UNIVERSITATEA DE STAT DE MEDICINĂ ŞI FARMACIE “NICOLAE TESTEMIŢANU”       DEVELOPMENT OF THE          DECIDIUOUS &        ...
TOOTH STRUCTURECROWN(anatomical& clinical)NECK  ROOT
Hard tissues of the tooth:• ENAMEL• DENTIN• CEMENTUMSoft tissue of the tooth:•DENTAL PULP(crown pulp & rootcanal)
Tooth development begins from the 6th week of the                  intrauterine development2 embryonic origins:I. Ectoderm...
2 main processes in the tooth            development• Crown formation• Root formation (is usually completed  approximately...
FUNCTIONAL STAGES OF TOOTH DEVELOPMENT• Initiation• Proliferation• Morpho-differentiation and  Histo-differentiation• Appo...
MORPHOLOGICAL STAGES    OF TOOTH DEVELOPMENT•   Bud stage•   Cap stage•   Bell stage (early & late)•   Early & late crown•...
Correlation of morphological stages of   tooth development and functional features     Morphological stage           Main ...
BUD stage       CAP stage             LATE CROWN stageBELL stage
Tooth development• The first recognizable sign of tooth  development in humans occurs during the  5-6th week of intrauteri...
PRIMITIVE EPITHELIAL BAND  1           2Is subdivided into: 1. VESTIBULAR LAMINA                2. DENTAL LAMINA
VESTIBULAR LAMINA• It is an ectodermal epithelial extension from the  lining of the oral cavity that proliferates into the...
DENTAL LAMINA• it is derived from the ectodermal epithelial  lining of the oral cavity. These epithelial  cells form a she...
12
THE MAXILLARY AND MANDIBULAR DENTAL LAMINAE
THE INITIATION. BUD STAGE•Epithelial cells are inductors in the tooth development•Epithelial cells produce growth factors ...
•The progressive proliferation of the dental lamina into theectomesenchyme results in the formation of a DENTAL BUDat the ...
DENTAL BUD is a future ENAMEL ORGAN
DENTAL BUD• The dental bud looks like a round mass of  proliferating epithelial cells and it is  surrounded by condensatio...
BUD stage
DENTAL BUD
DENTAL BUD                                      Dental bud - is                                     the future enamel     ...
Cap stage• The dental bud differentiates into a cap-shaped  enamel organ.• The epithelial dental organ looks like a head c...
PROLIFERATION. CAP stage      - enamel organ      - dental papilla      - dental sacare differentiated at this stage
ENAMEL ORGAN                             1                             2Enamel organ consists of:    31. Outer enamel epit...
ENAMEL KNOT• appears    as    a     densely     packed  accumulation of cells projecting from the  inner enamel epithelium...
ENAMEL KNOT
ENAMEL KNOT
ENAMEL CORD• A linear group of cells collectively termed  the enamel cord traverses the stellate  reticulum. It is a tempo...
ENAMEL CORD
Enamel niche   Successional lamina
Dental papilla & dental sac• The concentration of ectomesenchyme,  which is in part enveloped by the  invaginated inner en...
CAP stage            7 – dental papilla            8 – dental sac
HISTO-DIFFERENTIATION & MORPHO-    DIFFERNTIATION. BELL stage
ENAMEL ORGAN (bell                                 stage)                    Consists of 4 epithelia:                    1...
Stratum intermedium• The layer adjacent to the inner enamel  epithelium is the stratum intermedium,  and will become impor...
ENAMEL ORGAN           2.                    3.1.                     4.
• Preameloblasts initiate the differentiation  of odontoblasts which arise from cells in  the dental papilla. The odontobl...
INNER ENAMEL EPITHELIUMPREAMELOBLASTS                        ODONTOBLASTS            Initiate the differentiation         ...
PREDENTINFormation of the PREDENTIN – DENTIN initiate theformation of the ENAMEL
REGRESSING OF THE DENTAL LAMINAAn invasion of mesenchymal tissue corresponds with the disruptionof the dental lamina
REGRESSING OF THE DENTAL LAMINAEpithelial pearl formations are evident in the regressing dentallamina.
DENTAL PULP Successional lamina
DENTAL GERM OF THE PERMANENT TOOTH
LATE BELL stage                  Is characterized of:                  -Appearance of                  dentin             ...
APPOSITION. LATE CROWN stage• Deposition of the dentin & enamel occurs by apposition  with alternation of active & resting...
