Module 3- Part 1Anatomy

National Diploma in Dental Nursing

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

Anatomy

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

1. Structures of the oral cavity

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

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

2. The teeth

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

Tooth structure

1. Labial surface is in contact with lips2. Buccal surface is in contact with cheeks3. Lingual surface is next to the tongue.4. Palatal surface is next to the palate5. Mesial surface is toward the midline6. Distal surface is towards the back of the

mouth7. Incisal edge is the cutting edge of anterior (front) teeth8. 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.

Crown Surfaces

Tooth structureEnamel

1. Protective outer layer of crowns2. Hardest substance in body – to withstand forces of

chewing3. Transluscent – yellowish colour of teeth is due to

dentine 4. Produced by cells called ameloblasts5. 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 substance7. Has no nerve endings – insensitive to pain8. Can not be repaired once destroyed by caries

Tooth structureDentine

1. Forms bulk of crown & roots2. Protected by the much harder enamel3. Harder than bone4. Yellowish in colour5. Produced by cells called odontoblasts which line

the pulp cavity6. Composed of dentinal tubules which contain nerve

endings – sensitive to stimuli like temperature

Tooth structurePulp 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 foramen5. The part of pulp cavity located in the root is the root canal. 6. The root canals widen into the pulp chamber7. pulp horns are extensions of the pulp chamber which point upward toward the cusps

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

The teeth

Types of teeth in the two dentitions

DECIDUOUS DENTITION PERMANENT DENTITION

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 16Second molar E 29 27

Eruption dates of Deciduous Teeth

TOOTH NUMBER UPPER ERUPTION DATES IN YEARS

LOWER ERUPTION DATES IN YEARS

Central incisor 1 7 -8 6-7Lateral incisor 2 8-9 7-8Canine 3 10-12 9-10First premolar 4 9-11 9-11Second premolar 5 10-11 9-11First molar 6 6-7 6-7Second molar 7 12-13 11-12Third molar 8 18-25 18-25

Eruption dates of Permanent Teeth

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)

Upper teeth with 1 root: Central and lateral incisors, canines, Second premolar

Upper teeth with 2 roots: First premolarUpper 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 molarsVariable roots: Upper and lower third molars

(wisdom ) teeth

Tooth roots

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. The fifth cusp on the upper first molar is called the Cusp of Carabelli

5 cusps

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

The teeth

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 bone2. cementum3. periodontal ligament4. gingiva

Supporting structures of the teethAlveolar 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 OsteoblastsBone 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 cementoblasts3. anchors the roots to the periodontal ligament4. composed of cementocyte cells in a collagen

matrix5. 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 chewing3. 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.

Alveolar bone

Lamina dura

Periodontal ligament

Cementum

Furcation of roots

Cemento Enamel Junction (CEJ)

Gingiva (gum)

Gingival sulcus/crevice

Interdental papilla

Periodontal ligament

Cementum

Lamina dura

Periodontal ligament

Cementum

Interdental or Interproximal space

Contact point

Structures of periodontium

Healthy gingiva

- Pink- Firm- Sharply pointed papillae- Gingival crevice is 2-3

mm deep- Do not bleed on probing

Interdental papilla

Any Questions???