Download Dental Anatomy - Harriet Ellis

National Diploma in Dental Nursing
Module 3- Part 1
Anatomy
Anatomy
 In this module you will learn about:
 1. Structures of the oral cavity
 2. The teeth – function, types, structure
 3. Supporting structures of the teeth
 4. Anatomy of the skull
 5. Muscles of mastication and facial expression
 6. Salivary glands
 7. Nerve supply to head and neck region
1. Structures of the oral cavity
The oral cavity or mouth is the first part of the
gastrointestinal tract and the airway – the
place where food and air enter the body
Structures of the oral cavity
 The oral cavity is surrounded
by the cheeks (called Buccae
in Latin) & the lips (called
Labia in Latin)
 The upper or superior lip &
the lower or inferior lip are
attached to the gingiva by
folds of soft issue called labial
frenula
 Please note: 1 frenulum but
many frenula
 The vestibule is the space
between the cheeks/lips and
the teeth
Structures of the oral cavity
 The palate forms the roof of
the mouth & the floor of the
nasal cavity (nose)
 The bony anterior part of
the palate is called hard
palate
 Palatine raphe is the midline
of the palate
 The soft, mobile posterior
part of the palate is called
soft palate
 The uvula is a soft tissue
projection of the soft palate
and helps with the formation
of some sounds
Structures of the oral cavity
 The palatine tonsils are
part of the immune
system and protect the
body from disease
 Palatoglossal and
palatopharyngeal arches
are the border between
the oral cavity and the
pharynx (throat)
 The pharynx behind the
mouth is called the
oropharynx
Structures of the oral cavity
 The tongue (called Lingua in
Latin and Glossa in Greek) is
a muscular organ
 The tongue helps with:
mastication (chewing),
deglutition (swallowing),
articulation (sound
formation and taste
sensation
 The tongue is attached to
the floor of the mouth by
the lingual frenulum
Structures of the oral cavity
 The gingiva or gums are
part of the soft tissue
lining the inside of the
mouth
 The gingiva surrounds the
teeth and forms a tight
seal around them
2. The teeth
 Teeth are small calcified, whitish structures found in the jaws of
humans and many other animals.
 In humans the teeth have
 the following functions:
 1. To chew food during mastication
 2. To help with sound formation during speech
 3. To provide support for the jaws, cheeks and lips and so contribute
to facial appearance
Tooth structure
Tooth structure
 The part of the tooth which is visible in the oral cavity is called the
crown
 The neck of the tooth is the border between the crown and the root.
The gingiva is attached to the neck of a tooth
 The roots are buried inside the alveolar bone of the jaws which keeps
the teeth firmly in place
Crown Surfaces
1. Labial surface is in contact with lips
2. Buccal surface is in contact with cheeks
3. Lingual surface is next to the tongue.
4. Palatal surface is next to the palate
5. Mesial surface is toward the midline
6. Distal surface is towards the back of the mouth
7. Incisal edge is the cutting edge of anterior (front)
teeth
8. Occlusal surface is the chewing surface of the
posterior (back) teeth
Pits and fissures – grooves
Cusps - pronounced elevations on the occlusal
surfaces of a tooth terminating in a conical or
rounded surface.
Tooth structure
Enamel
1. Protective outer layer of crowns
2. Hardest substance in body – to withstand forces of chewing
3. Transluscent – yellowish colour of teeth is due to dentine
4. Produced by cells called ameloblasts
5. Composed of 96% inorganic matter – calcium & phosphorus in
form of hydroxyapatite prisms. Prisms run at 90° to surface.
6. Prisms are held together by inter-prismatic substance
7. Has no nerve endings – insensitive to pain
8. Can not be repaired once destroyed by caries
Tooth structure
Dentine
1. Forms bulk of crown & roots
2. Protected by the much harder enamel
3. Harder than bone
4. Yellowish in colour
5. Produced by cells called odontoblasts which line the pulp
cavity
6. Composed of dentinal tubules which contain nerve endings –
sensitive to stimuli like temperature
Tooth structure
Pulp
1. Found at the core of the tooth, under the dentine, in the
pulp cavity.
2. Contains blood vessels, nerves and connective tissue.
3. Blood supply provides nutrients that keep the tooth alive.
4. Blood vessels & nerves enter the root through apical
foramen
5. The part of pulp cavity located in the root is the root canal.
6. The root canals widen into the pulp chamber
7. pulp horns are extensions of the pulp chamber which point
upward toward the cusps
The teeth
 Throughout their life humans have 2 sets of teeth
 1. Deciduous dentition – the set of baby or milk teeth which erupt
(appear in the mouth) when a baby is a few months old and are
exfoliated (fall out) when the person reaches 12-13 years of age.
 2. Permanent dentition – set of adult teeth which begin to replace
the deciduous teeth when the person is around 6 years of age.
The teeth
 The teeth are arranged in 2 arches in the upper and lower
jaws.
 The upper jaw is called the MAXILLA and so the upper teeth
can also be called maxillary teeth
 The lower jaw is called the MANDIBLE and so the lower teeth
can also be called mandibular teeth.
