20. Formation, structure, and remodeling of the alveolar bone.
Covers how the alveolar bone that holds the tooth sockets forms, starting from the dental follicle and the Hertwig's root sheath, and how osteoblasts lay down matrix that mineralises around collagen fibres. It then explains remodelling through the balance of osteoblasts and osteoclasts, with a table of the bone's parts (alveolar bone proper, supporting bone, septa and crest) and a summary of clinical points such as periodontitis and extraction socket healing.
Topic 20 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 2 sections, about 590 words (4 min of reading), with 15 flashcards.
In this note
FORMATION, STRUCTURE AND REMODELLING OF ALVEOLAR BONE
Summary and extra points
FORMATION, STRUCTURE AND REMODELLING OF ALVEOLAR BONE
Alveolar bone is thickened ridge of bone that contains the tooth sockets (dental alveoli) on the jaw bones (mandible and maxilla).
Bone contains perforating fibres from the PDLs called Sharpey’s Fibres, which are bundles of collagen fibres embedded in alveolar bone proper, and small foramina through which nerves and vessels pass
The bone lining the socket is constantly remodelled for adaptation to occlusal stresses, so the newly formed bone has no sharpey’s fibres
Alveolar bone is also called Lamina Dura
Development
When crown and root develop, the mesenchyme of dental sac begins to form the PDLs adjacent to the newly formed cementum
Bundles of fibres from PDLs (sharpey’s) fibres insert into outer portion of bone and cement, providing support for developing tooth
Mesenchyme of dental sac forms the alveoli of alveolar bone, surrounding the PDL
Formation of Alveolar Bone
On the upper jaw, from mesenchyme to the upper jaw
On the lower jaw, from the mesenchyme of the first bronchial arch
After beginning of the tooth germ development, a loose bone nest is formed around each tooth germ
Under the influence of Hertwig’s Root Sheath, cells of the outermost part of dental follicle differentiate into osteoblasts
Formation of osteoblasts form laminated bone that upholsters the inside of the dental alveolus
Sharpey’s fibres are inserted into the matrix and it mineralizes
Osteoblasts begin secretion of bone matrix and its mineralization
Osteoblasts secrete matrix vesicles, collagen fibres and proteoglycans
Through epitaxy, apatite crystals are formed which grow, merge and fill the spaces between the collagen fibres
Bone trabeculae grow and anastomose, and osteoclasts remain in the bone
Alveolar bone is formed in parallel with the construction of the root of the tooth
Remodelling of alveolar bone
Alveolar bone and the process can be metabolised by 2 types of cells:
Osteoblasts→ cells which secrete new bone matrix
Osteoclasts→ cells capable to digest the alveolar bone, responsible also for bone resorption
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