Ch 5. Skeletal System The Teeth- pages 473-475

Function of Teeth Digestive: via mastication (chewing) Teeth aid in mechanical digestion, in conjunction with the tongue, by breaking food into smaller pieces This speeds up the chemical digestive process

Arrangement and Dentition Location: located in sockets called alveoli Mandible (lower) Maxilla (upper) Deciduous Teeth (milk teeth) : primary dentition Appear at 6 months Completed 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 Teeth Established at the end of adolescence Full set is 32 teeth Wisdom (third molars): Emerge between 17-25 years old Can be absent in some individuals Impacted 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 food Canines: to tear and pierce Premolars (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 Permanent Teeth = 32 total On each layer: 2I, 1C, 2M = 5 10 x 2 = 20 On each layer: 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 tissue Root: An extension of the pulp cavity, which contains the blood and nerve supply Surrounded by cementum – a calcified connective tissue

Nerve/Arterial Supply & Disorders The trigeminal nerve is the main nerve supplying teeth The 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 eat Don’t let sugar sit on your teeth Floss daily Go to the dentist at least 2x/year to get cleanings ONLY TAKE CARE OF THE TEETH YOU WANT TO KEEP!