Digestive System: Outcome: I can describe the structure of a tooth and accurately label the teeth anatomically. Drill: What is the function of the uvula?

Components of a Tooth Crown Dentin Occlusal surface Pulp cavity Enamel Neck Gingival sulcus Cementum Periodontal ligament Root Root canal Apical foramen © 2015 Pearson Education, Inc. Figure 22.7 1

Teeth Regions of a tooth Crown Neck Root Portion projecting into the oral cavity from the surface of the gums Neck The boundary between the crown and root Root Portion below the gum line Sits in a bony tooth socket called an alveolus © 2015 Pearson Education, Inc.

Teeth Components of a tooth The bulk of each tooth is composed of dentin Mineralized matrix similar to bone but contains no cells Pulp cavity The interior chamber of the tooth Occlusal surface Portion of the crown used for crushing, slicing, or chewing © 2015 Pearson Education, Inc.

Teeth Components of a tooth (continued) Enamel Gingival sulcus Covers the dentin of the crown Hardest biologically manufactured substance Composed of calcium phosphate Requires calcium, phosphate, and vitamin D for formation and resistance to decay Gingival sulcus Shallow groove surrounding the base of the neck Epithelial attachment blocks bacteria from accessing deeper tissues around the root © 2015 Pearson Education, Inc.

Teeth Components of a tooth (continued) Cementum Periodontal ligament Covers the dentin in the root Less resistant to erosion than dentin Periodontal ligament Creates gomphosis articulation between root dentin and alveolar bone Root canal Narrow tunnel within the root of the tooth Passageway for blood vessels and nerves to the pulp cavity Opening into the root canal is the apical foramen © 2015 Pearson Education, Inc.

Types of Teeth Incisors Cuspids Bicuspids Molars Upper jaw Lower jaw © 2015 Pearson Education, Inc. Figure 22.7 2

Teeth Four types of teeth Each with a distinctive shape and root pattern Incisors Blade-shaped teeth with a single root Located at the front of the mouth Useful for clipping or cutting Cuspids (or canines) Conical with a sharp ridgeline and pointed tip Used for tearing or slashing © 2015 Pearson Education, Inc.

Teeth Four types of teeth (continued) Bicuspids (or premolars) Have flattened crowns with prominent ridges Used for crushing, mashing, or grinding Molars Very large flattened crowns with prominent ridges Adapted for crushing and grinding © 2015 Pearson Education, Inc.

Teeth Two sets of teeth Formed during embryonic development Primary dentition (deciduous teeth) Also called primary teeth, milk teeth, or baby teeth At 2 years of age 20 deciduous teeth 5 on each side of upper and lower jaws 2 incisors, 1 cuspid, 2 deciduous molars © 2015 Pearson Education, Inc.

Central incisors (7.5 mo)* Primary dentition Central incisors (7.5 mo)* Lateral incisor (9 mo) Cuspid (18 mo) Deciduous 1st molar (14 mo) Deciduous 2nd molar (24 mo) Deciduous 2nd molar (20 mo) Deciduous 1st molar (12 mo) Cuspid (16 mo) Lateral incisor (7 mo) Central incisors (6 mo) Deciduous teeth *Indicates month of eruption © 2015 Pearson Education, Inc. Figure 22.7 3

Teeth Two sets of teeth (continued) Secondary dentition Gradually replace primary dentition Primary teeth fall out or are pushed aside by secondary teeth Three additional molars appear on each side of the upper and lower jaws Third molars are called wisdom teeth 32 total permanent teeth © 2015 Pearson Education, Inc.

Figure 22.7 4 Central incisors (7–8 yr)* Lateral incisor (8–9 yr) Secondary dentition Central incisors (7–8 yr)* Lateral incisor (8–9 yr) Cuspid (11–12 yr) 1st Premolar (10–11 yr) Maxillary dental arcade 2nd Premolar (10–12 yr) 1st Molar (6–7 yr) 2nd Molar (12–13 yr) 3rd Molars or wisdom teeth (17–21 yr) 2nd Molar (11–13 yr) 1st Molar (6–7 yr) 2nd Premolar (11–12 yr) Mandibular dental arcade 1st Premolar (10–12 yr) Cuspid (9–10 yr) Lateral incisor (7–8 yr) Central incisors (6–7 yr) Adult teeth, upper and lower jaws *Indicates year of eruption © 2015 Pearson Education, Inc. Figure 22.7 4

Teeth Dental diseases Gingivitis Inflammation of the gingivae Stimulation from brushing and massaging gums can strengthen those epithelial attachments Severe cases usually caused by bacterial infection Can progress to erosion of gums, root damage, and tooth loss © 2015 Pearson Education, Inc.

Teeth Dental diseases (continued) Tooth decay Generally results from action of bacteria (normally found in the mouth) Bacteria adhere to tooth surfaces and trap food particles Produce deposits called dental plaque © 2015 Pearson Education, Inc.

How many primary and secondary teeth are there in humans? Digestive System: Exit Ticket: How many primary and secondary teeth are there in humans?