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152 Cards in this Set
- Front
- Back
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The stomadodeum is considered the ________________.
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Primitive Oral Cavity
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The stomatodeum is bound by which two plates?
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Cardiac & Neural
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Which membrane allows for the depression of the stomodeum to increase, and what does it normally separate?
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The buccopharyngeal membrane
Separates the stomodeum and the pharnyx (foregut). |
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How do the stomodeum and dental lamina relate?
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Stomodeum gives rise to oral epithelium which will invaginate into ectomesenchyme to create dental lamina
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What event is considered the "first event in the development of the face," and when does this occur?
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Disintegration of the buccopharyngeal membrane, 4th week
(Allows the stomadeum to increase in depth) |
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_____________ includes the event relating to origins and formation of teeth.
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Odontogenesis
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The stomodeum is a shallow depression on which embryonic layer surface?
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Ectoderm
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Permanent & Primary teeth begin forming when?
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4th month - in utero (primary)
at birth (perm) |
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Odontogenesis refers to the events of tooth development beginning in what week of gestation?
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6th week
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Compare the components of mesenchyme and ectomesenchym
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Both are mesodermally derived, undifferentiated loose CT, and ectomesenchyme also includes Cranial NCC's that migrate into arch 1
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The pathways that drive tooth development are interactions between what layers?
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Epithelial
Mesenchyme (the dental lamina (epithelial) releases factors to cause the ectomesenchyme to differentiate via transcription factors) |
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Growth factors released by ____________ induce differentiation of ______________ via transcription factors (protein production).
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Dental lamina
Ectomesenchyme |
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Two transcription factors expressed by ectomesenchyme are ______ and _______. When these factors aren't present, what anomaly results?
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Msx-1, Pax-9
Tooth agenesis |
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Compare missense and nonsense mutations
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Missense - substitution in base, leads to coding of wrong protein
Nonsense - leads to stop codon, premature stop of synthesis, and lack of protein formation |
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What common anomaly will result if a mutation in PAX-9 occurs?
MSX-1? Missense mutation? Nonsense mutation? |
PAX- 9 Posterior teeth agenesis
MSX-1 Nonsyndromic premolar agenesis Missense - Premolar/Molar agenesis Nonsense - Cleft lip/palate or both |
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Summarize Primary Epithelial Band formation, when it happens, and what what other cells are nearby or involved
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6-7th week of gestation
Ectodermal epi (oral epi) forms in presumptive jaws. Leads to horseshoe band of epi cells which will become lamina (dental and vestibule), and ectomesenchyme is below. Epi/Ecto separated by basal lamina. Allows us to see placodes for all 20 teeth, but cannot yet differentiate what tooth type they will be. |
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Odontogenesis is signified by the presence of what structure?
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Dental lamina
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Which pharyngeal arch is responsible for initiation of tooth formation? In addition, which NCC's are necessary?
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First Arch Epithelium
Cranial NCC's Experiments done w/ 2nd arch epi or trunk cells do not produce tooth bud or additional oral structures. |
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The first arch epithelium loses it's odontogenic potential on/around what day? Where is the potential transferred?
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12th day
To ectomesenchyme Mesenchymal tissue has influence on fate of epithelium (if you combine incisor epi w/molar mesenchyme, you get a molar) |
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Histologic odontogenesis is present on which day, and which structure is present?
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11th day
Thickening of oral epi in arch Lh-6 & 7 are present on day 9 as mesenchymal transcription factors |
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Define cleidocranial displaysia
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One mutated copy of Cbfa-1
Leads to failure of tooth eruption due to: Lack of primary root resorption Fibrous gingiva Supernumary teeth as buds |
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Partial Adontia terms for # of teeth missing are:
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Hypodontia (1-5)
Oligodontia (6+) DUE TO DISTURBANCE OF DL |
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Mesioden is the most common form of
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Hyperdontia
Extra tooth. Mesioden btw central incisors on max DUE TO DISTURBANCE OF DL |
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Mutation in Pax-9 leads to
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Mutations or agenesis in posterior teeth
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Mutations in Msx-1 lead to
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Nonsyndromic PM agenesis
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Summarize the field/homeobox code theory
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Tooth shape is the result of overlapping field in ectomesenchyme that express different homeobox genes.
