the periodontium

Question 1

what is the periodontium made up of?

Answer 1

• gingivae
• PDL
• bone
• cementum

Question 2

what is the function of the bone?

Answer 2

• holds tooth in place via pdl fibres
• absorbs and distributes masticatory forces
• cortical and trabecular bone
• 1st sign of bone loss is loss of lamina dura (cortical plate) on radiograph
• loss irreversibly with periodontitis

Question 3

describe the gingival tissues?

Answer 3

• free gingival groove- not attached to tooth surface
• attached gingivae- forms protective cuff round tooth to protect underlying pdl and bone from bacterial invasion- thick keratinised tissue more resistant- tightly bound to bone.
• alveolar mucosa- overlying alveolar bone- less keratinised

Question 4

describe the pdl

Answer 4

• attaches tooth to bone via principal collagen fibres (sharpay) that are attached to cementum and bone
• acts as shock absorber
• allows for normal physiological movement of up to 0.2mm

Question 5

describe the cementum

Answer 5

• provides attachment of tooth to bone
• protects root dentine
• resistant to absorption

Question 6

what is the junctional epithelium?

Answer 6

• JE is found at or coronal to the ACJ in health
• JE is a 1mm thick epithelial attachment which attaches to the tooth via hemidesmosomes and extends apically around 2-3mm.
• it has large intracellular spaces and is therefore leaky
• in disease it becomes ulcerated and migrates apically following periodontal destruction