PREDENTIN   ENAMEL                DENTIN
APPOSITION, LATE CROWN stage                        POINT OF                       MATURATIONPOINT OF MATURATION is the pl...
STELLATE EPITHELIUM INVOLUTION
Outer enamel epithelium, intermedium epithelium & stellateepithelium become thinner and together form STRATIFIEDEPITHELIUM
REDUCED ENAMEL EPITHELIUM• Takes part in the crown modeling• Induces the dentinogenesis of the crown &  root• Assists in e...
REDUCED ENAMEL EPITHELIUM (A)Consists of: stratified epithelium & resting ameloblastsB – ameloblasts, C - capillary
ROOT FORMATION• Begins after complete formation of the  tooth crown & continues after the eruption.• Key elements, that ta...
CERVICAL LOOPThe layer of low columnarcells of the inner enamelepithelium is continuous withthe layer of cuboidal cells th...
EPITHELIAL ROOT SHEATH OF HERTWIG
EPITHELIAL ROOT SHEATH OF HERTWIG
ROOT FORMATION• After complete formation of the crown of the  tooth, the root begins to form. An extension of  the enamel ...
EPITHELIAL ROOT SHEATH OF HERTWIG &       EPITHELIAL DIAPHRAGM                      EPITHELIAL ROOT SHEATH                ...
EPITHELIAL DIAPHRAGM
EPITHELIAL DIAPHRAGM
EPITHELIAL DIAPHRAGM             DENTAL PULPEPITHELIALDIAPHRAGM                  APICAL FORAMEN
• Hertwigs root sheath determines the  number, size and shape of roots and  is presumably the inductor of dentin  formatio...
THE EPITHELIAL ROOT SHEATH OF           HERTWIG• The epithelial root sheath is made up of inner  and outer enamel epitheli...
Tooth eruption is defined as“ The  movement of a tooth from its site of development within the alveolar process to its fun...
Stage of tooth eruption• Pre-eruptive• Eruptive (intraosseous  & extraosseous)• Post-eruptive
Factors consideration in tooth             eruption• development of  periodontium, root, pulp,  alveolar bone• events duri...
Gubernacular canalGubernacular cord  Eruptive Pathway
FORCES of Tooth Eruption • Root Formation • Pressure ( Pulp and  Hydrostatic ) • Periodontal Ligament • Bone Remodeling
ERUPTION – intraosseous stage
ERUPTION – extraosseous stage
Dezvoltarea dintilor.engl
Dezvoltarea dintilor.engl
Dezvoltarea dintilor.engl
Dezvoltarea dintilor.engl
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Dezvoltarea dintilor.engl

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Dezvoltarea dintilor.engl

  1. 1. UNIVERSITATEA DE STAT DE MEDICINĂ ŞI FARMACIE “NICOLAE TESTEMIŢANU” DEVELOPMENT OF THE DECIDIUOUS & PERMANENT TEETH CATEDRA HISTOLOGIE, CITOLOGIE ŞI EMBRIOLOGIE
  2. 2. TOOTH STRUCTURECROWN(anatomical& clinical)NECK ROOT
  3. 3. Hard tissues of the tooth:• ENAMEL• DENTIN• CEMENTUMSoft tissue of the tooth:•DENTAL PULP(crown pulp & rootcanal)
  4. 4. Tooth development begins from the 6th week of the intrauterine development2 embryonic origins:I. Ectoderm - oral epithelium - enamelII. Ectomesenchyme (neural crests)– dentin, cement, dental pulp, periodontal ligament
  5. 5. 2 main processes in the tooth development• Crown formation• Root formation (is usually completed approximately 2 -3 years after the tooth erupts)
  6. 6. FUNCTIONAL STAGES OF TOOTH DEVELOPMENT• Initiation• Proliferation• Morpho-differentiation and Histo-differentiation• Apposition• Root development
  7. 7. MORPHOLOGICAL STAGES OF TOOTH DEVELOPMENT• Bud stage• Cap stage• Bell stage (early & late)• Early & late crown• Early root formation
  8. 8. Correlation of morphological stages of tooth development and functional features Morphological stage Main functional activityDental lamina Initiation of tooth germBud stage Proliferation (cell division)Cap stage Proliferation Beginning of histo-differentiationBell stage Prominent histo-differentiation Morpho-differentiationEarly crown stage Apposition (formation of dentin & enamel)Late crown stage Continued apposition of dentin & enamel including enamel maturationEarly root stage Formation of radicular dentin & cementum
  9. 9. BUD stage CAP stage LATE CROWN stageBELL stage
  10. 10. Tooth development• The first recognizable sign of tooth development in humans occurs during the 5-6th week of intrauterine life.• At this time is characteristic the appearance of vestibular & dental laminae as a result of proliferation of oral epithelium.
