Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy


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  • Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy

    2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
    3. 3.
    5. 5. What is Growth?     Growth refers to increase in size- Todd Growth usually refers to an increase in size and number – Proffit Self multiplication of living substance – J.S. Huxley Entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility Meridith
    6. 6. What is Development?   It is the progress towards maturity – Todd Development refers to all the naturally occurring unidirectional changes in the life of an individual from its existence as a single cell to its elaboration as a multifunctional unit terminating in death Moyers
    8. 8. Prenatal Growth  It’s the most dynamic phase and is divided as •Preimplantation period •Embryonic period •Fetal period
    9. 9. Formation of the Pharyngeal Arches  The mesoderm of the lateral plate of the ventral foregut becomes segmented to form a series of five distinct bilateral mesenchymal swelling called as the Pharyngeal Arches.
    10. 10. th week
    11. 11. 4 week embryo
    12. 12. Contents of each arch     Skeletal element Striated muscle Nerve Artery
    13. 13. Internal view of pharyngeal floor and cut arches
    14. 14.
    15. 15. Mandibular Arch     Meckel’s cartilage Musculature Mandibular nerve Artery- maxillary and external carotid
    16. 16. Meckel’s cartilage    41th- 45th day of I.U.L Provides a template Extends from Otic capsule –Midline or Symphysis
    17. 17. Ossification of Meckel’s cartilage  Mandibular division of trigrminal nerve Neurotrophic factor Osteogenesis
    18. 18. Ossification of Meckel’s cartilage  In 6th week IU
    19. 19. Ossification of Meckel’s cartilage Trough for dev. teeth Trough for dev. teeth 1°centre of ossification 1°centre of ossification below Infr alv. Nerve & Infr alv. Nerve & Incisive branch Incisive branch around
    20. 20. Ossification of Meckel’s cartilage   Ossification spreads dorsally and ventrally •Body •Ramus Ossification stops at the site that will become mandibular lingula
    21. 21. Fate of Meckel’s cartilage       Meckel’s cartilage lacks enzyme phosphatase It disappears by 24th week of conception A small part transforms into sphenomandibular and anterior malleolor ligaments Ventral end forms accessory endochondral ossicles Meckel’s cartilage dorsal to mental foramen gets resorbed on the lateral surface. Immediately lateral to resorbing cartilage,intramembranus bony trabeculae are being formed.
    22. 22. Fate of Meckel’s cartilage Woven bone Woven bone 5th month 5th month Lamellar bone + haversian system Lamellar bone + haversian system
    23. 23. Fate of Meckel’s cartilage Coronoid cartilage Condylar cartilage 10th & 14th week Sec. accessory cartilage Angular cartilage Mental ossicle
    24. 24.  Secondary cartilage of coronoid process  Develop within temporalis muscle   Incorporated into intramembranus bone of ramus Disappear before birth
    25. 25.    Secondary cartilage at Mental region 1 or 2 small cartilage ossify mental ossicles(7th month) in fibrous tissue of symphysis It gets incorporated into intramembranous bone symphysis menti 1st postnatal year synostosis syndesmosis
    26. 26. Condylar cartilage      Serves as a growth site Brings changes in the mandibular position and form Growth increases during puberty Peak 12 – 14 years Ceases by 20 years
    27. 27. Types Of Ossification   Mandible is the first bone to be ossified (6th week) There are two types of ossification :  INTRAMEMBRANOUS  ENDOCHONDRAL
    28. 28. Intramembranous bone formation Mesenchyme Collagen fibre Osteoblast Osteoid matrix Calcium salts Osteoblasts Bone lamella
    29. 29. Intramembranous bone formation
    30. 30. Intramembranous bone formation
    31. 31. Endochondral bone formation Mesenchymal cells Hyaline cartilage Alkaline phosphatase Primary areolae Calcified Blood vessels Secondary areolae osteoid Lamella of bone
    32. 32. Endochondral bone formation
    33. 33. Endochondral bone formation
