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134 Cards in this Set
- Front
- Back
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What are the stages of odontogenesis?
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Initiation stage
Bud stage Cap stage Bell stage Apposition stage Maturation stage |
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When, in development, is the initiation stage?
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6th-7th weeks
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When, in development, is the bud stage?
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8th week
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When, in development, is the cap stage?
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9-10th week
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When, in development, is the bell stage?
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11th-12th week
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Initial teeth for both primary and permanent dentitions develop in which region of the mouth?
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anterior mandibular followed by anterior maxillary
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When do the primary and permanent dentitions form (fetal, embryonic, neonatal, etc.)?
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primary--embryonic and fetal
permanent--fetal |
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Name the stage: ectoderm lining stomodeum gives rise to oral epithelium and then to dental lamina, adjacent to deeper mesenchyme and NCC and separated by a basement membrane
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Initiation stage
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Growth of dental lamina that penetrates growing mesenchyme
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bud stage
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Enamel organ forms and surrounds mass of dental papilla from the mesenchyme and is surrounded by a mass of mesenchyme called the dental sac. Formation of the tooth germ
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cap stage
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differentiation of enamel organ with four cell types and the dental papilla into two cell types
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bell stage
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dental tissues secreted as matrix in successive layers
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apposition stage
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dental tissues fully mineralize to their mature levels
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maturation stage
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T/F: The teeth have the longest developmental period of any set of organs in the body
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true
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T/F: Mesenchymal tissues must influence the ectodermal tissues in order for initiation of odontogenesis to occur
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True
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at the beginning of odontogenesis, the outer portion of the ectoderm gives rise to what?
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oral epithelium
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separates oral epithelium and the underlying mesenchyme
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basement membrane
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main processes involved in initiation stage
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induction
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main processes involved in bud stage
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proliferation
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main processes involved in cap stage
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proliferation, differentiation, morphogenesis
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main processes involved in bell stage
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proliferation, differentiation, morphogenesis
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main processes involved in apposition stage
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induction and proliferation
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main processes involved in maturation stage
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maturation
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Embryological background of enamel
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enamel organ (ectoderm)
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Embryological background of dentin
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dental papilla (NCC)
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Embryological background of cementum
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dental papilla (NCC)
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Embryological background of alveolar bone
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mesoderm
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type of tissue: enamel
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epithelial
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type of tissue: dentin
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CT
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type of tissue: cementum
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CT
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type of tissue: alveolar bone
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CT
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Formative cells of enamel
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ameloblasts
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Formative cells of dentin
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odontoblasts
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Formative cells of cementum
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cementoblasts
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Formative cells of alveolar bone
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osteoblasts
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incremental lines: enamel
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Lines of Retzius
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incremental lines: dentin
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Imbrication lines of Ebner
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incremental lines: cementum
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Arrest and reversal lines
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incremental lines: alveolar bone
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Arrest and reversal lines
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Mature cells: enamel
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none--lost with eruption
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Mature cells: dentin
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only dentinal tubules with processes
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Mature cells: cementum
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cementocytes
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Mature cells: alveolar bone
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osteocysts
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resorptive cells: enamel
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odontoclasts
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resorptive cells: dentin
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odontoclasts
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resorptive cells: cementum
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odontoclasts
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resorptive cells: alveolar bone
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osteoclasts
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mineral (inorganic) level: enamel
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96%
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mineral (inorganic) level: dentin
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70%
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mineral (inorganic) level: cementum
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65%
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mineral (inorganic) level: alveolar bone
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60%
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Organic and water levels: enamel
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Organic: 1%
Water: 3% |
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Organic and water levels: dentin
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Organic: 20%
Water: 10% |
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Organic and water levels: cementum
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Organic: 23%
Water: 12% |
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Organic and water levels: alveolar bone
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Organic: 25%
Water: 15% |
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Tissue formation possible, for enamel, after eruption?
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no
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Tissue formation possible, for dentin, after eruption?
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yes
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Tissue formation possible, for cementum, after eruption?
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yes
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Tissue formation possible, for alveolar bone, after eruption?
