1. Marginal or free gingiva
2. Attached gingiva
3. Interdental gingiva.

		Alveolar mucosa	Attached gingiva
1	Colour	Red	Pink
2	Surface texture	Smooth and shiny	Stippled
3	Epithelium	• Thinner • Nonkeratinized • No Rete pegs	• Thicker • Parakeratinized • Rete pegs present
4	Connective tissue	• More loosely arranged • More blood vessels	• Not so loosely arranged • Moderate blood vessels

• Maxillary incisor region – 3.5 to 4.5 mm
• Mandibular incisor region – 3.3 to 3.9 mm
• Maxillary first premolar – 1.9 mm
• Mandibular first premolar – 1.8 mm
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1. Gives support to the marginal gingiva.
2. Provide attachment or a solid base for the movable alveolar mucosa for the action of lips, cheeks and tongue.
3. Withstand frictional stresses of mastication and toothbrushing.
4. Acts as a barrier for passage of inflammation.
5. Provide resistance to tensional stress: Attached gingiva serves as a buffer to free gingival margin and mobile alveolar mucosa.

1. Attached gingiva.
2. Centre of Interdental papilla.

• Facial gingiva of the maxilla
• Facial gingiva of the mandible
• Lingual gingiva of the mandible.

1. Epithelium:
   1. Oral epithelium:
      • Stratum basale
      • Stratum spinosum
      • Stratum granulosum
      • Stratum corneum
   2. Sulcular epithelium
   3. Junctional epithelium
2. Basal lamina: Epithelium – connective tissue interface.
3. Connective tissue/Lamina propria:
   1. Cells:
      • Fibroblasts
      • Mast cells
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      • Eosinophils
      • Macrophages
      • Adipose cells
      • Inflammatory cells – neutrophil, plasma cells, lymphocyte
   2. Fibres:
      • Collagen fibers
      • Reticulin fibers
      • Elastic fibers
   3. Neurovascular bundles.

1. Principle cell: Keratinocytes
2. Non-keratinocytes/Clear cells:
   1. Langerhan cells
   2. Merkel cells
   3. Melanocytes.

1. Langerhan cells: are responsible for communication with immune system by acting as antigen – presenting cells for lymphocytes.
2. Melanocytes:
   1. Synthesize melanin which is responsible for providing color to gingiva.
   2. Are responsible for the barrier to UV damage.
3. Merkel cells: acts as tactile perceptors.

• Internal basement lamina is junctional epithelium – tooth interface.
• External basement lamina is junctional epithelium – connective tissue interface.

1. Tight junctions
2. Adhesive junctions
   1. Cell to cell
      1. Zonula adherens
      2. Desmosomes
   2. Cell to matrix
      1. Focal adhesions
      2. Hemidesmosomes
3. Communicating (gap) junctions.

1. Dentogingival group: These fibres extend from the cementum apical to junctional epithelium and course laterally and coronally into lamina propria of the gingiva. Provide gingival support.
2. Alveologingival group: These fibres arise from the alveolar crest and insert coronally into lamina propria of the gingiva. Attaches attached gingiva to alveolar bone.
3. Circular group: This group of fibres encircles the teeth in a cuff or ring like fashion. Maintain contour and position of free marginal gingiva.
4. Transseptal fibres: These are the group of prominent horizontal fibres located interproximally that extends from cementum of one tooth to the cementum of the neighbouring tooth. Maintain relationship of adjacent teeth, protect interproximal bone.
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5. Dentoperiosteal group: On the oral and vestibular surfaces of jaws, dentoperiosteal group of fibres extends from the tooth, passing over the alveolar crest to blend with fibres of the periosteum of the alveolar bone. Anchors tooth to bone, protect periodontal ligament.
6. Semicircular group: Group of fibres which attach at the proximal surface of a tooth, immediately below the cementoenamel junction, go around the facial or lingual marginal gingiva of the tooth and attach on the other proximal surface of the same tooth.
7. Transgingival group: Fibres that attach in the proximal surface of one tooth, transverse the interdental space diagonally, go around the facial or lingual surface of the adjacent tooth, again traverse diagonally the interdental space and attach in the proximal surface of the next tooth. Secure alignment of teeth in the arch.
8. Intergingival group: These fibres run parallel to dentition on vestibular and oral surfaces. They provide contour and support for the attached gingiva.
9. Interpapillary group: They are seen in the interdental gingiva extending in a faciolingual direction. Provide support for interdental gingiva.
   Dentogingival, dentoperiosteal and alveologingival fibres group provide the attachment of gingiva to the tooth and to the bony structure. Fibres of circular, semicircular, transgingival, intergingival and transseptal bundles connect teeth to one another.

