Tooth Anatomy 

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The tooth anatomy includes the crown, which is the portion of the tooth exposed to the oral cavity, and one or more roots, which are enveloped in bone and the periodontium.

The crown of each tooth has 5 surfaces, as follows:

Buccal (facing the cheek or lip)

Lingual (facing the tongue)

Mesial (between the teeth)

Distal (between the teeth)

Chewing (occlusal for molars and premolars, incisal for incisors and canines)

In the transverse section, the tooth has 3 distinct layers, as follows:

A surface enamel layer covering only the crown

An inner layer of dentin in both the crown and the root

The core area, known as the pulp, which contains nerves, arteries, and veins ^[1]

Radiographically, the layers are easily identifiable because they have different radiopacities. Enamel is the most mineralized of the calcified tissues of the body, and it is the most radiopaque of the 3 tooth layers. Dentin is less radiopaque than enamel and has a radiopacity similar to that of bone. The pulp tissue is not mineralized and appears radiolucent. ^[2]

The anatomy of the tooth is displayed in the image below.

Primary (ie, deciduous) teeth number 20, ^[3] and secondary (ie, adult) teeth number 32. A phase of mixed dentition exists, depending on the age of the patient (typically, 6-14 y). This phase is associated with simultaneous exfoliation or the eruption of primary and secondary teeth (see Tables 1-2).

Table 1. Calcification and Eruption Sequence of Primary Dentition (Open Table in a new window)

Primary Teeth Calcification Begins (Weeks In Utero)

Enamel Completed (Months after Birth)

Eruption (Months after Birth)

Maxilla

Central incisor

13-16

1.5

8-12

Lateral incisor

14.5-16.5

2.5

8-13

Canine

15-18

9

16-22

First molar

14. 5-16.5

6

13-19

Second molar

16-23.5

11

25-33

Mandible

Central incisor

13-16

2.5

6-10

Lateral incisor

14.5-16.5

3

10-16

Canine

16-18

9

17-23

First molar

14.5-17

5.5

14-18

Second molar

17-19.5

10

23-31

Table 2. Calcification and Eruption Sequence of Secondary Dentition (Open Table in a new window)

Permanent Teeth Calcification Begins (Months)

Eruption (Years)

Maxilla

Central incisor

3-4

7-8

Lateral incisor

10-12

8-9

Canine

4-5

11-12

First premolar

8-21

10-11

Second premolar

24-27

10-12

First molar

0-1

5-6

Second molar

30-36

12-13

Mandible

Central incisor

3-4

6-7

Lateral incisor

3-4

7-8

Canine

4-5

9-10

First premolar

21-24

10-12

Second premolar

27-30

11-12

First molar

0-1

5-6

Second molar

30-36

12-13

Sustercic D, Sersa I. Human tooth pulp anatomy visualization by 3D magnetic resonance microscopy. Radiol Oncol. 2012 Mar. 46(1):1-7. [Medline]. [Full Text].

Gray H, Lewis WH. Gray’s Anatomy of the Human Body. 20th Ed. New York, NY: Bartleby; 2000. [Full Text].

Bossù M, Valletta A, Fiore R, Riccitiello F, D’Amora M, Coppolino F, et al. [Deciduous dentition: anatomical study by µ-CT]. Recenti Prog Med. 2013 Jul-Aug. 104(7):425-9. [Medline].

Primary Teeth Calcification Begins (Weeks In Utero)

Enamel Completed (Months after Birth)

Eruption (Months after Birth)

Maxilla

Central incisor

13-16

1.5

8-12

Lateral incisor

14.5-16.5

2.5

8-13

Canine

15-18

9

16-22

First molar

14. 5-16.5

6

13-19

Second molar

16-23.5

11

25-33

Mandible

Central incisor

13-16

2.5

6-10

Lateral incisor

14.5-16.5

3

10-16

Canine

16-18

9

17-23

First molar

14.5-17

5.5

14-18

Second molar

17-19.5

10

23-31

Permanent Teeth Calcification Begins (Months)

Eruption (Years)

Maxilla

Central incisor

3-4

7-8

Lateral incisor

10-12

8-9

Canine

4-5

11-12

First premolar

8-21

10-11

Second premolar

24-27

10-12

First molar

0-1

5-6

Second molar

30-36

12-13

Mandible

Central incisor

3-4

6-7

Lateral incisor

3-4

7-8

Canine

4-5

9-10

First premolar

21-24

10-12

Second premolar

27-30

11-12

First molar

0-1

5-6

Second molar

30-36

12-13

A Ross Kerr, DDS Clinical Associate Professor, Department of Oral & Maxillofacial Pathology, Radiology and Medicine, New York University College of Dentistry

Disclosure: Nothing to disclose.

Thomas R Gest, PhD Professor of Anatomy, Department of Medical Education, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine

Disclosure: Nothing to disclose.

Tooth Anatomy 

Research & References of Tooth Anatomy |A&C Accounting And Tax Services
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