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Preclinical periodontology

PeriodontologyBranch of Dentistry deals with the diseases & treatment of Periodontium

Periodontiumsupporting tissues supporting teeth in the arches

Periodontium composed from four partsGingivaPeriodontal ligamentCementum Alveolar bone


Periodontal diseases have afflicted humans since the dawn of history & studies showed that destructive periodontal diseases as evidenced by bone loss affected ancient egypt


Oral hygiene was practiced by sumerians as seen gold toothpicks found in excavations at ORbabylonians & assyrians suffered from periodontal problems & they were treating them by Gingival massage combined with various herbal medications

Later on, during golden age of arabic science & medicine, Ibn Sina was greatest physicians with his text the Canon that involve Gingival disease as bleeding gum, ulcers ,recession & separation of gum & epulis


Abul Qasim described role of calculus deposit in etiology of periodontal disease & technique of scaling the teeth using a set of instruments that he developed,he also wrote in details splinting loose teeth with gold wire

Histology & Anatomy of periodontium

Histology & Anatomy of periodontium
Gingiva Together with hard palate form masticatory mucosa its part of oral mucosa that covers Alveolar process & surround the neck of teeth

Gingiva is of three parts

attached Marginal Interdental papillae

Marginal(Free,unattached)

terminal edge of Gingiva surrounding teeth in a collar-like fashion

Marginal(Free,unattached)

its demarcated from Attached Gingiva by shallow linear depression known as free Gingiva groove in about 50% of people, its positioned at a level corresponding to level of CEJ


Pink in color firm in consistency scalloped outline free Gingiva rounded in such away that small sulcus is formed

its of 1.5-2mm in depth& about 1mm in width

InterDental papillae

its shape determine by contact relationship, in anterior region is pyramidal in molar its more flattened in BL direction & consist of 2 papillae & col shape( valley like depression ) connect them & conform to shape of the above contact area

in absence of proximal tooth contact Gingiva is firmly bound over Interdental bone & form smooth rounded surface


firm & tightly bound to underlying periosteum & extend to movable & loose oral mucosa where its separated from it by Mucogingival junction
Attached Gingiva


Its pink in color with stippling (orange peel) in 40% of people due to presence of minute depression in oral epithelium at the collection of retepege
Attached Gingiva


Its width range between 1-9mm & gradually increase with age due to occlusal wear so teeth is slowly erupt


More in maxilla  than mandible with least width in the 1st premolar regionpalatal surface in maxilla blends imperceptibly with equally firm, resilient palatal mucosa

Gingival contourmarginal Gingiva envelops teeth in collar like fashion & follows a scalloped outline on Facial & oral surfacesIt form a straight line along teeth with flat surfaces


on teeth with labial version as upper canine, the normal contour is accentuated & Gingiva located farther apically

teeth with lingual version, Gingiva becomes horizontal & thickened shelf-like that its aggravated by local irritation of Dental Plaque

Microscopical Anatomy

Epithelium covers Free Gingiva is differentiated into Oral Epithelium facing oral cavity & covers free & Attached Gingiva,sulcular epithelium lining the sulcus & Junctional Epithelium bringing Gingiva in contact with tooth

Oral Epithelium are keratinized stratified squamous cells with retepeges while Sulcular & Junctional are not keratinized ,only Sulcular one of them has retepeges

Epithelium composed of

1- basal cells layer faces basement membrane & its mitotic activity induces new cells that migrate to surface 2- spinous cells layer 3- granular cells layer


4- keratinized cells layer; keratine filled flattened cell, deprived of energy production & its of 2 types, Orthokeratine without nucli & parakeratine with nucli
Epithelium composed of



Oral Epithelium also has melanocytes, langerhans & non-specific cells that are stellate cells

Melanocytes

pigment containing cells , they synthesize melanin, melanin granules that phagocytosed & contained within other cells of epithelium & connective tissue called melanophages or melanophores

Langerhanse

immune cells that react with Ag, its belong to mononuclear phagocyte system (reticuloendothelial system) as modified monocyte derived from bone marrow

Merkel cells

located in deeper layer of epithelium harbor nerve ending & connected to adjacent cells by desmosoms, its identified as tactile perceptors

Hemidesmosom

Cell membrane of epithelial cells that face Basement Membrane has a no. of electron dense thicker zones appearing at various intervals along cell membrane, tonofilament of cytoplasm converge toward these structure It involves in attachment of epithelial cells to Basement Memrane

Pair of adjacent Hemidesmosom form Desmosom among adjacent cells

Junctional Epithelium
Its formed by joining of Reduced Enamel Epithelium (ameloblast + outer Enamel epithelium) & Oral Epithelium


Its 0.25-1.35mm in coronoapical dimension & about 0.15mm wide Larger cells, wider intercellular space & less desmosoms
Junctional Epithelium


The junctional epithelium is attached to the toothsurface (epithelial attachment) by mean of an internal basal lamina and to the gingival connective tissue by anexternal basal lamina that has the same structure as other epithelial-connective tissue attachments elsewherein the body.

The internal basal lamina consists of a lamina densa adjacent to the enameland a lamina lucida to which hemidesmosomes are attached Organic strands from the enamel appear to extend into the lamina densa

The junctional epithelium attaches to afibrillar cementum present on the crown  (usually restricted to an areawithin 1 mm of the cementoenamel junction) and root cementum in a similar manner

The attachment of the junctional epithelium to the tooth is reinforced by the gingival fibers, which brace the marginal gingiva against the tooth surface

For this reason, the junctional epithelium and the gingival fibers are considered a functional unit, referred to as the dentogingival unit

Connective tissues of Gingiva

Composed of
Collagen fibers (60%), fibroblast(5%), vessels, nerves & matrix (35%) with mast cells, macrophage, lymphocyte, neutrophil, plasma cells

Connective tissue fibers are produced by fibroblast & divided into collagen , reticulin & elastic fibers


Collagen fibers are predomanent one & theirsynthesis is started inside fibroblasts that produce


tropocollagen molecules composed of 3 chains of polypeptide then they are secreted outside to start polymerization where they are aggregated longitudinally to produce protofibril that aggregated laterally to collagen fibrils which bundle together to form Collagen fibers

Reticular fibers 

occur in loose connective tissue surrounding blood vessels & adjacent to Basement membrane

Elastic fibers system

composed of oxytalan, elaunin & elastin fibers destributing among collagen fibers

Collagen fibers arrange in groups of bundles with destinct oreintation ;

1- Circular; in free Gingiva 2- Dentogingival from root to free Gingiva 3- Dentopereosteal to attached Gingiva ( both groups called Gingivodental ) 4- Transeptal to the root of neighboring tooth across interdental septum

Function ?

1-Give Gingiva its resiliency & 2- attached it to tooth 3-provide rigidity to resist force of mastication without being deflected away from tooth 4- unite the free Gingiva with cementum & adjacent Attached Gingiva

Matrix ground substance

derived mostly from fibroblast & some from mast cell & blood, composed from water, Glyco- Protein like Fibronectin , Polysaccharide Molecules ,proteoglycans mainly Hyaluronic Acid & Chondroitin Sulphate,

Matrix (ground substance)

it transports water, Electrolyte & Nutrient to & from cells , also this Macromoleculs important for resiliency of Gingiva