Development of mandible /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Development of mandible /certified fixed orthodontic courses by Indian dental academy

  1. 1. DEVELOPMENT OF MANDIBLE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com  www.indiandentalacademy.com
  2. 2. Contents Introduction  Prenatal growth  Ossification  Concept of remodeling  Postnatal growth  Clinical implications  www.indiandentalacademy.com
  3. 3. Introduction Measurements in the ceph show the results of Growth of something, somewhere, at some time, But of what? Why? And in response to which Biologic stimuli or energies? www.indiandentalacademy.com
  4. 4. Prenatal Growth www.indiandentalacademy.com
  5. 5. Prenatal Growth www.indiandentalacademy.com
  6. 6. Prenatal Growth www.indiandentalacademy.com
  7. 7. Prenatal Growth 36-38 day Iul Ectomesenchymal cells Epi. Of 1st arch www.indiandentalacademy.com Osteogenic Memb.
  8. 8. Prenatal Growth 6th week www.indiandentalacademy.com
  9. 9. Prenatal Growth 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
  10. 10. Prenatal Growth Fate of Meckel’s cartilage www.indiandentalacademy.com
  11. 11. www.indiandentalacademy.com
  12. 12. Prenatal Growth New bone Woven bone Woven bone 5th month i. u. 5th month i. u. Lamellar bone + haversian system Lamellar bone + haversian system www.indiandentalacademy.com
  13. 13. Prenatal Growth 10th & 12th week Sec. accessory cartilage www.indiandentalacademy.com
  14. 14. Prenatal Growth  Secondary cartilage of coronoid process  Develop within temporalis muscle  Incorporated into IMB of ramus  Disappear before birth www.indiandentalacademy.com
  15. 15. Prenatal Growth Sec. cartilage at Mental region  1 or 2 small cartilage mental ossicles(7th IUL)  Incorporated into IMB  syndesmosis synostosis www.indiandentalacademy.com
  16. 16. Prenatal Growth Sec. Condylar cartilage (10th week of IUL)  Grow interstitially & appositionally  14th week 1st evidence of Endochondral bone formation  www.indiandentalacademy.com
  17. 17. 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
  18. 18. 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
  19. 19. 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
  20. 20. Post Natal Growth  Types of ossification  Mechanism of bone growth  Anatomy  Theories of growth www.indiandentalacademy.com
  21. 21. Types Of Ossification Mandible is the second bone in the body to be ossified  There are two types of ossification :   INTRAMEMBRANOUS  ENDOCHONDRAL www.indiandentalacademy.com
  22. 22. Intramembranous Ectomesenchyme Epithelium Osteogenic membrane Osteoblast Centre of ossification Osteoid matrix www.indiandentalacademy.com
  23. 23. Intramembranous www.indiandentalacademy.com
  24. 24. Intramembranous www.indiandentalacademy.com
  25. 25. Endochondral Mesenchymal cells osteoblast Cart. Matrix of glycoproteins Cart. template Blood vessels Osteoid matrix mineralized www.indiandentalacademy.com
  26. 26. Endochondral www.indiandentalacademy.com
  27. 27. Endochondral www.indiandentalacademy.com
  28. 28. Clinical significance In postnatal life distinction b/w two is of no significance: # of intramembranous bone  Surface remodelling of endochondral bone  Prenatal life – congenital defects  Achondroplasia – Endochondral bone  Cleidocranial dysostosis – Intramembranous bone  Osteogenesis Imperfecta – both type  www.indiandentalacademy.com
  29. 29. 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
  30. 30. Mechanisms Of Bone Growth Growth Of The Mandible Primarily Involve 1. Bone remodelling 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
  31. 31. www.indiandentalacademy.com
  32. 32. Anatomy www.indiandentalacademy.com
  33. 33. Theories Of Growth www.indiandentalacademy.com
  34. 34. Theories Of Growth www.indiandentalacademy.com
  35. 35. Other Theories  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
  36. 36. 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
  37. 37. “The human mandible has no one design for “The human mandible has no one design for life. Rather it adapts and remodels through life. Rather it adapts and remodels through the seven stages of life, from the slim the seven stages of life, from the slim arbiter of things to come in the infant, arbiter of things to come in the infant, through a powerful dentate machine and through a powerful dentate machine and even weapon in the full flesh of maturity, even weapon in the full flesh of maturity, to the pencil thin, porcelain like problem to the pencil thin, porcelain like problem that we struggle to repair in the adversity that we struggle to repair in the adversity of old age.” of old age.” D.E. Poswillo, 1988 D.E. Poswillo, 1988 www.indiandentalacademy.com
  38. 38. Post Natal Growth And Development GROWTH TIMING Growth of width of mandible is completed first, then growth in length and finally growth in height www.indiandentalacademy.com
  39. 39. Post Natal Growth And Development WIDTH OF MANDIBLE  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
