Ten Cate's Oral histology - Development, Structure and function Flashcards
According to Ten Cate’s Oral histology - Development, Structure and function, During which stage of development can the enamel organ be first identified?
Cap Stage
According to Ten Cate’s Oral histology - Development, Structure and function, What germ layer is the enamel organ derived from and what structure gives rise to it?
Ectoderm and dental lamina
According to Ten Cate’s Oral histology - Development, Structure and function, What is in the centre of the enamel organ?
The center of the enamel organ is termed the stellate reticulum.
According to Ten Cate’s Oral histology - Development, Structure and function, What is the enamel knot?
A group of non-dividing epithelial cells found in the cap stage of development within the stellate reticulum of molar teeth, may be important to developing the cusp pattern of molars, but unknown.
According to Ten Cate’s Oral histology - Development, Structure and function, What is morphodifferentiation? What phase of development does it occur during?
When the tooth crown assumes its final shape, bell stage
According to Ten Cate’s Oral histology - Development, Structure and function, What is the cervical loop?
Location where inner and outer enamel epithelium meet at the reflection of the epithelium
According to Ten Cate’s Oral histology - Development, Structure and function, At what location of the enamel organ are cells dividing to give the tooth it’s full size?
Cervical loop
According to Ten Cate’s Oral histology - Development, Structure and function, What is the first layer of dentin laid down called?
Mantle dentin
According to Ten Cate’s Oral histology - Development, Structure and function, Do ameloblasts make enamel first, or do odontoblasts make dentin first?
Odontoblasts, but ameloblasts secrete protein first, which may be inductive signal to odontoblasts
According to Ten Cate’s Oral histology - Development, Structure and function, What are the three components of the tooth germ?
Enamel organ, dental papilla, dental follicle
According to Ten Cate’s Oral histology - Development, Structure and function, What will the cells of the enamel organ produce, and eventually become?
Produce enamel (duh), many will be shed when tooth erupts but some will contribute to the junctional epithelium
According to Ten Cate’s Oral histology - Development, Structure and function, What will cells of the dental papilla eventually become, and what will they produce?
Eventually will become odontoblasts and cells of the pulp, produce dentin
According to Ten Cate’s Oral histology - Development, Structure and function, What will cells of the dental follicle become and what will they produce?
Cementoblasts, produce cementum, and PDL fibroblasts, produce and remodel PDL
According to Ten Cate’s Oral histology - Development, Structure and function, What is the purpose of hertwigs epithelial root sheath, what cells does it come from?
Epithelial cells that cause ectomesenchyme of the dental papilla to become root odontoblasts. Proliferation of the cervical loop of the enamel organ in an apical direction,
According to Ten Cate’s Oral histology - Development, Structure and function, What is the eventual fate of hertwigs epithelial root sheath?
Most of the root sheath breaks up, but leaves behind cell rests of mallasez
According to Ten Cate’s Oral histology - Development, Structure and function, What happens when hertwigs epithelial root sheath breaks up?
Cells of the dental follicle (sac) come into contact with the newly formed root dentin, causes them to differentiate into cementoblasts to begin forming cementum
According to Ten Cate’s Oral histology - Development, Structure and function, What is the chemical makeup of bone?
Organic 33% (mostly type I collagen) Inorganic (hydroxyapatite) 67%
According to Ten Cate’s Oral histology - Development, Structure and function, What is RANK, Where is it found?
receptor-activated nuclear factor κB, on osteoclasts and pre-osteoclasts. Membrane bound receptor
According to Ten Cate’s Oral histology - Development, Structure and function, What is RANKL, Where is it found?
receptor-activated nuclear factor κB Ligand, on Osteoblasts and pre-osteoblasts, membrane bound ligand for RANK (which is on the osteoclast)
According to Ten Cate’s Oral histology - Development, Structure and function, What is OPG, where is it found?
Soluble decoy ligand for RANK – binds to but does not activate RANK. Produced by osteoblasts and pre-osteoblasts
According to Ten Cate’s Oral histology - Development, Structure and function, In bone homeostasis, what is a cutting cone?
A group of osteoclasts moving through bone and resorbing
According to Ten Cate’s Oral histology - Development, Structure and function, In bone homeostasis what is a filling cone?
A group of new osteoblasts and pre-osteoblasts that are generating new bone along behind a group of osteoclasts
According to Ten Cate’s Oral histology - Development, Structure and function, What is the first layer laid down by osteoblasts during remodelling and what is it’s composition and purpose?
Cement or reversal line, non collagenous matrix proteins like bone sialoprotein and ostepontin. Acts as a cohesive, mineralized layer to stick new bone to old
According to Ten Cate’s Oral histology - Development, Structure and function, What is the composition of enamel?
96% mineral and 4% organic material and water
According to Ten Cate’s Oral histology - Development, Structure and function, What are the three phases of enamel production?
Pre-secretory
Secretory
Maturation
According to Ten Cate’s Oral histology - Development, Structure and function, What is happening during the presecretory phase?
differentiating ameloblasts acquire their phenotype
change polarity
develop an extensive protein synthetic apparatus
prepare to secrete the organic matrix of enamel
According to Ten Cate’s Oral histology - Development, Structure and function, What is happening during the secretory phase?
ameloblasts elaborate and organize the entire enamel thickness, resulting in the formation of a highly ordered, partially mineralized, tissue.
According to Ten Cate’s Oral histology - Development, Structure and function, During which stage of tooth development does enamel form?
Bell stage
According to Ten Cate’s Oral histology - Development, Structure and function, What is happening during the maturation phase?
ameloblasts “modulate” and transport specific ions required for accretion of mineral
According to Ten Cate’s Oral histology - Development, Structure and function, What is different about the first layer of enamel produced?