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Summarize the clone model
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Tooth class is derived from clones of ectomesenchymal cells which are programmed by epithelium to produce teeth. The Molar clone ecto induces lamina to start development. When tooth reaches critical size, bud is initiated and the next bud will not start until the progress zone escapes zone of inhibition
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6 stages of tooth development
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Initiation 6-7 weeks
Bud 8 weeks Cap 9-10 weeks Bell 11-12 weeks Apposition - varies Maturation - varies |
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Initiation of tooth formation begins on what day?
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37th
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Bud stage of development is denoted by the presence of what feature?
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Dental lamina
First epithelial incursion into ectomesenchyme |
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What are the peripheral and core cell shapes of the cells inside the dental lamina?
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Peripheral - cuboidal
Core - stellate |
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Placodes for 20 deciduous teeth are developed by?
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Interaction between ectomesenchyme (papilla) and overlying lamina (epithelium)
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Tooth bud development proceeds in what order?
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Ant-Post
Mand-Max ASYNCHRONOUS |
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A enamel organ with 3 layers signifies a transition between what two developmental stages?
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Bud to cap
Also signifies onset of morphological differences |
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Lateral lamina becomes present at which stage, and how does it occur?
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Early Cap stage
As tooth bud enlarges, it 'drags' the lamina out, creating lateral lamina as it travels |
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The Tooth Germ is made up of:
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Enamel organ
Dental follicle Dental Papilla |
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What histologic feature of the cap stage is responsible for the "cap" name?
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The enamel organ forming 'cap' over condensing ectomesenchyme
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Cells of which part in the tooth germ initiate dentin formation, and from which area does dentin formation occur?
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Cells of the enamel organ
Occurs in dental papilla |
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Cells in core of EO responsible for?
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SR
Will secrete proteoglycans Connected via desmosones Spread apart by extracellular fluid (star shape) |
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Define shapes of preliminary OEE and IEE cells
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OEE - squamous to low cuboidal
IEE - cuboidal to low columnar |
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Cervix of future tooth is represented by
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Cervical loop
IEE+OEE Will become CEJ |
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The cells of the dental papilla will diff into?
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Peripheral - dentin
Core - pulp |
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Succedaneous tooth buds are formed via
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Succedaneous lamina
Grows posterior to the primary buds on lingual side (except for lateral canine) |
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Perm molars are developed via
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Posterior extensions of dental lamina - begins at 5th month of gestation
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Vestibular lamina responsible for what structures?
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vestibule of mouth
oral mucosa lining of lips/cheeks alveolar mucosa gingiva Salivary glands Parotid, submandibular, sublingual |
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Which 3 salivary glands are formed by vestibular lamina?
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Submandibular
Sublingual Parotid |
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At what stage is the enamel knot present?
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Cap stage (SI cells from EO flatten and extend from IEE)
Ectomesenchymal cells tell EK to express signaling molecules After first EK disappears, others appear at future cusp tips of molars |
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What is the purpose of the enamel knot?
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Orchestrate cuspal morphogenesis
Control folding of IEE One cusp - one knot, etc Apoptosis of knot cells to terminate signaling of structure |
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Which growth factors are utilized by the enamel knot?
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EGF & FGF 4
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During Bell stage, the core enamel organ cells serve what purpose?
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secrete GAG's into extracellular matrix, hydrophillic environment draws in water and increases EO volume. Also, transports nutrients and Ca++ from nearby BV's to ameloblasts
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What purpose does the SI serve?
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High alkaline phosphotase activity to take phosphate from nearby BV's and take to EO
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During Bell stage, what happens to OEE cells
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Fluted nearby vessels will fill invaginated areas
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The cervical loop is made up of
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IEE and OEE cells
Will give rise to HERS, become the place where crown meets root. |
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Mitosis of cervical loop cells does what?
