Structure of teeth.

Supporting structures.

Deciduous tooth morphology.

Secondary tooth morphology

General arrangement of teeth is called the dentition

Primary dentition

Contains the deciduous teeth

Secondary dentition

Contains the permanent teeth

Mixed dentition

Contains some deciduous and some permanent teeth

Mixed dentition sometimes called ugly ducking stage

Supported by the maxillary bone

Belong to the maxillary arch

Figure courtesy Hu-Friedy

What is the bone called that supports the teeth?

What is special about it?

Supported by the mandibular bone

Belong to the mandibular arch

Figure courtesy Hu-Friedy

Give me the names of parts of the mandible?

Ramus

Mandibular body

Angle of the mandile

Coronoid process

Condylar process

Give me the names of the 2 foramen in the mandible

Mental

Mandibular

Figure courtesy Hu-Friedy

Incisors

Canines

Molars

Premolars

Posterior teeth

Anterior teeth

Canines known as eye teeth

Designed to bite or cut food

The biting surface is called the incisal edge.

Central incisor larger than lateral incisor.

Flattened crown with one root.

Upper central incisor is largest of all incisors.

Figure courtesy Hu-Friedy

Upper premolars 2 roots

Designed to cut and tear food

Upper canines larger than lowers.

Large conical crown with pointed incisal edge and one long root.

Upper canines have longest of all roots.

Used for tearing and chewing food

All have two cusps, equal size in uppers, smaller lingual cusp in lowers.

Upper first premolar has two roots (buccal and palatal), all others have one root.

Known as peridontium

4 parts

Tooth

Alveolar bone

Periodontal ligament

Cementum

All have large occlusal surface for grinding and chewing food.

All upper molars have three roots (palatal, mesiobuccal and distobuccal)

All lower molars have two roots (mesial and distal).

Upper first molar has five cusps, fifth one called ‘cusp of carabelli’.

Lower first molar has five cusps, three buccal and two lingual.

All other molars have four cusps.

Roots in third molars vary in number, uppers are often fused together.

Figure courtesy Hu-Friedy

Enamel

Dentine

Pulp

Cementum

Periodontal ligament

Lamina Dura (Compact bone)

Cancellous Bone (spongy bone)

In a normal mouth all incisal edges and cusps of upper and lower teeth interlock to give a stable bite (occlusion).

The upper arch is usually wider so that the lower teeth bite into the middle of the upper teeth, or onto the cingulum of the incisors and canines.

a-6 months

b- 8 months

c- 18 months

d- 12 months

e- 24 months

Each tooth consists of a crown and root

The crown is covered by enamel

The root is covered by cementum

The crown and root are joined at the cementenamel junction

The cervical line separates the crown and root

These are approx ages

An easy way to work out eruption dates

Lowers Uppers

1-7

2-8

3-9 3-11

4-10 4-9

5-11 5-10

6-6

7-12

8-18

Hardest tissue in the body

Covers the crown

Thickest over the tips of the crown

Thinnest where crown meets the root

Colour is determined by thickness

Figure courtesy Hu-Friedy

12 years

All permanent teeth erupted except the third molars

It is made up of 96% inorganic crystals arranged as prisms

Main mineral crystals are hydroxyapatite.

Junction where enamel meets dentine is called the amelodentinal junction.

Contains no nerves or blood vessels and therefore cannot experience sensitivity.

Non-living tissue which cannot grow or repair itself, but can remineralise after acid attack.

Can exchange minerals, especially fluoride, to form fluorapatite crystal which make the enamel surface harder still and more resistant to acid attack.

8-10 years

Canines not quite erupted

No premolars yet

7’s not in

Lower right e present but you can see roots starting to resorb.

Forms the bulk of the crown and root of the teeth

Covered by enamel in the crown

Covered by cementum in the root

Living tissue

Receives nutrition from dentinal tubules running from the pulp

Tubules are involved with toothache

Figure courtesy Hu-Friedy

7-8 years

6’s erupted

Central’s and laterals erupted

e’s still present

It is up to 80% inorganic.

It is composed of hollow tubules containing fibrils, which are sensory endings from the cells forming the dentine.

It is therefore a living tissue, and can transmit sensitivity.

It is formed by ondontoblast cells, which lie at the edge of the pulp chamber.

It can repair itself by producing secondary dentine.

Secondary dentine also forms as part of the natural ageing process.

Caries progresses rapidly through dentine because of its hollow nature.

The cementum is the layer covering dentine of the root.

It normally lies beneath the gingiva.

It allows attachment of the tooth to the supporting structure of the periodontal ligament.

Calcium Hydroxyapatite

Similar chemically to bone

Figure courtesy Hu-Friedy

Difficult to recreate on computer so sometime UR UL LL and LR use to define quadrant

Pulp is the soft tissue within the tooth structure.

Surrounded by dentine

Consists of connective tissue, blood vessels and nerves

Odontoblasts present on the wall of the pulp chamber

Pulp Canals

Figure courtesy Hu-Friedy

Palmers charting

It allows the tooth to feel hot, cold, touch, pain by stimulation of fibrils in dentine.

Vessels enter the tooth through the apical foramen, at the end of each root apex.

These tissues are enclosed within the pulp chamber of the tooth.

Chamber is lined by ondontoblast cells.

Gradual formation of secondary dentine with age causes pulp chamber to decrease in size and become narrower.

Not letters but numbers

1-5

Periodontal tissues

Attachment tissues

Alveolar bone

Periodontal ligament

Cementum

This is a specialised fibrous tissue which attaches the teeth to the alveolar bone and surrounding tissues.

Fibres are made up of protein called collagen.