1. From connective tissue into crevice – Gingival fluid exudates, PMNs, Ig, complement and various cells of immune system.
2. From crevice to connective tissue – Foreign material such as carbon particles, trypan blue.

1. Along the junctional epithelium, sub-epithelial vessels are parallel to the surface and are made up mostly of venules rather than 6capillaries. These venules have a greater disposition towards increased permeability than do capillaries and arterioles and they are more susceptible to haemorrhage and thrombosis.
2. Few tight junctions
3. Minimal cytoplasmic filaments
4. Higher number of intercellular spaces
5. Lower number of desmosomes.

1. Act as barrier
2. Provide attachment to tooth
3. Has rapid turnover rate
4. Secretes antimicrobial peptides—defensins, calprotectin and cathelicidin
5. Allow GCF flow.

1. Permeability
2. Degeneration
3. Deattachment
4. Lateral and apical proliferation.

• Dentogingival plexus: Plexus of blood vessels beneath junctional epithelium. The blood vessels in this plexus have a thickness of approximately 40 µm, which means that these are mainly venules. In healthy gingiva, no capillary loops occur in dento gingival plexus.
• Subepithelial plexus: Plexus of blood vessels beneath oral epithelium of free and attached gingiva, yield thin capillary loops, of 7 µm to each connective tissue papilla.
• Intermediate plexus (Sicher 1966): Fibers arising from cementum and bone are joined in midregion of periodontal ligament space giving rise to a zone of distinct appearance in light microscope. It was believed that the intermediate plexus provide a site where rapid remodeling of fibres occurs, allowing adjustment in the ligament to be made to accommodate small movements of tooth. However, evidence derived from electron microscope provide no support for this and was believed to be artifact.

		Oral epithelium	Sulcular epithelium	Junctional ep thel um
1	Keratinization	Keratinized	Non-keratinized	Non-keratinized
2	Rete pegs	Present	Absent	Absent
3	Strata granuloma and corneum	Present	Lacking	Lacking
4	Merkel cells	Present	Absent	Absent
5	Langerhan cells	Present	Few	Absent
6	Type IV collagen in basal lamina	Present	Absent	Absent
7	Tight junctions	More	Few	Few
8	Acid phosphatase activity	Present	Lacking	Lacking
9	Glycolytic enzyme activity	High	Lower	Lower
10	Intercellular space	Narrower	Narrower	Wider

1. Free gingiva and gingival sulcus is mainly supplied by supraperiosteal arterioles.
2. Col is supplied mainly by vessels of periodontal ligament.
3. Attached gingiva is supplied by supraperiosteal arterioles, arterioles that emerge from the crest of the interdental septa and vessels of periodontal ligament.

(i)	Mandibular incisors region drains into	-	Submental lymph nodes
(ii)	Buccal gingiva of maxilla, Buccal and lingual gingiva of mandibular premolar and molar region	-	Submandibular lymph nodes
(iii)	Third molar region	-	Jugulodigastric lymph nodes.

1. Vascular supply
2. Thickness of epithelium
3. Degree of keratinization of epithelium
4. Presence of pigment containing cells.

Category 0:	No pigmentation
Category 1:	Solitary unit(s) of pigmentation in papillary gingiva without formation of continuous ribbon between solitary units.
Category 2:	At least 1 unit of formation of continuous ribbon extending from two neighbouring solitary units.

1. Shape of the teeth
2. Teeth alignment in the arch
3. Location and size of the area of proximal contact
4. Dimensions of the facial and lingual gingival embrassures.

1. Contour of the proximal tooth surface
2. Location and shape of the contact area
3. Dimensions of the gingival embrassures.

1. Developmental origin -
   1. Reduced enamel epithelium
   2. Coronal cementum
   3. Dental cuticle
   4. Subsurface enamel matrix
2. Acquired coating -
   1. Salivary pellicle
   2. Bacterial coating
      1. Plaque
      2. Material alba
   3. Calculus
   4. Subsurface pellicle
   5. Surface stains.