 In the deciduous dentition there are 10 teeth per arch
 In the permanent dentition there are 16 teeth per arch
Types of teeth in the two dentitions
DECIDUOUS DENTITION
PERMANENT DENTITION
Eruption dates of Deciduous
Teeth
TOOTH
LETTER
UPPER ERUPTION DATES
in MONTHS
LOWER ERUPTION
DATES in MONTHS
Central incisor
A
10
8
Lateral incisor
B
11
13
Canine
C
19
20
First molar
D
16
16
Second molar
E
29
27
Eruption dates of Permanent
Teeth
TOOTH
NUMBER
UPPER ERUPTION DATES IN
YEARS
LOWER ERUPTION
DATES IN YEARS
Central incisor
1
7 -8
6-7
Lateral incisor
2
8-9
7-8
Canine
3
10-12
9-10
First premolar
4
9-11
9-11
Second premolar
5
10-11
9-11
First molar
6
6-7
6-7
Second molar
7
12-13
11-12
Third molar
8
18-25
18-25
Eruption of Permanent Teeth
Eruption of Permanent Teeth
• Permanent incisors and
canines replace deciduous
incisors & canines
• First premolars replace first
deciduous molars
• Second premolars replace
deciduous second molars
• First permanent molar erupts
behind the deciduous teeth
Deciduous Teeth
Upper permanent central incisor
Upper permanent lateral incisor
Upper permanent canine
Upper permanent first premolar
Upper permanent second premolar
Upper permanent first molar
Upper permanent second molar
Upper permanent third molar
(wisdom tooth)
Lower permanent central incisor
Lower permanent lateral incisor
Lower permanent canine
Lower permanent first premolar
Lower permanent second premolar
Lower permanent first molar
Lower permanent second molar
Lower permanent third molar
(wisdom tooth)
Tooth roots
Upper teeth with 1 root:
Central and lateral incisors,
canines, Second premolar
Upper teeth with 2 roots:
First premolar
Upper teeth with 3 roots:
First, second molars
Lower teeth with 1 root:
Central & lateral incisors, canines,
first & second premolars
Lower teeth with 2 roots
First, second molars
Variable roots:
Upper and lower third molars
(wisdom ) teeth
Tooth cusps
TOOTH
NUMBER OF CUSPS
Cuspid teeth – canines
1 cusp
Bicuspid teeth – premolars
2 cusps
Molars except upper and
lower first molars
4 cusps
Upper and lower first molars. 5 cusps
The fifth cusp on the upper
first molar is called the Cusp
of Carabelli
The teeth
 The incisors and canines are the
anterior or front teeth
 The premolars and molars are the
posterior or back teeth.
 We always count the teeth starting
with the teeth near the midline
(central incisors) going backward.
 The midline is an imaginary line
which divides the body in half
Differences between deciduous &
permanent teeth
Deciduous teeth : 20 in number Permanent teeth – 32 in number
(there are no deciduous premolars and third molars)
Deciduous teeth :
Are much smaller
Are whiter
Have thinner enamel & larger pulp chambers
Roots are more splayed & thinner
Roots shorten with age
Supporting structures of the teeth
The supporting structures of the teeth are collectively known as the
periodontium.
These structures surround and support the teeth, keeping them in
the maxilla and mandible.
The periodontium consists of:
1. alveolar bone
2. cementum
3. periodontal ligament
4. gingiva
Supporting structures of the
teeth
Alveolar bone
The alveolar bone or alveolar process is the thickened ridge of
bone that contains the tooth sockets.
The alveolar process contains a layer of compact bone next to the
periodontal ligament called lamina dura. The lamina dura is
attached to the cementum by the periodontal ligament.
The less dense bone forming the jaws is the spongy bone.
Bone is made by cells called Osteoblasts
Bone is resorbed (broken down) by cells called Osteoclasts
Supporting structures of the
teeth
Cementum
1. covers the dentine in the roots
2. produced by cells called cementoblasts
3. anchors the roots to the periodontal ligament
4. composed of cementocyte cells in a collagen matrix
5. meets the enamel at the neck of the tooth at the
cemento-enamel junction (CEJ)
Periodontal ligament (PDL)
1. Made of collagen firers which connect cementum to lamina
dura.
2. Acts as a shock absorber during chewing
3. Contains pressure sensors which tell the brain how much
pressure is exerted on a tooth – brain tells us how hard to bite.
Supporting structures of the teeth
Gingiva (gums)
1. Pink fleshy tissue covering the alveolar process.
2. Connected to underlying bone by gingival fibres.
3. Forms a tight seal around necks of teeth.
4. Gap between gingiva and neck of tooth is the gingival crevice or sulcus.
5. The interdental gingiva which fills the embrasures (interdental spaces)
between the contact points of 2 teeth is the interdental papilla.
6. The contact point is the point at which the crowns of 2 neighbouring
crowns touch.
Structures of
periodontium
Cementum
Interdental or
Interproximal space
Contact
point
Interdental
papilla
Gingival
sulcus/crevice
Cementum
Periodontal
Periodontal
ligament
Periodontal
ligament
ligament
Lamina
Lamina
dura
dura
Alveolar
bone
Gingiva
(gum)
Cemento
Enamel
Junction
(CEJ)
Furcation
of roots
Healthy gingiva
- Pink
- Firm
- Sharply pointed papillae
- Gingival crevice is 2-3 mm
deep
- Do not bleed on probing
Interdental papilla
Any Questions???