    34. 34. ENDOCHONDRAL  Cartilage template is replaced by endochondrial bone INTRAMEMBRANOUS  Direct deposition of osseous tissue in periosteal membrane  Indirect bone growth  Direct bone growt  Slow expansion  Rapid expansion
    35. 35. Parts Of Mandible Derived From 1. INTRAMEMBRANOUS OSSIFICATION i. Whole body of mandible except the anterior part ii. Ramus of mandible as far as mandibular foramen 2 . ENDOCHONDRAL OSSIFICATION i. Anterior portion of the mandible (symphysis) ii. Part of ramus above the mandibular foramen iii. Coronoid process iv. Condylar process
    36. 36. Neonatal mandible     Ascending Ramus low and wide Large Coronoid process Body – open shell containing tooth buds and partially formed deciduous teeth Mandibular canal that runs low in the body
    37. 37. Neonatal mandible
    38. 38. Differential growth During fetal life During fetal life 8 weeks -- mandible > maxilla 8 weeks mandible > maxilla 11 weeks -- mandible = maxilla 11 weeks mandible = maxilla 13 – 20 weeks maxilla > mandible 13 – 20 weeks maxilla > mandible At Birth At Birth Mandible tends to be retrognathic Mandible tends to be retrognathic Early post natal life -- orthognathic Early post natal life orthognathic
    39. 39. Post Natal Growth  Mechanism of bone growth  Theories of growth  Anatomy
    40. 40. Mechanisms Of Bone Growth Growth Of The Mandible Primarily Involve 1. Bone remodeling Process Of Bone Deposition And Resorption 2. Cortical drift Combination of bone deposition and resorption resulting in growth movement towards deposition surface 3. Displacement Movement of whole bone as a unit I) Primary displacement II) Secondary displacement
    41. 41.
    42. 42. Theories of growth
    43. 43. Theories of growth
    44. 44. Other theories for growth   ENLOW’S “V” PRINCIPLE The growth and enlargement of bones occur towards wide end of ‘V’ due to differential deposition and resorption
    45. 45. Enlow’s Counterpart Principle   ‘The growth of any given facial or cranial part relates specifically to other structural and geometric “counter” parts in the face and cranium’. Eg. Maxillary arch is counter part of mandibular arch. Regional part Regional part counter part counter part Balanced growth Balanced growth
    46. 46. Anatomy
    47. 47. Growth timings   The overall growth of mandible takes place at different stages. First there is increase in its  Width  Length  Height
    48. 48. Width    Growth in width is completed before adolescent growth spurt Intercanine width does increase after 12 years Both molar and bicondylar width shows small increase until growth in length ends
    49. 49. Growth in length    Growth in length continues through puberty Girls - 14-15 years Boys - 18-19 years
    51. 51. Main sites of post natal growth in the Mandible  Condylar cartilage  Posterior border of the Rami  Alveolar ridges
    52. 52. Condylar cartilage Site of growth for ramus and body of mandible Dual function articular articular growth growth Not a primary Centre of growth but rather site of growth 2° in evolution 2° in evolution 2° in embryonic origin 2° in embryonic origin 2°to adaptive changes 2°to adaptive changes
    53. 53. Is the Condylar cartilage the principle force that produces the displacement of the mandible ? For many years considered primary growth center Condyle absent yet mandible positioned normally Considered secondary cartilage -no intrinsic growth potential
    54. 54.    Condylar cartilage and functioning muscles translate the mandible and in the absence of one the other does best to compensate Integrity of periosteum is important When environment changes compensatory contributions are enhanced
    55. 55. Current Concept   Condylar cartilage does have a measure of intrinsic genetic programming But extra condylar factors are needed to sustain this activity Physiologic inductors Intrinsic and extrinsic biomechanical forces ENLOW : Increase pressure – growth inhibition Decrease pressure – stimulates growth based mainly on animal experiments
    56. 56. Age changes in mandible
    57. 57. Ramus    Moves progressively posterior by:POSTERIOR PART Deposition Resorption ANTERIOR PART
