Q.1. What is Gingiva?
It is the part of oral mucosa that covers the alveolar processes of the jaw and surrounds the neck of the teeth.
Q.2. What are the parts of Gingiva?
- Marginal or free gingiva
- Attached gingiva
- Interdental gingiva.
Q.3. What are the differences between Alveolar mucosa and Attached gingiva.
Smooth and shiny
• No Rete pegs
• Rete pegs present
• More loosely arranged
• More blood vessels
• Not so loosely arranged
• Moderate blood vessels
Q.4. What is the width of attached gingiva?
It is the distance between mucogingival junction and the projection on the external surface of the bottom of gingival sulcus/periodontal pocket.
Width of attached gingiva on facial aspect –
- 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
Q.5. What is the significance of attached gingiva?
- Gives support to the marginal gingiva.
- Provide attachment or a solid base for the movable alveolar mucosa for the action of lips, cheeks and tongue.
- Withstand frictional stresses of mastication and toothbrushing.
- Acts as a barrier for passage of inflammation.
- Provide resistance to tensional stress: Attached gingiva serves as a buffer to free gingival margin and mobile alveolar mucosa.
Q.6. Where stippling is normally present on gingiva?
- Attached gingiva.
- Centre of Interdental papilla.
Q.7. What is Col?
It is a valley like depression which connects the facial and lingual papillae and conforms to the shape of the interproximal contact areas.
Q.8 What is mucogingival junction and its clinical importance?
It is the interface between the more apically located alveolar mucosa and the more coronally located attached gingiva.
Clinical importance of the mucogingival junction is in measuring the width of attached gingiva.
Q.9 Where is mucogingival junction normally present?
Mucogingival junction is present on the three gingival surfaces:
- Facial gingiva of the maxilla
- Facial gingiva of the mandible
- Lingual gingiva of the mandible.
The palatal gingiva of the maxilla is continuous with the tissue of the palate, which is bound down to the palatal bones. Because the palate is devoid of freely movable alveolar mucosa, there is no mucogingival junction.
Q.10 Write salient microscopic features of gingiva.
- Oral epithelium:
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum corneum
- Sulcular epithelium
- Junctional epithelium
- Basal lamina: Epithelium – connective tissue interface.
- Connective tissue/Lamina propria:
- Mast cells
- Adipose cells
- Inflammatory cells – neutrophil, plasma cells, lymphocyte
- Collagen fibers
- Reticulin fibers
- Elastic fibers
- Neurovascular bundles.
Q.11 Write the cells present in the gingival epithelium.
- Principle cell: Keratinocytes
- Non-keratinocytes/Clear cells:
- Langerhan cells
- Merkel cells
Q.12 What are the functions of non-keratinocytes?
- Langerhan cells: are responsible for communication with immune system by acting as antigen – presenting cells for lymphocytes.
- Synthesize melanin which is responsible for providing color to gingiva.
- Are responsible for the barrier to UV damage.
- Merkel cells: acts as tactile perceptors.
Q.13 Where melanin is formed and stored?
Melanin is synthesized in an organelle called, premelanosomes/melanosomes in melanocytes cells. Melanin is stored in melanophages/melanophores.
Q.14 What is the ratio of melanocytes to keratinocytes producing epithelial cells?
Q.15 What is basal lamina?
Basal lamina is a structural entity of epithelial origin of 300 – 400 Å thick which is visible only under electron microscope. It consists of electrolucent zone called lamina lucida and an inner electrodense zone called lamina densa.
Q.16 What is internal basement lamina and external basement lamina?
- Internal basement lamina is junctional epithelium – tooth interface.
- External basement lamina is junctional epithelium – connective tissue interface.
Q.17 Classify various junctional complexes present in gingiva.
- Tight junctions
- Adhesive junctions
- Cell to cell
- Zonula adherens
- Cell to matrix
- Focal adhesions
- Communicating (gap) junctions.
Q.18 What is Dentogingival unit?
The junctional epithelium and gingival fibres together forms a functional unit called as dentogingival unit.
Q.19 Which type of collagen is present in gingiva?
Type I, III, IV, V, VI.
Q.20 Write about gingival fibre's position and function.
- 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.
- Alveologingival group: These fibres arise from the alveolar crest and insert coronally into lamina propria of the gingiva. Attaches attached gingiva to alveolar bone.
