86+ quick-fire dental facts • tap a card to flip
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
The secretory product of odontoblasts is:
1) Topocollagen.
2) Calcium salts.
3) Mantle dentin.
4) Hydroxyapatite
Maxillary lateral incisor agenesis:
This is the most common congenital absence of a permanent tooth in the maxillary
anterior region, accounting for about 20% of all dental anomalies.
Coronal developmental invagination (DI):This is a common anomaly in the
permanent maxillary lateral incisor, usually appearing as an accentuation of the
lingual pit.It's often bilateral.
Peg-shaped crown:This is a common alteration in the maxillary lateral incisor.
With age, tubules become occluded by peritubular dentin deposition and hydroxyapatite crystals, forming sclerotic or transparent dentin. This starts at the root apex and progresses coronally, protecting the pulp. Secondary dentin deposition also reduces the pulp chamber, and pulp stones increase.
Which is considered as age change?
1). Transparent dentin (sclerotic dentin)
2). Cellular cementum
3). Primary dentin
4). Enamel spindle
Primary dentin is the most regular and dense. Secondary dentin has fewer tubules and is more wavy. Tertiary or reparative dentin has even fewer, irregular, and often atubular areas. All are calcified with hydroxyapatite and made by mesenchymal odontoblasts.
Primary dentin differs from secondary and reparative dentin in that:
1). Its matrix is calcified
2). Its inorganic component is hydroxyapatite
3). It usually has greater number of tubules per unit area
4). It is produced by mesenchymal cells
Permeability is inversely proportional to the distance from the pulp. Near the pulp, there are more and wider tubules, making it more permeable. This is important for bonding, sensitivity, and bacterial ingress.
Which dentin is most permeable?
1). Sclerotic dentin
2). Primary dentin near pulp (more tubules, wider)
3). Transparent dentin
4). Reparative dentin
Tertiary dentin includes reactionary dentin (formed by existing odontoblasts with slightly irregular tubules) and reparative dentin (formed by newly differentiated odontoblast-like cells from DPSCs after odontoblast death). Reparative dentin is atubular, bone-like, and localized under caries or attrition.
Reparative dentin (tertiary dentin):
1). Contains regular and numerous tubules
2). Obliterates apical foramen
3). Forms on localized regions of pulpal surface
4). Formation induced by inner dental epithelium
Von Korff fibers are argyrophilic fibers, initially type III collagen, with a corkscrew pattern. They form the matrix for mantle dentin.
Von Korff fibers are:
1). Coarse collagen fibers in mantle dentin from dental papilla
2). Elastic fibers in PDL
3). Oxytalan fibers
4). Enamel fibers
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