The periodontium

Question 1

what is the periodontium?

Answer 1

the structures that support or hold the teeth in their proper position in the alveolar process
- divided into 2 units

Question 2

what are the 2 units of the periodontium?

Answer 2

1 - gingival unit

2 - attachment unit or apparatus

Question 3

what are the 3 parts of the gingival unit?

Answer 3

consists of
1 - free gingiva/unattached gingiva
2 - attached gingiva
3 - alveolar mucosa

Question 4

what are the 3 parts of the attachment apparatus for teeth in their sockets?

Answer 4

1 - alveolar bone
2 - PDL
3 - cementum

Question 5

what is the free gingiva?

Answer 5

extends from the gingival margin to the base of the sulcus. light pink. 0.5-2.5 mm in depth

Question 6

what common tissue makes up free and attached gingiva? what else is attached gingiva made up of?

Answer 6

both are composed of masticatory mucosa. attached gingiva has a thick epithelial and keratinized, underlying mucosa is composed of dense collagenous fibers that help the tissue withstand trauma. fibers are attached to bone and cementum

Question 7

where is the attached gingiva?

Answer 7

extends from the base of the sulcus to the mucogingival junction

Question 8

what is alveolar mucosa?

Answer 8

lining mucosa
- described as: thin and freely moveable; tears or injures easily; epithelium covering this lining mucosa is thin and nonkeratinized; composed of loose connective tissue and muscle fibers

Question 9

where is alveolar mucosa?

Answer 9

continuous from the mucogingival junction to the lining of the cheeks and lips and floor of the mouth (lining mucosa)

Question 10

what is the sulcus?

Answer 10

the space between the free gingiva and the tooth, 0.5 mm - 3 mm in depth

Question 11

what is gingival papilla/interdental papilla?

Answer 11

the free gingiva located in the triangular shaped interdental spaces between the teeth
- the tissue’s apex is sharp on anterior teeth and more blunt on posterior teeth

Question 12

what affects the shape of the papilla?

Answer 12

• the location of the contact area of the adjacent teeth
• the shape of the interproximal surfaces of adjacent teeth
• the CEJ of adjacent teeth

Question 13

how can we tell when there is inflammation in the papilla?

Answer 13

easily recognized because papilla takes on:

• a reddened colour
• the tissue becomes puffy
• the apex becomes blunt
• if gingiva appears pink but it is clearly bulbous we write red to identify inflammation

Question 14

what is the epithelium like in the gingival sulcus?

Answer 14

• nonkeratinized, where the more outer portion is keratinized

Question 15

what does the gingival groove identify?

Answer 15

• the base of the sulcus if it is visible

Question 16

how does attached gingiva appear?

Answer 16

often has stippled surface that resembles an orange peel (rete peg formation causes stippling)

Question 17

what type of epithelium makes up the attached gingiva?

Answer 17

• (keratinized) stratified squamous cell epithelium

Question 18

what causes the stippling in the attached gingiva?

Answer 18

the rete peg formation, which is created by the irregular binding of the epithelium to bone by collagen fibers giving the look of stippling

Question 19

what colour is gingiva?

Answer 19

• varies from light to dark depending on the individual’s pigmentation. the darker a person’s skin is, the more apt the tissue will be dark due to melanin.
• healthy gingiva will be pink, more red = likely inflammation. regardless of pigmentation, we still write pink, never brown

Question 20

what are fibroblasts?

Answer 20

the cells that make up the collagenous fibers of the attached gingiva

Question 21

what are Sharpey’s fibers?

Answer 21

the fibers that are embedded in the cementum from the papillary tissues. at the ends of connective tissue fibers that are embedded in cementum and bone

Question 22

what 3 types of fiber group help surround and support the teeth?

Answer 22

1 - gingival fiber group
2 - the transseptal fiber group
3 - the periodontal fiber group

Question 23

what is the function of the gingival fiber group? (4)

Answer 23

1 - to keep the gingiva closely attached to the tooth surface
2 - assist in preventing the free gingiva from peeling away, and keep the attached gingiva firmly attached
3 - prevent migration of the junctional epithelial attachment (sulcus)
4 - resist recession of the gingiva

Question 24

there are 4 groups of gingival fibers. what are they used for?

Answer 24

• gingival fibers pass out of the cementum/alveolar bone in small bundles
• they act to support the marginal (free) gingival tissues in relation to the tooth (sphincter like ‘pulling of purse strings’)
• they are located in the lamina propria (connective tissue of the gingiva)

Question 25

what are the 4 groups of gingival fibers?

Answer 25

1 - dentogingival fibers 2 - alveologingival fibers 3 - dentoperiosteal fibers 4 - circular fibers

Question 26

what are dentogingival fibers?

