Functions of Periodontal Ligament

Which component of the periodontium forms the outer covering of the anatomic root?

What is the main finding of gingivitis?

Which factor determines the color of the attached and marginal gingiva?

What is responsible for the normal pigmentation of the skin, the gingiva, and the remainder of the oral mucous membrane?

What is the position of the gingiva related to?

What is responsible for compensating for tooth eruption and attrition by forming new cementum?

What is the main function of the periodontal ligament?

According to the text, which theory states that the displacement of the tooth is largely controlled by fluid movements?

What is the function of the periodontal ligament cells when exposed to physical forces?

What is the primary function of bone tissue?

What is bone tissue composed of?

What is the role of nerve bundles in the periodontal ligament?

Which branch of science investigates and treats the diseases and structures of the periodontium?

What is the term used to define the excessive production of cementum on the root surface of a tooth?

What is the term for the process of bone formation, remodeling, and regulation of remodeling?

What is the term used to define the fusion of cementum with alveolar bone, leading to loss of tooth mobility?

What are the physical functions of the periodontal ligament related to?

Which factors affect the remodeling of alveolar bone?

What constitutes approximately two thirds of the bone structure?

Which proteins are cell-adhesion proteins important for the adhesion of both osteoclasts and osteoblasts?

What is the major pathway of bony changes in shape, resistance to forces, repair of wounds, and calcium and phosphate homeostasis in the body?

Which process involves the creation of an acidic environment on the bone surface, leading to the dissolution of the mineral component of bone?

What covers the outer surface of bone and consists of an inner layer composed of osteoblasts surrounded by osteoprogenitor cells?

Where is the red marrow found in the adult skeleton?

What is the average thickness of cementum at the age of 60 years?

Which condition refers to a prominent thickening of the cementum, largely an age-related phenomenon?

What may be differentiated from hypercementosis based on its location outside the shadow of the periodontal ligament and the lamina dura?

What is the term for fusion of the cementum and the alveolar bone with obliteration of the periodontal ligament?

What is the function of the periodontal ligament that involves protection of vessels and nerves from injury by mechanical forces?

What may be caused by local or systemic factors, or it may occur without apparent etiology (i.e., idiopathic)?

Where do the intraseptal vessels continue to vascularize?

Where are the vessels within the periodontal ligament contained?

Which region are arteriovenous anastomoses seen more frequently in?

What accompanies the arterial supply in the periodontal ligament?

Where do lymphatic channels that drain the region just beneath the junctional epithelium pass into?

What is the significance of arteriovenous anastomoses according to the text?

What do the gingival vessels anastomose with?

Where do venules receive the blood in the periodontal ligament?

What supplements the venous drainage system in the periodontal ligament?

Which region do lymphatic channels pass through after draining the periapical region?

Define hypercementosis and distinguish it radiographically.

Explain the clinical importance of ankylosis.

List the physical functions of the periodontal ligament and explain the occlusal forces.

Explain bone formation, remodeling, and the regulation of remodeling.

Define vascularization, venous drainage, and the lymphatic system of alveolar bone.

Explain the structural functions and clinical importance of the periodontal ligament.

What is the main function of the periodontal ligament?

What is the main finding of periodontitis?

What is responsible for the normal pigmentation of the gingiva?

What is the physiological function of cementum?

What is the average thickness of cementum on the coronal half of the root?

What are the components of gingival antimicrobial defense mechanisms?

What is the term for fusion of the cementum and the alveolar bone with obliteration of the periodontal ligament?

What is the average thickness of cementum at the age of 60 years?

What covers the outer surface of bone and consists of an inner layer composed of osteoblasts surrounded by osteoprogenitor cells?

Explain the clinical importance of ankylosis.

What is responsible for compensating for tooth eruption and attrition by forming new cementum?

Explain bone formation, remodeling, and the regulation of remodeling.

