Teeth is organ of mastification or chewing. Mechanical digestion begins when teeth break down ingested food.
Teeth embadded in sockets of alveolar ridges of the mandible (lower jaw) and maxilla (upper jaw).
Periodontal Ligament (PDL)
Teeth are hold in their sockets by connective tissue. Periodontal ligaments is fibrous joint that anchors root of tooth to the alveolar bone socket.
Types of Sets/ Dentition
Humans develop two different sets of dentition -
1. Temporary Teeth/ Milk teeth/ Baby teeth/ Primary dentition/ Deciduous teeth
2. Permanent Teeth/ Adult Teeth/ Secondary dentition
1. Temporary Teeth/ Milk teeth/ Baby teeth
Deciduous teeth or primary teeth, also known as baby teeth, milk teeth, or temporary teeth.
Temporary teeth in baby commonly begin to come in about 6 months after birth.
There are 20 primary teeth; 10 teeth in the upper and 10 teeth in lower jaw.
Types of Temporary Teeth
4 incisors; for cutting
2 Canine ; for tearing
4 molars ; for grinding
Child to begin shed /losing their deciduous teeth around the age of 6 years and milk teeth replaced with permanent teeth between age of 6-12 years.
2. Permanent Teeth/ Adult Teeth/Secondary teeth
Primary (baby) teeth usually start coming in at the age of 6 months, and permanent teeth usually start coming in at between 6-12 years old.
Permanent dentition has a total 32 teeth in adult, including wisdom teeth.
Total number of teeth is 32; 16 in the upper jaw and 16 in the lower jaw.
Types of Permanent Teeth
4 incisors; for cutting
2 Canine ; for tearing
4 premolars; for grinding
6 molars; for grinding
Structure of Teeth
1. Crown
Visible part of tooth.
2. Neck
Also called the dental cervix, lies between crown and root.
3. Root
Root is under gums, anchors tooth to jawbone.
4. Enamel
Hardest outer white covering of the crown, protective layer on the crown.
5. Dentine
Sensitive yellowish avascular portion, layer underlying the enamel. It helps in absorbing pressure from eating, provides support to enamel.
6. Cementum
Layer of connective tissue that binds the roots of teeth.
7. Pulp cavity
Located at centre of the teeth. pUlp chamber containing blood vessels, nerves and lymphatic vessels.
Narrow expansion of pulp cavity called root canal.
8. Periodontal ligament
Fibrous joint that anchors root of tooth to alveolar bone socket. It composed of fibrous connective tissue. This ligament allow for teeth to be attached to surrounding alveolar bone via the cementum.
9. Alveolar bone
Located on the jaw bones which hold the teeth, jaw bone supporting the tooth.
10. Gingiva (gum)
Soft tissue covering alveolar bone.
11. Gingival sulcus
Small space between tooth and gums.
Function of Teeth
1. Masticating; mechanically break down food by cutting and crushing
2. Cut, tear and grind ingested food, mixed with saliva then swallowed
3. Shaping the face
4. Aids in speech
Gums
Gums is called gingiva. It is dense fibrous connective tissue covered with mucus membrane surrounds the upper and lower jaws.
Gingiva attach to neck of root and cementum. It surrounds neck of the teeth and provide support to teeth.
Gingiva composed of fibrous tissue covered by mucous membrane and keratinized stratified squamous epithelium.
Parts of Gingiva
1. Free gingiva
2. Attached gingiva
Function of Gingiva
1. Reduce friction during chewing
2. Keep teeth in place
3. Provide physical barrier against bacteria
4. Surrounds and protects teeth and underlying bone
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