Does not contain rods
According to Ten Cate’s Oral histology - Development, Structure and function, What is the cytoplasmic extension of the ameloblast called?
Tome’s process NB Don’t confuse with Tomes Fibre – the odontoblast process
According to Ten Cate’s Oral histology - Development, Structure and function, What is the difference between rod and interrod enamel?
Orientation of their crystals – chemically the same
According to Ten Cate’s Oral histology - Development, Structure and function, Describe the formation of rod and interrod enamel?
Proximal portion of tomes process secretes enamel around the periphery of the process, which creates a pit in which tomes process resides. This creates the interrod enamel, which is continuous with that produced by adjacent ameloblasts.
Tomes process elongates as more interrod enamel is laid down, and the distal portion of the process makes enamel with crystals oriented in a different direction. This makes the rod.
As the rod grows it squishes the tip of the process out of existence and the thin space where it last was becomes filled with organic material to become the rod sheath. The ameloblast continues retreating as more enamel is laid down.
According to Ten Cate’s Oral histology - Development, Structure and function, What is different about the last layer of enamel formed?
It has no rods.
According to Ten Cate’s Oral histology - Development, Structure and function, What parts of enamel are thought to be continuous with one another?
Initial layer, interrod enamel and last layer – all deposited by the same proximal portion of Tomes process
According to Ten Cate’s Oral histology - Development, Structure and function, When is enamel fully mineralized?
During the maturation phase
According to Ten Cate’s Oral histology - Development, Structure and function, How much mineral is deposited initially when enamel is being laid down?
Approx 30%
According to Ten Cate’s Oral histology - Development, Structure and function, When are most of the enamel proteins removed?
During the maturation phase
According to Ten Cate’s Oral histology - Development, Structure and function, What is the mechanism for removing enamel protein?
Degradation by extracellular proteolytic enzymes and escape through leaky distal junctions of the smooth ended ameloblasts
According to Ten Cate’s Oral histology - Development, Structure and function, What is modulation with respect to ameloblasts?
During the maturation phase of enamel secretion, they alternate back and forth between ruffle ended and smooth ended
According to Ten Cate’s Oral histology - Development, Structure and function, Describe the cell:cell junctions of ameloblasts during modulation?
Smooth ended ameloblast – tight proximal junctions, leaky distal junctions Ruffle ended ameloblast – tight distal junctions, leaky proximal junctions
According to Ten Cate’s Oral histology - Development, Structure and function, How does calcium get to the mineralizing enamel when the ameloblasts are in the ruffle ended morphology versus in the smooth ended morphology during modulation?
Ruffle ended ameloblasts - Goes through the ameloblast and secreted via the ruffles (this configuration has tight distal junctions); travels between ameloblasts in the smooth ended configuration (this configuration has leaky distal junctions)
According to Ten Cate’s Oral histology - Development, Structure and function, What are Striae of Retzius?
Cause unknown, but they are horizontal dark bands in the enamel, usually seen on ground sections
According to Ten Cate’s Oral histology - Development, Structure and function, What are hunter Schreger bands?
Optical phenomenon resulting in an appearance of alternating light and dark bands in enamel. Caused by different orientation of enamel rods
According to Ten Cate’s Oral histology - Development, Structure and function, What are enamel tufts, what is their clinical significance?
Branching defects in the enamel beginning at the DEJ and radiating into the enamel, contain greater amount of enamel matrix protein No known clinical significance
According to Ten Cate’s Oral histology - Development, Structure and function, What are enamel lamellae and how can they be distinguished from fractures?
Linear, longitudinally oriented defects in enamel, extending from the surface to a variable depth. Filled with organic material (this is how they are distinguished from fractures, as a fracture will not contain organic material.
According to Ten Cate’s Oral histology - Development, Structure and function, What is globular dentin?
Dentin that has arisen as a result of calcospheric deposition of dentin, as in the mantle dentin, which forms from matrix vesicles
According to Ten Cate’s Oral histology - Development, Structure and function, What is the granular layer of Tomes?
A layer that appears between the root dentin and cementum that can only be seen on ground sections under transmitted light. May represent a special arrangement of collagen and non collagen proteins in this area.
According to Ten Cate’s Oral histology - Development, Structure and function, What is interglobular dentin?
Areas of unmineralized and hypomineralized dentin in between areas of globular dentin. Usually seen in mantle dentin or circumpulpal dentin near the mantle dentin.
According to Ten Cate’s Oral histology - Development, Structure and function, What are the 4 zones of the pulp?
(1) the odontoblastic zone at the pulp periphery;
(2) a cell-free zone of Weil beneath the odontoblasts, which is prominent in the coronal pulp;
(3) a cell-rich zone, where density is high, which again is seen easily in coronal pulp adjacent to the cell-free zone;
(4) the pulp core, which is characterized by the major vessels and nerves of the pulp
According to Ten Cate’s Oral histology - Development, Structure and function,
Name the PDL fibre bundles shown here
Apical group
oblique group
horizontal group
alveolar crest group
interradicular group
(Transseptal group - doesn’t attach to bone, but shown here)
According to Ten Cate’s Oral histology - Development, Structure and function,
Name the gingival fibre bundles shown here:
Dentogingival group
dentoperiosteal group
alveologingival group
circular group
(Transseptal not shown)
According to Ten Cate’s Oral histology - Development, Structure and function,
Name the gingival fibres show here, from the vantage between teeth:
Circular fibres,
dentogingival,
alveologingival
Dentoperiosteal
(Transeptal not shown)