 

1. Periodontal ligament fibres
2. Cellular elements
3. Ground substances
   1. Glycosaminoglycans
   2. Glycoproteins.

1. Transseptal group-
   Functions:
   1. Reconstructed even after destruction of the alveolar bone has occurred in the periodontal disease.
   2. Responsible for returning teeth to their original state after orthodontic therapy.
   Position:
   • Extends interproximally over alveolar bone crest and embedded in the cementum of adjacent teeth.
2. Alveolar crest group-
   Functions:
   1. Prevent extrusion
   2. Prevent lateral tooth movements
   Position:
   • Extends obliquely from the cementum just beneath the junctional epithelium to the alveolar crest.
3. Horizontal group-
   Position:
   • Extends at right angles to the long axis of the tooth from cementum to alveolar bone.
4. Oblique group-
   Functions:
   1. Bear vertical masticatory stresses
   2. Transform vertical stress into tension on the alveolar bone.
   Position:
   • Extends from the cementum in a coronal direction obliquely to the bone.
5. Apical group-
   Functions:
   1. Prevents tooth tipping
   2. Resists luxation
   3. Protects neurovascular supply to the tooth.
   Position:
   • It radiates in irregular fashion from cementum to bone at apical region of socket.
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6. Interradicular group-
   Functions:
   1. Prevents luxation
   2. Prevents tooth tipping and torquing.
   Position:
   • Found only between roots of multirooted tooth running from cementum into bone, forming crest of interradicular septum.

1. Connective tissue cells:
   1. Synthetic cells
      • Osteoblasts
      • Fibroblasts
      • Cementoblasts
   2. Resorptive cells
      • Osteoclasts
      • Fibroblasts
      • Cementoclasts
2. Epithelial cells: Epithelial rests of malassez
3. Immune system cells:
   1. Neutrophils
   2. Lymphocytes
   3. Macrophages
   4. Mast cells
   5. Eosinophils
4. Cells associated with neurovascular elements
5. Progenitor cells.

• Epithelial rests of Malassez – These are remnants of Hertwig's root sheath. They are present close to cementum through out the periodontal ligament and more in apical and cervical areas. When stimulated they proliferate and participate in the formation of periapical cysts and lateral root cysts.
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• Cementicles – These are global masses of cementum arranged in concentric lamellae that lie free in the periodontal ligament or adhere to the root surface.

1. Apical vessels
2. Penetrating vessels from the alveolar bone
3. Anastomosing vessels from the gingiva

1. Supportive:
   • Attaches the teeth to the bone.
   • Transmit occlusal forces to the bone.
   • Maintain gingival tissues in their proper relationship to the teeth.
   • Resist the impact of occlusal forces acting as a shock absorber.
   • Protect the blood vessels and nerves from injury by mechanical forces.
2. Sensory: Capable of transmitting
   • Tactile
   • Pressure
   • Pain sensations by trigeminal pathways.
3. Nutritive: Supply nutrients to
   • Cementum
   • Bone
   • Gingiva through blood vessels and lymphatics.
4. Homeostatic/formative: Helps in the formation and resorption of
   • Cementum
   • Bone during physiologic tooth movement and repair of injuries.

 

1. Fibroblasts which produce extrinsic sharpey's fibers.
2. Cementoblasts which produce intrinsic fibres of the cementum matrix.

1. Inorganic: 40 – 50% – Hydroxyapatite
2. Organic: 50%
   • Collagen: Type I, III, V, XII, XIV
   • Non-collagenous: Fibronectin, bone sialoprotein, osteopontin, osteocalcin, osteonectin, alkaline phosphatase
   • Formative cells: Cementoblast
   • Degradative cells: Cementoclast/Odontoclast
   • Adhesion molecule: Cementum attachment protein
   • Growth factor: Insulin like growth factor

1. Acellular afibrillar cementum (AAC): 1–15 µm. It consists of only mineralized ground substance, which is a product of cementoblasts. Cells, collagen (extrinsic and intrinsic) fibres are absent. It forms coronal cementum.
2. Acellular extrinsic fibre cementum (AEFC): 30–230 µm. It consists of sharpey's fibers and lacks cells, which is a product of fibroblasts and cementoblasts. It is found in cervical third of the root.
3. Cellular mixed stratified cementum (CMSC): 100–1000 µm. It consists of extrinsic and intrinsic fibers and cells which is a product of fibroblasts and cementoblasts. It is found in apical third of roots and in furcation areas.
4. Cellular intrinsic fibre cementum (CIFC): It consists of cells and intrinsic fibres, lacking extrinsic collagen fibres, which is a product of cementoblasts. It fills resorption lacunae.
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5. Intermediate cementum: It consists of cellular remnants of Hertwig's sheath embedded in calcified ground substance. It is present near cementodentinal junction.