  11. 11. PRIMITIVE EPITHELIAL BAND 1 2Is subdivided into: 1. VESTIBULAR LAMINA 2. DENTAL LAMINA
  12. 12. VESTIBULAR LAMINA• It is an ectodermal epithelial extension from the lining of the oral cavity that proliferates into the underlying ectomesenchyme of the maxilla and the mandible lateral to the dental lamina. The central cells of this lamina disintegrate to form the sulcus which is the space between the maxilla and the mandible on one side and the lips and the cheeks on the other side.
  13. 13. DENTAL LAMINA• it is derived from the ectodermal epithelial lining of the oral cavity. These epithelial cells form a sheet-like structure that extends into specific areas of the ectomesenchymal tissues within the alveolar processes of the maxilla and mandible. These areas are parts of the developing dental arch regions where teeth form and eventually erupt.
  14. 14. 12
  15. 15. THE MAXILLARY AND MANDIBULAR DENTAL LAMINAE
  16. 16. THE INITIATION. BUD STAGE•Epithelial cells are inductors in the tooth development•Epithelial cells produce growth factors (TGFß1, BMP2, IGF),that transmit the role of inductor through the basementmembrane to ectomesenchyme
  17. 17. •The progressive proliferation of the dental lamina into theectomesenchyme results in the formation of a DENTAL BUDat the distal end of the dental lamina.
  18. 18. DENTAL BUD is a future ENAMEL ORGAN
  19. 19. DENTAL BUD• The dental bud looks like a round mass of proliferating epithelial cells and it is surrounded by condensation of ectomesenchymal tissues which form the dental papilla and dental sac.
  20. 20. BUD stage
  21. 21. DENTAL BUD
  22. 22. DENTAL BUD Dental bud - is the future enamel organ Ectomesenchyme of this region – is the future dental papillaEctomesenchyme of this region – is the future dental sac
  23. 23. Cap stage• The dental bud differentiates into a cap-shaped enamel organ.• The epithelial dental organ looks like a head cap with a round convex side and a straight or slightly concave one.• During the cap stage are formed the dental papilla & dental sac.
  24. 24. PROLIFERATION. CAP stage - enamel organ - dental papilla - dental sacare differentiated at this stage
  25. 25. ENAMEL ORGAN 1 2Enamel organ consists of: 31. Outer enamel epithelium2. Stellate reticulum3. Inner enamel epithelium
  26. 26. ENAMEL KNOT• appears as a densely packed accumulation of cells projecting from the inner enamel epithelium into the dental papilla.
  27. 27. ENAMEL KNOT
  28. 28. ENAMEL KNOT
  29. 29. ENAMEL CORD• A linear group of cells collectively termed the enamel cord traverses the stellate reticulum. It is a temporary structure with no known function.
  30. 30. ENAMEL CORD
  31. 31. Enamel niche Successional lamina
  32. 32. Dental papilla & dental sac• The concentration of ectomesenchyme, which is in part enveloped by the invaginated inner enamel epithelium, is named the dental papilla.• The dental sac is a concentration of ectomesenchyme that encircles the enamel organ and the dental papilla.
  33. 33. CAP stage 7 – dental papilla 8 – dental sac
  34. 34. HISTO-DIFFERENTIATION & MORPHO- DIFFERNTIATION. BELL stage
  35. 35. ENAMEL ORGAN (bell stage) Consists of 4 epithelia: 1. Outer enamel epithelium 2. Stellate epithelium 3. Stratum intermedium 4. Inner enamel epithelium1. 2. 3. 4.
  36. 36. Stratum intermedium• The layer adjacent to the inner enamel epithelium is the stratum intermedium, and will become important in transporting nutrients to the future ameloblasts.
  37. 37. ENAMEL ORGAN 2. 3.1. 4.
  38. 38. • Preameloblasts initiate the differentiation of odontoblasts which arise from cells in the dental papilla. The odontoblasts are called preodontoblasts before they begin the production of dentin.
