01 Anatomy of the Periodontium Flashcards
What are the functions of the periodontium?
- Tooth support and attachment
- Mechanosensory feedback and protection
- Nourish tooth and surrounding structures
What determines the shape of the interdental papilla?
- Contact relationship between teeth
- Width of proximal surfaces of teeth
- Course of CEJ
What shape is the interdental papilla of:
a) anterior
b) posterior
a) Pyramidal
b) More flattened
Where is the col related? How does its structure affect its clinical significance?
- Soft tissue valley at the interdental papilla
- Non-keratinised
- Provides path of least resistance for bacteria to invade CT, more likely to have deep PDs
Describe the structure of attached gingiva.
- Parakeratinised masticatory mucosa
- No submucosa, LP attached directly to underlying AB
- Firm, coral pink
- Stippling in 40% of adults
- FGG (coronal border) in 30-40% of adults
- MGJ (apical border) stable throughout life
Where is the widest and narrowest band of KG in the maxillary arch?
- Widest: Incisors
- Narrowest: Premolars
Where is the widest and narrowest band of KG in the mandibular arch?
- Widest buccal: Incisors
- Narrowest buccal: Premolars
- Widest lingual: Molars
- Narrowest lingual: Incisors
What are the functions of KG/AG?
- Protect periodontium from mechanical injury
- Dissipate pulling forces on gingival margin (Friedman 1957)
- Resist attachment loss and soft tissue recession (Ruben 1979)
- Discourage subgingival plaque formation from improper pocket closure (Friedman 1962)
- Favour removal of food particles during mastication and proper OH practices with adequate vestibular depth (Carranza and Carraro 1970)
Is it important to have KG/AG?
Preferable, but not necessary
What are the differences between thin and thick periodontal phenotypes?
Profile. Texture. Width. Shape. Bone. Reaction.
- Profile: thin has highly scalloped vs. thick has relatively soft tissue and bone contours
- Soft tissue texture: thin is delicate and friable vs. thick is dense and fibrotic
- Width of KG/AG: thin has minimal amounts vs. thick has relatively large amounts
- Bone thickness: thin has a thin bone with bony dehiscences and fenestrations vs. thick has thick bony ledges
- Reaction to insults: thin reacts readily with gingival recession vs. thick relatively resistant to acute trauma and reacts with pocket/intrabony defect formation (greater PDs)
- Shape of tooth: thin is triangular vs. thick is square
What methods are available to determine gingival phenotype?
- Visual inspection (Kao et al 2008)
- Transgingival probing (Claffey and Shanley 1986)
- Probe transparency (Kan et al 2003 - preferred)
- Ultrasonic device (Muller et al 1999)
- CBCT (Januario et al 2008)
Why is probe transparency the preferred method to determine gingival phenotype?
- Fast
- Cheap
- Easy to do
- Part of periodontal probing
What are the 3 types of gingival epithelium?
- Oral epithelium
- Sulcular epithelium
- Junctional epithelium
Compare the relative thickness of gingival tissue.
- Epithelium = 0.5mm
- LP = 1mm
- Glandular tissue = 1.5mm
Describe the structure and clinical significance of sulcular epithelium.
- Extends from crest of gingival margin to base of the gingival crevice, lines gingival sulcus
- Merges seamlessly with JE
- Non-keratinised/parakeratinised SSE
- Acts as semi-permeable membrane allowing injurious bacterial products pass into gingiva
Describe the structure and function of junction epithelium.
- Epithelial collar surrounding teeth
- Extends from CEJ to the base of the sulcus (up to 2mm)
- Non-keratinised SSE 15-30 cells thick at the base and tapers off to a single cell apically
- 3-4 cell layers thick but increases to 10-20 layers with age
- Length of JE depends on stage of eruption, physiological migration with age and response to inflammation
- Attachment to the tooth by hemidesmosomes via cell-to-cell attachment, also acts as a specific site for signal transduction to regulate gene expression, cell proliferation and differentiation
- Barrier against bacterial invasion, rapid turnover as JE repairs in 5-7 days (Taylor and Campbell 1971)
What is GCF and its functions?
- Gingival crevicular fluid seeps into the gingival sulcus from gingival CT, through sulcular epithelium
- GCF increases during inflammation
- Cleans material from the sulcus
- Plasma proteins to improve adhesion of epithelium to tooth
- Antimicrobial properties
- Antibody activity to defend gingiva
What are the components of gingival connective tissue (LP)?
Major components embedded in amorphous ground substance (matrix):
- Collagen fibers (60% CT vol)
- Fibroblasts (5% CT vol)
- Vessels and nerves (35% CT vol)
Cell types:
- Fibroblasts
- Mast cells
- Macrophages
- Inflammatory cells (PMN leukocytes, lymphocytes & plasma cells)
How do the features of gingival collagen relate to its function?
- Mainly type I collagen arranged in dense principal bundles
- Faster turnover rate than other parts of the oral cavity
- Papillary layer: finger-like extensions in depressions delineated by rete ridges
- Reticular layer: located beneath rete ridges
- Support free gingiva
- Bind attached gingiva to AB and teeth, thus resisting masticatory loads
What are the 5 types of CT fibers?
- Circular fibers
- Alveolo-gingival
- Dento-gingival
- Dento-periosteal
- Trans-septal
What are the functions of CT fibers?
- Provide rigidity to withstand forces of mastication
- Brace marginal gingiva firmly against tooth
- Unite free marginal gingival with root cementum and adjacent attached gingiva
What are the 5 types of PDL fibers?
- Alveolar crest
- Horizontal
- Oblique
- Apical
- Inter-radicular
Describe the structure and function of the LP matrix.
- Produced mainly by fibroblasts
- Medium to embed CT cells
- Main constituents are protein-carbohydrate macromolecules
- Essential for the maintenance of normal function of CT
- Transportation of water, electrolytes, nutrients, and metabolites between CT cells to maintain osmotic pressure
- Provides resilience of gingiva
Describe the blood supply of the periodontium.
Before entering socket: superior/inferior alveolar artery > dental artery > intra-septal artery
Entered socket: rami perforantes > penetrates bundle bone and anastomoses with periodontal vessels in PDL space > blood vessels in PDL form a polyhedral network surrounding the roo
Free gingiva collateral circulation receives blood from:
- Supraperiosteal blood vessels
- PDL blood vessels
- AB blood vessels
