The Gingiva Embryology, Anatomy, Histology & Biochemistry
Dr. Khansa Ababneh
Periodontium
Tissues which surround & support the teeth.
Periodontium • Gingiva • Periodontal ligament
• Alveolar bone • Cementum
Tooth Development & Eruption
Periodontal tissues develop during tooth development
Development of the periodontium role of epithelial-mesenchymal interactions
Oral epithelium
Gingival epithelium
Ectomesenchyme (dental follicle)
PDL Alveolar bone Cementum Gingival CT
Oral mucosa
Masticatory mucosa
Lining mucosa
Specialised mucosa
GINGIVA
Part of masticatory mucosa Fibrous mucosa surrounding necks of teeth covers the coronal portion of the alveolar process
GINGIVA 3 main parts: •
Free gingiva
•
Attached gingiva
3.
Interdental gingiva
Free gingiva
From gingival margin to the free gingival groove (FGG) at the level of the CEJ. Can be separated form the tooth by a probe Depth of gingival sulcus (crevice) : 0-3 mm.
Attached gingiva
Extends from the FGG to the mucogingival junction (MGJ)
Attached gingiva
On the palate, the whole mucosa is keratinised and there is
No MGJ
Attached gingiva
Firmly attached to underlying bone to: withstand
masticatory forces
withstand
forces of tooth brushing
prevent
movement of marginal gingiva
Width varies in different parts of the mouth;
between right & left sides
between different people
with age (increases)
For example
Maxilla, buccally: widest around incisors, narrowest around premolars
Mandible, lingually narrowest around incisors, widest around molars.
Is the width of the attached gingiva important? Which is more important; width or thickness?
Keratinised Vs Attached Attached gingiva
Keratinised gingiva FG + AG
KG
Interdental gingiva
Also: interdental papilla.
Shape determined by:
Contact relationship between teeth width of proximal surfaces shape of the CEJ.
Anterior : Pyramidal Molars : Flattened in a buccolingual direction. Between buccal & lingual papillae
COL
Clinical Features of normal (healthy) gingiva
Colour: pink (physiologic/racial pigmentation)
Contour: scalloped outline
Margins: thin, knife-edge.
Surface texture: stippled
Consistency: resilient
Pointed interdental papillae
Probing depth: 0-3 mm.
No bleeding on probing (BOP).
HISTOLOGY The gingiva consists of 2 main types of tissue:
1. 2. •
Epithelium Connective tissue Epithelium is attached to the underlying connective tissue by a basement membrane.
Epithelium
Stratified squamous epithelium (parakeratinised) Function:
Protection of underlying structures while permitting selective interchange with the oral environment
Active production of cytokines, adhesion molecules, growth factors and enzymes
Examples: β-defensins, IL-1 β, IL-8, EGF
Main cell type :
keratinocyte
4 layers of cells: 1. stratum basale (basal cell layer) 2. stratum spinosum (spinous cell layer) –
stratum granulosum (granular cell layer)
4. stratum corneum (corneal or horny cell layer)
Structure
•
The oral mucosa is mostly parakeratinised: stratum corneum retains pyknotic nuclei
•
Difference between ortho- & parakeratinisation
•
Cytokeratin (K1-K19)
•
Other proteins: keratolinin, involucrin & filaggrin.
Other cell types
within the gingival epithelium Langerhans
cells: modified monocytes found
in the suprabasal layer, playing a role in immunity Merkel
cells: in deeper layer of epitheium,
contain nerve endings Melanocytes:
in basal and spinous cell layer,
contain melanin
Types of Gingival Epithelium
Oral epithelium
Sulcular epithelium
Junctional epithelium
Oral epithelium Faces the oral cavity, is parakeratinised, shows rete pegs and connective tissue papillae (responsible for the stippled texture). Turnover rate 10-12 days.
Sulcular epithelium Faces the tooth without contacting it. Thin nonkeratinised stratified squamous epithelium (no granulosum and corneum layers), extends from the coronal end of the junctional epithelium to the crest of the gingival margin. Acts as a semipermeable membrane.
Junctional epithelium
Provides contact between gingiva & tooth. Stratified squamous nonkeratinised epithelium. 3-4 cells thick in early life, increasing to 10-20 later. Basal and suprabasal layers. Length = 0.25-1.35 mm. No rete pegs.
Junctional Epithelium
Derived from the reduced enamel epithelium Attachment to tooth: inner basal lamina Attachment to gingival connective tissue: outer basal lamina Lamina densa & lamina lucida
ECM of Epithelium
Not abundant in gingival epithelium
PG: CD44, HA, syndecan, decorin
Glycoproteins: integrin family, e.g.: α2β1, and ICAM-1 (in Jep & Oep)
Differences between gingival epithelia
Cell size/tissue volume in JE is > in OE
Intercellular spaces in JE are > in OE
No of desmosomes in JE is < in OE
Difference in cytokeratin expression & cell surface markers JE originates from REE; OSE & OE originate from oral mucosa
Renewal of gingival epithelium Cell division
Cell shedding
The Dentogingival junction
Enamel + cementum (CEJ) + junctional epithelium + gingival fibres + adhesion proteins.
Dentogingival epithelium
Gingival Crevicular fluid (GCF)
In gingival sulcus
Cleaning & antimicrobial effects
Increases adhesion of gingiva to tooth.
Connective Tissue •
Cells:
2. 3. 4. 5. 6.
fibroblasts, mast cells, macrophages, neutrophils, lymphocytes, plasma cells.
Collagen fibres Extracellular matrix (ECM) Nerves Blood vessels Lymphatics
Fibres
Collagen, elastin, reticulin & oxytalan fibres.
Provide structure, framework, increase elasticity and resiliency of gingiva.
Fibres
Arranged in groups :
Transseptal
Circular
Dentogingival
Dentoperiosteal
ECM
Medium in which all other components are embedded. Consists of: water, proteins, glycoproteins, proteoglycans & growth factors: Collagen type I , III, V & VI Proteoglycans: decorin, biglycan, versican Integrins Fibronectin