  39. 39. INNER ENAMEL EPITHELIUMPREAMELOBLASTS ODONTOBLASTS Initiate the differentiation of
  40. 40. PREDENTINFormation of the PREDENTIN – DENTIN initiate theformation of the ENAMEL
  41. 41. REGRESSING OF THE DENTAL LAMINAAn invasion of mesenchymal tissue corresponds with the disruptionof the dental lamina
  42. 42. REGRESSING OF THE DENTAL LAMINAEpithelial pearl formations are evident in the regressing dentallamina.
  43. 43. DENTAL PULP Successional lamina
  44. 44. DENTAL GERM OF THE PERMANENT TOOTH
  45. 45. LATE BELL stage Is characterized of: -Appearance of dentin -Appearance of enamel -Transformation of the dental papilla into DENTAL PULP -Morphological changes appear in the dental sac
  46. 46. APPOSITION. LATE CROWN stage• Deposition of the dentin & enamel occurs by apposition with alternation of active & resting states
  47. 47. PREDENTIN ENAMEL DENTIN
  48. 48. APPOSITION, LATE CROWN stage POINT OF MATURATIONPOINT OF MATURATION is the place at which for the firsttime appear dentin & enamel.
  49. 49. STELLATE EPITHELIUM INVOLUTION
  50. 50. Outer enamel epithelium, intermedium epithelium & stellateepithelium become thinner and together form STRATIFIEDEPITHELIUM
  51. 51. REDUCED ENAMEL EPITHELIUM• Takes part in the crown modeling• Induces the dentinogenesis of the crown & root• Assists in enamel formation & in the formation of dentin-gum connection• Isolates the enamel from the connective tissue of the dental sac• Takes part in the tooth eruption
  52. 52. REDUCED ENAMEL EPITHELIUM (A)Consists of: stratified epithelium & resting ameloblastsB – ameloblasts, C - capillary
  53. 53. ROOT FORMATION• Begins after complete formation of the tooth crown & continues after the eruption.• Key elements, that take part in the root formation, are:1. Cervical loop – that is transformed into EPITHELIAL ROOT SHEATH OF HERTWIG , that differentiates into EPITHELIAL DIAPHRAGM2. Dental sac
  54. 54. CERVICAL LOOPThe layer of low columnarcells of the inner enamelepithelium is continuous withthe layer of cuboidal cells thatform the outer enamelepithelium at the structuretermed the cervical loop.
  55. 55. EPITHELIAL ROOT SHEATH OF HERTWIG
  56. 56. EPITHELIAL ROOT SHEATH OF HERTWIG
  57. 57. ROOT FORMATION• After complete formation of the crown of the tooth, the root begins to form. An extension of the enamel organ, called the epithelial root sheath of Hertwig, continues to grow apically. The epithelial root sheath induces the differentiation of odontoblasts which form root dentin. The apical most portion of the root sheath turns inward toward the radicular pulp cavity (that portion of the pulp cavity inside the root) and is called the epithelial diaphragm.
  58. 58. EPITHELIAL ROOT SHEATH OF HERTWIG & EPITHELIAL DIAPHRAGM EPITHELIAL ROOT SHEATH OF HERTWIG EPITHELIAL DIAPHRAGM
  59. 59. EPITHELIAL DIAPHRAGM
  60. 60. EPITHELIAL DIAPHRAGM
  61. 61. EPITHELIAL DIAPHRAGM DENTAL PULPEPITHELIALDIAPHRAGM APICAL FORAMEN
  62. 62. • Hertwigs root sheath determines the number, size and shape of roots and is presumably the inductor of dentin formation in the developing root.
  63. 63. THE EPITHELIAL ROOT SHEATH OF HERTWIG• The epithelial root sheath is made up of inner and outer enamel epithelial layers without the other two interposing layers. Following the induction of odontoblast and dentin formation, the epithelial root sheath disintegrates forming epithelial rests, small groups of epithelial cells that can remain around the root.
  64. 64. Tooth eruption is defined as“ The movement of a tooth from its site of development within the alveolar process to its functional position in oral cavity,”
  65. 65. Stage of tooth eruption• Pre-eruptive• Eruptive (intraosseous & extraosseous)• Post-eruptive
  66. 66. Factors consideration in tooth eruption• development of periodontium, root, pulp, alveolar bone• events during eruption – eruptive pathway: gubernacular canal
  67. 67. Gubernacular canalGubernacular cord Eruptive Pathway
  68. 68. FORCES of Tooth Eruption • Root Formation • Pressure ( Pulp and Hydrostatic ) • Periodontal Ligament • Bone Remodeling
  69. 69. ERUPTION – intraosseous stage
  70. 70. ERUPTION – extraosseous stage

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