The Normal Periodontium Question And Answers

Gingival Col

Gingival col is valley like depression of interproximal contact areas which connect lingual and buccal interdental papilla.
In the area of gingival col, gingival epithelium is nonkeratinized which is replaced by continuous cell division.
Morphology of col differs between anterior and posterior teeth. Anteriorly col is pyramid shaped and posteriorly it is flattened.
When gingiva is inflamed or hyperemic, col is exaggerated.
Epithelium of col sends numerous extensions in underlying connective tissue.
Gingival col is the site where oral hygiene accessibility is not possible. It is the area of food entrapment.
As col consists of non-keratinized epithelium, so it is prone to inflammation and represent the frequent site for initiation of disease.
Col confirms the shape of interproximal contact areas.

Periodontium Anatomy Functions Diagram

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Gingival Fibers

Connective tissue of marginal gingiva is densely collagenous and consist a prominent system of collagen fiber bundles known as gingival fiber bundles.

Arrangement of Gingival Fibers

Arrangement of gingival fibers is described as principal group of five bundles and secondary group of minor fibers consisting of six sets.

Principal Group Fibers

Dentogingival fibers: They project from the cementum in a fan-like conformation towards the crest and outer surface of the marginal gingiva. They provide support to the gingiva by attaching it to the tooth.
Alveolar gingival fibers: They extend from the periosteum of the alveolar crest coronally into the lamina propria. Their function is to attach the gingiva to the alveolar bone.
Dentoperiosteal fibers: They arise from the cementum near the cementoenamel junction and insert into the periosteum of the alveolar bone and protect the periodontal ligament.
Circular fibers: They surround the tooth in a cuff or ring-like fashion and course through the connective tissue of the marginal and attached gingiva.
Trans-septal fibers: They are located interproximally, they extend from cementum of one tooth to the cementum of the neighboring tooth. Their function is to protect the interproximal bone and maintain tooth-to-tooth contact.

Fibers of the Secondary Group

Periosteogingival fibers: They extend from the periosteum of the alveolar bone to the attached gingiva. They help to attach the gingiva to the alveolar bone.
Inter-papillary fibers: They are seen in the interdental gingiva extending in a faciolingual direction and support the gingival papilla.
Transgingival fibers: These are seen in and around the teeth with in the attached gingiva. They maintain the alignment of teeth in the arch.
Intercircular fibers: They extend from the cementum on distal surface of a tooth splaying buccally and lingually around the next tooth and are inserted on the mesial surface.
Intergingival fibers: They are seen within the attached gingiva adjacent to the basement membrane extending mesiodistally. They provide support and contour for the attached gingiva.
Semicircular fibers: They extend from the mesial surface of a tooth to the distal surface of same tooth in a half circle.
Oxytalin fibers: They are present in all connective tissue structures of the periodontium. The function of these fibers is yet unknown.
Elastin fibers: Elastin fibers are only present in connective tissue of the gingiva and periodontal ligament. They are also seen in the connective tissue of alveolar mucosa in large numbers.

Functions of Gingival Fibers

To brace the marginal gingiva fimly against the tooth.
These fibers provide rigidity to withstand the forces of mastication without being deflcted away from the tooth surface.
To stabilize attached gingival to alveolar process and tooth.
Helps to maintain epithelial seal to tooth.
To provide stability to tooth.

Active and Passive Tooth Eruption

Active Tooth Eruption

Active eruption is the movement of teeth in the direction of the occlusal plane.
When the teeth reach their functional antagonists, the gingival sulcus and junctional epithelium are still on the enamel, and the clinical crown is approximately two-thirds of the anatomic crown.
Active eruption is coordinated with attrition; the teeth erupt to compensate for tooth substance worn away by attition.
Attrition reduces the clinical crown and prevents it from becoming disproportionately long in relation to the clinical root, thus avoiding excessive leverage on the periodontal tissues,
Ideally, the rate of active eruption keeps pace with tooth wear, preserving the vertical dimension of the dentition.
As teeth erupt, cementum is deposited at the apices and furcations of the roots, and bone is formed along the fundus of the alveolus and at the crest of the alveolar bone.
In this way, part of the tooth substance lost by attrition is replaced by lengthening of the root, and socket depth is maintained to support the root.

