Enamel Flashcards
What’s enamel prisms /rods and from where originate ?
The enamel prisms or rods are the basic structural component of enamel.
They originate at the dentino-enamel junction and extend through the thickness of the enamel surface.
The prisms appear cylindrical in longitudinal sections and take up key-hole or fish-scale pattern in cross-sections
What’s Striae of Retzius ? They have another name what’s called ?
These appear as brownish bands in ground sections and illustrate incremental pattern of enamel.
Striae of Retzius represent the rest periods of ameloblast during enamel formation, therefore, also called as growth circles, similar to annual rings on a tree
we could definitely identify striae of retzius, debris, and cracks under under how much magnification ?
×50
What’s the three morphological patterns of prism arrangement ?
Type 1 - shallow prisms
Type 2 - well-defined prisms
Type 3 - microporosities in *3000 magnification
When prisms were measured under ×6000 magnification and the results showed larger prisms in ?
posterior than in anterior teeth
What’s the most common prisms structure On the mesial and distal surfaces, of Posteriors and anteriors ?
Type 2 well defined
What’s the most common prisms in mesial structure ?
Type 2 well defined
Which type of prisms prodeminate in mesial Incisal edge of posterior ?
Type 1 shallow
Which type of prisms prodeminant in mesial Incisal edge of anterior ?
Type 2
Which type The incisal third of distal surface showed predominant pattern in the anterior teeth?
Type 1, shallow prism
Which type The incisal third of distal surface showed predominant pattern in the anterior teeth?
Type 1, shallow prism
Which surface showed equal distribution between Type 1 and 2 prism patterns ?
The labial surface of anterior teeth
Which surface showed predominant Type 1 shallow prism pattern ?
lingual surface of anterior teeth
Which surface showed predominant Type 1 shallow prism pattern ?
lingual surface of anterior teeth
Which surface showed predominant Type 2 prism pattern ?
Lingual surface posterior teeth
Occlusal surface of posteriors showed predominant ?
Type 2 prism pattern
Which teeth have more big and small prisms ?
Anteriors 5.0microns
Posteriors 5.35 microns
What does The surface enamel is composed of ?
enamel prisms or rods, rod sheaths, and cementing interprismatic substance.
What does The surface enamel is composed of ?
enamel prisms or rods, rod sheaths, and cementing interprismatic substance.
What’s enamel rods / prisms ? From where does they originate ?
the basic structural component of enamel.
They originate at the dentino-enamel junction and extend through the thickness of the enamel surface.
The prisms appear cylindrical in longitudinal sections and take up key-hole or fish-scale pattern in cross-sections.
What’s 2 pattern of prisms ?
Majority of the prisms were smooth with some grooves, and few showed abundant microporosities.
Another secondary pattern seen only in the incisal third was the exposed prisms.
Explain the arrragment of enamel rods ?
The rods are oriented so that the heads face toward the cusp tip and the tails toward the cervical margin.
What’s the composition of each rod ?
The enamel crystallites that compose each rod exhibit differing orient-ation within these two regions.
The crystallites are composed of hydroxyapatite (90% of the inorganic component of mature enamel).
The space between the crystallites is occupied by the organic matrix (2%) and water (12%).
Rods oriention ? And were they in clockwise and vertical ?
Rods are oriented perpendicular to dentinoenamel junction and follow a wavy course in clockwise and anticlockwise direction.
Toward incisal/occlusal surface, these become almost vertical
What’s the inclination of Cervical enamel rods of deciduous and permanent teeth ? And clinical significant ?
incisally or occlusally, while in permanent teeth these are inclined apically.
avoid unsupported enamel rods at gingival floor, cavosurface bevel (15 to 20°) at gingival margin is given by using gingival margin trimmer
What’s the inclination of Cervical enamel rods of deciduous and permanent teeth ? And clinical significant ?
incisally or occlusally, while in permanent teeth these are inclined apically.
avoid unsupported enamel rods at gingival floor, cavosurface bevel (15 to 20°) at gingival margin is given by using gingival margin trimmer
Where is the thinnest enamel ?
CEJ KNIFE EDGE , cervical area
Where is the thinnest enamel ?
CEJ KNIFE EDGE , cervical area
Enamel in nature is translucent which factors affect its color ?
i. Thickness of enamel; young anterior teeth appear translucent gray or bluish near incisal edges. It appears yellowish in cervical areas due to thin enamel from which color of underlying dentin is visible (Fig. 3.3A).
ii. Shade of underlying dentin.
iii. Presence of stains in enamel.
iv. Anomalies occurring during developmental and mineralization stage, antibiotic usage and fluorosis, etc. affect the color of teeth
Why all all enamel rods should be supported by healthy dentin base ?
Because of more compressive strength of dentin than enamel, dentin acts as a cushion for enamel when masticatory forces are applied on it.
Therefore, during tooth preparation, to have maximum strength of underlying remaining tooth structure all enamel rods should be supported by healthy dentin base .
