Theroies of growth /certified fixed orthodontic courses by Indian dental academy


Published on

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.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit ,or call

Published in: Education
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Theroies of growth /certified fixed orthodontic courses by Indian dental academy

  1. 1. THEORIES OF GROWTH INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. CONTENTS 1. Paradigms in craniofacial biology 2. Various theories of growth --The Genetic theory --Sicher’s Sutural Dominance theory --Scott’s hypothesis --Moss’ functional matrix hypothesis --Van Limborgh’s theory
  3. 3. Hypothesis -- An assumption not proved by experiment or observation. -- It is assumed for the sake of testing its soundness or to facilitate investigation of a class of phenomena.
  4. 4. Theory --A supposition or an assumption based on certain evidence or observations but lacking scientific proof. When a theory becomes generally accepted & firmly established, it is called a doctrine or principle … Theory requires a basis of sound evidence, while hypothesis is thoughtful conjecture of the meaning of incomplete evidence
  5. 5.  Kuhn defined the terms: “ Normal Science” &“Paradigms” as pertaining the field of craniofacial biology.
  6. 6. Normal Science: defined as research findings generally agreed to be basic to a scientific field. Paradigm:It is a conceptual scheme that encompasses individual theories and is accepted by a scientific community as a model and foundation for further research.
  7. 7.  Scientific revolution --A change in paradigm brought about by inconsistencies within the old scheme or by technologic developments that permit scientists to ask new questions & gain new data is called a scientific revolution
  8. 8. EVOLUTION OF VARIOUS PARADIGMS g As new paradigms emerge ,a new normal science for the field emerges. :Kuhn & Carlson
  9. 9. PARADIGMS IN CRANIOFACIAL BIOLOGY THE GENETIC PARADIGM  BRODIE ,assumed facial configuration under genetic control  Research focussed on growth sites for this control: the sutures ,craniofacial cartilages and periosteum  Assumption was made that cartilages and facial sutures were under genetic control and brain determined the vault dimensions
  10. 10.  In 1940’s 2 events reflected changing ideas about dominant genetic paradigm :  1)marked increase in use of animals in craniofacial research  2)introduction of jaw and facial electromyography Other developments included the use of radioopaque implants, vital dyes & in vivo,in vitro transplantations.
  12. 12. Functional Paradigm  Rise of functional paradigm was when Melvin Moss adopted van der Klauuw’s ideas & published a paper in American Journal of physical anthropology in 1960 and called it the “functional matrix hypothesis”. (Moss & Young)  Moss suggested skeletal tissues were passive and under direct control of functional components to which craniofacial skeleton adapted.
  13. 13.  It focused on craniofacial growth from exactly opposite view as genomic paradigm.  Emphasized the epigenetic interaction of intrinsic and extrinsic factors that result in variation in craniofacial form.  Also placed emphasis on potential of modification of craniofacial growth & form using principles of orthodontics and dentofacial orthopedics.
  14. 14. The Functional Paradigm
  15. 15.  Change of concepts with time regarding the cranial differentiation in embryonic skull and later regarding the chondrocranial & desmocranial growth (from Limborg,j.v.: A new view on the control of the morphogenesis of the skull, Acta morph ,Neer Scand, 1970)
  16. 16. Cranial differentiation in embryonic skull
  17. 17.
  18. 18. Sicher’s sutural dominence theory
  19. 19. Scott’s hypothesis
  20. 20. Moss hypothesis
  21. 21. Interrelation of all control factors
  22. 22. The Genetic Theory  Simply said genes determine all  These are primary controls for initiation & formation of facial structures.  These genes are same in all animals.
  23. 23.  Intrinsic genetic information necessary for the differentiation of cranial cartilages and bones is supplied by neural crest cells.  Importance of intrinsic genetic factors in controlling craniofacial differentiation is considerably high
  24. 24.  Primary genetic control determines certain initial features  From investigations two conclusions seen a) inheritance of facial dimensions - polygenic b) no more than one fourth of variability of any dimension in children be explained by that dimension in parents
  25. 25. Sutural Dominance Theory (Sicher)  Sicher introduced that sutures were causing most of growth  Primary event in sutural growth - connective tissue proliferation between the two bones.  This creates the space for oppositional growth at the borders of the two bones.
