basic science anatomy of the tooth

DENTAL DENTAL

ANATOMY ANATOMY

FOR THE ENT FOR THE ENT

RESIDENTRESIDENTHedyeh Javidnia, PGY2November 7, 2008

Dental AnatomyDental Anatomy OdontogenesisOdontogenesis Types of DentitionTypes of Dentition Tooth SurfacesTooth Surfaces Mandibular & Mandibular & Maxillary Maxillary

AnatomyAnatomy

ObjectivesObjectivesObjectivesObjectives. .. .

Anatomy of a tooth.Anatomy of a tooth.

a. Anatomical crown- portion of a. Anatomical crown- portion of tooth covered with enamel tooth covered with enamel

Dental Anatomy

Anatomic Anatomic crowncrown

b.b. Clinical crownClinical crown- visible part of - visible part of tooth tooth above the gum lineabove the gum line..

Anatomical crown

Clinical crown

Dental Anatomy

c. Rootc. Root

(1) Part of tooth embedded in (1) Part of tooth embedded in the alveolar process and covered the alveolar process and covered by cementum. by cementum.

Dental Anatomy

d. Apex- tapered end of root d. Apex- tapered end of root tip.tip.

e. Apical foramen-opening at e. Apical foramen-opening at the root tip.the root tip.

Dental Anatomy

Tissues of the tooth.Tissues of the tooth.a. Enamela. Enamel

(1)(1) Makes up anatomic crown. Makes up anatomic crown. (2)(2) Hardest material in the human bodyHardest material in the human body(3)(3) Incapable of remodeling and repair.Incapable of remodeling and repair.

Dental Anatomy

Enamel

b.b. DentinDentin(1) (1) Makes up bulk of tooth.Makes up bulk of tooth.

(2)(2) Covered by enamel on crown Covered by enamel on crown and cementum on the root.and cementum on the root.

(3)(3) Not as hard as enamel.Not as hard as enamel.(4) (4) Exposed dentin is often Exposed dentin is often

sensitive to cold, hot, sensitive to cold, hot, air, and air, and touch (via dentinal touch (via dentinal tubules).tubules).

Dental Anatomy

DentinEnamel

Dentinal Tubules

c. Cementumc. Cementum (1) Covers root of tooth. (1) Covers root of tooth. (2) Overlies the dentin and joins (2) Overlies the dentin and joins

the the enamel at the cemento-enamel enamel at the cemento-enamel junction (CEJ).junction (CEJ).

(3)(3) Primary function is to anchor Primary function is to anchor the tooth to the bony socket the tooth to the bony socket with attachment fibers.with attachment fibers.

Dental Anatomy

DentinEnamel

Dentinal Tubules

Cementum

d. Pulpd. Pulp (1) Made up of blood vessels (1) Made up of blood vessels

and nerves entering through and nerves entering through the apical foramen. the apical foramen.

(2) Contains connective tissue, (2) Contains connective tissue, which aids interchange which aids interchange between pulp and dentin. between pulp and dentin.

Dental Anatomy

DentinEnamel

Dentinal Tubules

CementumPulp

4. Periodontium4. Periodontium a. Alveolar process.a. Alveolar process. (1) Bone extensions of the maxillae and (1) Bone extensions of the maxillae and

mandible that supports the teeth.mandible that supports the teeth. (2) Cortical plate is the dense outer (2) Cortical plate is the dense outer layer layer of bone covering the spongy of bone covering the spongy (cancellous) (cancellous) bonebone

Dental Anatomy

DentinEnamel

Dentinal Tubules

CementumPulpAlveolar ProcessCortical Plate

Spongy Bone

b. Periodontal ligaments.b. Periodontal ligaments.

(1)(1) Dense connective fibrous tissues that Dense connective fibrous tissues that connect teeth to the alveolar bone.connect teeth to the alveolar bone.

(2)(2) One end is embedded in cementum One end is embedded in cementum and other end in bone.and other end in bone.

(3)(3) Supports and protects the tooth from Supports and protects the tooth from normal shock.normal shock.

Dental Anatomy

DentinEnamel

Dentinal Tubules


Spongy Bone

Periodontal Ligaments

c. Gingiva - surrounds the teeth and c. Gingiva - surrounds the teeth and covers the alveolar process.covers the alveolar process.

Dental Anatomy

DentinEnamel

Dentinal Tubules


Spongy Bone

Periodontal Ligaments

Gingiva

Odontogenesis

A. Bud StageB. Cap StageC. Bell StageD and E. Dentinogenesis and

amelogenesisF. Crown formationG. Root Formation H. Eruption

A. Bud Stage

• Bud stage is characterized by rounded, localized growth of epithelium surrounded by proliferating mesenchymal cells, which are packed closely beneath and around the epithelial buds

Meckel’scartilage

Intramembranousossification

B. Cap Stage

Vestibular lamina

When the appropriate depth is reached, the basal layer at the tip of the dental lamina thickens, forming a concavity.

C. Bell Stage

• Continued growth leads to bell stage, where the enamel organ resembles a bell with deepening of the epithelium over the dental papilla

• Continuation of histodifferentiation (Inner dental epithelium - ameloblasts and Dental papilla - odontoblasts)

Dental lamina

Outer dentalepithelium

Inner dentalepithelium

Dental papilla

Dental follicleCervical loop

At the same time or soon after the first layer of dentin (mantle dentin) is formed,the inner dental epithelial cells differentiate into ameloblasts and secrete enamelproteins. The ameloblasts will then start laying down organic matrix ofenamel against the newly formed dentinal surface. The enamel matrix willmineralize immediately and form the first layer of enamel. The formation ofenamel is called amelogenesis.

