Post natal growth and development /certified fixed orthodontic courses by Indian dental academy


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Post natal growth and development /certified fixed orthodontic courses by Indian dental academy

  1. 1.
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. Contents      Introduction Terminologies Concepts of growth Osteogenesis Regional development Cranium Nasomaxillary complex Mandible
  4. 4. Contents    Clinical implications Conclusion References
  5. 5. What is post natal growth??  Post natal growth is the first 20 years of growth after birth.  It comprises of 3periods;
  6. 6. How does it differ from prenatal growth??  Prenatal growth is characterized by a rapid increase in cell numbers and fast growth rates  Postnatal growth is characterized by declining growth rates and increasing maturation of tissues.
  7. 7. Terminologies  Primary cartilage  Secondary cartilage  Growth centre – location at which independent growth occurs  Growth site – mere location at which growth occurs
  8. 8. Terminologies Deposition – addition of new bone to the bony surface by osteoblastic activity  Resorption – removal of bone due to osteoclastic activity ++ + 
  9. 9. Terminologies  Cortical drift –  Displacement – Primary displacement Secondary displacement
  10. 10.  Remodeling – reshaping of the outline of the bone by selective resorption of bone in some areas and deposition in other areas  Relocation – relative movement in space of a bony structure, due to bone deposition on one side and resorption on the other side
  11. 11.  concepts Cephalocaudal growth Scammon’s growth curve Enlow’s counterpart principle
  12. 12. Cephalocaudal gradient of growth
  13. 13. Differential growth[scammon’s growth curve]
  14. 14. Enlow’s counterpart principle  Growth of any given facial or cranial part relates specially to other structural and geometric counterparts in the face or cranium  Regional relationships exist ---craniofacial region  Balanced counterparts growth = Regional and corresponding enlarge to same extent  Imbalance in regional relationship is due to differences in  Amount of growth  Direction  Time
  15. 15. Different parts and their counterparts Part Counterpart Palate Anterior cranial fossa Middle cranial fossa Ramus of the mandible Maxillary arch Mandibular arch Maxillary tubeosity Lingual tuberosity Bony maxilla Corpus of the mandible
  16. 16. Osteogenesis  Mechanism of bone formation Endochondral Intramembranous
  17. 17. Five steps to Endochondral bone formation  Hypertrophy of chondrocytes and matrix calcifies  Invasion of blood vessels and the connective tissue  Osteoblasts differentiate and produce osteoid tissue  Osteoid tissue calcifies  Membrane covers bone and is essential
  18. 18. Five steps to Intramembranous bone formation  Osteoblasts produce osteoid tissue  Cells and blood vessles are encased  Osteoid tissue is produced by membrane cells  Osteoid calcifies  Essential membrane covers the bone
  19. 19. Regional development   Functions Growth Mechanisms and sites Timing Compensatory mechanisms Theoretical and Clinical issues
  20. 20. Cranium  Cranial vault  Basicranium
  21. 21. Cranial vault Functions: protection of brain- primary function Growth 1)Mechanisms and sites  Cranium grows ---as brain grows  Accelerated during infancy, 90% of it is complete by 5th year
  22. 22.  As brain expands, bones of calvaria are displaced correspondingly outwards  Primary displacement causes tension in the sutural membranes – immediate response– sutural edges  At same time new bone is also formed on the flat surfaces– both, ecto- &endocranial
  23. 23.
  24. 24.  Arc of curvature of the whole bone decreases and the bone becomes flatter and remodeling not extensive.
  25. 25.
  26. 26. To summarise,  Increase in cranial width Primarily through “fill-in” ossification of proliferating connective tissue in the coronal.lamboidal.interparital.paritosphenoidal and paritotemporal sutures.
  27. 27.  Increase in cranial length Growth of the cranial base– active response at the coronal suture  Increase in cranial height Activity of parietal sutures along with occipital, temporal and sphenoidal contiguous ossious structures
  28. 28. According to Davenport  Length of brain case at different ages is as follows: Age Growth in % Birth 63 6 months 76 1 year 82 2 year 87 3 years 89 5 years 91 10 years 95 15 years 98
  29. 29. Timing  Growth under the influence of the expansion of the enclosed brain  Brain growth largely completed by early childhood  Cranial vault --- one of the first regions to attain full size
  30. 30. Basicranium Functions  Adapted to upright the body posture  Development of large cerebral hemispheres  Articulates the skull with vertebral column, mandible and maxillary region
  31. 31.  Buffer zone between brain, face and pharyngeal region  Template for facial growth
  32. 32.  The neural side of cranial floor different from calvaria  The endocranial surface of basicranium is resorptive in most areas  Further, fossa accomplished by enlargement direct is remodeling involving on the outside with resorption inside.