  26. 26.  The connective tissue in sutures of both the nasomaxilary complex and vault produced forces which separated the bones.  The theory held sutures, cartilage and periosteum responsible for facial growth and assumed all under tight intrinsic genetic control.
  27. 27. Shortcomings of Sutural theory .It is clear now that sutures are not primary determinants of growth. Two evidences in support are: 1)Sutures & periosteal tissues lack innate growth potential,proved by transplanting a suture 2)Growth at sutures responds to outside influences,as compression and tension.
  28. 28.  For eg. If cranial or facial bones are pulled apart at sutures, new bone fills in and if suture is compressed the growth will be impeded.  Sutures are thus areas that react-not primary determinants.  Thus sutures are growth sites,not growth centres.
  29. 29. Growth Center: Those areas of craniofacial skeleton that have:  tissue seperating capabilties  innate  not growth potential influenced by external factors  e.g.Synchondrosis and nasal septal cartilage.
  30. 30. Growth Site: Locations at which active skeletal growth occur but as a secondary ,compensatory effect  lacking direct genetic influence  effected  e.g. by external influences. sutures and periosteum
  31. 31. Scott’s Hypothesis  Held that cartilaginous portions of head, nasal capsule, mandible and cranial base dominate facial growth.  Specifically emphasized how the cartilage of nasal septum paced the growth of maxilla.  Sutural growth came in response to growth of other str. including cartilaginous structures. Scott,1954
  32. 32. Condylar cartilage as growth determinant
  33. 33. Growth at nasal septum causes downward & forward translation of maxilla
  34. 34. Growth of maxilla on basis of Scott’s theory -Nasomaxillary complex grows as a unit. -Cartilaginous nasal septum serves as pacemaker for maxillary growth -Cartilage is so located so that its growth leads to forward and downward translation of maxilla. -Forces from the growing cartilage pulled apart the sutures which then responds by new bone formation leading to growth.
  35. 35. Experiments to verify Scott’s theory  Two kinds of experiments carried out to test the theory:  1. Transplantation experiments  2. Removal of cartilage. Transplantation experiments  not all skeletal cartilage act same when transplanted.
  36. 36.  Epiphysis plate of long bone continued to grow in new location.  Spheno-occipital synchondrosis also grows when transplanted, but not as well.  Nasal septal cartilage found to grow nearly as well as others.  No growth found when mandibular condyle transplanted.
  37. 37. Cartilage removal experiments  Extirpating a young rabbits septum causes a considerable deficit in growth of midface.  Gilhuus- Moe and Lund demonstrated that after fracture of condyle in a child there was an excellent chance that it would regenerate to app. its original size
  38. 38. Effect of removing nasal septum on forward growth of mid face Mid face deficiency in a man whose nasal septum was removed at age of 8
  39. 39. Shortcomings of Scott’s Theory  Transplantation experiments have revealed that condyle has no innate growth potential.  It is a growth site and not a growth center  Influenced by local factors  growth at condyle is entirely reactive
  40. 40. FUNCTIONAL MATRIX HYPOTHESIS (Melvin Moss)  Bone & cartilage lack growth determination  They grow in response to intrinsic growth of associated tissues,since the genetic coding for craniofacial skeletal growth is outside the bony skeleton.  These associated tissues are termed,functional matrices.
  42. 42.  The head is a region within which certain functions occur.  Every function is completely carried out by a functional cranial component. Functional Matrix Skeletal Unit
  43. 43. . All growth changes in the size, shape, and spatial position and, indeed, the very maintenance in being, of all, skeletal units are always secondary to temporally primary changes in their specific functional matrices.
