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

    1. 1. GROWTH AND DEVELOPMENT OF MANDIBLE www.indiandentalacademy.com
    2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    3. 3. www.indiandentalacademy.com
    4. 4. CONTENTS        DEFINITIONS PRENATAL GROWTH POSTNATAL GROWTH FACTORS AFFECTING GROWTH AGE CHANGES IN MANDIBLE ANOMOLIES IN DEVELOPMENT MANDIBLE REFERENCES www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    7. 7. •PRENATAL •POSTNATAL www.indiandentalacademy.com
    8. 8. Prenatal Growth  It’s the most dynamic phase and is divided as •Preimplantation period •Embryonic period •Fetal period www.indiandentalacademy.com
    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. www.indiandentalacademy.com
    10. 10. th 4www.indiandentalacademy.com week
    11. 11. 4 www.indiandentalacademy.com week embryo
    12. 12. Contents of each arch     Skeletal element Striated muscle Nerve Artery www.indiandentalacademy.com
    13. 13. Internal view of pharyngeal floor and cut arches www.indiandentalacademy.com
    14. 14. www.indiandentalacademy.com
    15. 15. Mandibular Arch     Meckel’s cartilage Musculature Mandibular nerve Artery- maxillary and external carotid www.indiandentalacademy.com
    16. 16. Meckel’s cartilage    41th- 45th day of I.U.L Provides a template Extends from Otic capsule –Midline or Symphysis www.indiandentalacademy.com
    17. 17. Ossification of Meckel’s cartilage  Mandibular division of trigrminal nerve Neurotrophic factor Osteogenesis www.indiandentalacademy.com
    18. 18. Ossification of Meckel’s cartilage  In 6th week IU www.indiandentalacademy.com
    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 www.indiandentalacademy.com 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 www.indiandentalacademy.com
    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. www.indiandentalacademy.com
    22. 22. Fate of Meckel’s cartilage Woven bone Woven bone 5th month 5th month Lamellar bone + haversian system Lamellar bone + haversian system www.indiandentalacademy.com
    23. 23. Fate of Meckel’s cartilage Coronoid cartilage Condylar cartilage 10th & 14th week Sec. accessory cartilage Angular cartilage Mental ossicle www.indiandentalacademy.com
    24. 24.  Secondary cartilage of coronoid process  Develop within temporalis muscle   Incorporated into intramembranus bone of ramus Disappear before birth www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    27. 27. Types Of Ossification   Mandible is the first bone to be ossified (6th week) There are two types of ossification :  INTRAMEMBRANOUS  ENDOCHONDRAL www.indiandentalacademy.com
    28. 28. Intramembranous bone formation Mesenchyme Collagen fibre Osteoblast Osteoid matrix Calcium salts Osteoblasts www.indiandentalacademy.com Bone lamella
    29. 29. Intramembranous bone formation www.indiandentalacademy.com
    30. 30. Intramembranous bone formation www.indiandentalacademy.com
    31. 31. Endochondral bone formation Mesenchymal cells Hyaline cartilage Alkaline phosphatase Primary areolae Calcified Blood vessels Secondary areolae osteoid www.indiandentalacademy.com Lamella of bone
    32. 32. Endochondral bone formation www.indiandentalacademy.com
    33. 33. Endochondral bone formation www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    37. 37. Neonatal mandible www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    39. 39. Post Natal Growth  Mechanism of bone growth  Theories of growth  Anatomy www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    41. 41. www.indiandentalacademy.com
    42. 42. Theories of growth www.indiandentalacademy.com
    43. 43. Theories of growth www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    46. 46. Anatomy www.indiandentalacademy.com
    47. 47. Growth timings   The overall growth of mandible takes place at different stages. First there is increase in its  Width  Length  Height www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    49. 49. Growth in length    Growth in length continues through puberty Girls - 14-15 years Boys - 18-19 years www.indiandentalacademy.com
    50. 50. Growth in height   CONTINUES IN BOTH THE SEXES FOR A LONGER PERIOD GROWTH INCREASE OCCURS WITH CONCOMITANT ERUPTION OF TEETH AND CONTINUES TO INCREASE THROUGH OUT LIFE AND DECREASES IN ADULT LIFE www.indiandentalacademy.com