		Acellular Cementum	Cellular Cementum
1	Formation	Forms before tooth reaches occlusal plane	Forms after tooth reaches occlusal plane
2	Cells	Does not contain any cells	Contains cementocytes
3	Location	Coronal portion of the root	Apical portion of the root
4	Rate of formation	Slower	Faster
5	Incremental lines	More	Sparse
6	Function	Forms after regenerative periodontal surgical procedure	Contributes to the length of root during growth
7	Calcification	More calcified	Less calcified
8	Sharpey's fibres	More	Less
9	Regularity	Regular	Irregular
10	Thickness	20 – 50 µm near the cervix, 150 – 200 µm near the apex	Thickness of 1 to several mm

• In about 60 – 65% — Cementum overlaps enamel.
• In about 30% — Edge to edge butt joint.
• In about 10% — Space present between cementum and enamel.

1. Paget's disease – hypercementosis
2. Hypopituitarism – decrease cementum formation
3. Cleidocranial dysplasia – defective cementum formation
4. Hypophosphatasia – no cementum formation.

 

1. Compact bone: External plate of cortical bone
2. Alveolar bone proper: Inner socket wall, Cribriform plate, Lamina dura, Bundle bone.
3. Trabecular bone: Cancellous trabeculae which is present between these two compact layers. It is also called as supporting alveolar bone.

1. Inorganic: 67% Hydroxyapatite
2. Organic: 33%
   • Collagen – 28%
   • Non-collagenous protein – 5%.

1. Osteocalcin
2. Osteonectin
3. Osteopontin
4. Bone sialoprotein
5. Bone proteoglycan biglycan
6. Bone proteoglycan II decorin
7. Thrombospondin
8. Bone morphogenetic proteins (BMPs).

1. Bone formation: Synthesize organic matrix of bone.
2. Cell to cell communication and maintenance of bone.
3. Bone resorption: Produces proteases, which are involved in matrix degradation and matrix maturation.
4. Produces:
   • Type I collagen
   • Non-collagenous protein
   • Osteocalcin
   • Osteopontin
   • Osteonectin
   • Various proteoglycans.

1. Acid phosphatase
2. Aryl sulfatase
3. β-glucoronidase
4. Several cysteine proteinase such as cathepsin B and L
5. Tissue plasminogen
6. Activator TPA
7. MMP-I
8. Lysosymes.

1. Systemic factors:
   1. Parathyroid hormone
   2. Parathyroid related peptide
   3. Vitamin D₃
   4. Thyroid hormone
2. Local factors:
   1. Prostanoids
   2. Lipoxygenase metabolites
   3. Cytokines: IL – 1, IL – 4, TNF – α, TNF – β, IL – 6
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3. Growth factors:
   1. EGF
   2. TGF – α
   3. TGF – β
   4. PDGF
4. Bacterial factors:
   1. Lipopolysaccharides
   2. Capsular material
   3. Peptidoglycans
   4. Lipoteichoic acids.

• Woven bone: The interwined collagen fibrils are oriented in many directions showing wide interfibrillar spaces. More non-collagenous matrix, proteins and cementocytes are present. It has low biomechanical strength. It is formed very quickly.
• Lamellar bone: Collagen fibres are thicker and arranged in ordered sheets consisting of aligned and closely packed fibrils. Less non-collagenous matrix, proteins and cementocytes are present. It is formed very slowly.
• Bundle bone: It is the bone adjacent to periodontal ligament, which contains great number of Sharpey's fibres. It is localized within alveolar bone proper consisting of thin lamellae arranged in layers parallel to the root, with intervening appositional lines.

• Fenestration-Isolated areas in which root is denuded of bone and root surface is covered by gingiva and periosteum, where marginal bone is intact.
• Dehiscence-When the denuded areas extend through the marginal bone, the defect is called dehiscence.

• Bone modeling: The process by which the overall size and shape of bone is established is called as bone modeling. It extends from embryonic bone development to the pre-adult period of human growth, which is continuous and covers a large surface.
• Bone remodeling: The replacement of old bone by new is called bone turnover remodeling. It does not stop when adulthood is reached, although its rate slows down, which is cyclical and usually covers a small area.

• Periosteum consists of an inner layer of osteoblasts surrounded by osteoprogenitor cells, which have the potential to differentiate 17into osteoblasts, and an outer layer rich in blood vessels and nerves and composed of collagen fibres which penetrate the bone, binding the periosteum to the bone.
• Endosteum is composed of a single layer of osteoblasts and a small amount of connective tissue. The inner layer is the osteogenic layer and the outer is the fibrous layer.