and distal roots of two-rooted teeth and in

**133**

**Author(s)** Chourasia et al. [52]

Muriithi

Kenya

M

3.3

7.9

–

87.3

–

1.1

–

–

–

–

–

–

–

(2012)

D

50.3

18.5

1.6

22.2

5.3

–

–

–

–

–

–

–

et al. [54]

Kim et al.

Korea

M

1.8

20.2

0.3

76.9

0.5

–

–

–

–

0.1

0.2

–

–

(2013)

D

66.6

19

0.3

11.8

2.1

–

–

–

–

–

–

–

–

[51]

Zhang

China

M

0.9

5.6

4.8

87.7

0.9

–

–

–

–

–

–

–

–

et al. [59]

Torres

Chile

M

2.9

19

28.5

21.9

21.9

21.9

3.6

–

–

–

–

–

–

2015

D

78.8

–

12.4

–

5.8

–

2.9

–

–

–

–

–

–

et al. [56]

Torres

Belgium

M

1.4

5

33.6

16.4

42.9

–

0.7

–

–

–

–

–

–

(2015)

D

72.9

–

17.1

–

9.3

–

0.7

–

–

–

–

–

–

et al. [56]

Celikten

Turkey

M

2.4

34.9

–

62.7

–

–

–

–

–

–

–

–

–

(2016)

D

84

11.8

0.3

3.4

0.3

0.3

–

–

–

–

–

–

–

et al. [53]

Madani

Iran

M

7.3

31.5

2

57

2

–

–

–

–

–

–

–

–

et al. [57]

Martins

Portugal

M

1.1

46.5

–

41.9

–

4.1

–

–

0.9

2.1

0.2

3.2

–

(2017)

D

70.9

12.4

9.6

2.3

3.2

0.9

–

–

0.5

–

–

–

0.2

et al. [30]

Pérez-Heredia

Spain

M

–

51.3

–

37.8

0.8

1.7

–

1.7

–

5.9

–

–

–

(2017)

D

72.3

18.5

5.9

2.5

–

–

–

–

–

–

0.8

–

–

et al. [33]

(2017)

D

79.8

10.7

4.6

3.3

1.3

–

–

–

–

–

–

–

–

(2015)

D

65.9

2.4

0.3

9.2

–

–

–

–

–

–

–

–

–

India (2012)

M D

65.3

20.6

1.3

9.3

3.3

–

–

–

–

–

–

–

–

–

36.6

–

54

0.6

8

0.6

–

–

–

–

–

–

**Country (year)**

**Root**

**Type (1-1)**

**Type (2-1)**

**Type (1-2-1)**

**Type (2-2)**

**Type (1-2)**

**Type (2-1-2)**

**Type (1-2-1-2)**

**Type (2-3-1)**

**Type (2-1- 2-1)**

**Type (3-2)**

**Type (2-3-2)**

**Type (3-2-1)**

**Type (1-2-1- 2-1)**

*Morphology of Root Canal System of Maxillary and Mandibular Molars*

*DOI: http://dx.doi.org/10.5772/intechopen.84151*

–


#### *Morphology of Root Canal System of Maxillary and Mandibular Molars DOI: http://dx.doi.org/10.5772/intechopen.84151*

*Human Teeth - Key Skills and Clinical Illustrations*

**132**

**Figure 16.**

**Figure 17.**

*root canal, (C) apical third of root canals.*

*middle third of root canal, (C) apical third of root canals.*

it could have from one to six canals [44]. The most common form is to have three canals (two mesial canals and one distal canal). **Table 7** presents the root and canal number in different populations. Regarding root canal configurations, type (1-1) prevailed mostly in mesial and distal roots of two-rooted teeth and in

*Mandibular second molar with three canals (two mesial + one distal) (A) coronal third of root canals, (B)* 

*Mandibular first molar with three canals (two mesial and one distal) the mesial canals shape have the ribbon type I by Kim, while the distal canal shape is long oval (A) coronal third of root canals, (B) middle third of* 


## **Table 5.**

**135**

**Figure 19.**

**Figure 18.**

*Morphology of Root Canal System of Maxillary and Mandibular Molars*

*Mandibular second molar with C-shaped canal (A) Sagittal view of mandibular second molar, (B) coronal* 

*Mandibular second molar two canals (one oval mesial + one round distal)(A) coronal third of root canals,* 

*(B) middle third of root canal, (C) apical third of root canals.*

*third of root canals, (C) middle third of root canal, (D) apical third of root canals.*

*DOI: http://dx.doi.org/10.5772/intechopen.84151*

*Root canal configurations of mandibular first molars in different populations.*

*Morphology of Root Canal System of Maxillary and Mandibular Molars DOI: http://dx.doi.org/10.5772/intechopen.84151*

