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Pre natal and post-natal development of maxilla part 2/certified fixed orthodontic courses by Indian dental academy


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Pre natal and post-natal development of maxilla part 2/certified fixed orthodontic courses by Indian dental academy

  1. 1. Pre-natal and Post- natal Development of Maxilla Continued….. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. PALATOGENESIS www.indiandentalacademy. com
  3. 3. End of 5 TH week IUL 12 TH week IULEnd of 6th Week IUL Beginning of 9th week CRITICAL PERIOD www.indiandentalacademy. com
  4. 4. The entire palate develops from two primorida – •The primary palate, and •The secondary palate www.indiandentalacademy. com
  5. 5. Week 6: A cut between the maxillary and the mandibular prominences and tipping the top of the head back allows visualization of the developing palate. •The secondary palatal shelves are considered to be part of the maxillary prominences. www.indiandentalacademy. com
  6. 6. Week 6: The medial nasal prominences merge in the midline to smooth the median furrow. This fusion produces a wedge- shaped mass of mesenchymal tissue known as the intermaxillary segment. www.indiandentalacademy. com
  7. 7. Week 6: After the oronasal membrane ruptures, The intermaxillary segment will form the anterior part of the palate, the primary palate (circled). This section is cut like the last one (b/w maxillary & mandibular prominences) 1. 2. 3. 4. 5. 6. www.indiandentalacademy. com
  8. 8. • A higher magnification view of the circled area illustrates the oronasal membrane that is beginning to break down. www.indiandentalacademy. com
  9. 9. Week 7: A parasagittal cut illustrates that the oronasal membrane breaks down to allow continuity between the nasal pit and the common oral and nasal cavities. www.indiandentalacademy. com
  10. 10. Secondary Palatal Shelves Week 8: A frontal cut illustrates that the tongue is initially interposed between the secondary palatal shelves. www.indiandentalacademy. com
  11. 11. The two lateral maxillary palatal shelves and the primary palate of the frontonasal prominence—are initially widely separated due to the vertical orientation of the lateral shelves on either side of the tongue. www.indiandentalacademy. com
  12. 12. Elevation of head and lower jaw www.indiandentalacademy. com
  13. 13. Mechanism of palatal shelf elevation *Intrinsic Force within the shelf (accumulation and hydration of hyaluronic acid) *Accumulation of Glycosaminoglycans *EGF(epidermal growth factor) andTGF (transforming growth factor h3) stimulate production of Hyluronan *Increase in vascularity *Contraction of elastic fibres or muscle fibres. *Unequal division in the palatal and the oral epithelium *Neurotransmitters like Serotonin *Increase in MMP-3 *Upregulation of Vimentin expression *Master controlling gene is FSP-1 (gene encoding a fibroblast-specific protein) , ssh www.indiandentalacademy. com
  14. 14. • Pressure differences between the nasal and oral regions due to tongue muscle contractions may account for the palatal shelf elevation. This occurs at about 8th and 9th week p.c.. It is possible that the nerve supply to tongue is sufficiently developed to provide neuromuscular guidance to the intricate activity of palatal elevation followed by closure. www.indiandentalacademy. com
  15. 15. • Shelf elevation and fusion begin a few days earlier in male than in female embryos, possibly accounting for sex differences in the incidence of cleft palate. www.indiandentalacademy. com
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  18. 18. During palate closure, the mandible becomes more prognathic and the vertical dimension of the stomodeal chamber increases, but maxillary width remains stable, allowing shelf contact to occur. Also, forward growth of Meckel’s cartilage relocates the tongue more anteriorly, concomitant with upper-facial elevation. www.indiandentalacademy. com
  19. 19. The transition from vertical to horizontal is completed within hours www.indiandentalacademy. com