Passive Tooth Eruption

Passive eruption is the exposure of teeth by apical migration of gingiva.
Passive eruption is now considered as pathologic process.
Passive eruption is divided into the following four stages:
- Stage 1: The teeth reach the line of occlusion. The junctional epithelium and base of the gingival sulcus are on the enamel.
- Stage 2: The junctional epithelium proliferates so that part is on the cementum and part is on the enamel. The base of the sulcus is still on the enamel.
- Stage 3: The entire junctional epithelium is on the cementum, and the base of the sulcus is at the cementoenamel junction. As the junctional epithelium proliferates from the crown onto the root, it does not remain at the cementoenamel junction any longer than at any other area of the tooth.
- Stage 4: The junctional epithelium has proliferated farther on the cementum. The base of the sulcus is on the cementum, a portion of which is exposed. Proliferation of the junctional epithelium onto the root is accompanied by degeneration of gingival and periodontal ligament fibers and their detachment from the tooth. The cause of this degeneration is not understood. At present, it is believed to be the result of chronic inflammation and therefore a pathologic process.

Mast Cells

Mast cells are the defense cells of PDL along with macrophages and eosinophills.

Shape of cell: Round or oval

Shape of nucleus: Round

Diameter: 12 to 15 µm.

Mast cells are often associated with blood vessels and are characterized by numerous cytoplasmic granules. Granules are dense membrane bound vesicles of varying sizes.
When cell is stimulated, it degranulates. Granules consist of heparin and histamine
Physiologic role of heparin in mast cells is not clear.
Histamine plays a role in inflmmatory reaction.
Mast cells have been shown to degranulate in response to antigen-antibody reactions.
Mast cells may play an important role in regulating endothelial and fibroblast cell population.

Stippling and its importance

Answer. The surface of normal gingiva has a pitted or textured appearance characterized by numerous small depressions and elevations giving the tissue an orange-peel appearance known as stippling.

Stippling Importance

Stippling is a feature of healthy gingiva and reduction or loss of stippling is a common sign of gingival disease. It is restored after treatment.
Microscopically, it represents the contours of epithelial connective tissue interface where bottom of the pit corresponds to the deep ridges or rete pegs of the epithelium in the lamina propria of connective tissue. The elevations of stippling correspond to the projection of papillae of connective tissue.
Both elevations and depressions are covered by an overlying layer of keratinized stratified squamous epithelium.
Stippling is a form of adaptive specialization or reinforcement for function as the rete pegs arrangement between the epithelium and connective tissue provides an excellent mechanical stability and increased surface area, that can bear more masticatory forces.
The degree of keratinization appears to be related to stippling. Hyperkeratosis results in a leathery texture, and drug-induced gingival overgrowth produces a nodular surface.

Criteria of Presence of Stippling from Birth till Death of Person

The pattern and extent of stippling vary among individuals or in different areas of same mouth according to age and sex. It is absent in infancy, appears at about 5 years of age, increases until adulthood and begins to disappear in old age.

Different Types Of Cementum According To Schroder’s Classification.

Cementum is Defined as a calcified avascular mesenchymal tissue that forms the outer covering of the anatomic root. It provides anchorage mainly to the principal fibers of periodontal ligament.

Schroder’s Classification

Depending on location, morphology and histological appearance, Shroeder and Page have classifid cementum as:

Acellular afirillar cementum (AAC): It contains only the mineralized ground substance. It does not contain collagen fibers nor does it exhibit entrapped cementocytes. It is a product of cementoblasts and is found almost exclusively on the enamel near the cementoenamel junction with a thickness of 1 to 15 µm.
Acellular extrinsic fier cementum (AEFC): By definition it is composed primarily of Sharpey’s fibers of periodontal, ligament but does not contain cementocytes. Developmentally they come to occupy the coronal one half of the root surface. Its thickness is between 30 and 230 µm.
Cellular mixed stratifid cementum (CMSC): It harbors both intrinsic (cementoblasts derived) and extrinsic (firoblast derived) fibers and may contain cells. In humans, it is seen in the apical third of the roots, apices and furcation areas. Its thickness varies from 100 to 1000 µm.
Cellular intrinsic fier cementum (CIFC): It contains only intrinsic fibers secreted by cementoblasts and not by the periodontal ligament firoblasts. In humans it fills the resorption lacunae.
Intermediate cementum (or) the hyaline layer of Hopewell Smith: It is an ill-Defined zone extending from precementoenamel junction to the apical 1/3rd of the root. It appears to contain cellular remnants of Hertwigs sheath embedded in calcified ground substance. The significance of this layer is that, it contains enamel like proteins, which helps in attachment of cementum to dentin. It has been observed by many that, when this layer is removed during root planning procedure, the resultant reparative cementum that is formed will not be attached firmly on the dentin.