*Human Teeth - Key Skills and Clinical Illustrations*

**134**

**Author(s)**

**Country** 

**Root**

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**(1-1)**

**(2-1)**

**(1-2-1)**

**(2-2)**

**(1-2)**

**(2-1-2)**

**(1-2-1-2)**

**(2-3-1)**

**(2-1-**

**(3-2)**

**(2-3-2)**

**(3-2-1)**

**(1-2-1-**

**2-1)**

**2-1)**

**(year)**

Gambarini

West

M

41

59

Europe

D

100

–

–

–

–

–

–

–

–

–

–

–

–

(2018)

et al. [58]

**Table 5.**

*Root canal configurations of mandibular first molars in different populations.*

*Mandibular second molar with C-shaped canal (A) Sagittal view of mandibular second molar, (B) coronal third of root canals, (C) middle third of root canal, (D) apical third of root canals.*

#### **Figure 19.**

*Mandibular second molar two canals (one oval mesial + one round distal)(A) coronal third of root canals, (B) middle third of root canal, (C) apical third of root canals.*


**137**

**Author(s)** Pawar et al. [61]

**Table 6.**

*Root canal configurations of mandibular second molars in different populations.*

India (2017)

M D

61.1

18.2

–

7.5

–

–

–

–

–

–

–

–

–

7.2

32.5

0.9

45.2

1

–

–

–

–

–

–

–

–

**Country (year)**

**Root**

**Type (1-1)**

**Type (2-1)**

**Type (1-2-1)**

**Type (2-2)**

**Type (1-2)**

**Type (2-1-2)**

**Type (1-2- 1-2)**

**Type (3-1)**

**Type (2-1- 2-1)**

**Type (3-2)**

**Type (2-3- 2-1)**

**Type (3-2-1)**

**Type (3-2-3- 2-1)**

*Morphology of Root Canal System of Maxillary and Mandibular Molars*

*DOI: http://dx.doi.org/10.5772/intechopen.84151*


*Human Teeth - Key Skills and Clinical Illustrations*

**136**

**Author(s)** Al-Qudah

Jordan

M

16.1

32.6

3.5

40.3

3.5

1

0.3

–

–

0.3

–

0.3

–

(2009)

D

79

7.7

2.6

4.5

5.5

–

–

–

–

–

–

–

–

and

Awawdeh

[16]

Neelakantan

India

M

8.4

2

1.4

63.1

5.2

–

–

2

–

1.1

–

–

–

(2010)

D

64.9

4.6

0.6

11

1.7

–

–

–

–

–

–

–

–

et al. [68]

Ceperuelo

Spain

M

12.5

56.2

18.7

–

6.2

–

–

–

–

–

–

–

–

(2014)

D

81.2

6.2

–

6.2

–

–

–

–

–

–

–

–

–

et al. [69]

Torres et al.

Chile

M

17.5

7.2

48.4

4.1

20.6

–

2.1

–

–

–

–

–

–

(2015)

D

99

–

–

–

1

–

–

–

–

–

–

–

–

[56]

Torres et al.

Belgium

M

11.7

5.3

37.2

14.9

28.78

–

2.13

–

–

–

–

–

–

(2015)

D

98.4

–

–

–

1.06

–

–

–

–

–

–

–

–

[56]

Celikten

Turkey

M

7.1

32.3

0.2

60.3

–

–

–

–

–

–

–

–

–

(2016)

D

96.3

2.5

–

1

–

0.2

–

–

–

–

–

–

–

et al. [52]

Kim et al.

Korea

M

13.9

37.7

1.2

44.5

2.6

–

–

–

–

–

–

–

–

(2016)

D

96.6

2.1

–

0.9

0.4

–

–

–

–

–

–

–

–

[62]

Pérez-Heredia et al.

Spain

M

3

78.2

–

14.9

1

–

–

1

–

2

–

–

–

(2017)

D

92.1

2

3

3

–

–

–

–

–

–

–

–

–

[33]

Martins et al.

Portugal

M

8.1

63.9

5.2

18.1

0.5

1.6

–

–

0.4

0.2

0.4

1.4

0.2

(2017)

D

93.5

0.5

4.2

0.4

1.4

–

–

–

–

–

–

–

–

[30]

Madani et al.

Iran

M

18.1

28

5.7

42.9

3.3

0.8

–

–

–

–

–

–

–

(2017)

D

91.7

3.3

0.8

1.6

1.6

–

–

–

–

–

–

–

–

[57]

**Country** 

**Root**

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**Type** 

**(1-1)**

**(2-1)**

**(1-2-1)**

**(2-2)**

**(1-2)**

**(2-1-2)**

**(1-2-**

**(3-1)**

**(2-1-**

**(3-2)**

**(2-3-**

**(3-2-1)**

**(3-2-3-**

**2-1)**

**2-1)**

**2-1)**

**1-2)**

**(year)**