  33. 33.  Various cranial fossae Anterior Middle Posterio
  34. 34.  Middle and posterior fossae divided by the petrous elevation  Olfactory fossae separated by crista galli  The right and left middle cranial fossae--- longitudinal midline sphenoidal elevation  Right and left anterior and posterior cranial fossae---- longitudinal midline bony ridge
  35. 35. Mechanism and Sites  Elongation at synchondroses  Cortical drift and remodeling  Sutural growth This combination provides  Differential growth enlargement between the cranial floor and calvaria  Expansion of confined contours in the various endo cranial fossae  Maintenance of passages and housing for vessels and nerves
  36. 36.  Midventral segment of cranial floor grows much slowly than the floor of the laterally located fossae.  Expansion of hemispheres--- sutural growth and cortical drift
  37. 37.
  38. 38.  Midline part ---- synchondroses  Retention left from primary cartilges of chondrocranium
  39. 39.   Synchondroses Spheno-ethmoidal Cartilaginous band between the sphenoid and ethmoid bones. Ossifies by 5-25 years  Intersphenoidal Cartilaginous band between 2 parts of sphenoid; ossifies by birth
  40. 40.  Intra-occipital Ossifies by 3-5 years  Spheno-occipital Principal growth cartilage during childhood period Provides a pressure adapted bone growth mechanism
  41. 41.
  42. 42. Bone remodeling seen in cranial base    1- resorption on the anterior wall of middle cranial fossa 2- deposition on the orbital face of sphenoid 3-anterior displacement of ant. cranial fossa
  43. 43.    4-Elevation of petrous temporal bone Lowering of the foramen magnum Perimeter of the foramen enlarges
  44. 44.
  45. 45. Nasomaxillary complex Functions  Important role in mastication (attachments of teeth and muscles)  Provides significant portion of airway  Houses olfactory nerve endings  Encloses eyes  Adds resonance to the voice through the sinuses contained within the region
  46. 46. Nasomaxillary complex Mechanisms and Sites  Growth observed at Sutures Nasal septum Periosteal and endosteal surface Alveolar process  According to Mills “maxilla increases in size by subperiosteal activity postnatally
  47. 47. Maxilla The growth mechanism is produced by  Displacement  Growth at sutures  Surface remodelling
  48. 48.  Primary displacement Active, downward and forward Maxillary tuberosity lengthening posteriorly  Secondary displacementPassive, downward and forward direction Cranial base– middle cranial fossa grows anteriorly
  49. 49. Which is the biomechanical force underlying the maxillary displacement??  Primary displacement- anterior and inferior as it grows and lengthens posteriorly  Nature of this displacement--- reviewed historically
  50. 50. Controversies regarding maxillary displacement  Maxillary tuberosity
  51. 51.  Bone growth within the various maxillary sutures produces pushing-apart of the bones, with resultant thrust of whole maxilla being displaced anteriorly and inferiorly as well.
  52. 52. Nasal septum theory – Scott  Pressure accomodating expansion of nasal septal cartilage– source of physical force  Drawbacks Source of displacement is multifactorial Experimental studies– surgical deletion affected the growth process; not that they control growth process
  53. 53.
  54. 54.  Functional matrix concept Facial bones grow in a sub-ordinate growth control relationship with all surrounding, pace-making soft tissues Note  Concept five Operation of growth fields – carried out by osteogenic membrane and other
  55. 55. Growth at sutures  Fronto-nasal  Fronto- maxillary  Zygomatic-temporal  Zygomatico-maxillary  Pterygo-palatine   All are oblique; more or less parallel to each other Downward and forward growth
  56. 56.
  57. 57.  Surface remodelling Increase in size Change in shape Change in functional relationship
  58. 58.  Resorption occurs on the lateral surface of orbital rim leading to lateral movement of the eye ball  Floor of orbit-deposition in superior, lateral and anterior direction
  59. 59.
  60. 60.  Bone deposition along posterior margin of maxillary tuberosity  Bone resorption occurs on lateral wall of nose
  61. 61.  Also on the floor of the nasal cavity Increase in height of maxilla
  62. 62.  Face enlarges by width  As teeth upright alveolar height increases  Except mesial wall others resorb – increase in size of maxillary sinus
  63. 63.