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Elongates EO leading to "bell shape"
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The disintegration of dental lamina during ___________ stage will proceed the reconnection of tooth to oral epi, forming _______________ epithelium
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Bell
Junctional |
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Molar buds occur during disintegration of DL via
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Extension of posterior DL
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IEE folding determines?
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Crown pattern
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Epithelial pearls occur due to what structure?
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Dental lamina
Epi balls covered in CT Can degenerate, be phagocytosed, can cause eruption cysts or be odontomes or supernumaries |
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Ectomesenchyme around the tooth germ form dental sac which give rise to.....
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cementum, PDL, CT of gingiva, alveolus
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Which structures do not have NCC origin?
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Enamel organ, OEE, IEE, SR, SI
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During the apposition phase, the ameloblasts and odontoblast proceed in which direction?
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From occlusal to the cervical loop
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Upon the first differentiation of IEE cells in the apposition phase, what happens to the OEE cells?
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EO fluid is resorbed, collapsing OEE onto SI (decrease of SR cells at cusp tip)
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The first differentiation in the apposition phase occurs with what cells?
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IEE cells to preameloblasts
Elongate, become polarized with Nucleus at occlusal end |
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What additional factors aid in the peripheral ectomesenchymal cells differentiating to preodontoblasts?
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Signaling molecules from acellular/BM zone
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Msx-1 & 2 are secreted by which cells
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Preodontoblasts & Odontoblasts
Allow cell biologist to see what stage cells have differentiated to |
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The acellular zone is filled/covered by what cells, and at what time?
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Preodontoblast cells prior to differentiating to odontoblasts
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The predentin laid by odontoblasts consists of?
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Type 1 collagen
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When the predentin is mineralized to _____________ dentin, it initiates the differentiation of ____________ to _____________
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mantle
preameloblast ameloblast |
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In order for the differentiation of preamelobasts to amelobasts to occur, what events must be complete?
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Ectomesenchymal cells in DP
Odontoblasts preDentin Mante Dentin |
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The first layer of enamel is called?
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Aprismatic
30% mineralized |
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What is different about aprismatic enamel from regular enamel?
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No rods present
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In order for the enamel to become more calcified, what processes must occur?
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Organic matrix breakdown
Crystals elongate and widen |
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Enamel is laid at what rate?
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4 micrometers/day
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The BM that allows the continued epi/ecto interaction between preamelo and preodonto is called (was btw DP and IEE prior to differentiation)?
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The Membrana Performative
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The DEJ is formed once what two materials are laid?
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Mantle dentin and aprismatic enamel (secreted into membrana performative or BL)
Function as one unit |
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The 'rod space' left by tomes' process appears as a ______ in the surface of enamel
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Depression
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The 3 Stages of the Ameloblast Life Cycle are:
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1. Presecretory - Change of polarity. Exit cell cycle, elongate, develop protein synthesis organelles, prepare to secrete organic matrix
2. Secretory/Formative - Organize enamel thickness 3. Maturation - Modulate/transport ions for mineralization |
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The 5-6 Functional Stages of Ameloblasts are:
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1. Morphogenic
2. Histodifferentiation 2.5 Initial secretory 3. Secretory (formative) 4. Maturative 5. Maturative proper 6. Protective |
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The Morphogenic stage of ameloblasts include what characteristics?
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IEE > Preameloblast
Central Nuclei Little golgi, RER, organelles spread throughout cell |
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Histodifferentiation stage is initiated by growth factors secreted by ____________ which causes _____________ to differentiate.
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Odontoblasts
Preamelobasts to ameloblasts |
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Cytological changes during the histodifferentiation stage of the ameloblast include:
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Nuclei moves toward tooth surface
Secretory end gets rER, golgi, mito Additional junctional complex connecting ameloblasts BM begins to fragment as a result of mantle dentin formation |
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Actin filaments in junctional complexes are called _________. Their purpose is:
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Terminal webs
Regulate passage of materials throughout material and 'lock' cells in line |
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The main difference of the secretory and initial secretory stage is the presence of?