  20. 20. Week 9: The palatal shelves become positioned above the tongue to allow for fusion in the midline. www.indiandentalacademy. com
  21. 21. Week 9: Fusion begins The secondary palatal shelves change their contours towards a midpoint from which they fuse anteriorly and posteriorly. At this point, the nasal septum grows downwardly from the fused medial nasal processes. www.indiandentalacademy. com
  22. 22. Medial Edge Epithelium. (M.E.E.) During the initial stage of the fusion process, MEE cells form a midline epithelial seam (MES) separating mesenchymes of the two apposing shelves. www.indiandentalacademy. com
  23. 23. For the complete fusion of the palate, the MEE acts as a barrier: Epithelium cells of MEE transforms into connective tissue cells. Epithelium undergoes necrosis. (not supported as microscopic structure Doesn’t show any necrotic cells) Epithelial cells migrate towards oral and nasal cells. www.indiandentalacademy. com
  24. 24. • Release of MMP (Matrix metalloproteinase) causes disintegration of the cells and allows the connective tissue to mix up. • Balance between the MMP and TIMMP (Tissue inhibiting MMP) www.indiandentalacademy. com
  25. 25. The loss of epithelial continuity in the area of the shelf contact was originally described as a classic example of apoptosis (programmed cell death). Two other mechanisms may also play a role in palatal shelf fusion. Migration of the basal cells into the mesenchyme and differentiation of these cells into mesenchymal cells. Cells near the periphery appear to migrate to the nearest epithelial surface, and then differentiate into either oral or nasal epitheliumwww.indiandentalacademy. com
  26. 26. • Since the differentiation patterns of MEE cells in the cultured single palatal shelf is similar to that observed during palatal fusion (Mori et al. , 1994; Martínez-Álvarez et al. , 2000), it is clear that terminal differentiation of MEE cells is not necessarily dependent on palatal shelf contact and midline seam formation in vitro Int. J. Dev. Biol. 48: 307-317 (2004) TOSHIYA TAKIGAWA and KOHEI SHIOTA www.indiandentalacademy. com
  27. 27. Week 10 Fusion of the palatal shelves with each other and with the nasal septum separates the nasal cavities from the oval cavity. www.indiandentalacademy. com
  28. 28. • Fusion of the three palatal components initially produces a flat unarched roof to the mouth. www.indiandentalacademy. com
  29. 29. Ossification • Ossification of the palate proceeds during the 8th week post conception from the spread of bone into the mesenchyme of the fused lateral palatal shelves and from trabeculae appearing in the primary palate as ―premaxillary centers,‖ all derived from the single primary ossification centers of the maxillae. www.indiandentalacademy. com
  30. 30. • Posteriorly, the hard palate is ossified by trabeculae spreading from the single primary ossification centers of each of the palatine bones. Most posterior part - no ossification - soft palate www.indiandentalacademy. com
  31. 31. Week 10 The four maxillary incisors develop within the primary palate. Fusion completes at week 12. www.indiandentalacademy. com
  32. 32. Note: tongue has been removed. www.indiandentalacademy. com
  33. 33. MID PALATAL SUTURE • Appears at 10 ½ wk IU • Growth ceases b/w 1 - 2 yrs • But no synostosis till adulthood • RME can be done • Obliteration starts in adolesence but complete fusion occurs by 30 yrs. www.indiandentalacademy. com
  34. 34. Palatal Vault • Eruption of teeth – Deepening of palatal vault www.indiandentalacademy. com
  35. 35. Musculature of palate • Tensor veli palatini 40 days 1st arch • Palatopharangeous 45 days • Levator veli palatini 8th week 2nd arch • Palatoglossus 9th week • Uvular muscle 11thweek 2nd arch www.indiandentalacademy. com
  36. 36. MAXILLARY SINUS • First to develop at 10th week IU. • Develop from middle meatus by primary pneumatization in ecto- ethmoidal cartilage • Secondary pneumatization in ossifying maxilla starts at 5th month IU. www.indiandentalacademy. com