Causes of Cemental Hypertrophy

Accelerated elongation of tooth: This owes to the loss of an antagonist and accompanied by cemental hypertrophy as a result of inherent tendency to maintain normal width of PDL.
Inflmmation of a tooth: Inflmmation at the apex of tooth root usually occurring as a result of pulpal infection sometime leads to cemental hypertrophy.
Tooth repair: On an occasion, occlusal trauma results in mild root resorption. Such resorption is repaired by cemental hypertrophy.
Paget’s disease of bone: This is a disease of bones characterized by excessive cemental hypertrophy over the roots of teeth.

Salivary Antibacterial Factors

Saliva contains numerous inorganic and organic factors that influence bacteria and their products in the oral environment. Inorganic factors include ions and gases, bicarbonate, sodium, potassium, phosphates, calcium, florides, ammonium, and carbon dioxide. Organic factors include lysozyme, lactoferrin, myeloperoxidase, lactoperoxidase, and agglutinins such as glycoproteins, mucins, b2-macroglobulins, fironectins and antibodies.

Lysozyme is a hydrolytic enzyme that cleaves the linkage between structural components of the glycopeptides muramic acid-containing region of the cell wall of certain bacteria in vitro.
Lysozyme works on both gram-negative and gram-positive organisms; its targets include Veillonella species and Actinobacillus actinomycetemcomitans. lt probably repels certain transient bacterial invaders of the mouth.
The lactoperoxidase-thiocyanate system in saliva has been shown to be bactericidal to some strains of Lactobacillus and Streptococcus by preventing the accumulation of lysine and glutamic acid, both of which are essential for bacterial growth.
Another antibacterial finding is lactoferrin, which is effective against Actinobacillus Species.
Myeloperoxidase, an enzyme similar to salivary peroxidase, is released by leukocytes and is bactericidal for
Actinobacillus but has the added effect of inhibiting the attachment of Actinomyces strains to hydroxyapatite.

Tooth Ankylosis

Fusion of alveolar bone and cementum with obliteration of periodontal ligament is known as tooth ankylosis.

Ankylosis occurs more frequently in the deciduous dentition.
Ankylosis generally occurs in teeth with cemental resorption.
It represents a form of abnormal repair.
Ankylosis occurs after reimplantation, trauma to a tooth, etc.
Ankylosis results in resorption of root and its replacement by bone.
Clinically ankylosed tooth lacks physiologic abnormality of normal tooth which is the diagnostic sign for ankylotic resorption.
Ankylosed tooth have a metallic percussion sound.
As periodontal ligament is replaced with bone in ankylosis, proprioception is lost because pressure receptors in periodontal ligament are vanished away or do not function correctly.

Cellular part of the Periodontal Ligament

Cellular part of the Periodontal Ligament Key Features

Periodontal ligament is a connective tissue structure which surrounds the root and connects it with the bone.
Periodontal ligament is continuous with lamina propria of gingiva.
Cellular part of the Periodontal Ligament communicates with marrow spaces of alveolar bone.
Cellular part of the Periodontal Ligament average width is 0.2 mm and with ranges from 0.15 to 0.38 mm.
Cellular part of the Periodontal Ligament remains in form of hourglass with narrow portion around middle third of root.
PDL diminish around the teeth which are not functional and increases in width in hyperfunctional teeth.
Turnover of fibers and ground substance of tooth is high while turnover of cells is slow.
Previously PDL was also known as gomphosis, desmodont, pericementum, alveolodental ligament and periodontal membrane.