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The Tomes' process
Won't appear until secretory/formative stage |
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Main goal of ameloblast during secretory stage is:
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protein synthesis
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The BM between the ameloblasts and odontoblasts disappears during the __________ ameloblast stage
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Secretory
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Summarize the intracelluar processes during secretory amelobast phase
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Golgi apparatus + abundant rER in distal cell, release packaged proteins (matrix) through Tomes' during stage
This is done in response to mantle dentin |
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The proximal portion of the distal junctional complex runs from _________ to _________ and the distal portion is from ______________ to _____________.
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Distal junction to top of enamel
Enamel tip to end of tomes' process that is interdigitating with enamel |
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The Rod/Interrod configuration of enamel is due to what portion of the amelobast?
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Tomes' process
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During the Maturative Proper stage, ameloblasts alter between which two configurations?
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Ruffle Ended & Smooth Ended
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The main goal of the ameloblast during the maturative stage is
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Mineralize enamel from the existing 30% to 96%
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Once the ameloblast loses it's Tomes' process during the _________ stage, it is considered a ____________ cell
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Maturative
Postsecretory |
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During maturative stage, the ameloblasts resorb _______ and ______ and replace by _________ and __________
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Water, Protein
Calcium, Phosphate |
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Enamel maturation is hallmarked by?
Enamel hardening is hallmarked by? |
Increase in crystal #
Increase in crystal size (width, thickness) that are seeded in formative amelogenesis |
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The junctional complexes of the different ameloblast forms during maturation proper are:
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Ruffle: leaky prox, tight dis
Smooth: leaky dis, tight prox |
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Enamel maturation occurs in what sequence/direction?
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Apical ---> incisal
Lease mature enamel to most mature enamel |
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Purpose of ruffle-ended amelobast includes:
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Endo activity!!!
Pump Ca++, bicarb, and phosphate ions into ameloblast to transport into matrix |
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Purpose of smooth-ended amelobast includes:
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No endo activity
Removal of matrix proteins and water |
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The mechanism for the loss of organic matrix is due to:
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Enamel Matrix Serine Proteinase (EMSP 1)
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At the end of the Maturation proper stage, what layer is the last thing applied to surface enamel?
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Basal lamina
Hook to enamel w/hemidesmosomes Regulates in/out of enamel layer |
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The cellular sheath formed in the protective stage is the ______ and is formed by_______
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REE
Reduced enamel epithelium Formed by Postameloblasts, SI, SR, OEE |
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What is the fate of the coronal and cervical areas of REE?
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coronal - destroyed at eruption (primary enamel cuticle)
cervical - junctional epithelium |
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The enamel matrix is composed of
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Noncollagenous enamel proteins and enzymes
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The most abundant protein in the enamel matrix is
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Amelogenin (90%)
Hydrophobic, low MW protein that surround crystals on long axis |
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Amelogenins are found at what area of enamel?
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Throughout enamel except for growth sites
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Main 2 purposes of amelogenins is
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Regulate crystal growth and orientation during formation
Prevent crystal fusion |
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Membrane infoldings on ameloblasts due to
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the rapid fusion of secretory granuals released against mantle dentin - initial ename w/o rods
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Enamel mineralization occurs _________ after enamel matrix secretion
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Immediately
Dentin has time lapse btw predentin and dentin |
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Prox Tomes' responsible for which enamel matrix?
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Interrod
Secretion from adjoining ameloblasts leave pit for distal Tomes' |
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Distal Tomes' responsible for which enamel matrix?
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Rod/prisms that fill pit from interrod/prox tomes
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Rod and Interrod enamel are _______ in composition, but vary in _______ of crystals
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Composition
Orientation |
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The are in which interrod enamel and rod enamel blend is called
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The Zone of Confluence
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Enamel Biomineralization is
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the process by which enamel proteins mediate the formation of hydroxyapetite crystals from Ca++ and phosphate
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T/F
Enamel has a preEnamel layer similar to dentin or osteoid |
False
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T/F
Amelogenins provide physical support but NOT structural function |
True
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Proteins secreted by ameloblast mineralize what % of enamel?