What are the two theories pertaining to the mechanism of tooth support and transmission of forces to the bone?

Explain the arrangement of principal fibers in relation to the application of axial force to a tooth.

What is the turnover rate of collagen synthesis in the periodontal ligament compared to the gingiva and the skin, as established in the rat molar?

What is the approximate volume of blood vessels in the rodent molar's periodontal ligament?

What are the four types of neural terminations within the periodontal ligament?

What are the main minerals found in the inorganic matter of bone tissue?

What are the primary components of the organic matrix of bone?

What is the function of osteopontin and bone sialoprotein in bone structure?

What is the major pathway of bony changes involved in resistance to forces, repair of wounds, and calcium and phosphate homeostasis?

What is the process by which bone resorption is coupled with bone formation?

What are the primary cells involved in bone remodeling and what tissues do they act upon?

What is the physiological change that occurs in the bone marrow from the embryo to the adult?

What is the role of venules in the periodontal ligament?

Where do lymphatic channels pass through after draining the periapical region?

What is the significance of arteriovenous anastomoses according to the text?

Where are the vessels within the periodontal ligament contained?

What supplements the venous drainage system in the periodontal ligament?

Which region are arteriovenous anastomoses seen more frequently in?

What do the gingival vessels anastomose with?

What is the physiological function of cementum?

What is the main finding of gingivitis?

What is responsible for compensating for tooth eruption and attrition by forming new cementum?

The average thickness of the cementum increases ______ between the ages of 11 and 70 years, with the greatest increase seen in the apical region.

Abnormalities in the thickness of cementum may range from an absence or paucity of cellular cementum (i.e., cemental aplasia or ______) to an excessive deposition of cementum (i.e., cemental hyperplasia or hypercementosis).

The term ______ refers to a prominent thickening of the cementum. It is largely an age-related phenomenon, and it may be localized to one tooth or affect the entire dentition.

The spikelike type of hypercementosis generally results from excessive tension caused by orthodontic appliances or ______ forces.

Ankylosis occurs in teeth with cemental resorption, which suggests that it may represent a form of abnormal ______.

The periodontal ligament is continuous with the connective tissue of the gingiva, and it communicates with the marrow spaces through vascular channels in the ______.

The periodontium consists of four main components: gingiva, periodontal ligament, cementum and ___________ bone.

Gingivitis is an inflammatory lesion that is limited only to the gingiva and does not extend to the periodontal attachment (cement, periodontal ligament and ___________ bone) resulting from the interaction between the dental plaque's biofilm and the host's immuneinflammatory response.

The color of the attached and marginal gingiva is generally described as “coral pink”; it is produced by the vascular supply, the thickness and degree of keratinization of the epithelium, and the presence of ___________ -containing cells.

Cementum is the calcified, avascular mesenchymal tissue that forms the outer covering of the anatomic root. It does not physiological resorption and ___________.

The thickness of cementum on the coronal half of the root varies from 16 to 60 µm, which is about the thickness of a ___________.

Cementum formation is most rapid in the apical regions, where it compensates for tooth eruption, which itself compensates for ___________.

The principal fibers of the periodontal ligament are the major factor in supporting the tooth and transmitting forces to the ______.

The displacement of the tooth is largely controlled by ______ movements, with fibers having only a secondary role.

Periodontal ligament and alveolar bone cells are exposed to physical forces in response to mastication, parafunction, speech, and orthodontic tooth movement. Cells of the periodontal ligament participate in the formation and resorption of cementum and bone, which occur during physiologic tooth movement, during the accommodation of the periodontium to occlusal forces, and during the ______ of injuries.

The periodontal ligament supplies nutrients to the cementum, bone, and gingiva by way of the blood vessels, and it also provides lymphatic drainage as discussed later in this chapter. In relation to other ligaments and tendons, the periodontal ligament is highly vascularized tissue; almost 10% of its volume in the rodent molar is ______ vessels.