    58. 58. Ramus Superior part of ramus below sigmoid notch lingual-deposition Buccal-resorption Lower part of ramus below the Coronoid process Buccal-deposition Lingual-resorption
    59. 59. Ramus
    60. 60. Coronoid process  Deposition on lingual side  Resorption on buccal surface
    61. 61. Coronoid process ‘’V’ PRINCIPLE OF ENLOW Lingual surface
    62. 62. Body of mandible    The increase in width of the mandible occurs primarily due to resorption on the inside and deposition on the outside Increase in length occurs due to drift of the ramus posteriorly Increase in height occurs due to eruption of the teeth
    63. 63. Body of mandible
    64. 64. Ramus corpus junction   Inferior Border of junction - resorption Forms Antegonial notch
    65. 65. Antegonial notch Size depends upon ramus – corpus angle
    66. 66. Lingual Tuberosity   Grows posterior and medial by deposition Resorptive field belowLingual fossa
    67. 67. Alveolar Process    Adds to the height and thickness of the mandibular body Teeth absent fails to develop Teeth extracted resorbs
    68. 68. Alveolar Process   Maintain occlusal relationship during differential mandibular & midfacial growth– buffer zones Maintains vertical height
    69. 69. Alveolar Process Lingual movement of anteriors Lingual movement of anteriors
    70. 70. Mental Protuberance   Formed by mental ossicles from accessory cartilage and ventral end of Meckel’s cartilage Poorly developed in infants
    71. 71. Mental Protuberance   Forms by osseous deposition during childhood Prominence is accentuated by bone resorption above it
    72. 72. Mental Protuberance    Reversal between 2 growth fields Concave  convex Reversal line could be High or low
    73. 73. Chin  Protrusive chin is unique human trait  More prominent in male  Less prominent in female
    74. 74. Symphysis Menti   Limited growth till fusion No widening after fusion
    75. 75. Mental Foramen
    76. 76. Growth rotation  The ramus undergoes remodeling rotation this produces displacement rotation as a whole
    77. 77. Rotation is of two type  Internal rotation Intramatrix  External rotation Matrix
    78. 78. Growth rotation       The rotation is considered forward if growth is more posteriorly than anteriorly. The rotation is considered backward if growth is more anteriorly than posteriorly. Short face -forward growth Long face -backward growth Males-slight forward growth Females-slight backward growth
    79. 79. Factors Affecting Growth A) Systemic Factors 1. Genetic 2. Hormonal imbalance 3. Nutrition 4. Systemic illness or chronic illness 5. Localized alteration/ diseases of uterus 6. Systemic illness in mother
    80. 80. B) Local factors 1. Vascular abnormality 2. Lymphatic disturbance 3. Neurologic disease 4. Local infection 5. Ear infection or mastoiditis 6. Ankylosis 7. Trauma or fracture 8. Birth injury
    81. 81. Age changes in mandible
    82. 82. Radiographs of midsagital section’s of mandible Pre-extraction High well-rounded Post-extraction
    83. 83. Knife edge Low well rounded With out cortical layer on crest Low well rounded with cortical layer on crest
    84. 84. ANOMALIES OF MANDIBLE  Syndromes associated with mandibular abnormality •Pierre-Robin’s syndrome •Treacher-collins syndrome
    85. 85. Pierre-Robin’s syndrome
    86. 86. Treacher-collins syndrome
    87. 87. ANOMALIES OF MANDIBLE  Congenital •Agnathia •Micrognathia •Macrognathia
    88. 88. ANOMALIES OF MANDIBLE  Developmental •Torus Mandibularis •Achondroplasia •Stafne’s cyst •Odontogenic cyst
    89. 89. Torus mandibularis
    90. 90. Stafne’s cyst
    91. 91. REFERENCES      Oral histology, development, structure and function – A.R. Ten Cate, 4th Edition The essentials of facial growth – Enlow and Hans, 1st Edition. Orthodontics principles and practice – Graber, 3rd edition Craniofacial Embryology- GH Sperber, 4th edition Textbook of oral pathology– William Shafer, 5th Edition
    92. 92. REFERENCES   Orthodontics art and science- Bhalajhi,3rd edition Human embryology- Inderbir singh,7th edition
    93. 93. Thank you Leader in continuing dental education