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Intertubular dentin makes up the main body between tubules. It contains about 30% organic matrix (mostly collagen I) and apatite. It is less mineralized than peritubular dentin, which is hypermineralized and lacks collagen.
Which statement about intertubular dentin is true?
1). More mineralized than peritubular
2). Forms bulk between tubules, contains Type I collagen network, less mineralized than peritubular, contains proteoglycans
3). No collagen
4). Forms inside tubule
Sometimes, mineralization of dentin begins in small globular areas that fail to coalesce into a homogenous mass. This results in zones of hypomineralization between the globules.
These zones are known as globular dentin or interglobular spaces. Thus, demonstrating defect of mineralization and not of matrix formation, the dentinal tubules pass uninterruptedly through interglobular dentin.
Odontoblasts are protein-synthesizing cells with abundant RER, Golgi, and mitochondria. They have one main process (Tomes' fiber) and are connected by junctional complexes. A striated border is characteristic of intestinal absorptive cells, not odontoblasts.
Which is NOT present in odontoblasts?
1). Golgi saccules
2). Rough endoplasmic reticulum
3). Desmosome-like junctions
4). Numerous processes forming striated border
Interglobular Dentin:
Sometimes, mineralization of dentin begins in small globular areas that fail to coalesce into a homogenous mass. This results in zones of hypomineralization between the globules.
These zones are known as globular dentin or interglobular spaces. Thus, demonstrating defect of mineralization and not of matrix formation, the dentinal tubules pass uninterruptedly through interglobular dentin.
When calcospherites fail to fuse during calcification of dentin matrix then
1 Interglobular dentin is formed
2 Dead tracts are found in formed dentin
3 Irregular dentin results
4 None
Tertiary dentin is the least tubular and is sometimes atubular. It may contain cell inclusions.
Which dentin contains fewest tubules?
1). Primary
2). Secondary
3). Tertiary / reparative dentin (osteodentin)
4). Mantle dentin
Vitamin D deficiency leads to hypomineralization due to a low calcium-phosphate product. Globular mineralization fails, increasing interglobular dentin.
Cause of interglobular dentin increased in rickets:
1). Vitamin D deficiency leads to failure of calcospherite fusion
2). Fluoride excess
3). Calcium excess
4). Vitamin A deficiency
Sclerotic dentin is a vital defense mechanism. Peritubular dentin thickens and occludes the tubule to reduce permeability and slow caries progression.
Sclerotic dentin is formed:
1). Before eruption
2). As defensive response to mild caries, attrition, age
3). Only after extraction
4). Only in enamel
Predentin is always at the pulp-dentin interface as a 10-30 micron unmineralized layer. Dentinal tubules pass through interglobular areas. Tubules contain the odontoblast process, fluid, and nerve endings in the inner third.
Which is true:
1). Predentin between primary and secondary dentin
2). Dentinal tubules do not pass through interglobular dentin
3). Physiological secondary dentin contains dentinal tubules
4). Many large collagen bundles in dentinal tubules
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