    51. 51. Main sites of post natal growth in the Mandible  Condylar cartilage  Posterior border of the Rami  Alveolar ridges www.indiandentalacademy.com
    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 www.indiandentalacademy.com 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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    56. 56. Age changes in mandible www.indiandentalacademy.com
    57. 57. Ramus    Moves progressively posterior by:POSTERIOR PART Deposition Resorption ANTERIOR PART www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    59. 59. Ramus www.indiandentalacademy.com
    60. 60. Coronoid process  Deposition on lingual side  Resorption on buccal surface www.indiandentalacademy.com
    61. 61. Coronoid process ‘’V’ PRINCIPLE OF ENLOW Lingual surface www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    63. 63. Body of mandible www.indiandentalacademy.com
    64. 64. Ramus corpus junction   Inferior Border of junction - resorption Forms Antegonial notch www.indiandentalacademy.com
    65. 65. Antegonial notch Size depends upon ramus – corpus angle www.indiandentalacademy.com
    66. 66. Lingual Tuberosity   Grows posterior and medial by deposition Resorptive field belowLingual fossa www.indiandentalacademy.com
    67. 67. Alveolar Process    Adds to the height and thickness of the mandibular body Teeth absent fails to develop Teeth extracted resorbs www.indiandentalacademy.com
    68. 68. Alveolar Process   Maintain occlusal relationship during differential mandibular & midfacial growth– buffer zones Maintains vertical height www.indiandentalacademy.com
    69. 69. Alveolar Process Lingual movement of anteriors Lingual movement of anteriors www.indiandentalacademy.com
    70. 70. Mental Protuberance   Formed by mental ossicles from accessory cartilage and ventral end of Meckel’s cartilage Poorly developed in infants www.indiandentalacademy.com
    71. 71. Mental Protuberance   Forms by osseous deposition during childhood Prominence is accentuated by bone resorption above it www.indiandentalacademy.com
    72. 72. Mental Protuberance    Reversal between 2 growth fields Concave  convex Reversal line could be High or low www.indiandentalacademy.com
    73. 73. Chin  Protrusive chin is unique human trait  More prominent in male  Less prominent in female www.indiandentalacademy.com
    74. 74. Symphysis Menti   Limited growth till fusion No widening after fusion www.indiandentalacademy.com
    75. 75. Mental Foramen www.indiandentalacademy.com
    76. 76. Growth rotation  The ramus undergoes remodeling rotation this produces displacement rotation as a whole www.indiandentalacademy.com
    77. 77. Rotation is of two type  Internal rotation Intramatrix  External rotation www.indiandentalacademy.com 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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    81. 81. Age changes in mandible www.indiandentalacademy.com
    82. 82. Radiographs of midsagital section’s of mandible Pre-extraction High well-rounded Post-extraction www.indiandentalacademy.com
    83. 83. Knife edge Low well rounded With out cortical layer on crest Low well rounded with cortical layer on crest www.indiandentalacademy.com
    84. 84. ANOMALIES OF MANDIBLE  Syndromes associated with mandibular abnormality •Pierre-Robin’s syndrome •Treacher-collins syndrome www.indiandentalacademy.com
    85. 85. Pierre-Robin’s syndrome www.indiandentalacademy.com
    86. 86. Treacher-collins syndrome www.indiandentalacademy.com
    87. 87. ANOMALIES OF MANDIBLE  Congenital •Agnathia •Micrognathia •Macrognathia www.indiandentalacademy.com
    88. 88. ANOMALIES OF MANDIBLE  Developmental •Torus Mandibularis •Achondroplasia •Stafne’s cyst •Odontogenic cyst www.indiandentalacademy.com
    89. 89. Torus mandibularis www.indiandentalacademy.com
    90. 90. Stafne’s cyst www.indiandentalacademy.com
    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 www.indiandentalacademy.com
    92. 92. REFERENCES   Orthodontics art and science- Bhalajhi,3rd edition Human embryology- Inderbir singh,7th edition www.indiandentalacademy.com
    93. 93. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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