- Circular group: This group of fibres encircles the teeth in a cuff or ring like fashion. Maintain contour and position of free marginal gingiva.
- 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.
- 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.
- 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.
- 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.
- Intergingival group: These fibres run parallel to dentition on vestibular and oral surfaces. They provide contour and support for the attached gingiva.
- 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.
Q.21 What is the clinical significance of Transseptal fibres?
The transseptal fibres collectively form an interdental ligament connecting all the teeth of the arch. This ligament, although belonging to the supra-alveolar fibre apparatus, appears to be uniquely important in maintaining the integrity of the dental arch. It is rapidly reformed after excision. Residual portions of transseptal fibres are seen, even in advanced stages of resting periodontal disease.
Q.22 What is the normal length of junctional epithelium?
0.25 – 1.35 mm
Q.23 Discuss permeability of junctional epithelium.
Junctional epithelium allows two-way movement of variety of substances:
- From connective tissue into crevice – Gingival fluid exudates, PMNs, Ig, complement and various cells of immune system.
- From crevice to connective tissue – Foreign material such as carbon particles, trypan blue.
Q.24 Why junctional epithelium is easily penetrated?
- Along the junctional epithelium, sub-epithelial vessels are parallel to the surface and are made up mostly of venules rather than capillaries. These venules have a greater disposition towards increased permeability than do capillaries and arterioles and they are more susceptible to haemorrhage and thrombosis.
- Few tight junctions
- Minimal cytoplasmic filaments
- Higher number of intercellular spaces
- Lower number of desmosomes.
Q.25 What are the functions of junctional epithelium?
- Act as barrier
- Provide attachment to tooth
- Has rapid turnover rate
- Secretes antimicrobial peptides—defensins, calprotectin and cathelicidin
- Allow GCF flow.
Q.26 What are the problems related to junctional epithelium?
- Lateral and apical proliferation.
Q.27 Write peculiar feature of junctional epithelium.
Junctional epithelium is the only attachment in the body between soft tissue and a calcified tissue which is exposed to the external environment.
Q.28 What is Dentogingival plexus, Sub-epithelial plexus and Intermediate plexus?
- 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.
Q.29 What is the difference between Oral, Sulcular and Junctional epithelium?
Junctional ep thel um
Strata granuloma and corneum
Type IV collagen in basal lamina
Acid phosphatase activity
Glycolytic enzyme activity
Q.30 What is the arterial supply of various parts of gingiva?
- Free gingiva and gingival sulcus is mainly supplied by supraperiosteal arterioles.
- Col is supplied mainly by vessels of periodontal ligament.
- Attached gingiva is supplied by supraperiosteal arterioles, arterioles that emerge from the crest of the interdental septa and vessels of periodontal ligament.
Q.31 Describe the lymphatic drainage of periodontium.
Mandibular incisors region drains into
Submental lymph nodes
Buccal gingiva of maxilla, Buccal and lingual gingiva of mandibular premolar and molar region
Submandibular lymph nodes
Third molar region
Jugulodigastric lymph nodes.
Q.32 Which factors determine the colour of gingiva?
- Vascular supply
- Thickness of epithelium
- Degree of keratinization of epithelium
- Presence of pigment containing cells.
Q.33 Classify gingival pigmentation.
Gingival pigmentation was classified according to modification of melanin index.
Solitary unit(s) of pigmentation in papillary gingiva without formation of continuous ribbon between solitary units.
At least 1 unit of formation of continuous ribbon extending from two neighbouring solitary units.
Q.34 Which factors determine the contour of gingiva?
- Shape of the teeth
- Teeth alignment in the arch
- Location and size of the area of proximal contact
- Dimensions of the facial and lingual gingival embrassures.
Q.35 Which factors determine the shape of interdental gingiva?
- Contour of the proximal tooth surface
- Location and shape of the contact area
- Dimensions of the gingival embrassures.
Q.36 What is the oxygen consumption of normal gingiva?
QO2(oxygen) 1.6 ± 0.37
The respiratory activity of epithelium is approximately 3 times greater than that of connective tissue and the respiratory activity of the sulcular epithelium is approximately twice that of whole gingiva.
Q.37 Name various coatings present on tooth.