  44. 44. Functional Cranial Component Functional Matrices Skeletal unit Periosteal Capsular Macro Micro I I I I (teeth,muscles) (orofacial, (endocranial (coronoid,angular neurocranial) surface of calvaria)
  45. 45. FUNCTIONAL MATRIX :  all soft tissues and spaces that perform a given function SKELETAL UNIT:  bony structures that support the functional matrix and are necessary for that function
  46. 46. Skeletal units May be compressed of bone,cartilage,or tendinous tissues Macroskeletal unit  when adjoining portions of a number of neighbouring skeletal units are united to function as a single cranial component e.g maxilla and mandible Microskeletal unit  when a bone consists of a number of skeletal units , these skeletal units are termed microskeletal units e.g coronoid ,condyle processes of mandible
  47. 47. Microskeletal unit Macroskeletal unit
  48. 48. In the mandible, •a coronoid microskeletal unit related to the functional demands of the temporalis muscle; •an angular microskeletal unit related to the activity of both the masseter and medial pterygoid muscles; •an alveolar unit related to the presence and position of teeth; and • a basal microskeletal unit related to the inferior alveolar neurovascular triad matrix.
  49. 49.  Contiguous microskeletal units are independent of each other.  This implies that changes in the size, shape, or position of the coronoid process as a result of primary, changes in temporalis muscle are relatively independent of such changes in other mandibular microskeletal units.
  50. 50.  The term functional matrix is by no means equivalent to what is commonly understood as "soft tissues," this is, muscles, glands, nerves, vessels, fat, etc., although all of these are obviously included within the concept. Teeth are also a functional matrix. When this functional grows or is moved, the related skeletal unit (the alveolar bone) responds appropriately to this morphogenetically primary demand.  Their designation as periosteal and capsular most clearly indicates the sites of their activity.
  51. 51. Periosteal matrix :  Immediate local functional environment ,typically associated with muscles,glands,blood vessels and nerves,fat etc  Act directly and actively upon their related sk.units, thereby bringing about transformation. Capsular matrix :  Organs and spaces that occupy a broader anatomical complex.  Act indirectly and passively on related sk.units, thereby producing secondary, compensatory translation in space.
  52. 52. PERIOSTEAL MATRICES  All non skeletal functional units adjacent to skeletal unit form the periosteal matrices  All skeletal units in formal sense, arise, exist, grow and are maintained while totally embedded within their functional periosteal matrices
  53. 53.  All responses of skeletal units to periosteal matrices brought about by complementary and inter related processes of osseous deposition and resorption  They act by bringing transformation of the related skeletal units  E.g – coronoid process and temporalis muscle
  54. 54.  Removal of the mammalian temporalis muscle, or its denervation, experimentally, postinfectively, or posttraumatically, invariably results in an actual diminution of coronoid process size and shape or, indeed, in its total disappearance.  Similarly, it is well established that functional hypertrophy or hyperactivity of the temporalis muscle is productive of increased coronoid process size and also alteration of its shape  . The coronoid process does not grow first and thus provide a "platform" upon which the temporalis muscle can then alter its functions.
  55. 55.  While muscles are excellent examples of periosteal function matrices, they do not comprise this entire category.  Blood vessels, nerves and glands produce morphologic changes in their related skeletal units in a completely homologus manner
  56. 56. CAPSULAR MATRICES  All functional cranial components (functional matrices plus skeletal units ) arise, grow, operate & are maintained within a series of cranial capsules  2 capsules– neurocranial capsule orofacial capsule
  57. 57.  These capsules as a whole are sandwitched between two covering layers. --Skin & dura mater in neurocranial capsule --Skin & mucosa in orofacial capsule  All spaces intervening between function components themselves, and between them and the limits of the capsule, are filled with indifferent loose connective tissue.
  58. 58.  Each capsule surrounds and protects a capsular functional matrix - in one case, the neural mass which consists of the brain plus leptomeninges and cerebrospinal fluid; in the second case, the oronasopharyngeal functioning spaces.  The common factor in both cases is that the capsular matrices exist as volumes.  Capsules expands due to volumetric increase of capsular matrix.
  59. 59. NEUROCRAINAL CAPSULE  Capsule’s covering layers are made up of skin and dura mater.  The composition of this capsule is -- Five layers of scalp, --then the bone itself, and finally, --the two layered dura mater.
