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 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, 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 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, 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 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, 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