- Developmental origin -
- Reduced enamel epithelium
- Coronal cementum
- Dental cuticle
- Subsurface enamel matrix
- Acquired coating -
- Salivary pellicle
- Bacterial coating
- Material alba
- Subsurface pellicle
- Surface stains.
B. PERIODONTAL LIGAMENT
Q.1 What is the width of periodontal ligament?
0.15 to 0.38 mm
Q.2 What is the shape of periodontal ligament space?
Hour-glass shape: Periodontal ligament is thinnest at the axis of rotation in the middle and widens coronally and apically.
Q.3 What are the constituents of periodontal ligament space?
- Periodontal ligament fibres
- Cellular elements
- Ground substances
Q.4 Write functions and position of each group of periodontal ligament fibres.
- Transseptal group-Functions:
- Reconstructed even after destruction of the alveolar bone has occurred in the periodontal disease.
- Responsible for returning teeth to their original state after orthodontic therapy.
- Extends interproximally over alveolar bone crest and embedded in the cementum of adjacent teeth.
- Alveolar crest group-Functions:
- Prevent extrusion
- Prevent lateral tooth movements
- Extends obliquely from the cementum just beneath the junctional epithelium to the alveolar crest.
- Horizontal group-Position:
- Extends at right angles to the long axis of the tooth from cementum to alveolar bone.
- Oblique group-Functions:
- Bear vertical masticatory stresses
- Transform vertical stress into tension on the alveolar bone.
- Extends from the cementum in a coronal direction obliquely to the bone.
- Apical group-Functions:
- Prevents tooth tipping
- Resists luxation
- Protects neurovascular supply to the tooth.
- It radiates in irregular fashion from cementum to bone at apical region of socket.
- Interradicular group-Functions:
- Prevents luxation
- Prevents tooth tipping and torquing.
- Found only between roots of multirooted tooth running from cementum into bone, forming crest of interradicular septum.
Q.5 Which is the largest group of periodontal ligament fibres?
Oblique group of periodontal ligament fibres.
Q.6 Which types of collagen is present in periodontal ligament?
Type I, III, V, VI, XII (FACIT).
Q.7 What are the various cells of periodontal ligament?
- Connective tissue cells:
- Synthetic cells
- Resorptive cells
- Epithelial cells: Epithelial rests of malassez
- Immune system cells:
- Mast cells
- Cells associated with neurovascular elements
- Progenitor cells.
Q.8 What is the remarkable feature of Periodontal ligament (PDL) collagen?
There is rapid turnover rate of PDL collagen, with half life of only 10 – 15 days, which is about 5 times faster than gingival collagen, which in turn is renewed more rapidly than dermal collagen.
Q.9 What is Epithelial rests of Malassez and cementicles?
- 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.
- Cementicles – These are global masses of cementum arranged in concentric lamellae that lie free in the periodontal ligament or adhere to the root surface.
Q.10 Describe blood supply of periodontal ligament.
The blood supply is derived from the inferior and superior alveolar arteries and reaches the periodontal ligament from 3 sources:
- Apical vessels
- Penetrating vessels from the alveolar bone
- Anastomosing vessels from the gingiva
Q.11 What is the position of blood vessels in periodontal ligament space?
They are present in the interstitial spaces of loose connective tissue between the principal fibres which runs longitudinally connected in the net like plexus closer to the bone than cementum.
Q.12 How are the capillaries of periodontal ligament different from the capillaries of other connective tissues?
The capillaries of periodontal ligament are fenestrated while in other connective tissues they are continuous. Due to fenestration, they have greater ability of diffusion and filtration which is related to high metabolic requirements of periodontal ligament and its high rate of turnover.
Q.13 What are the functions of periodontal ligament?
- 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.
- Sensory: Capable of transmitting
- Pain sensations by trigeminal pathways.
- Nutritive: Supply nutrients to
- Gingiva through blood vessels and lymphatics.
- Homeostatic/formative: Helps in the formation and resorption of
- Bone during physiologic tooth movement and repair of injuries.
Q.1 What is cementum?
Cementum is calcified avascular mesenchymal tissue that forms the outer covering of the anatomic root.
Q.2 Who first demonstrated cementum microscopically?
Two pupils of Purkinje in 1835.
Q.3 Which types of collagen are present in cementum?
Type I – 90%, III, V, XII (FACIT), XIV
Q.4 What are the sources of collagen fibres of cementum?
- Fibroblasts which produce extrinsic sharpey's fibers.