Acts as a shock absorber when tooth undergoes normal chewing movements, so that the tooth can bounce a little in its socket and not fracture.

Destruction of periodontal ligament occurs during periodontal disease.

The bony extensions of the maxilla and mandible, where the teeth are formed and from where they erupt into the mouth.

Special bone found only in the jaws.

Sole purpose is to support the teeth during their lifetime.

When teeth are extracted, alveolar bone gradually resorbs away.

Outer layer is hard compact bone, with the surface being called the lamina dura.

Inner layer is cancellous bone, sponge like in appearance to allow blood vessels and nerves to run through.

Destruction of the alveolar bone can occur during periodontal disease.

The cementum is the layer covering dentine of the root.

It normally lies beneath the gingivae.

It allows attachment of the tooth to the supporting structure of the periodontal ligament.

This is the correct term for the gums.

In health they are light pink in colour with a stippled (orange peel) surface.

Form a 2mm crevice (gingival crevice) around the necks of each tooth, above periodontal ligament.

Gingivitis occurs when this area becomes inflamed.

Inflamed gingivae are red and shiny, with a swollen appearance.

Two sets of teeth develop in a person’s lifetime

The deciduous dentition contains 20 teeth

The permanent dentition contains 32 teeth

And for a period of time a child will have a mixed dentition

Containing some deciduous teeth and some permanent teeth

The first teeth to appear are the deciduous incisor teeth at about 6 months

The last teeth to appear are the deciduous second molars at 2 ½ years

Figure courtesy Hu-Friedy

Tooth Eruption age

Central incisors 6 to 8 months

Lateral incisors 7 to 9 months

First molars 12 to 16 months

Canines 16 to 21 months

Second molars 21 to 30 months

Deciduous teeth in general resemble their corresponding permanent teeth but there are some important differences.

Deciduous teeth are much smaller.

There is adequate space so crowding is uncommon.

Deciduous crowns are whiter.

Pulp chambers of deciduous teeth are relatively larger, their enamel is much thinner.

Deciduous incisors and canines are smaller versions of their permanent successors.

Deciduous molars have the same number of roots as permanent molars but differ in other respects.

The crowns of deciduous molars are more bulbous.

To provide space for the developing premolar, the roots of deciduous molars are more divergent than those of permanent molars.

Deciduous 2nd molars resemble miniature 1st permanent molars; but the shape of deciduous 1st molars is much less typical, having a pronounced mesio-buccal bulge.

The permanent teeth replace the deciduous teeth

The first permanent teeth to appear are the mandibular first molars

These teeth erupt behind the deciduous second molars

The next permanent teeth to erupt are the central and lateral incisors

Figure courtesy Hu-Friedy

Tooth Eruption age

First molars 6 to 7 years

Central incisors

6 to 8 years

Lateral incisors

7- 9 years

Canines

9 to 11 years

First premolars

10 to 12 years

Second premolars

10 to 12 years

Second molars

12 to 13 years

Third molars 17 to 22 years

Mesial – nearest the midline

Distal – furthest from the midline

Lingual – facing the tongue

Buccal – facing the cheek

Occlusal – chewing surface

Figure courtesy Hu-Friedy

Labial – facing the lip

Mesial – nearest the midline

Distal – furthest from the midline

Lingual – facing the tongue

Incisal edge – biting surface of anterior teeth

Figure courtesy Hu-Friedy

Tooth identification

The dentition – permanent or deciduous

The arch – maxillary or mandibular

The quadrant – right or left side of the mouth

The tooth type – incisor, canine, premolar or molar

Figure courtesy Hu-Friedy

Palmer notation Tooth description

Permanent maxillary right second premolar

Permanent maxillary left third molar

Permanent mandibular left lateral incisor

Permanent mandibular right canine

Assigns a letter to the deciduous tooth depending on its position relative to the midline

Central incisors are closest to the midline and are given the letter A

The second molars are furthest and are given the letter E

Deciduous tooth Symbol assigned

Central incisor A

Lateral incisor B

Canine C

First molar D

Second molar E

Figure courtesy Hu-Friedy

Palmer Notation Tooth description

Deciduous maxillary right second

molar

Deciduous maxillary left first molar

Deciduous mandibular left lateral

incisor

Deciduous mandibular right canine

Uses a two-digit number to identify each tooth

The first digit identifies the quadrant

The permanent quadrants are numbered from 1 through to 4

The second digit identifies the tooth

The permanent teeth are numbered from 1 through to 8

Permanent tooth Number assigned

Central incisor 1

Lateral incisor 2

Canine 3

First premolar 4

Second premolar 5

First molar 6

Second molar 7

Third molar 8

Figure courtesy Hu-Friedy

Notation Tooth description

11 Permanent maxillary right central incisor

16 Permanent maxillary right first molar

23 Permanent maxillary left canine

28 Permanent maxillary left third molar

34 Permanent mandibular left first premolar

37 Permanent mandibular left second molar

42 Permanent mandibular right lateral incisor

45 Permanent mandibular right second permolar

Uses a two-digit number to identify each tooth

The first digit identifies the quadrant

The deciduous quadrants are numbered from

5 through to 8

The second digit identifies the tooth

The deciduous teeth are numbered from

1 through to 5

Deciduous tooth Number Assigned

Central incisor 1

Lateral incisor 2

Canine 3

First molar 4

Second molar 5

Figure courtesy Hu-Friedy

Notation Tooth description

51 Deciduous maxillary right central incisor

54 Deciduous maxillary right first molar

63 Deciduous maxillary left canine

65 Deciduous maxillary left second molar

74 Deciduous mandibular left first molar

75 Deciduous mandibular left second molar

82 Deciduous mandibular right lateral incisor

81 Deciduous mandibular right central incisor