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12 Cards in this Set

  • Front
  • Back
Characteristics of bone
Compact (dense) bone is around the perimeter of the mandible and maxilla.
The compact bone surrounds trabecular (cancellous or spongy) bone.
Spaces in the trabecular bone contain fat and marrow.
Bone erosion by osteoclasts
Osteoclasts attach the “ruffled border” of their plasma membrane to the mineralized surface of bone. This makes a sealed environment that the osteoclasts pump protons (H+) into. Acid demineralizes the bone and exposes the organic matrix. Osteoclasts also release enzymes that break down the collagen fibrils (CF) of the protein matrix. The cavity produced by the acid and enzymes is Howship’s lacuna (HL). Osteoclasts absorb the degraded organic and inorganic bone matrix by endocytosis at the ruffled border. Transport vesicles are released at the membrane opposite the ruffled border (transcytosis).
Dental implants
Dental Implants placed in spongy bone initially rely upon the stability offered by compact bone to avoid early movement which impedes or inhibits osseointegration.
Complete Description of the Periodontal Ligament
The periodontal ligament (PDL) is a tough, fibrous layer that connects the cementum of the tooth to the alveolar bone of the mandible and maxilla. The PDL is normally about a tenth of a millimeter thick and it can be seen on dental x-rays as a black line surrounding the root. Abnormal widening may be a sign of overloading and trauma from tooth grinding or a biting irregularity.
          The PDL is composed of groups of collagen fibers produced by fibroblasts and cementoblasts.  The fibers run in several different directions to support the tooth during biting or chewing. The PDL absorbs shock and transmits chewing forces from the tooth to the bone. It normally gives a little so that the tooth can move slightly in its socket. When alveolar bone and PDL are lost from gum disease, the tooth becomes increasingly loose. A healthy PDL normally prevents bacterial invasion around the root.
          The PDL is sensitive to pressure and pain and provides necessary sensory formation for applying appropriate pressure during biting and chewing.     
Periodontal Ligament simplified
The root of the tooth is composed of dentin (d), covered with cementum (c) and it is held in the alveolus (A) by the periodontal ligament (PL). Both the gingiva (G) and the periodontal ligament have abundant blood vessels (BV).
What are sharpey's fibers?
Sharpey’s Fibers (SF) are type I collagen fibers that bridge the cementum, periodontal ligament and alveolar bone. dentin (d), cementum (C), dentinocemental junction (arrows), collagen fibers (CF), periodontal ligament (PL), blood vessels (BV). Sharpey’s fibers of the periodontal ligament are type I collagen fibrils that extend from the periodontal ligament (right) into the cementum. Fibers within the cementum are mineralized. In addition to the Sharpey’s fibers, the periodontal ligament also contains finer textured fibers of types III and XII collagen.
What is the Bundle Bone?
Where large groups of periodontal ligament (PDL) fiber bundles (arrows in left image and FB in right image) insert into the bone of the alveolar socket it is called bundle bone.
Describe Sharpey's fibers in acellular cementum.
The periodontal ligament (A) is made of collagen fibers that course between the cementum (E) and the alveolar bone. The fibers embedded in the outer layer of cementum are Sharpey's fibers (B). They project into the cementum between groups of cementoblasts (D), and lie perpendicular to the surface of the cementum (Sharpey’s fiber direction indicated by the blue arrow). The cementoblasts also lay down fine collagen fibers in the cementum which lie parallel to the surface of the cementum (fine collagen fiber direction indicated by the green arrow).
Principles fiber bundles of the PDL
1.The alveolar crest group, is attached to the cementum just below the cemento-enamel junction and runs downward and outward to insert into the rim of the alveolus.
2.The horizontal group, just apical to the alveolar crest group, runs at right angles to the long axis of the tooth from cementum to bone just below the alveolar crest.
3.The oblique group is the most numerous in the PDL and runs from the cementum in an oblique direction to insert into bone coronally around the root.
4.The apical group, radiates from the cementum around the apex of the root to the bone, forming the base of the socket.
5.The interradicular group, is found only between the roots of multi-rooted teeth and runs from the cementum into the interradicular crest of the alveolar bone.
Gingival Ligament
Although not strictly part of the PDL, other groups of collagen fibers are associated with maintaining the functional integrity of the periodontium. They are found in the lamina propria of the gingiva and collectively form the Gingival Ligament. Five groups of fiber bundles compose this ligament:
1.Dentogingival group. These are the most numerous fibers, extending from cervical cementum to the lamina propria of the free and attached gingivae.
2.Alveologingival group. These fibers radiate from the bone of the alveolar crest and extend into the lamina propria of the free and attached gingivae.
3.Circular group. This small group of fibers forms a band around the neck of the tooth, interlacing with other groups of fibers in the free gingiva and helping to bind the free gingiva to the tooth.
4.Dentoperiosteal group. Running apically from the cementum over the periosteum of the outer cortical plates of the alveolar process, these fibers insert into the alveolar process or the vestibular muscle and floor of the mouth.
5.Transseptal fiber system. These fibers run interdentally from the cementum just apical to the base of the junctional epithelium of one tooth over the alveolar crest and insert into a comparable region of the cementum of the adjacent tooth. Together these fibers constitute the transseptal fiber system, collectively forming an interdental ligament connecting all the teeth of the arch. The supracrestal fibers, particularly the transseptal fiber system, have been implicated as a major cause of postretention relapse of orthodontically positioned teeth. The inability of the transseptal fiber system to undergo physiologic rearrangement has led to this conclusion. Although the rate of turnover is not as rapid as in the PDL, studies have shown that the transseptal fiber system is capable of turnover and remodeling under normal physiologic conditions, as well as during therapeutic tooth movement. A sufficiently prolonged retention period following orthodontic tooth movement then would seem reasonable to allow reorganization of the transseptal fiber system to ensure the clinical stability of tooth position.
What is gingival col?
Gingival Col is that portion of the interdental gingiva of molar teeth that is located between the oral and the vestibular papillae.
What is the transspetal ligament?
The transseptal ligament is composed of collagen fibers that run between adjacent teeth over the alveolar crest.