Answer 26

extend from the cervical cementum outward and upward into the lamina propria

Question 27

what are alveologingival fibers?

Answer 27

extend upwards from the alveolar crest into the lamina propria

Question 28

what are the dentoperiosteal fibers?

Answer 28

extend facially and lingually from the cementum, pass over the crest of bone, and turn apically between the outer periosteum of the alveolar process and the outer epithelium of the attached gingiva

Question 29

what are the circular fibers?

Answer 29

form a band around the neck of a tooth and are interlaced

Question 30

what is the transeptal fiber group?

Answer 30

fibers that are just above the alveolar crest of bone that travel completely across the IP space and attach to the cementum of the adjacent tooth

Question 31

what is the periodontal group?

Answer 31

periodontal ligaments = dense connective tissues organized into fiber groups - PDL connects the cementum covering the root of the tooth with the alveolar bone of the socket wall - the fibers are designed to support the tooth in its socket and hold it firmly in normal relationship to the surrounding soft and hard tissues - the fibers also act as the sensory receptors, necessary for the proper positioning of the jaws during normal functioning

Question 32

where does the blood supply of the gingival tissue originate? where do those vessels originate from?

Answer 32

in the supraperiosteal vessels. those, in turn, originate from the lingual, mental, buccal, intraorbital and palatine arteries. gingiva is rich in vascularity, as is alveolar mucosa which is redder because of shallower blood vessels

Question 33

what are the 4 functions of the attachment unit? what do each of these functions do?

Answer 33

- supportive: hold teeth in place - formative: replace cementum (specialized cells called cementoblasts), PDL (fibroblasts) and alveolar bone (osteoblasts) - nutritive: supplied by the blood vessels - sensory: supplied by the nerves which act as an indicator of the pressure or pain around a tooth

Question 34

what other function does the PDL have?

Answer 34

also acts as a suspensory mechanism for the teeth that cushions the impact between tooth and bone on the exertion of pressure

Question 35

what are the 2 types of cementum? how does cementum grow?

Answer 35

- acellular: always covers the cervical (coronal) 3rd of the root and extends over the root but not the apical portion - cellular: like bone in character and covers the apical 3rd of the root - cementum grows by apposition (addition) of new layers

Question 36

what is the alveolar process?

Answer 36

- supports the teeth in their functional positions in the jaws - cortical plate is dense outer covering of the spongy bone that makes up the central part of the alveolar process (hard bone)

Question 37

what is the alveolar crest?

Answer 37

- the highest point of the alveolar ridge

Question 38

what is the alveolar socket?

Answer 38

- the cavity within the alveolar process that surrounds the root of a tooth

Question 39

what is the lamina dura?

Answer 39

- thin compact bone lining the alveolar socket and alveolar crest

Question 40

what are the 5 periodontal fiber groups?

Answer 40

``` 1 - alveolar crest fibers 2 - horizontal fibers 3 - oblique fibers 4 - apical fibers 5 - interradicular fibers ```

Question 41

what are alveolar crest fibers?

Answer 41

retain tooth and resist lateral movement

Question 42

what are horizontal fibers?

Answer 42

restrain lateral movement

Question 43

what are oblique fibers?

Answer 43

resist forces to the long axis of the tooth, most numerous fibers

Question 44

what are apical fibers?

Answer 44

prevent tipping, resist twisting, protect blood and nerve supply

Question 45

what are interradicular fibers?

Answer 45

- only multirooted teeth (resist tipping and twisting)

Question 46

what are the 2 forces within the mouth that allow for movement of the teeth? why is this?

Answer 46

- mesial drift (allows forward movement) - eruption forces (will migrate occlusally until it occludes with an antagonist) because the PDL allows for movement of the teeth, they have the potential to drift, rotate or be compressed within the alveolus

Question 47

what clinical consideration do we need to take into consideration regarding the PDLs?

Answer 47

- teeth can move in the alveolar bone - forces must be present - osteoclastic and osteoblastic cells are in action: the net effect is that the tooth is moving away from the force by remodelling bone; one side-bone is destroyed, the other is formed

Question 48

what are the 5 types of forces?

Answer 48

1 - active eruption: compensation for occlusal abrasion 2 - mesial drift: compensation for proximal abrasion 3 - masticatory occlusal forces: tooth occlusion during chewing 4 - orthodontic forces: pressure to fix maloccusion 5 - traumatic occlusal forces: teeth being subject to premature contact during occlusion

Question 49

what are the consequences of force?

Answer 49

- active eruption and mesial drift cause tipping, drifting and rotation - occlusal trauma is not a constant consistent force. it does not result in movement as much as it does tooth mobility (the PDL space is widened and can be visible on a radiograph; the tooth can become loose and mobile in the socket)