McMillian Flashcards
what are the stages of tooth development?
Initiation
Bud
Cap
Bell
What week does odontogenesis occur?
6th Prental week
What are the two tissue types of initiation of odontogenesis
- Oral epithelium (Dental Lamina) 2. Ectomesenchyme
Steps of Initiation of Odontogenesis 2 steps
- Formation of all hard tissues and soft tissue surrounding the tooth
- Induction is the main process involved
Hard tissue of teeth
Enamel
Dentin
Cementum
Soft tissue of teeth
PDL
pulp
What is the primary epithelial Band formation ?
week 6-7
- Thickened epithelium (ectoderm) in location of future jaw
- Rapid Cell Division
Primary Epithelial Band Formation gives rise to …
Dental Lamina and Vestibular Lamina
Bud Stage occurs at which week?
8th week prenatally
What happens in Bud Stage?
Dental Lamina grows into a bud and penetrates/influences the growing ectomesenchyme
What does the stellate reticulum make?
Glycosaminoglycans (attracts water)
The Bud becomes the
Enamel organ shaped like a cap (Cap stage)
In the Cap Stage Mesenchyme becomes
Dental Papilla
In the cap stage Inner Enamel epithelial cells become
Ameloblasts
What makes the Ameloblasts ?
Inner enamel epithelial cells
What are Ameloblasts?
Cells during tooth development that deposit tooth enamel
What are Stellate Reticulum ?
Star shaped cells connected to each other Makes Glycosaminoglycans
In the cap stage the dental follicle surrounding ?
Dental Papilla and Enamel Organ
Developmental Abnormalities occurring in the Cap Stage
- Dens in dente (Dens Invaginalis)
- Fusion
- Gemination
Dens in dente ( dens invaginalis)
- Tooth within a tooth
- Enamel organ expands more than it should and it invaginates into the dental papilla
(Cap Stage)
Fusion
- Fewer number of teeth
- Extra wide crown with one pulp cavity
- Union of two teeth by dentin and enamel
(Cap Stage)
Gemmination
- Correct Number of Teeth
- Wide Bifid Crown
- One tooth germ attempting to divide into two
What makes the tooth germ ?
- Enamel Organ
- Dental Papilla
- Dental Follicle
Histodifferentiation
Bell Stage
- In the enamel organ
- Stellate reticulum →inner & outer enamel epithelia
Ameloblasts start forming ……..
What stage?
Bell Stage
enamel at cusp tips and move outward
Odontoblasts start forming….
(What stage?)
Bell Stage
- start formin dentin and move inward
What forms the crown ?
(What stage)
Bell Stage
- inner enamel epithelium
When does the dental lamina disintegrates?
Bell Stage
Histodifferentiated enamel organ
(What stage)
Early Bell Stage
Cervical loop region is supported up the basal lamina
Bell stage abnormalities
- Macrodontia
- Microdontia (peg lateral)
- Amelogenesis Imperfect (enamel deffect -yellow)
- Dentinogenesis Imperfecta (deffective dentin- opaque)
Tooth germ→Dental Follicle→ (3)
Dental Follicle→Cementoblasts→Cementum
Dental Follicle→Fibroblasts →Periodontal Ligament
Dental Follicle→Osteoblasts →Alveolar Bone
Tooth Germ→Dental Papilla → (2)
Dental Papilla →Odontoblasts→Dentin
Dental Papilla →Undifferentiated Mesenchymal →Pulp
cells Fibroblasts
Tooth germ→Enamel organ →Cervical loop
Ceverical Loop→Hertwig’s root sheath→Root Form
Tooth Germ→Enamel Organ→?
to get to Primary Juctional Epithelium
stellate reticulum→ inner+ outer enamel epithelium→ reduced enamel epithelium→ Primary Juctional Epithelium
What do the inner enamel epithelial cells become?
Tooth Germ→Enamel Organ→Inner Enamel Epithelium→Ameloblasts→Enamel
What are the two types of Dentin?
Primary Dentin
Secondary Dentin
Primary Dentin
While tooth is forming and erupting
Secondary Dentin
After the tooth has erupted and root almost done
Tertiary Dentin
Response to trauma
(Attrition, Caries, Dental Restorations)
Types of Primary Dentin
- Mantle Dentin
- Interglobular ( or Globular Dentin)
- Circumpulpal Dentin
Mantle Dentin
Next to DEJ
Large collagen fibers
Primary Dentin
Interglobular (or Globular) Dentin
know this
Globules are Calcified
Intergloubular spaces are hypomineraized
Primary Dentin
Circumpulpal Dentin
- Bulk of the Dentin
- Thinner in the root
- has small collagen fibers
Primary Dentin
Peritubular Dentin
- Hypermineralized
- Found in dentin except near pulp and interglobular dentin
Intertubular Dentin
- Primary product of odontoblasts
- Lies between tubules
Dead Tracts
- Death of odontoblasts due to old age and trauma
- Tubules are open
Sclerotic Dentinal Tubules
- Permeabile to pulp eliminated (pulp protection)
- increase with age
(Dentinal fluid in tubule crystalizes )
Another name for sclerotic Dentinal tubules
Transparent dentin
Lines of Von Ebner
- Dentin growth lines
- Every 5 days 20 microns are formed
Neonatal Line
- Only primary teeth
- Dentin before birth is superfical (perfect)
- Neonatal Line
- Dentin after birth is deep ( more imprefections)
Granular Layer of Tomes in Root Dentin
Interface of collagen and noncollagenous matrix proteins between cementum and dentin
Dentinogenesis
formation of dentin via
- Odontoblasts
- Predentin
- Enamel
Predentin
Unmineralized Dentin
Odontoblasts remain functional for________
Ameloblasts remain functional for_________
Odontoblasts- functional for life
Ameloblasts stop
What does the mineralization of predentin do to the odontoblast ?
Lengthens them
(no other diifrentiation can occur)
Dentin is formed in two phases
- Predentin-organic matrix deposited
- inorganic mineral substance is added
Mineralization of Predentin
- Crystals of Calcium Hydroxyapetite appear in the matrix vesicles
- Crystals grow and rupture the membrane and clump with other crystals