  64. 64.  Zygomatic bone moves in posterior direction.  Anterior nasal spine prominence increases due to bone deposition
  65. 65. Maxillary height  Sutural growth toward the frontal and zygomatic bones  Appositional growth towards the alveolar process
  66. 66. Maxillary width  Growth in median sutures  Vertical drift of posterior teeth with lateral expansion---- alveolar divergence  Mutual transverse rotations of maxillae--separation of the halves more posteriorly than anteriorlyMaxillary length  Apposition on the maxillary tuberosity  Sutural growth towards the palatine bone
  67. 67. Mandible   Mandible undergoes the largest amount of growth post-natally and also exhibits the largest variability The functional parts includeRamus Corpus Angle of mandible Lingual tuberosity The alveolar process The chin
  68. 68. Functions  Mastication  Maintenance of airway  Speech  Facial expression
  69. 69. Ramus Function  Provides an attachment base for masticatory muscles  Plays key role in placing the corpus and dental arch into ever-changing fit with the growing maxilla and the limitless structural variations of face
  70. 70. Mechanisms and sites  Moves posteriorly ; combination of resorption and deposition  Resorption –anterior ramus while deposition posteriorly---drift posteriorly  Functions of remodel— Accommodate the increasing mass of masticatory Enlarged breadth of pharyngeal space Lengthening of corpus
  71. 71. Corpus  As anterior border of ramus resorbs – posterior drift  Conversion of earlier ramus into posterior part of the body.  Thus body of the mandible lengthens
  72. 72. Ramus to corpus remodeling conversion  Ramus relocated in a posterior direction; Bony arch length increased  Resorption of anterior border of ramus---- making room for the last molar
  73. 73. Coronoid process  Follows V principle  Lingual surface faces- 3 directions— posterior, superior and medial  Lengthens vertically- V oriented vertically
  74. 74.  Deposition occurs on lingual surface  Also posterior movement seen – V oriented horizontally
  75. 75. Angle of the mandible  Lingual side- resorption antero-inferiorly while deposition postero-superiorly  Buccal side vice versa  This results in flaring of mandible
  76. 76. The lingual tuberosity
  77. 77. Alveolar process  Develops in response to tooth buds  As teeth erupt the alveolar process erupt  Adds height and thickness to body of mandible
  78. 78. Chin  A specific human characteristic; recent man only  As age advances the growth of chin becomes significant  Sexual and genetic factors
  79. 79. Mechanism  Cartilage is special non-vascular tissue  Secondary type of cartilage  Endochondral mechanism of bone formation—due to variable levels of compression  Proliferative process – upward and backward growth of condyle
  80. 80. Height  Ramus height increases correlate with corpus length  Anterior mandibular height is related to dental development and overall downward and forward growth of mandible
  81. 81. Width  Bigonial and bicondylar diameter increase– divergence of mandible  Most width increases as it grows longer (Enlow’s V principle)
  82. 82. Length  By combination of resorption and deposition at the ramus-corpus interface
  83. 83.
  84. 84. Facial form and anatomic basis for malocclusions Dolicocephalic facial form  Brain inhorizontally long and relatively narrow  Basicranium more flat and horizontally longer  Nasomaxillary complex in a protrusive position relative to mandible  Mandible – downward and backward
  85. 85. Brachycephalic  Brain – rounder and wider  Basicranium more upright and short  Nasomaxillary complex is short horizontally  Retrusive maxilla and a more relatively prognathic mandible  Prognathic profile, Class III molar relarionship
  86. 86. Condyle  Anatomic part of special significance  Evolutionary changes  Earlier thought to be the master center; now a regional field of gowth– regional adaptive growth
  87. 87.  Interrelationship among brain form, facial profile & occlusal type predisposes --- facial form and malocclusion Examples  Caucasian groups-dolichocephalic headform, Class II malocclusions and retrognathic profile
  88. 88. Clinical implications of growth in 3 dimensions Sequence of growth cessation  Growth in width --- transverse plane  Growth in length ---- antero-posterior plane  Growth in height----- vertical plane
  89. 89. Transverse plane  Growth completed before adolescent growth spurt
  90. 90.  Minimally affected by adolescent growth changes Example 1: 13 year old girl with cross bite; transverse growth ceased. procedures ruled out. Interceptive Role of midpalatal suture in lateral displacement of palatal shelves is minimal ○ Maxillary expansion even after suture closure should be possible
  91. 91. Antero-posterior plane,  Jaws to continue throughout puberty  For example, 13 yearold girl- orthognathic maxilla and retrognathic mandible; myofunctional appliances can be given In case of retrognathic maxilla, protraction of maxilla not indicated beyond 14 years
  92. 92. Vertical plane  Growth occurs upto 18-19 years  Most common discrepancies Open bite--- Skeletal / Dental Deep bite--- Skeletal / Dental
  93. 93. END