  37. 37. www.indiandentalacademy. com
  38. 38. Post natal growth of maxilla www.indiandentalacademy. com
  39. 39. • General features • Three dimensional growth of maxilla Height (Vertical) Width (Transverse) Length (Ant-Post) • Theories of growth Sutural Cartilaginous Functional matrix theory • Key factors in Nasomaxillary remodelling www.indiandentalacademy. com
  40. 40. Displacement • Primary displacement • Secondary displacement www.indiandentalacademy. com
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  42. 42. www.indiandentalacademy. com
  43. 43. Reversal line • Directions of growth sequentially undergo reversals • A reversal line showing the crossover between resorptive and depository growth fields seen in microscope • Factors affecting reversal shape of bone muscle attachments rotations growth fields www.indiandentalacademy. com
  44. 44. Post natal growth of maxilla apposition resorption MOSS Transformation Translation SUTURES Displacement Surface remodeling CRANIAL BASE MAXILLA www.indiandentalacademy. com
  45. 45. Mechanism of growth • Sutural • Nasal septum • Surface apposition and resorption on periosteal and endosteal surfaces • Alveolar process • Spheno occipital synchondrosis www.indiandentalacademy. com
  46. 46. • Surface apposition • Sutural growth • Nasal septum growth • Spheno occipital synchondrosis www.indiandentalacademy. com
  47. 47. • In contrast to cranial base maxilla is dominated by intra membranous ossification • Endochondral bone growth seen at the ethmoid bone and nasal septum www.indiandentalacademy. com
  48. 48. Surface apposition www.indiandentalacademy. com
  49. 49. Growth according to various theories • Sutural Theory (Weinman &Sicher) • Cartilagenous Theory ( Scott) • Functional Matrix Theory (Moss) www.indiandentalacademy. com
  50. 50. Sutural Theory Bone growth in various maxillary sutures Causes pushing apart of bone Resultant thrust on whole maxilla in forward and downward direction www.indiandentalacademy. com
  51. 51. www.indiandentalacademy. com
  52. 52. Shortcomings of sutural theory • Not pressure related - Tension adapted tissue. • No innate growth potential. • Crouzon’s syndrome www.indiandentalacademy. com
  53. 53. Cartilagenous Theory www.indiandentalacademy. com
  54. 54. www.indiandentalacademy. com
  55. 55. www.indiandentalacademy. com
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  57. 57. www.indiandentalacademy. com
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  64. 64. www.indiandentalacademy. com
  65. 65. Primary Pneumatization • Ethmoid air cells from the middle and superior meatus and sphenoethmoid recess invade the ectethmoid nasal capsule (primary pneumatization), from the 4th month post conception. www.indiandentalacademy. com
  66. 66. Secondary Pneumatization • Secondary pneumatization occurs between birth and 2 years as groups of 3 to 15 air cells grow irregularly to form the ethmoid labyrinth www.indiandentalacademy. com
  67. 67. www.indiandentalacademy. com
  68. 68. www.indiandentalacademy. com
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  70. 70. Vimentin • Vimentin is a member of the intermediate filament family of proteins. Intermediate filaments are an important structural feature of eukaryotic cells. They, along with microtubules and actin microfilaments, make up the cytoskeleton www.indiandentalacademy. com
  71. 71. • Human fibroblast stromelysin (also called transin or matrix metalloproteinase-3) is a proteoglycanase closely related to collagenase (MMP1) with a wide range of substrate specificities. It is a secreted metalloprotease produced predominantly by connective tissue cells. Together with other metalloproteases, it can synergistically degrade the major components of the extracellular matrix (Sellers and Murphy, 1981). Stromelysin is capable of degrading proteoglycan, fibronectin, laminin, and type IV collagen, but not interstitial type I collagen. matrix metalloproteinase-3 www.indiandentalacademy. com
  72. 72. www.indiandentalacademy. com Thank you For more details please visit