Normal PeriodontiumCHAPTER 1

The attached gingiva or functional mucosa extends from the free gingival groove to the mucogingival junction where it meets the alveolar mucosa. The attached gingiva is a mucoperiosteum which is tightly bound to the underlying alveolar bone.

Stippling varies considerably, most prominent on facial surfaces and often disappears in old age. Cause of stippling appears to coincide with epithelial rete pegs.

Width of attached gingiva varies from 0–9 mm.

In the past, it was assumed that attached gingiva was necessary to maintain the health of gingival margin by separating the stable margin from mobile alveolar mucosa, but this does not appear to be the case in clean mouth. Thus it has given rise to controversy that any width, even a zero width, is acceptable if the tissue is healthy.

The gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of teeth. Beneath the epithelial integument resides the gingival connective tissue compartment also referred to as the lamina propria. The lamina propria exhibits an exquisitely complex architecture which anticipates its functions. Approximately, 60–65% of the connective tissue compartment of healthy gingiva is occupied by collagen, with the individual fibrils highly organized into discrete and easily discernible fiber bundles.

The connective tissue of the gingiva is organized to keep the gingival margin tight around the neck of the tooth and to maintain the integrity of the dentogingival attachment.

The principal cell type of the gingival epithelium, as well as of other stratified squamous epithelia, is the keratinocyte. The main function of the gingival epithelium is to protect the deep structures, while allowing a selective interchange with the oral environment. This is achieved by proliferation and differentiation of the keratinocytes.

Mast cells, which are distributed throughout the body, are numerous in the connective tissue of the oral mucosa and the gingiva. It is a large spherical or elliptical mononuclear cell. Its nucleus is small relative to the size of the cell and in histologic preparations frequently is obscured by the large number of intensely staining granules that occupy its cytoplasm. In human beings the principal contents of the granules are histamine and heparin. They play a role in maintaining normal tissue stability and vascular homeostasis. Histamine is known to be important in initiating the vascular phase of an inflammatory process.

Biological width is defined as the physiologic dimension of the junctional epithelium and connective tissue attachment.

The gingiva has a rich blood supply derived from three sources:

The interdental gingiva occupies the gingival embrasure which is the interproximal space beneath the area of tooth contact. Interdentally the gingiva adapts its shape to the form, size and the position of adjacent teeth. Therefore in the vestibular/oral dimension, the interdental portion of the gingiva is narrow between the front teeth and broader between premolars and molars.

“Pigmentation” is defined as coloration, either normal or pathologic of the skin or tissues resulting from a deposit of pigment. Color of attached and marginal gingiva is coral pink produced by:

“Melanin”, non-hemoglobin derived brown pigment responsible for oral tissues pigmentation and skin. Present in all and absent or diminished in Albinos. According to ‘Dummett’ distribution of pigmentation.

Gingival pigmentation may be due to exogenous or endogenous factors.

There are three zones of gingival epithelium:

Consists of a collar like band of stratified squamous non-keratinizing 9epithelium. It is 3–4 layers thick in early life but the number of layers increases with age to 10–20. It is the only gingival epithelium with two distinct basal laminas, one on each surface.

Composed of four layers:

Massaging the gingiva with tooth brush/interdental devices produces epithelial thickening, increases keratinization and increases mitotic activity in epithelial connective tissue.

Gingival sulcus is the shallow crevice or space around the tooth, bounded by the surface of the tooth on one side and the epithelium lining the free margin of the gingiva on the other side.

Clinical evaluation: By introducing periodontal probe and estimation of the distance it penetrates. Probing depth of clinically normal gingival sulcus – 2 to 3 mm.

Active eruption: It is the movement of teeth in the direction of occlusal plane.

Passive eruption: It is the exposure of teeth by the apical migration of gingiva.

If the epithelium proliferates along the tooth surface before the cells from other tissues reach the area, the result will be a long junctional epithelium.

Gingival innervations are derived from fibers arising from nerves in the periodontal ligament and from the labial, buccal and palatal nerves.

The functions of periodontal ligament can be broadly categorized into:

Protection to vessels and nerves: Periodontal ligament provides soft tissue casing in order to protect the vessels and nerves from injury due to mechanical forces.

It has a rich vascular supply and provides nutrition to the bone, cementum and gingiva.

These are non-keratinocytes of gingival epithelium. These are present in low numbers and are found in basal and suprabasal layers in close contact with adjacent intraepithelial nerve endings. They contain numerous membrane bands dense granules in cytoplasm nearest the nerve endings and over all dendritic sheath. These cells occur in clusters and are identified as tactile receptors.

These cells arise from bone marrow and come to occupy the gingival epithelium. These cells have receptors for immunoglobulins and complement. The presence of surface antigens makes them to have a defensive role against the microoraganisms.

Periodontal ligament contains four types of cells. They are:

The most important elements of the periodontal ligament are the principal fibers, which are collagenous and arranged in bundles and follow a wavy course. Terminal portions of principal fibers that insert into cementum and bone are called Sharpey's fibers. Sharpey's fibers have a central uncalcified core, surrounded by peripheral calcified portion.

They contain collagen as constituent molecule which is arranged in fibrils with striations. Type of collagen found in principal fibers is type I.

The term lamina dura means interdental septum normally presents a thin, radio-opaque border that is adjacent to the periodontal ligament and at the alveolar crest. It is a radiological term used to describe “alveolar bone proper”. Alveolar bone proper is thin, compact bone present immediately surrounding the roots. This appears radiographically as a continuous white line, but in reality it is perforated by numerous small foramina and traversed by blood vessels lymphatics and nerves, which pass between the periodontal ligament and the bone. Even though lamina dura appears radio-opaque, it is not highly calcified as adjacent bone. Increased radioopacity is due to geometrical positioning of bone plate.

Terminal portions of principal fibers that insert into cementum and bone are called Sharpey's fibers. They have a central uncalcified core, surrounded by peripheral calcified portion.

Periodontal ligament other than collagen fibers contains two immature forms of elastin fibers. They are:

16Orientation: Run parallel to the root surface in vertical direction and bend to attach to cementum, in cervical third of root.

Dental cementum–The dynamic tissue covering of the root.

It is also called primary cementum which forms during root formation. It is the first formed cementum present in cervical one-third of root, formed before tooth reaches the occlusion, hence called acellular, because it doesn't contain cementocytes.

It is also called secondary cementum which forms after the eruption of the tooth and responds to functional demands formed after the tooth reaches the occlusal plane.

Components: Less number of Sharpey's fibers, cementocytes in lacunae, which like osteocytes in bone, communicate with each other through a network of canaliculi.

Primary function of cementum is to furnish a medium for the attachment of collagen fibers that bind the tooth to alveolar bone.

Cementum: Calcified avascular mesenchymal tissue that forms the outer covering of the anatomic root.

Enamel: Calcified avascular mesenchymal tissue that forms the outer covering of the anatomic crown.

Fenestrations: Isolated/Circumscribed areas in the alveolar bone in which the root is denuded of bone and marginal bone is intact.

Dehiscence: Denuded areas of the root which extend through the marginal bone. In these areas root surface is covered only by periosteum and overlying gingiva.

Etiology: Due to A. Prominent root contours, B.Tooth malpositions, C. Thin bony plates.

May complicate periodontal surgery while reflecting the periodontal flaps. Hence, partial thickness flaps have to be elevated. Progression of periodontal diseases will be more rapid in these cases.