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Tooth Anatomy 

  • Author: A Ross Kerr, DDS; Chief Editor: Thomas R Gest, PhD  more...
 
Updated: Sep 25, 2013
 

Gross Anatomy

Composition

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)

Transverse section

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.

Tooth anatomy. Tooth anatomy.

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

 

 
Contributor Information and Disclosures
Author

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.

Chief Editor

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

Disclosure: Received royalty from Lippincott Williams & Wilkins for other.

References
  1. 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].

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

  3. 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].

 
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Tooth anatomy.
Table 1. Calcification and Eruption Sequence of Primary Dentition
  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
  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
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