Junctional Epithelium

Junctional epithelium consists of a collar-like band of stratified squamous non-keratinized epithelium.
It is 3–4 layer thick in early life but increases with age upto 10 to 20 layer.
The length of junctional epithelium ranges from 0.25 to 1.35 mm.
These cells can be grouped in two strata: the basal layer that faces the connective tissue and the suprabasal layer that extends to the tooth surface.
The proliferative layer which leads to most of the cell divisions is located in contact with the connective tissue. Shedding surface of junctional epithelium is located at the coronal end which forms bottm of gingival sulcus.
Junctional epithelium is formed by conflence of the oral epithelium and the reduced enamel epithelium at the time of eruption.
Junctional epithelial cells are interconnected by few desmosomes and occasionally by gap junctions.
Junctional epithelium, mainly at its basal cell layers is innervated by the sensory nerve fibers.
Division of junctional epithelium is there in three zones i.e. coronal, middle and apical.
Junctional epithelium is attached to the tooth surface by means of an internal basal lamina and to the gingival connective tissue by an external basal lamina which has the same structure as other epithelial–connective tissue attachments elsewhere in the body.
External basal lamina consists of same structure and the composition as other basement membranes, elsewhere in the body while the internal basal lamina has different structural and molecular characteristics. This lacks the common basement membrane components i.e. collagen Type 4 and 7, most laminins forms.
The internal basal lamina consists of a lamina densa (adjacent to the enamel) and a lamina lucida to which hemidesmosomes are attached. Hemidesmosomes have a decisive role in the fim attachment of the cells to the internal basal lamina on the tooth surface.
Junctional epithelial cells migrate in the coronal direction to free surface where they desquamate. As the surface area occupied by basal cells is more than bottm of sulcus, exfoliation occurs at extremely high rate.
Attachment of the junctional epithelium to the tooth is reinforced by the gingival fibers, which brace the marginal gingiva against the tooth surface. So, the junctional epithelium and gingival fibers are considered as functional unit.
Dentogingival unit: Dentogingival unit = junctional epithelium + gingival fibers.
Intercellular spaces of junctional epithelium give a pathway for fluid and transmigrating the leukocytes. In absence of clinical signs of inflmmation, approximately 30,000 PMNs migrate per minute via junctional epithelium of all human teeth in the oral cavity.

Types of Cementoenamel Junction

The relation between cementum and enamel at cervical region of teeth is called as cementoenamel junction.

Types of Cementoenamel Junction

End-to-end approximating junction (But Junction):
- In approximately 30% of all teeth cementum meets the cervical end of enamel in a relatively sharp line.
Overlapping junction:
- The cementum overlapping the enamel:
  - In approximately 60% of teeth, cementum overlaps the cervical end of enamel for short distance.
  - This occurs when the enamel epithelium degenerates at its cervical termination permittng connective tissue to come in direct contact with enamel surface which produce a laminated, electron dense, reticular material termed as a fibrillar cementum.
- Enamel overlapping cementum junction:
  - Recent observations by researchers by optical microscopy showed fourth type of junction known as enamel-overlapping cementum junction.
Gap junction:
- The absence of connecting enamel and cementum:
  - In about 10% of teeth enamel and cementum do not meet. In such cases, there is no cemento enamel junction. This occurs when enamel epithelium in cervical portion of roots delayed in the separation from dentin. In this case, dentin is an external part of the surface of the root.

Dentogingival Unit

Dentogingival unit was first discovered by Listgarten in 1970.

Attachment of junctional epithelium to the tooth is reinforced by the gingival fibers which brace marginal gingiva against the tooth surface, due to this junctional epithelium and gingival fibers are considered as a functional unit known as dentogingival unit.
Dentogingival unit is of importance because of its anatomical location.
Both the components of dentogingival unit afford biological protection.

Cementum

Cementum is a calcified avascular mesenchymal tissue that forms the outer covering of anatomic root.

Features of Acellular Cementum

is Acellular Cementum the fist cementum formed and covers the cervical third of root.
Acellular cementum is devoid of cells.
It is seen at the coronal portion of root.
Formation of acellular cementum is slow.
Acellular cementum forms before teeth reaches the occlusal plane, its thickness ranges from 30 to 230 µm.
Sharpey’s fibers form the most structure of acellular cementum.
Most of the Sharpey’s fibers are inserted at right angles to root surface and penetrate inside the cementum while other enter at different directions.
Arrangement of collagen fibers is more organized in acellular cementum.
Cementoid is absent in this cementum.
Main function of acellular cementum is anchorage.
Under light microscope, it appears structureless, incremental lines are closer and there is mineralization of Sharpey’s fibers.

Features of Cellular Cementum

Cellular cementum forms after tooth reaches the occlusal plane.
It is seen in the apical half of root surface.
Formation of cellular cementum is rapid.
Cellular cementum is irregular and consists of cells known as cementocytes which reside in lacunae and communicate with each other by anastomoting canaliculi.
Cellular cementum is less calcified.
Sharpey’s fibers occupy the small portion of cellular cementum.
Sharpey’s fibers here are completely or partially calcified.
Cementoid formation is seen over its surface.
Main function of cellular cementum is repair and adaptation.
Under light microscope, it shows cementocytes, incremental lines are further apart, intrinsic fibers are densely packed and run parallel to surface, extrinsic fibers are large and haphazardly arranged.