Ameloblasts

First layer of enamel

Dentin

Odontoblasts

D. Amelogenesis

E. DentinogenesisDentin is formed by odontoblasts that differentiate from ectomesenchymal cells of dental papilla with influence from the inner dental epithelium

Differentiation of odontoblasts is mediated by expression of signaling molecules and growth factors in the inner dental epithelial cells

Incremental pattern of dentin and enamel formation from initiation to completion

F. Crown FormationGrowth areas of developing crown. Growth at cusp tip, intercuspal region, and cervical region

G. Root Formation

Development of root begins after the enamel and dentin formation has reached the future cementoenamel junction

Epithelial cells of the inner and outer dental epithelium proliferate from the

cervical loop of the enamel organ to form the Hertwig’s epithelial root sheath. The root sheath determines if a tooth has single or multiple roots, is short or long, or is curved ir straight

Hertwig’s epithelialroot sheath

Hertwig’s epithelialroot sheath

Inner dental epithelium

Outer dental epithelium

Stratum intermedium

Eventually the root sheath will fragment to form several discrete clustersof epithelial cells known as epithelial cell rests of malassez. These will persist in adults within the periodontal ligament

The epithelial rests appear as small clusters of epithelial cells which are located in the periodontal ligament adjacent to the surface of cementum. They are cellular residues of the embryonic structure known as Hertwig's epithelial root sheath.

Epithelial Cell Rests of Malassez

• Soon after root formation begins, tooth begins to erupt until it reaches its final position

• While roots are forming, the supporting structures of tooth also develop – periodontal ligament and cementum

• As the root sheath fragments, the dental follicle cells will penetrate between the epithelial cells and lie close to the newly formed root dentin

• These cells will differentiate into cementoblasts, which will make cementum

H. Tooth Eruption and Development of supporting structures

REVIEW: Odontogenesis

A. Bud StageB. Cap StageC. Bell StageD and E. Dentinogenesis and

amelogenesisF. Crown formationG. Root Formation H. Eruption

Types of DentitionTypes of DentitionTypes of DentitionTypes of Dentition

1. Deciduous (baby) teeth1. Deciduous (baby) teeth

a. Twenty ( 20) primary teeth.a. Twenty ( 20) primary teeth.

b. Arches - maxillary and mandibular.b. Arches - maxillary and mandibular.

c. Quadrants - each arch divided in half.c. Quadrants - each arch divided in half.

(1) Maxillary right and left.(1) Maxillary right and left.

(2) Mandibular right and left.(2) Mandibular right and left.

Enamel is thinner, pulp is thicker

d. Teeth in each quadrant.

(1) Central incisor

(2) Lateral incisor

(3) Cuspid

(4) 1st molar

(5) 2nd molar

Deciduous TeethDeciduous Teeth

f. Numbering system.f. Numbering system. (1) Alphabetical.(1) Alphabetical. (2) Maxillary - patient’s (2) Maxillary - patient’s right to left, “A” right to left, “A” through “J”. through “J”. (3) Mandibular - patient’s (3) Mandibular - patient’s

left to right, “K” thru left to right, “K” thru “T”. “T”.

Deciduous TeethDeciduous Teeth

K

L

M

NOP

QR

S

T

A

B

C

DF

H

I

J

EG

R L

MAXILLARY

MANDIBULAR

Types of DentitionTypes of DentitionTypes of DentitionTypes of Dentition

2. Permanent teeth.2. Permanent teeth.

a. Thirty-two (32) permanent a. Thirty-two (32) permanent teeth. teeth.

b. Arches - maxillary b. Arches - maxillary & mandibular. & mandibular.

R L

c. Quadrants.c. Quadrants.

(1) Maxillary right and left.(1) Maxillary right and left.

(2) Mandibular right and left.(2) Mandibular right and left.R L

Permanent TeethPermanent Teeth

d.d. Teeth in each quadrant.Teeth in each quadrant.

(1) Central incisor.(1) Central incisor.

(2) Lateral incisor.(2) Lateral incisor.

(3) Cuspid (canine).(3) Cuspid (canine).


(4) 1st bicuspid(4) 1st bicuspid

(5) 2nd bicuspid(5) 2nd bicuspid

(6) 1st molar(6) 1st molar

(7) 2nd molar(7) 2nd molar

(8) 3rd molar(8) 3rd molar

(wisdom tooth)(wisdom tooth)


1. Facial - next to cheeks & lips.1. Facial - next to cheeks & lips.

a. Labial- anterior facial.a. Labial- anterior facial.

b. Buccal - posterior facial.b. Buccal - posterior facial.

2.2. Lingual- next to tongue.Lingual- next to tongue.

3.3. Mesial - towards midline, an imaginary line Mesial - towards midline, an imaginary line between central incisors.between central incisors.

4.4. Distal- away from midline. Distal- away from midline.

5.5. Incisal- cutting edge of anterior teeth.Incisal- cutting edge of anterior teeth.

6.6. Occlusal- chewing surface of the posterior Occlusal- chewing surface of the posterior teeth.teeth.

Tooth SurfacesTooth SurfacesTooth SurfacesTooth Surfaces

7. Proximal surfaces - mesial 7. Proximal surfaces - mesial or distal surface of a tooth or distal surface of a tooth lying next to another lying next to another tooth.tooth.

8. Interproximal space 8. Interproximal space

(embrasure) - spaces between (embrasure) - spaces between teeth, filled with hard and teeth, filled with hard and soft tissue soft tissue (interdental papilla).(interdental papilla).


9. Cusps- pronounced 9. Cusps- pronounced elevations on the occlusal elevations on the occlusal surfaces of a tooth surfaces of a tooth terminating in a conical or terminating in a conical or rounded surface. rounded surface.


Anatomy of the Mandible

Anatomy of the Maxilla

The End!!The End!!

basic science anatomy of the tooth

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