  60. 60.  The calvarial bones consists of a number of contiguous skeletal units : outer table, inner table, diploic space (and variably sinuses). Each of these microkeletal units obviously has its specific periosteal matrix, muscles and vessels being good examples.
  61. 61. Neurocranial capsule
  62. 62. Acts to surround and protect neurocranial capsular matrix (brain, leptomeninges, csf)  Expansion of the neural mass is the primary event in the expansion of the capsule.The direction of this primary volumetric expansion is influenced by several environmental factors--degree of flexion of cranial base --mode of attachement of several orginised dural fiber tracts,which underlie the major calvarial suture systems. 
  63. 63.  The volumetric increase causes compensatory expansion of surrounding capsule which is brought about by mitotic activity of the capsular connective tissues  All embedded functional cranial components are passively translated in space & such spatial relocation takes place without involving the processes of osseous deposition or resorption
  64. 64. ORO FACIAL CAPSULE  Surround and protect oronasopharyngeal space.  Skin and mucous membrane form the limiting layers.  Embedded in this capsule are a no. of FCC,both periosteal matrices & related sk. unit ( for eg. Temporalis muscle / coronoid process, masseter & medial pterygoid / angular process)
  65. 65.  Volumetric growth of these spaces is the primary morphogenetic event in facial skull growth  Growth of functional spaces causes increase in the size of capsule  Followed by passive movement of functional cranial component
  67. 67. MANDIBULAR GROWTH  Mandibular condylar cartilages are not primary sites of mandibular growth. They are the Ioci at which secondary, compensatory periosteal growth occurs.  Mandibular growth, is seen as a combination of the morphologic effects of both capsular and periosteal matrices. The capsular matrix growth causes an expansion of the capsule as a whole. The enclosed and embedded macroskeletal unit (the "mandible" as a whole), accordingly, is passively and secondarily translated in space to successively new positions.
  68. 68.  In normal conditions the periosteal matrices related to the constituent mandibular microskeletal units also respond to this volumetric expansion.  Such an alteration in their spatial position inevitably causes them to grow ; that is, causes changes in their functional demands. These now call forth direct alterations in the size and shape of their microskeletal units.  The sum of translation plus changes in form comprises the totality of mandibular growth.
  69. 69.
  70. 70.
  71. 71.
  72. 72. VAN LIMBORGH’S THEORY --1970  Multifactorial Theory  Van Limborgh supports the functional matrix theory of Moss, acknowledges some aspects of Sicher’s theory & at the same time does not rule out genetic involvement.
  73. 73.  He suggested following five factors controls growth : 1 -- Intrinsic genetic factors 2 -- Local epigenetic factors Bone growth is determined by genetic control originating from adjacent structures 3 – General epigenetic factors Determining growth from distant structures. eg. Hormones
  74. 74. 4 – Local environmental factors eg. Habits, muscle force etc 5 –General environmental factors eg. Nutrition, oxygen etc. He summarized his views in following six points: 1. Chondrocranial growth is controlled mainly by the intrinsic genetic factors
  75. 75. 2. Desmocranial growth is controlled by any few intrinsic genetic factors. 3. The cartilaginous parts of the skull must be considered as growth centers 4.Sutural growth is controlled mainly by influences originating from the skull cartilages and from other adjacent skull structures
  76. 76. 5.Periosteal growth largely depends upon growth of adjacent structures 6.Sutural and periosteal growth are additionally governed by local non-genetic environmental influence.
  77. 77. CONCLUSION  Cranial growth is a combination of both spatial translation and transformation.  As new concepts, hypothesis & theories emerges, it may change the picture of craniofacial development.
  78. 78. REFERENCES 1.Primary role of functional matrices in facial growth— AJO,June 1969 2.The capsular matrix-AJO,nov 1969 3.Functional matrices-AJO,july 1969 4.Contemporary orthodontics—William.R.Profit 5.Handbook of orthodontics-Rorert.E.Moyers 6.Orthodontics Principles & practice-T.M.Graber 7.New vistas in orthodontics-Lysle.E.Johnston 8 Orthodontics the art and science-S.I.Balajhi
  79. 79. THANK YOU