Types and Arrangements of Teeth

Question 1

What is dentition?

Answer 1

The natural teeth in the jawbones

Question 2

What must hygienists know about dentition and why?

Answer 2

They must know the names, locations and functions of each tooth in order to assist patients in understanding the importance of keeping their teeth healthy for a lifetime

Question 3

What are the three types of dentitions in our lifetime?

Answer 3

Primary/deciduous: baby teeth
Mixed: both primary and permanent teeth have erupted
Secondary/permanent: adult teeth

Question 4

How many teeth do we have in each dentition and which are they?

Answer 4

20 in primary - all 6 anterior teeth on top and bottom + 4 molars where premolars would be
32 in permanent teeth - all teeth including wisdom teeth

Question 5

What is mixed dentition?

Answer 5

Occurs between approximately 6-12 years of age. Both primary and permanent teeth are present during this time. Usually the first tooth to fall out is a mandibular first molar or a mandibular central incisor. The period ends when the last primary tooth falls out UNLESS an adult still has one because there was no adult tooth to replace it

Question 6

What is permanent dentition?

Answer 6

Begins with exfoliation (shedding) of the last primary tooth. Growth of the jaw bone slows and eventually stops. Very little jaw growth as puberty has passed

Question 7

What are the two dental arches?

Answer 7

Maxillary arch and mandibular arch

Question 8

What is the maxillary arch?

Answer 8

It is the upper part of the mouth, is part of the skull and is in a fixed place so therefore incapable of movement. Teeth are set in the maxilla bone

Question 9

What is the mandibular arch?

Answer 9

Lower part of the jaw, capable of movement through the action of the TMJ (temporal mandibular joint)

Question 10

What teeth are there in the permanent dentition?

Answer 10

Anterior teeth on each arch: 2 central incisors, 2 lateral incisors, 2 canines
Posterior teeth on each arch: 4 premolars, 6 molars

Question 11

What are the three food processing functions?

Answer 11

Cutting, holding or grasping, grinding

Question 12

What are incisor teeth?

Answer 12

Single rooted teeth with relatively sharp and thin edge. Located at the front of the mouth , designed to cut food without the application of heavy forces. Incisor meaning that with which makes and incision or cut. Lingual side is shaped like a shovel to help guide food into the mouth. Incisal edge is the biting edge

Question 13

What are canines used for?

Answer 13

Designed for holding grasping and tearing foods

Question 14

Canines physical characteristics

Answer 14

Longest teeth in the human dentition, has the longest root and usually the last tooth to be lost. Because of sturdy crown, long root and location in the arch, the canine is often referred to as the cornerstone of the dental arch. Also, protect the jaw during teeth movement by supporting side to side lateral jaw movements

Question 15

What are premolars?

Answer 15

Found only in permanent dentition, cross between molars and canines but not as long as canines. Sometimes referred to as bicuspids. Hold and grind food, two or three cusps, bumps on biting surfaces, buccal cusp holds while the lingual cusp grinds

Question 16

What are molars?

Answer 16

Larger than premolars, most posterior teeth, chew and grind food. Cusps interlock with opposing molars to create a grinding effect. 4 or 5 cusps, maxillary and mandibular molars vary from each other in size and shape and number of cusps

Question 17

What are the surfaces on posterior teeth?

Answer 17

• Occlusal surfaces - chewing surfaces
• Facial/Buccal/Vestibular - cheek side/outside
• Lingual - tongue side
• Mesial - towards the midline
• Distal - away from the midline

Question 18

What are the surfaces on anterior teeth?

Answer 18

• Incisal - biting/cutting surface
• Labial/Facial - lip side/face side
• Lingual - tongue side
• Palatal inside on maxilla
• Mesial - toward the midline
• Distal - away from the midline

Question 19

What are the divisions of the root and where are they?

Answer 19

• Apical third (nearest the tip of the root)
• Middle third
• Cervical third (nearest the neck of the tooth) (near the CEJ)

Question 20

How do we divide the crown crosswise (horizontally)?
How do we divide the crown lengthwise (vertically)?
How do we divide the crown from an interproximal aspect (side view of the tooth)?

Answer 20

Crosswise
-cervical third
-middle third
-incisal/occlusal third
Lengthwise
-distal third
-middle third
-mesial third
Interproximal
-labial third
-middle third
-lingual third

Question 21

What are line angles?

Answer 21

An angle formed by the junction of two surfaces of a tooth crown along an imaginary line.

Question 22

What are point angles?

Answer 22

An angle formed by the junction of three surfaces at one point