periodontal tissues (OB2)

Question 1

tooth support tissues

Answer 1

• periodontium (peri -around in latin, odous = tooth in greek)
• > comprises periodontal ligament, alveolar bone, gingiva (gum) including junctional epithelium
• cementum (some include as part of the periodontium)

Question 2

components of periodontium

Answer 2

• periodontal ligament
• alveolar bone
• gingiva (gum) including junctional epithelium

Question 3

periodontal ligament (PDL)

Answer 3

• ligament that attaches around the tooth and attaches tooth to bone/soft tissue
• > dense fibrous connective tissue
• > occupies periodontal space between tooth and alveolar bone (~0.2mm wide)
• contains:
• > cells
• > fibres (principally collagen/strong structural protein, collagen fibres run OBLIQUELY in PDL)
• > ground substance
• > water
• > nerves (stimulated by abscess
• > blood vessels
• PDL = complicated structure in very small space

Question 4

functions of PDL (periodontal ligament)

Answer 4

• occupies space between tooth and bone
• attachment = tooth-bone
• support:
• > suspensory system
• > shock absorber
• > to withstand masticatory/chewing forces (500-700N… 1,500N)
• sensory:
• > highly innervated
• > sesnitive to mechanical touch
• > stimuli of nerves = sensation and pain

Question 5

alveolar bone

Answer 5

• surrounds tooth/ bone that tooth sits in
• rest of jaw bone = basal bone
• alveolus = ‘sac’/ ‘little cavity’/bony socket that the tooth sits in
• > if tooth is extracted, alveolar bone disappears over time due to reshaping (this creates problems for dentures as the denture sits on top of basal bone therefore implants hold the dentures in place as the alveolar bone has disappeared)

Question 6

different zones of jaw bone

Answer 6

• trabecular bone = spongy/cancellous bone, basal bone = trabecular bone
• cortical bone (dense outer surface of bone that forms a protective layer around the internal cavity), alveolar bone = cortical bone (very dense, thin and porous/full of holes)
• lamina dura (bone of tooth socket, bundle bone, cribiform plate, bundles of fibres into ligament, full of holes/is porous, looks dense in x-ray)

Question 7

inner layer of jaw bone

Answer 7

trabecular bone

Question 8

outer layer of jaw bone

Answer 8

cortical bone

Question 9

bone of tooth socket

Answer 9

lamina dura

Question 10

methods of applying local anaesthesia

Answer 10

• to upper incisors: pass needle through mucousa until it touches the surface of the cortical bone (outer part of jaw bone) and diffuses through holes as cortical bone is very porous (into lining mucosa)
• to lower molars: intraligamentary anaesthesia, injected into the periodontal ligament (putting needle between tooth and bone into ligament, anaesthesia flows out of holes)
• > into lining mucosa (flexible therefore can be pain free if done properly in some areas)
• > into a masticatory mucosa (tightly bound down therefore painful!)

Question 11

gingiva (gum)

Answer 11

• tissue around tooth covering bone

- a type of oral mucosa (masticatory mucosa)

Question 12

function of oral mucosa

Answer 12

• protection (lines the mouth):
• > mechanical protection (eg. protection from sharp foods)
• > bacterial protection
• > chemical protection (eg. against acids)
• > acts as a barrier to protect against dehydration
• sensation (richly innervated/filled with nerves)
• secretion (contains salivary glands and prevents dry mouth)
• thermal regulation (important in dogs - panting)

Question 13

2 tissues that make up oral mucosa

Answer 13

• epithelium (barrier on outside, which attaches to tooth)

- connective tissue (lamina propria, underneath epithelium)

Question 14

3 types of oral mucosa

Answer 14

• masticatory mucosa (chewing)
• lining mucosa (flexible, is thinner therefore is more flexible)
• specialised mucosa (contains gustatory mucosa which contains receptors for the sensation of taste)

Question 15

areas of masticatory mucosa

Answer 15

• in areas where mucosa is exposed to areas of mechanical damage
• > exists around teeth and onto hard palate
• > very unflexible/tough

Question 16

areas of lining mucosa

Answer 16

• is thinner than masticatory mucosa therefore is more flexible
• present where you want flexibility (inside of lips, underneath the tongue, valves)

Question 17

areas of gustatory mucosa

Answer 17

• gustatory mucosa contains receptors for the sensation of taste
• present at the back of the tongue/dorsal of tongue

Question 18

oral mucosa of the periodontium (around the teeth)

Answer 18

• gingival mucosa = masticatory mucosa (relatively thick epithelium, keratinised/tough, pink, firm, stippled)
• alveolar mucosa = lining mucosa (relatively thin epithelium, non-keratinised, red, loose/mobile, smooth)

Question 19

why is alveolar mucosa darker than gingival mucosa

Answer 19

-gingival mucosa is keratinised, alveolar mucosa is non-keratinised

Question 20

mucogingival junction

Answer 20

junction between oral mucosa of the periodontium (between alveolar mucosa and gingival mucosa)

Question 21

types of gingival mucosa

Answer 21

• free gingiva (directly around tooth/enamal)
• attached gingiva (between free gingivi and mucogingival junction), attached to alveolar bone
• free gingival groove (between free and attached gingiva)

Question 22

dento-gingival junction

Answer 22

• junction between tooth and gingiva (junctional epithelium which can leak)
• > gingival sulcus = between enamel and gingiva, space where bacteria can lie/glucose from food can get trapped

Question 23

cementum

Answer 23

part of tooth involved in tooth support