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yes
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vascularity: enamel
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no
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vascularity: dentin
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no
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vascularity: cementum
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no
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vascularity: alveolar bone
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yes
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innervation: enamel
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no
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innervation: dentin
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yes
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innervation: cementum
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no
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innervation: alveolar bone
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yes
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Disturbances in initiation stage?
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Anodontia
Supernumarary teeth |
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Disturbances in bud stage?
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macrodontia/microdontia
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Disturbances in cap stage?
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dens in dente
fusion gemination tubercle (extra cusp) |
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Disturbances in appostition and maturation stages?
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enamel pearl
enamel dysplasia dentinal dysplasia concresence |
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odontogenesis stage when anodontia disturbance occurs?
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initiation stage
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odontogenesis stage when supernumerary teeth disturbance occurs?
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initiation stage
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odontogenesis stage when macrodontia/microdontia disturbance occurs?
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bud stage
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odontogenesis stage when dens in dente disturbance occurs?
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cap stage
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odontogenesis stage when fusion disturbance occurs?
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cap stage
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odontogenesis stage when gemination disturbance occurs?
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cap stage
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odontogenesis stage when tubercle disturbance occurs?
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cap stage
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odontogenesis stage when enamel pearl disturbance occurs?
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apposition/maturation stage
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odontogenesis stage when enamel dysplasia disturbance occurs?
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apposition/maturation stage
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odontogenesis stage when dentinal dysplasia disturbance occurs?
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apposition and maturation stages
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odontogenesis stage when concresence disturbance occurs?
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apposition and maturation stages
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Heredity can play a role in all tooth development disturbances except which?
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fusion (pressure)
tubercle (trauma, pressure, or metabolic disease) enamel pearl (displaced ameloblasts to root surface concrescence (trauma or tooth crowding) |
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supernumerary teeth usually occurs where?
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between maxillary central incisors (mesiodens)
4th molars premolar region (perimolar) |
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macrodontia/microdontia usually involves which teeth?
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permanent maxillary lateral incisors and third molars
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tooth most commonly affected by dens in dente?
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permanent maxillary lateral incisor
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tubercle usually present where?
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permanent molars or cingulum of anterior teeth
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concrecense more commonly occurs here:
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permanent maxillary molars
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Stage where cellular differentiation begins in odontogenesis
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cap stage
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predominant physiological process occurring during cap stage
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morphogenesis
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define dental papilla
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inner mass of condensed mesenchyme under enamel organ in cap stage
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In odontogenesis, the basement membrane is the future site of what?
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DEJ
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dental sac (dental follicle) becomes what mature structures?
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periodontium:
cementum, PDL, and alveolar bone |
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dental papilla becomes what mature structures?
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dentin and pulp
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initiation of permanent dentition occurs during which stage of odontogenesis of primary teeth (what week)?
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cap stage: week 10
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Four cells found in enamel organ--(what stage)?
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bell stage:
inner enamel epithelium-->ameloblasts outer enamel epithelium-->protective barrier stellate reticulum stratum intermedium |
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during bell stage, dental papilla differentiates into these layers:
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outer cells--> odontoblasts
inner cells-->primordium of pulp |
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Describe formation of preameloblasts and why this is important
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-IEE cells become more columnar
-repolarization--nuclei move as far as possible from basement membrane -preameloblasts induce outer layer dental papilla cells differentiation into odontoblasts and they themselves turn into ameloblasts |
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Which matrix begins formation first? enamel matrix or dentin matrix?
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dentin matrix--this is why it is usually slightly thicker than enamel
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Describe formation of odontoblasts
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-signals from preameloblasts
-repolarization--nuclei migrate as far from BM as possible -secrete predentin (dentin matrix) by BM |
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Describe formation of ameloblasts, DEJ and enamel matrix
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-when in contact with predentin, BM disintegrates
-when preameloblasts contact predentin, they mature to ameloblasts -Tome's process of ameloblasts start to secrete enamel matrix--DEJ forms -matrix formation on both sides of DEJ is rythmic -odontoblasts learve an odonotblastic process contained in a dentinal tubule |
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Enamel dysplasia
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-occurs during appositional and/or maturation stages
-can be systemic or local -local from trauma or local infection -systemic from traumatic birth, systemic infcetion, nutritional deficienceis, or dental fluorosis |
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enamel hypoplasia
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reduction of quantity of enamel matrix--pitted and grooves in enamel surface
examples: Hutchinson's incisors and mulberry molars |
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congenital syphilis causes
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hutchinson's incisors and mulberry molars
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enamel hypocalcification
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reduction in quality of enamel maturation--opaque, yellow/brown teeth
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dental fluorosis can cause what?
