Root morphology

Question 1

What are the functions of the roots of teeth?

Answer 1

• sensory system
• external and internal reparative methods
• nourishment system of the tooth
• support and anchorage for the teeth

Question 2

What are the sensory functions of the pulp?

Answer 2

• nerves in the pulp elicit pain response (when the pulp tissue is affected and the nerve is stimulated, the only response is pain)

Question 3

How do teeth get nourishment?

Answer 3

inner pulp that contains blood vessels which carry nourishment to the tooth

Question 4

What are dental tubules?

Answer 4

Dental tubules stimulate pain response and carry the stimulus from the root surface to the pulp
- root caries, abrasion or resorption can allow tubules to open and transmit a stimulus

Question 5

How are roots a ‘warning system’?

Answer 5

Serve as a warning system to external and internal trauma. If the pulp canal becomes inflamed, then hot or cold can cause pain. The longer it takes for the pain to subside, the more damage to the pulp tissue

Question 6

What will happen to gases if the pulp is infected or necrotic?

Answer 6

Any gases present will expand within the tooth when it is heated will cause pain (ie. drinking coffee)

Question 7

Where are pressure and temperature felt?

Answer 7

In the nerve tissue within the surrounding bone, gingiva and periodontal ligaments

Question 8

What can root canals (pulp) respond to?

Answer 8

Pain only

Question 9

What are the pulp canals? How do they enter the tooth?

Answer 9

Pulp canals are the nourishment system for teeth, which is the arteries, veins and lymph tissues. They enter through the apical foramen

Question 10

How do the pulp canals help remove toxins like carbon dioxide? Why then are abscesses so harmful?

Answer 10

They exit through the apical foramen. If there is an abscess blocking the apical foramen, then the nerves and tissues inside the tooth could die of anoxia (lack of oxygen)

Question 11

What do odontoblasts do?

Answer 11

Allow reparative dentin to form in response to trauma (acts as a pulp protector)

Question 12

What is secondary dentin?

Answer 12

Dentin that forms after root formation is complete but is not in response to trauma, so not the same as reparative dentin

Question 13

What is hypercementosis?

Answer 13

The cellular cementum on the apical third can continue to form cementum, and if this is extreme, it is considered hypercementosis

Question 14

Why would hypercementosis take place?

Answer 14

A response to trauma or bone destruction

Question 15

Why are roots longer and wider than teeth?

Answer 15

More support

Question 16

What keeps the tooth from moving?

Answer 16

the width, shape, length, curvature and number of roots, concavities, and direction of the PDL fibres affects the direction and resistance to forces on a tooth

Question 17

Are teeth directly embedded in bone?

Answer 17

No, they are supported by bone by the periodontal ligament fibres (PDL) that attach from the cementum of the root to the alveolar bone

Question 18

What happens to the PDL when pressure is applied to a tooth?

Answer 18

The PDL fills the space between the tooth and bone, so when pressure is exerted on one side of the tooth, it compresses the fibres on the other side, which allows for slight, normal mobility of the tooth

Question 19

What is resorption in bone? When does it happen?

Answer 19

If pressure is strong enough to exert pressure on the BONE, then a resorption process is triggered. Osteoclasts will dissolves the bone in the area of pressure. When enough bone is dissolved the pressure ceases and the PDL will regain its normal width, and the tooth moves away from the external force to its newly remodelled area

Question 20

How does orthodontics move teeth?

Answer 20

By applying pressure on teeth to cause resorption of bone. This is acquired over an extended period of time due to small amounts of movement at a time

Question 21

How is orthodontics successful? If they are not held in their new position for the right amount of time, what will happen?

Answer 21

The tooth must be held in its new position for the fibres to remodel. If they are held in their new position for long enough, they will have time to relax and reposition. If not, they will relapse and move back

Question 22

Periodontal and Hygiene: things to consider…

Answer 22

• grooves and depressions make roots harder to clean
• molar roots are posteriorly located, are wider, and are more difficult to gain access to
• the mandibular canines can have grooves on the longitudinal axis making it difficult to clean
• furcation involvement can cause the most difficult access and thus periodontal problems

Question 23

What are clinical considerations for mandibular canines?

Answer 23

• mn canines have deep, longitudinal grooves and sometimes have 2 root canals (any tooth with one root but 2 canals often have grooves)
• mn canines can sometimes bifurcate in the apical area

Question 24

What can cause grooves on the mesial root of mandibular laterals?

Answer 24

• 2 canals

If one root has 2 canals, one is buccal and one is lingual

Question 25

Why is biofilm retention easier on the roots of teeth?

Answer 25

Roots are rougher than enamel

Question 26

Where can we find enamel pearls? What effect does this have on cleaning?

Answer 26

Usually found in the furcation areas, makes cleaning more difficult

Question 27

Anterior teeth usually have 1 large root canal per tooth. What are the exceptions to this?

Answer 27

- mn laterals - mn canines (can have more than 1 canal, sometimes can bifurcate on the canines)

Question 28

What is an orifice? What are additional orrifices called?

Answer 28

An opening into a root canal, additional are called accessory canals

Question 29

If the 1st molar on the mandible has extra canals, where are they usually located and how many total?

Answer 29

Possible to have 3 root canals, where 2 are in the mesial root and 1 is in the distal

Question 30

If the 1st molar on the maxilla has extra canals, where are they usually located and how many total?

Answer 30

Possible to have 4 root canals, with 2 canals in the mesiobuccal root most likely and the other ones in the lingual and distobuccal roots

Question 31

What must occur for 3rd molars to develop with more room? How are the roots in this case?

Answer 31

The 2nd molars must be gone by the age of 14, and the roots on the 3rd molars are often longer, straighter and the teeth are usually bigger