Bone tissue consists of two thirds inorganic matter and one third ______ matrix.

Bones support and protect the various organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable ______.

The intraseptal vessels continue to ______ the gingiva; these gingival vessels in turn anastomose with the periodontal ligament vessels of the cervical region.

The vessels within the periodontal ligament are contained in the interstitial spaces of loose connective tissue between the principal fibers, and they are connected in a netlike plexus that runs longitudinally and closer to the bone than the ______.

Lymphatics supplement the venous drainage system. Lymphatic channels that drain the region just beneath the junctional epithelium pass into the periodontal ligament and accompany the blood vessels into the ______ region.

The venous drainage of the periodontal ligament accompanies the ______ supply.

Arteriovenous anastomoses bypass the capillaries and are seen more frequently in apical and ______ regions; their significance is unknown.

Venules receive the blood through the abundant ______ network.

The vessels within the periodontal ligament are contained in the interstitial spaces of loose connective tissue between the principal fibers, and they are connected in a ______ plexus that runs longitudinally and closer to the bone than the cementum.

Lymphatics supplement the ______ drainage system.

The intraseptal vessels continue to ______ the gingiva.

The vessels within the periodontal ligament are contained in the interstitial spaces of loose connective tissue between the principal fibers, and they are connected in a netlike ______ that runs longitudinally and closer to the bone than the cementum.

The mineral salts are in the form of hydroxyapatite crystals of ultramicroscopic size and constitute approximately two thirds of the bone structure. The organic matrix consists mainly of collagen type I (90%), with small amounts of noncollagenous proteins such as osteocalcin, osteonectin, bone morphogenetic protein, phosphoproteins, and ______.

