Alveolar bone
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The document discusses the alveolar bone, including its definition, components, development, structure, clinical applications, and appearance on x-rays. It notes that the alveolar bone contains the tooth sockets and supports the teeth. The alveolar bone proper surrounds the tooth root and is perforated by Volkmann's canals. The supporting alveolar bone consists of cortical plates and spongy bone between the plates and alveolar bone proper. The alveolar bone undergoes remodeling and modeling during tooth movement and in response to functional forces.
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Alveolar bone
- 2. The students have to know 1- Definition of alveolar bone 2- Alveolar bone components 3- Alveolar bone development 4- Alveolar bone structure & its clinical applications 5- Alveolar bone appearance in x-ray 6- Physiologic & orthodontic movements related to the alveolar bone
- 3. • Alveolar bone is that part of the maxilla and mandible that contains the alveoli or sockets of the teeth and supports the teeth. • The alveolar socket is the cavity within the alveolar bone in which the root of the tooth is held by the periodontal ligament. If the teeth are lost the alveolar process disappears
- 4. • The alveolar bone between the roots of adjacent teeth is known as the Interdental Septum. • The alveolar bone between the roots of multi-rooted teeth is called the Inter- radicular Septum.
- 7. Alveolar bone & the basal bone
- 8. • Anatomically no boundary exists between the alveolar bone & the basal bone (body of the mandible and maxilla). An imaginary line at the root apices separates the alv. bone & the basal bone of the jaws. Alv. Bone Basal Bone
- 9. • The alv. bone develops with the formation and the eruption of teeth, when the teeth are congenitally messing (anodontia), the alv. bone do not develop at all. • The maintenance of the alv. bone is dependent on the presence of the teeth. When the teeth are lost, it gradually resorbs.
- 10. • Near the end of the 2nd month IUL. The outer and inner plates of the body of the maxilla and mandible grow in a vertical direction forming a groove that is opened towards the of the oral cavity. • The tooth germs are contained in this groove. • Gradually bony septa develop between the adjacent tooth germs.
- 11. • The actual alveolar process formation is associated with the root formation & the eruption process. • With the root formation the bony crypt is transformed into socket. • In fetal life the alveolar bone is formed, like the rest of the skeleton, of woven bone .
- 12. Structure of the alveolar process Adult alveolar process is composed of 2 parts : 1. Alveolar bone prope 2. Supporting bone.
- 13. Macro-anatomy Alveolar bone proper Supporting alveolar bone Inner & outer cortical plates Supporting Spongy bone ALVEOLAR PROCESS
- 14. •The alveolar bone proper is a thin layer of bone that surrounds the root and gives attachment to the principal PDL fibers. •It is perforated by numerous minute foramina (Volkman's Canals) that carry the BV & nerves into the periodontal ligament and that is why it is called the cribriform plate. •The term lamina dura (dura hard) is given to this layer of bone from its dense radiopaque appearance in X-ray 1- The alveolar bone proper
- 15. Cribriform Plate
- 17. Lamina Dura
- 18. The alveolar bone proper is made up of: A. Bundle bone adjacent to the PDL where the principal fibers are attached (bone of attachment) B. Compact bone which consists of superficial parallel lamellae & deeper portions made up of Haversian system Histology of the alveolar bone proper
- 19. Bundle bone Compact bone Bundles of the principal fibers are inserted into the bone as Sharpey's fibers
- 20. The bundle bone is the bone of attachment. It varies in thickness. According to the functional demands Always its thicker distally than mesially Mesial Distal ? bundle bone PDL Tooth root
- 21. • The supporting bone consists of 2 parts : • I) Cortical plates, which are made of compact bone • II) The spongy (cancellous) bone, which fills the area between these plates and the alveolar bone proper . . 2- Supporting alveolar bone
- 22. • The cortical plates of the alveolar processes are continuous with the labial & lingual cortical plates of the maxilla and mandible. • Generally, they are thinner in the maxilla than in the mandible.
- 23. In the region of the anterior teeth of both jaws the cortical plates are very thin and fused directly with the alveolar bone proper with no spongy bone in between .