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both enamel hypoplasia and enamel hypocalcification
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a certain type of enamel dysplasia with hereditary etiology--very little or no enamel
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amelogenesis imperfecta
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a certain type of dentin dysplasia with hereditary etiology--poorly formed dentin
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dentinogenesis imperfecta
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structure responsible for root development
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cervical loop
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what is the cervical loop
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cervical portion of enamel organ--bilayer rim of only IEE and OEE.
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When does root development begin?
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after crown is completely shaped and tooth starts to erupt
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How is Hertwig's root sheath made?
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cervical loop grows deeper into surrounding mesenchyme of the dental sac--encloses more of the dental papilla tissue
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cervical loop grows deeper into surrounding mesenchyme of the dental sac--encloses more of the dental papilla tissue. What is this structure called?
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Hertwig's root sheath
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Function of Hertwig's root sheath?
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shape root
induce dentin formation in root area |
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Why does Hertiwig's root sheath include odontoblastic differentiation in the root area but fail to differentiate into enamel-forming ameloblasts?
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Because there aren't stellate reticulum and stratum intermedium in this area.
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What happens in root formation
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-IEE of Hertwig's root sheath induce outer layer of dental lamina to form odontoblasts
-predentin is laid down -BM and Hertwig's root sheath disintegrate. |
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What are epithelial rests of Malassez?
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epithelial cell remnants from the disintegrate of Hertwig's root sheath--can become cystic
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What causes enamel pearls
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misplaced ameloblasts that migrate to the root area
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Describe the formation of the deninocemental junction (DCJ)
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-disintegration of Hertwig's root sheath allows cells of dental sac to contact dentin
-this contact induces these cells to become immature cementoblasts -cementoblasts undergo cementogenesis--lay down cementum matrix (cementoid) -cementoblasts become trapped in cementoid--become mature cementocytes -as cementoid calcifies, it is called cementum |
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Which cells form the dental pulp?
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central cells of the dental papilla
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Name the major component of the PDL
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collagen fibers
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What causes 2 or 3 roots to be formed as opposed to one?
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differential growth of Hertwig's root sheath
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What causes dilaceration?
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distortion of Hertwig's root sheath due to injury or pressure
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Where is dilaceration most common?
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permanent maxillary lateral incisors and canines, as well as molars
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Accessory roots (supernumerary roots) occur mainly where?
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mainly iwht permanent third molars
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What is passive eruption
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occurs with age--gingiva recedes; no actual tooth movement takes place
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Describe tooth eruption
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-after enamel appostition ceases, ameloblasts place a dental cuticle on the enamel surface
-layers of enamel organ compress into the reduced enamel epithelium (REE) -REE fuses with oral epithelium -REE secretes enzymes that create a tunnel in the fused tissue |
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Describe primary tooth shedding
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-osteoclasts absorb bone between primary and permanent tooth
-odontoclasts cause resorption in the primary tooth's root |
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residue that is formed on newly erupted teeth of both dentitions
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Nasmyth's membrane--fused tissue of REE and dental cuticle on enamel surface...picks up stains, but can be removed by polishing
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Generally, what is the relationship between erupting permanent teeth and primary teeth? What is the exception?
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permanent teeth erupt into oral cavity lingual to roots of primary tooth. exception is permanent maxillary incisors which are more facial
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odontogenic cyst that forms from the REE after the crown has formed and matured is called what?
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dentigerous cyst or follicular cyst
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dentigerous (follicular) cyst most common in what teeth?
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third molars
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What do you do when a dentigerous (follicular) cyst forms around the crown of a nonerupted impacted tooth?
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Remove it
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What do you do when a dentigerous (follicular) cyst forms around a developing tooth? "an eruption cyst"
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appears as fluctuant, blue, vesicle-like gingival lesion or partially erupted tooth and will disintegrate during eruption
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