- Cementoblasts which produce intrinsic fibres of the cementum matrix.
Q.5 Write biochemical composition of cementum.
- Inorganic: 40 – 50% – Hydroxyapatite
- 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
Q.6 Classify cementum.
Schroeder classified cementum as:
- 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.
- 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.
- 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.
- 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.
- Intermediate cementum: It consists of cellular remnants of Hertwig's sheath embedded in calcified ground substance. It is present near cementodentinal junction.
Q.7 Difference between Acellular and Cellular Cementum.
Forms before tooth reaches occlusal plane
Forms after tooth reaches occlusal plane
Does not contain any cells
Coronal portion of the root
Apical portion of the root
Rate of formation
Forms after regenerative periodontal surgical procedure
Contributes to the length of root during growth
20 – 50 µm near the cervix, 150 – 200 µm near the apex
Thickness of 1 to several mm
Q.8 What is intermediate cementum?
It is an ill defined zone near the cementodentinal junction of certain teeth that appears to contain cellular remnants of Hertwig's epithelial root sheath embedded in a calcified ground substance. It is also called as Layer of Hopewell Smith.
Q.9 What is the thickness of cementum?
In Coronal third — 16 – 60 µm (Thickness of hair)
In Apical third — 150 – 200 µm (Thickest)
Thicker in distal surfaces than mesial surfaces.
Q.10 Write normal variations in tooth morphology at CEJ.
- In about 60 – 65% — Cementum overlaps enamel.
- In about 30% — Edge to edge butt joint.
- In about 10% — Space present between cementum and enamel.
Q.11 Which type of cementum is desired following regenerative periodontal surgical procedure?
Acellular extrinsic fibre cementum.
Q.12 Name the conditions/diseases in which cementum formation is altered.
- Paget's disease – hypercementosis
- Hypopituitarism – decrease cementum formation
- Cleidocranial dysplasia – defective cementum formation
- Hypophosphatasia – no cementum formation.
D. ALVEOLAR BONE
Q.1 What is alveolar process?
It is the portion of maxilla and mandible that forms and supports the tooth sockets (alveoli).
Q.2 What are the parts of alveolar process?
- Compact bone: External plate of cortical bone
- Alveolar bone proper: Inner socket wall, Cribriform plate, Lamina dura, Bundle bone.
- Trabecular bone: Cancellous trabeculae which is present between these two compact layers. It is also called as supporting alveolar bone.
Q.3 Write chemical composition of bone.
- Inorganic: 67% Hydroxyapatite
- Organic: 33%
- Collagen – 28%
- Non-collagenous protein – 5%.
Q.4 Which types of collagen are present in the alveolar bone?
Type I - Mainly
Type III, V, XII, XIV – Traces.
Q.5 Write various Non-collagenous proteins in Bone Matrix.
- Bone sialoprotein
- Bone proteoglycan biglycan
- Bone proteoglycan II decorin
- Bone morphogenetic proteins (BMPs).
Q.6 What are the functions of osteoblast?
- Bone formation: Synthesize organic matrix of bone.
- Cell to cell communication and maintenance of bone.
- Bone resorption: Produces proteases, which are involved in matrix degradation and matrix maturation.
- Type I collagen
- Non-collagenous protein
- Various proteoglycans.
Q.7 Which are the enzymes released by Osteoclast?
- Acid phosphatase
- Aryl sulfatase
- Several cysteine proteinase such as cathepsin B and L
- Tissue plasminogen
- Activator TPA
Q.8 What is coupling?
It is interdependency of osteoblasts and osteoclasts in remodeling of the bone.
Q.9 What are various bone resorbing factors?
- Systemic factors:
- Parathyroid hormone
- Parathyroid related peptide
- Vitamin D3
- Thyroid hormone
- Local factors:
- Lipoxygenase metabolites
- Cytokines: IL – 1, IL – 4, TNF – α, TNF – β, IL – 6
- Growth factors:
- TGF – α
- TGF – β
- Bacterial factors:
- Capsular material
- Lipoteichoic acids.
Q.10 Difference between woven, lamellar bone and bundle bone.
- 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.
Q.11 What is fenestration and dehiscence?
- 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.
Q.12 What is bone modeling and bone remodeling?
- 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.
Q.13 What is periosteum and endosteum?
- 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.