  40. 40. Post Natal Growth And Development GROWTH IN LENGTH Growth in length continues through puberty  Girls—14-15 years  boys---18-19 years  www.indiandentalacademy.com
  41. 41. Post Natal Growth And Development  Main sites of post natal growth in the Mandible  Condylar cartilage  Posterior border of the Rami  Alveolar ridges www.indiandentalacademy.com
  42. 42. Condylar cartilage Secondary cartilage Dual function articular articular growth growth Not a pri. Centre of growth but rather 2° in evolution 2° in evolution 2° in embryonic origin 2° in embryonic origin 2°in adaptive responses to changing dev. 2°in adaptive responses to changing dev. www.indiandentalacademy.com
  43. 43. Is the Condylar cartilage the principle force that produces the displacement of the mandible ? For many years considered primary growth center FMH - Condyle absent yet mandible positioned normally Considered secondary cartilage -no intrinsic growth potential www.indiandentalacademy.com
  44. 44. Petrovic et al - Role of hormones Experiments involving transplantation of the condyle Johnston et al - Detached condyle from the body of mandible in guinea pigs Injection of papain - Inhibition of chondrogenesis Koski et al - Periosteal tension in condylar neck-lateral pterygoid- controls condylar growth www.indiandentalacademy.com
  45. 45.  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 is changed compensatory contributions are enhanced www.indiandentalacademy.com
  46. 46. 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 www.indiandentalacademy.com based mainly on animal experiments
  47. 47. Ramus  Moves progressively posterior by:Deposition POSTERIOR PART  Resorption  ANTERIOR PART www.indiandentalacademy.com
  48. 48. 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
  49. 49. Ramus www.indiandentalacademy.com
  50. 50. Ramus www.indiandentalacademy.com
  51. 51. Coronoid process Posterior Lingual surface Superior Medially Follows ‘v’ principle www.indiandentalacademy.com
  52. 52. Coronoid process ‘’V’ PRINCIPLE OF ENLOW www.indiandentalacademy.com
  53. 53. Coronoid process  Medial  Increases vertical length Deposition on lingual side Posterior Growth Resorption - buccal surface www.indiandentalacademy.com
  54. 54. 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
  55. 55. Ramus corpus junction  Inferior Border of junction - resorption  Forms Antegonial notch www.indiandentalacademy.com
  56. 56. Antegonial notch Size depends upon ramus – corpus angle www.indiandentalacademy.com
  57. 57. Lingual Tuberosity  Grows posterior and medial by deposition Resorptive field belowLingual fossa  www.indiandentalacademy.com
  58. 58. Alveolar Process Adds to the height and thickness of the mandibular body  Teeth absent fails to develop  Teeth extracted resorbs  www.indiandentalacademy.com
  59. 59. Alveolar Process  Maintain occlusal relationship during differential mandibular & midfacial growth– buffer zones  Maintains vertical height  Adaptive remodeling makes orthodontic tooth movement possible www.indiandentalacademy.com
  60. 60. Alveolar Process Lingual movement of anteriors Lingual movement of anteriors www.indiandentalacademy.com
  61. 61. Mental Protuberance  Formed by mental ossicles from accessory cartilage and ventral end of Meckel’s cartilage  Poorly developed in infants www.indiandentalacademy.com
  62. 62. Mental Protuberance  Forms by osseous deposition during childhood  Prominence is accentuated by bone resorption above it www.indiandentalacademy.com
  63. 63. Mental Protuberance  Reversal between 2 growth fields  Concave  convex  Reversal line could be High or low www.indiandentalacademy.com
  64. 64. Chin  Protrusive chin is unique human trait  More prominent in male  Less prominent in female Under dev. Of chin -- microgenia Under dev. Of chin microgenia www.indiandentalacademy.com
  65. 65. Symphysis Menti  Limited growth till fusion  No widening after fusion www.indiandentalacademy.com
  66. 66. Mental Foramen www.indiandentalacademy.com
  67. 67. 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 7. Drugs www.indiandentalacademy.com
  68. 68. 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 9. Habits www.indiandentalacademy.com
  69. 69. Anomalies of mandible  Some of the syndromes associated with mandibular abnormality i) Down’s syndrome i) Marfan’s syndrome ii) Turners syndrome iii) Kleinfelter’s syndrome iv) Pierre-robin syndrome v) Treacher- collin syndrome www.indiandentalacademy.com
  70. 70. 1. Congenital 2. Developmental • Agnathia • Infantile cortical hyperostosis • Achondroplasia • Macrognathia • Torus mandibularis • Facial hemihypertrophy • Stafne’s cyst • Facial hemiatropy • Odontogenic cyst • Odontogenic tumor • Micrognathia www.indiandentalacademy.com
  71. 71. Age Changes Of The Mandible www.indiandentalacademy.com
  72. 72. References Craniofacial embryology – SPERBER  Facial growth – ENLOW  Contemporary orthodontics – PROFFIT  Handbook of orthodontics – MOYERS  Principles and practice of orthodontics –GRABER  www.indiandentalacademy.com
  73. 73. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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