Where is the Dentinoenamel Junction?
The dentinoenamel junction (DEJ) is the border where five different structures meet: the cervical enamel, two superficial outer dentin layers (Tomes’ granular and Hopewell-Smith hyaline layers), located over the inner circumpulpal dentin, and cementum (afibrillar acellular cementum and fibrillar cellular cementum).
What is the appearance of the Dentinoenamel Junction?
The DEJ exhibits a scalloped appearance. The scalloped model has higher maximum tensile stresses than the straight model, but axial pressures would push the two tissue apart, leading to delamination of the DEJ during loading (mastication).
Why is the Dentinoenamel junction scalloped?
As a consequence, dentine and enamel would be pushed towards each other during loading (i.e., during mastication). These findings suggest that the scalloped nature of the DEJ confers a biomechanical advantage to the integrity of the tooth during mastication.
What is Amelodentinal Junction?
The plane or interface between the dentin of the tooth and the enamel crown; histological sections show it to be a scalloped boundary at the site of the basement membrane which separated the cell layers that formed the calcified enamel and dentin. Synonym: amelodentinal junction.
What are the organic substances of the Dentinoenamel Junction?
Dentin is approximately 55 vol% mineral, 30 vol% organic material (primarily type I collagen), and 15 vol% fluid [46], but dentin composition varies with the age and tooth type.
What are the Hypocalcified structures of enamel?
Some areas in enamel are hypocalcified: enamel spindles, enamel tufts, and enamel lamellae. Causal factors may occur locally, affecting only a single tooth, or they may act systemically, affecting all teeth in which enamel is being formed.
What are Ameloblasts?
Ameloblast: One of a group of cells originating from the ectoderm from which the dental enamel is developed; an enamel cell. The ameloblasts cover the papilla of the enamel organ.
What is dentin made of?
dentin, also spelled dentine, in anatomy, the yellowish tissue that makes up the bulk of all teeth. It is harder than bone but softer than enamel and consists mainly of apatite crystals of calcium and phosphate.
What is the first dentin formed?
The innermost layer of dentin is known as predentin, and is the initial dentin matrix that is laid down prior to mineralization.
What is Interglobular dentin?
Interglobular dentine (IGD) is an area of poorly mineralized dentine matrix. It has been reported that there is an association between the retraction of odontoblast processes (OP) and the formation of IGD. A variation of the extent of OP has been described depending on the region of the tooth and age.
What kind of Junction is the dentinoenamel junction?
The dentinoenamel junction or dentin-enamel junction ( DEJ) is the boundary between the enamel and the underlying dentin that form the solid architecture of a tooth . It is also known as the amelo – dentinal junction, or ADJ.
Is the amelo-dentinal junction a scalloped structure?
It is also known as the amelo – dentinal junction, or ADJ. The dentinoenamel junction is thought to be of a scalloped structure which has occurred as an exaptation of the epithelial folding that is undergone during ontogeny.
Why are the enamel rods in permanent teeth segmented?
The enamel rods are segmented because the enamel matrix is formed in rhythmic manner. In humans these segments seem to be of a uniform length of about: 10. The arrangement of enamel rods in the permanent teeth, in the cervical region, deviates from the horizontal in an:
How many enamel rods are in the lateral incisors?
B. The number of enamel rods is about 5 million in lower lateral incisors and 12 million in the upper first molar C. The length of enamel rods is greater than thickness of enamel because of oblique direction and wavy course of the rods.