Osteopontin and bone sialoprotein are cell-adhesion proteins that appear to be important for the adhesion of both ______ and osteoblasts. In addition, paracrine factors, including cytokines, chemokines, and growth factors, have been implicated in the local control of mesenchymal condensations that occur at the onset of organogenesis. These factors probably play a prominent role in the development of the alveolar processes. Remodeling is the major pathway of bony changes in shape, resistance to forces, repair of wounds, and calcium and phosphate homeostasis in the body. Indeed, the coupling of bone resorption with bone formation constitutes one of the fundamental principles by which bone is necessarily remodeled throughout its life. Bone remodeling involves the coordination of activities of cells from two distinct lineages, the osteoblasts and the , which form and resorb the mineralized connective tissues of bone. The bone matrix that is laid down by osteoblasts is nonmineralized osteoid. While new osteoid is being deposited, the older osteoid located below the surface becomes mineralized as the mineralization front advances. Bone resorption is a complex process that is morphologically related to the appearance of eroded bone surfaces (i.e., Howship lacunae) and large, multinucleated cells (). Osteoclasts originate from hematopoietic tissue and are formed by the fusion of mononuclear cells of asynchronous populations. When ______ are active rather than resting, they possess an elaborately developed ruffled border from which hydrolytic enzymes are thought to be secreted. These enzymes digest the organic portion of bone. The activity of ______ and the morphology of the ruffled border can be modified and regulated by hormones such as parathyroid hormone (indirectly) and calcitonin, which has receptors on the osteoclast membrane. Another mechanism of bone resorption involves the creation of an acidic environment on the bone surface, thereby leading to the dissolution of the mineral component of bone. This event can be produced by different conditions, including a proton pump through the cell membrane of the osteoclast, bone tumors, and local pressure translated through the secretory activity of the osteoclast. Ten Cate described the sequence of events in the resorptive process as follows: 1. Attachment of ______ to the mineralized surface of bone 2. Creation of a sealed acidic environment through the action of the proton pump, which demineralizes bone and exposes the organic matrix 3. Degradation of the exposed organic matrix to its constituent amino acids via the action of released enzymes (e.g., acid phosphatase, cathepsin) 4. Sequestering of mineral ions and amino acids within the osteoclast. Cells and Intercellular Matrix Osteoblasts, which are the cells that produce the organic matrix of bone, are differentiated from pluripotent follicle cells. Alveolar bone is formed during fetal growth by intramembranous ossification, and it consists of a calcified matrix with osteocytes enclosed within spaces called lacunae. The osteocytes extend processes into canaliculi that radiate from the lacunae. The canaliculi form an anastomosing system through the intercellular matrix of the bone, which brings oxygen and nutrients to the osteocytes through the blood and removes metabolic waste products. Blood vessels branch extensively and travel through the periosteum. The endosteum lies adjacent to the marrow vasculature. Bone growth occurs via the apposition of an organic matrix that is deposited by osteoblasts. Bone Marrow In the embryo and the newborn, the cavities of all bones are occupied by red hematopoietic marrow. The red marrow gradually undergoes a physiologic change to the fatty or yellow inactive type of marrow. In the adult, the marrow of the jaw is normally of the latter type, and red marrow is found only in the ribs, sternum, vertebrae, skull, and humerus. However, foci of the red bone marrow are occasionally seen in the jaws, often accompanied by the resorption of bony trabeculae. Periosteum and Endosteum Layers of differentiated osteogenic connective tissue cover all of the bone surfaces. The tissue that covers the outer surface of bone is termed periosteum, whereas the tissue that lines the internal bone cavities is called endosteum. The periosteum consists of an inner layer composed of osteoblasts surrounded by osteoprogenitor cells, which have the potential to differentiate into osteoblasts, and an outer layer rich in blood vessels and nerves and composed of collagen fibers and fibroblasts. Bundles of periosteal collagen fibers penetrate the bone, thereby binding the periosteum to the bone. The endosteum is composed of a single layer of osteoblasts and sometimes a small amount of connective tissue. The inner layer is the osteogenic layer, and the outer layer is the fibrous layer. Vascularization of the Supporting Structures Structures The blood supply to the supporting structures of the tooth is derived from the inferior and superior alveolar arteries to the mandible and maxilla, and it reaches the periodontal ligament from three sources: apical vessels, penetrating vessels from the alveolar bone, and anastomosing vessels from the gingiva. The branches of the apical vessels supply the apical region of the periodontal ligament before the vessels enter the dental pulp. The transalveolar vessels are branches of the intraseptal vessels that perforate the lamina dura and enter the ligament.

Blood vessels branch extensively and travel through the periosteum. The endosteum lies adjacent to the marrow vasculature. Bone growth occurs via the apposition of an organic matrix that is deposited by ______.

In the adult, the marrow of the jaw is normally of the latter type, and red marrow is found only in the ribs, sternum, vertebrae, skull, and humerus. However, foci of the red bone marrow are occasionally seen in the jaws, often accompanied by the resorption of bony trabeculae. Periosteum and Endosteum Layers of differentiated osteogenic connective tissue cover all of the bone surfaces. The tissue that covers the outer surface of bone is termed periosteum, whereas the tissue that lines the internal bone cavities is called ______.

The periosteum consists of an inner layer composed of osteoblasts surrounded by osteoprogenitor cells, which have the potential to differentiate into osteoblasts, and an outer layer rich in blood vessels and nerves and composed of collagen fibers and fibroblasts. Bundles of periosteal collagen fibers penetrate the bone, thereby binding the periosteum to the bone. The ______ is composed of a single layer of osteoblasts and sometimes a small amount of connective tissue.

The blood supply to the supporting structures of the tooth is derived from the inferior and superior alveolar arteries to the mandible and maxilla, and it reaches the periodontal ligament from three sources: apical vessels, penetrating vessels from the alveolar bone, and anastomosing vessels from the ______.

The branch of science that investigates and treats the diseases and structures of the periodontium is called ____________.

The displacement of the tooth is largely controlled by fluid movements according to the ____________ theory.