Perio Lecture 3

Study Notes

Epithelial tissue lines the body cavities, such as the mouth, stomach, and intestines.
The extracellular matrix that surrounds the cells is important for supporting the tissue and providing a framework for cells to migrate and interact with one another.
The most heavily keratinized epithelium of the body is found on the palms of the hands and soles of the feet.
Epithelial tissues are avascular-containing no blood vessels.
The epithelial layer receives oxygen and nourishment from blood vessels located in the underlying connective tissue via a process known as diffusion.
The epithelial-connective tissue interface is the boundary where the epithelial and connective tissues meet.
In most places in the body, the epithelium meets the connective tissue in a thin layer.
The gingival epithelium may be differentiated into three areas: oral epithelium, sulcular epithelium, and junctional epithelium.
The oral epithelium covers the outer surface of the free gingiva and attached gingiva and extends from the crest of the gingival margin to the mucogingival junction.
The oral epithelium is the only part of the periodontium that is visible to the unaided eye.
Keratin is a tough, fibrous structural protein that occurs in the outer layer of the skin and the oral epithelium.
In health, the junctional epithelium has a smooth tissue interface with the connective tissue (no wavy junctions).
The gingival fiber bundles provide the free gingiva with rigidity and reinforce the attachment of the junctional epithelium to the tooth.
The gingival fiber bundles unite adjacent teeth to maintain tooth positioning within the oral cavity.
The periodontal ligament consists of connective tissue fibers, cells, and extracellular matrix, mainly fibroblasts with some cementoblasts and osteoblasts.
The thickness of the PDL space ranges from 0.05 to 0.25 mm depending on the age of the patient and the function of the tooth.
The PDL supports the tooth in its socket and prevents tooth extrusion.
The PDL is supplied with nerve fibers that transmit tactile pressure (such as a tap with dental instrument against tooth) and pain sensations.
The PDL provides nutrients to the cementum and bone.
The PDL contains cementoblasts that produce cementum throughout the life of the tooth, while the osteoblasts maintain the bone of the tooth socket.
In response to severe pressure, cells of the PDL (osteoclasts) can induce rapid bone resorption and, sometimes, resorption of cementum.
Cementum is a mineralized tissue that covers the roots of teeth and helps to attach the tooth to alveolar bone.
In covering the root, cementum covers the dentin and seals the dentinal tubules.
Cementum is formed by cementoblasts and is composed of hydroxyapatite.
Cellular (secondary) cementum is distinguished by the presence of living cells in its structure and is deposited in intervals throughout the life of the tooth.
The cementum covering the root may have any one of three relationships with the enamel of the tooth crown.
Overlap – the cementum overlaps the enamel for a short distance (60 – 65%)
Meet – the cementum meets the enamel (also referred to as end-to-end relationship, occurs 30%)
Gap – a smal