Gingiva Flashcards
What structures compose the periodontium, and what is their shared function?
Gingiva, periodontal ligament, cementum, and alveolar bone. Although distinct in architecture and composition, they function as a single biological unit supporting teeth and absorbing forces.
Define periodontal phenotype and explain its clinical relevance.
Describes the combined features of gingival thickness, keratinized tissue width, and bone morphology; important because thin phenotypes are more prone to recession and bone loss, while thick phenotypes are more resistant to trauma and disease.
What are the three classifications of periodontal phenotype according to the 2017 World Workshop?
Thin-scalloped (delicate tissues, narrow zone), thick-flat (broad, fibrous tissues), and thick-scalloped (resilient but scalloped margins).
What three zones make up the oral mucosa, and what distinguishes each?
Masticatory mucosa (keratinized, covers gingiva and hard palate), specialized mucosa (tongue dorsum, taste buds), lining mucosa (nonkeratinized, cheeks, lips, soft palate).
Describe marginal (free) gingiva, its dimensions, and clinical landmarks.
Unattached gingiva forming the soft tissue wall of the gingival sulcus; typically ~1 mm wide, separated from attached gingiva by the free gingival groove; scalloped contour culminating at the gingival zenith.
What is the gingival sulcus, and what is considered a healthy sulcus depth?
V-shaped shallow crevice between tooth and marginal gingiva; healthy probing depth is 0–3 mm, with 0 mm possible only under ideal experimental conditions (e.g., germ-free animals).
Explain the difference between attached gingiva and keratinized gingiva.
Attached gingiva is firmly bound to alveolar bone; keratinized gingiva includes both attached and free gingiva; the width of keratinized gingiva = attached gingiva + marginal gingiva.
Where is attached gingiva widest and narrowest?
Widest: maxillary incisor region (3.5–4.5 mm). Narrowest: premolar region (~1.8–1.9 mm).
What determines the shape of the interdental papilla?
Presence or absence of proximal contacts, distance between contact point and bone crest, and presence of gingival recession. Forms can be pyramidal or “col”-shaped.
What are the main structural features of gingival epithelium?
Stratified squamous epithelium overlying connective tissue core; main cells are keratinocytes; minor populations include Langerhans cells, melanocytes, and Merkel cells.
What is the function of the basal lamina between gingival epithelium and connective tissue?
Anchors epithelial cells, separates tissue compartments, and regulates molecular diffusion between them.
Compare orthokeratinized and parakeratinized gingiva.
Orthokeratinized: no nuclei in superficial keratin layer (full keratinization). Parakeratinized: retains pyknotic nuclei; most common in gingiva.
What distinguishes sulcular epithelium from oral epithelium histologically?
Sulcular epithelium: nonkeratinized, no stratum granulosum or corneum, fewer rete pegs; adapts to the bacterial challenge.
How does sulcular epithelium contribute to periodontal disease?
Acts as a semipermeable membrane allowing bacterial products to penetrate into connective tissue; less permeable than junctional epithelium but susceptible to inflammation.
Describe the structure and significance of junctional epithelium.
Collar-like, nonkeratinized stratified squamous epithelium adhering to enamel or cementum; essential for periodontal health by forming an epithelial seal; ~0.97–1.14 mm in length.
What roles do Langerhans cells play in gingiva?
Dendritic cells presenting antigens to lymphocytes; abundant in outer epithelium, fewer in sulcular epithelium, absent in healthy junctional epithelium.
How do melanocytes affect gingival appearance?
Contribute to pigmentation; variation in oral mucosa color is due to melanin synthesis and degradation, not melanocyte number.
What is the function of Merkel cells in gingival epithelium?
Mechanoreceptors associated with sensory nerve endings; found in deeper epithelial layers.
What determines the rate of epithelial renewal in gingiva?
Proliferation in basal/suprabasal layers balanced by surface shedding; mitotic rates are higher in nonkeratinized areas and during gingivitis.
What changes occur in gingival fluid during health vs. inflammation?
Healthy sulcus has minimal transudate; inflammation increases flow, producing an exudate rich in immune factors like antibodies and antimicrobial peptides.
What are the predominant collagen types in gingival connective tissue?
Type I collagen (main tensile strength); Type IV collagen (supports basement membrane structures).
What are the three major groups of gingival fibers and their functions?
Gingivodental fibers: brace gingiva to tooth. Circular fibers: encircle teeth to maintain contour. Transseptal fibers: connect adjacent teeth across interdental space.
Which cells dominate the gingival connective tissue, and what are their roles?
Fibroblasts; synthesize collagen and regulate its breakdown via phagocytosis and collagenase secretion; essential for tissue remodeling and healing.
What are the primary blood supplies to the gingiva?
Supraperiosteal arterioles, periodontal ligament vessels, and arterioles from interdental bone; contribute to anastomotic network supporting tissue health.