Stippling of Gingiva

The surface of normal gingiva has a pitted or textured appearance characterized by numerous small depressions and elevations giving the tissue an orange- peel appearance known as stippling.

Stippling should be best viewed by drying the gingiva.
Stippling is a form of adaptive specialization or reinforcement for function.
Attached gingiva is stippled while marginal gingiva is not stippled.
Central portion of interdental papillae is stippled.
Stippling vary among the individuals and in various areas of same mouth.
Stippling is less prominent on lingual surfaces as compared to facial surfaces.
Microscopically stippling is produced by alternate round protuberances and depressions on gingival surface. Papillary layer of connective tissue project in elevation and the elevated and depressed areas covered by stratified squamous epithelium.
Stippling is the feature of healthy gingiva and reduction or loss of stippling is the sign of gingival disease. As gingiva become healthy stippling again regains after the disease.
Stippling varies with age, it is absent in infancy, appear in children at 5 years of age, increases till adulthood and disappear in old age.

Cementum

Cementum is calcified avascular mesenchymal tissue which forms the outer covering of anatomic root

Composition of Cementum

Cementum consists of 46% inorganic and 54% organic matter.
Inorganic portion consists of calcium and phosphate in form of hydroxyapatite. Trace elements are also present in the cementum. It consists of highest floride content of all the mineralized tissue.
Organic portion consists of 90% of Type I collagen, 5% of Type 3 collagen and 5% non – collagenous proteins such as enamel proteins, adhesion molecules like tenascin and fironectin, glycosaminoglycans like chondroitin sulphate, dermatan sulphate and heparin sulphate which constitutes the remaining organic matrix.
Two of the main sources of collagen fibers in cementum are:
- Sharpey’s fibers which are the embedded portion of principle fibers of periodontal ligament and are formed by firoblasts.
- Intrinsic fibers which are the fibers belonging to cementum matrix and are produced by cementoblasts.
Non-collagenous components of interfibrillar ground substance are proteoglycans, glycoproteins and phosphoproteins.

Functions of Cementum

Primary function of the cementum is to provide anchorage to tooth in its alveolus. It is achieved via collagen fiber bundles of periodontal ligament whose ends are embedded inside the cementum.
It plays an important role in maintaining the occlusal relationships whenever the incisal and occlusal surfaces are abraded because of attition, tooth supraerupt in order to compensate for loss and the deposition of new cementum occur at apical root area.
It act as major reparative tissue for the root surfaces and maintains integrity of root surface.

Non-keratinocytes

The various non-keratinocytes or clear cells are Langerhans cells, Merkel cells and melanocytes

Langerhans cells: They are dendritic cells located among keratinocytes at all suprabasal levels. They belong to the mononuclear phagocyte system (reticuloendothelial system) as modified monocytes derived from the bone marrow. They contain elongated granules, and they are considered macrophages with possible antigenic properties. Langerhans cells have an important role in the immune reaction as antigen-presenting cells for lymphocytes. They contain gspecifi granules (Birbeck granules), and they have marked adenosine triphosphatase activity. They are found in the oral epithelium of normal gingiva and in smaller amounts in the sulcular epithelium; they are probably absent from the junctional epithelium of normal gingiva.
Merkel cells: They are usually found in the basal cell layer of the gingival epithelium. These cells either appear individually or in clusters. These are not dendritic cells as melanocytes and Langerhans cells. These cells possess keratin tonofiaments and occasional desmosomes, which link them to adjacent cells. These cells are sensory in nature and respond to touch.
Melanocytes: They origin from neural crest cells located in the stratum basale and spinous cell layers of the oral gingival epithelium. Oral mucosal melanocytes were identified in the gingiva by Laidlaw and Cahn in 1932. Long dendritic processes from these cells are interposed between the keratinocytes of the epithelium. They lack tonofiaments and desmosomal connection to adjacent keratinocytes. Melanocytes are responsible for the barrier to ultraviolet (UV) damage and synthesize melanin, which is accountable for providing color to the gingiva. Melanin is synthesized in organelle called premelanosomes or melanosomes in melanocytes. Melanosomes consists of tyrosinase which hydroxylate tyrosine to dihydroxyphenylalanine which in turn is progressively converted to melanin. Melanin granules are phagocytosed and contained within other cells of epithelium and connective tissue known as melanophages or melanophores.