Ch 5. Skeletal SystemThe Teeth- pages 473-475

Function of TeethDigestive: via mastication (chewing)

Teeth aid in mechanical digestion, in conjunction with the tongue, by breaking food into smaller piecesThis speeds up the chemical digestive process

Arrangement and DentitionLocation: located in sockets called alveoli

Mandible (lower)Maxilla (upper)

Deciduous Teeth (milk teeth) : primary dentitionAppear at 6 monthsCompleted by 2 years (20 teeth)Fall out between 6-12 years

Permanent teeth get larger causing resorption Resorption of roots causes teeth to loosen

Permanent and Wisdom TeethPermanent:

Established at the end of adolescenceFull set is 32 teeth

Wisdom (third molars):Emerge between 17-25 years oldCan be absent in some individualsImpacted wisdom teeth:

Wisdom teeth remain embedded and push on the roots of other teeth Causes pressure and pain

Classification of Teeth:Classification by

shape and function:Incisors: to snip off

foodCanines: to tear

and piercePremolars

(bicuspids): 2-cusp grinders

Molars: 4-5 cusps; best grinders

Deciduous vs. Permanent Teeth

Numbers of Teeth (expressed as only half of the mouth)

Deciduous Teeth = 20 total• On each layer:

• 2I, 1C, 2M = 5• 2I, 1C, 2M = 5

• 10 x 2 = 20

Permanent Teeth = 32 total

• On each layer:

• 2I, 1C, 2P, 3M = 8 • 2I, 1C, 2P, 3M = 8

• 16 x 2 = 32

Tooth Structure:Teeth have 2 main regions:

Crown: (exposed part): Covered by enamel (hardest substance in the body) Dentin underlies enamel – comprises bulk of tooth

Similar to bone in mineral and collagen components Pulp: makes up the middle part of the tooth

Loose connective tissueRoot:

An extension of the pulp cavity, which contains the blood and nerve supply

Surrounded by cementum – a calcified connective tissue

Nerve/Arterial Supply & DisordersThe trigeminal nerve is the main nerve

supplying teethThe arterial supply comes from branches of the

carotid

Disorders:Gingivitis: inflammation of the gingiva

Caused by increased deposits of plaque which increase bacterial populations

Periodontitis: when gingivitis causes infection of the bone and the teeth fall out

Lesson Learned:Brush your teeth after

you eatDon’t let sugar sit on

your teethFloss dailyGo to the dentist at

least 2x/year to get cleanings

ONLY TAKE CARE OF THE TEETH YOU WANT TO KEEP!