- 24. They are thickest in the premolar and molar regions, where the Ling. plate is thicker than the buccal one. In the region of the mandibular third molar, the Lingual plate is thinner than the buccal one because of the presence of the
- 26. • During extraction, the last extraction movement is toward the thinner cortical plate.
- 27. • In the maxilla, the outer cortical plate is perforated by Volkman's Canals and may show defects in the posterior teeth region. • Larger defect exposing the root portion is known as fenestration. • If the defect includes the coronal alveolar crest it is called dehiscence.
- 28. Defect exposing the root portion defect includes the coronal alveolar crest
- 30. • It is found between the alv. bone proper and the cortical plates and between the alv. bone proper of the adjacent sockets. • Its degree of development is related to the forces of mastication. • It is absent in the anterior region of both jaws where the outer wall of the tooth sockets is very thin .
- 31. • Cancellous bone is very sensitive to variation in functional forces. The increase in functional force leads to formation of new dense bone. Decreased function leads to decrease in the volume of bone. • This can be observed in the cancellous bone of teeth which have lost their antagonists. Here the cancellous bone around the alveolus is reduced and the trabeculae become less numerous and very thin.
- 32. Radiographic appearance of alveolar bone Appears as a radioopaque (white) line adjacent to the root and separated from it by a radiolucent line (dark) representing the space of the periodontal ligament. Lamina dura
- 33. • The alveolar process is classified into 2 main types: • Type I: The interdental and interadicular trabeculae are regular and horizontal in a ladder-like arrangement, This type is more seen in the mandible Radiographic appearance of alveolar bone
- 34. • Type II: • The interdental and interadicular trabeculae are more numerous, delicate and irregularly arranged. This type is more seen in the maxilla
- 35. Type I Type II
- 36. Bone remodeling & Bone modeling • Bone formation occurs throughout life by a process called bone remodeling. During remodeling bone formation is usually preceded by bone resorption. • Bone formation is due to the tension (pull) of the periodontal ligament fibers. • Bone resorption is due to the pressure of the P.D.L fibers. • While the process by which the overall size and shape of bone is established is referred to as bone modeling.
- 37. Physiologic movement • Mesial drift • Occlusal movemen ( Poste eruptive movement ) Orthodontic movement During the orth. movement, the alv. bone is under the remodeling process . After orth. movement, the alv. bone undergo modeling process . Tooth movement
- 38. Mesial Drift • It is physiologic tendency of all teeth to move towards the midline • During mesial drift bone is apposed on the distal alveolar wall bone is resorbed on the mesial alveolar wall.
- 39. Occlussal Movement It is physiologic tendency of all teeth to move towards the occlussal plane During occlussal drift, there is periapical bone appossition causing tooth elongation
- 40. Self-Evaluation Review 1. Define alveolar 2. Discuss alveolar bone structure 3. True or False a. Alv. Bone is called cribriform plate because bundles of Sharpey’s fibers are inserted in it ( ) b. It is called lamina dura because it appears radiolucent in x-ray ( ) c. Bundles bone is more found in the distal wall of the alveolar process ( ) d. Cancellous bone of the supporting bone is very sensitive to variation in functional forces ( ) 4. Discuss the radiographic appearance of the alveolar bone 5. Discuss bone remodeling & modeling with its applications 6. In mesial drift bone…………….is found mesial alveolar bone & ……….. is found distal alveolar bone
- 41. • Antonio Nanci: Ten cat`s Oral Histology: Development, Structure, and Function, 8th ed. Elsevier Health Sciences, Mosby, 20`3 • Bhasker, S.N.: Orban’s Oral Histology and Embryology, Edition By G.S. Kumar, Mosby 13th ed. 2011 • Avery, J.K. : Oral development and Histology, 3rd ed New York Thieme 2002 • Avery, J.K., Daniel, J & Chiego, Jr: Essential of Oral Histology and Embryology. A clinical Approach 4th ed 2013 • Berkovitz, B.K.B., Holland, G.R. & Moxham, B.J.: Oral Anatomy, histology and Embryology, 4th ed Mosby 2009