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30%
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In order to yield 95% mineralization of enamel? What two items must be removed, and how is it completed?
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Protein and Water
Ameloblast modulation of ruffle/smooth configurations |
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The 'Sandwich Product' of mineralization is
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1. Aprismatic - no rods - heavily mineralized
2. Partial 20-30% surface to aprismatic enamel 3. Mineralization of surface enamel to 95% in opposite direction 4. Surface-most enamel highly calcified |
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The 5 steps of enamel mineralization are
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1. Enamel protein secreted
2. SI transfer Ca++ fro BV to amelo 3. Mineralization (sandwich) 4. Hydroxyapetite crystals form 5. Crystals grow in thickness |
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The three phases of the odontoblast are:
Their nucleus location is: |
Active Synthetic - nucleus basal
Transitional - nucleus displaced Quiescent - Nucleus apical w/infranuclear region full of organelles |
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The odontoblastic process function is:
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Secrete dentin matrix and then mineralize dentin
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The odontoblastic process contains:
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microtubules & filaments
Coated vesicles and pits that reflect pinocytotic activity |
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When odo process is surrounded by dentin, it is called
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tubular dentin
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The orientation of tubular dentin in the crown and root are:
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S-shaped
Straight |
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Dentin tubules have 4 components
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Serum fluid
Unmyelinated fibers Uncalcified matrix (protection of odo process) Type I/V collagen |
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The pattern of tertiary dentin is
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Irregular patterned tubules
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The rate of formation for primary and secondary dentin is
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Primary - fast and more mineralized
Secondary - slower and less mineralized |
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Of the pattern dentin, which are formed before and after apical foramen completion?
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Primary - before
Secondary - after |
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Which of peritubular or intertubular dentin is more calcified?
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Peritubular
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Which dentin is formed first
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Mantle dentin
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Von Korff's fibers are bundles of
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collagen
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Which dentin type has Von Korff's fibers?
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Mantle dentin
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Circumpulpal dentin is formed after
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Mante dentin
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The bulk of dentin is
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primary - circumpulpal
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Intertubular dentin is formed
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between dentinal dubules
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Dentin surrounding odontoblastic process is
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Peritubular dentin, highly calcified
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Dentin surrounding the pulpal wall is
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circumpulpal
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Pattern dentin that forms in response to trauma is
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Tertiary dentin
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T/F
Primary dentin is more mineralized then secondary |
T
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Dentin formed as a result of a dead tract is
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Reparative
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What type of tertiary dentin is made as a result of mild trauma that does NOT result in odontoblast death?
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Reactive
Upregulation of odontoblast |
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Interglobular and globular dentin are:
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Globular - no peritubular dentin, near DEJ
Interglobular - Between mantle/circumpulpal. Improper fusion |
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What dentin can arise as a result of excessive fluoride?
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Interglobular
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Sclerotic dentin can be found
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In the apical 1/2 of root
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Secondary dentin will mostly form
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in the roof and floor of pulp
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Reparative vs. reactive dentin is based on
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severity of trauma
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Von Korff's fibers are
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large diamater collagen fibrils that run parallel w/odo process through dentin
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Von Korff's fiber is Type ______ collagen and fibronectin
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III
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The crystals of dentin formation mineralize spread their crystals how?
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The crystals grow rapidly, membrane ruptures and spreads crystallites. Adjacent clusters form mineralized matrix
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The two dentin mineralization mechanisms are
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Simple percolation & Transport Systems
Percolation: issue fluid supersaturated with calcium/phosphate ions Transport: Minerals released into dentin via L-type Ca++ changels in BM and adenosinetriphosphate activity in distal cell |
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At what period after pDentin is laid does mineralization occur?
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24 hours
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The ______ crystals of dentin form between what collagen fibers (for mantle dentin)?
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HAP - type I
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Circumpulpal dentin mineralization occurs in what two patterns?
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Linear - Slow, uniform front
Globular - Quick rate, HAP crystals deposited and form calcospheres, grow, and fuse |
