Theories of cranio facial growth /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.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Theories of cranio facial growth /certified fixed orthodontic courses by Indian dental academy

  1. 1. THEORIES OF CRANIOFACIAL GROWTH INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Next Steps  Summarize any actions required of your audience  Summarize any follow up action items required of you www.indiandentalacademy.com
  3. 3. HOLY GRAIL OF CRANIOFACIAL BIOLOGY The search for a single theory of craniofacial growth that is both biologically accurate and clinically effective www.indiandentalacademy.com
  4. 4. VARIOUS ARGUMENTS  ROLES OF HEREDITY AND THE ENVIRONMENT IN CRANIOFACIAL GROWTH  EVOLUTION OF CONCEPTS REGARDING MECHANISMS OF CRANIOFACIAL GROWTH  EMPHASIS ON THE EMERGING FIELD OF GENETICS www.indiandentalacademy.com
  5. 5. NATURE AND NURTURE CONTROVERSY NATURE NURTURE Genetics Genetically Predetermined Biological Calvinism Effects of environment with little or no genomic basis Functional factors www.indiandentalacademy.com
  6. 6. FORM –FUNCTION PRINCIPAL It emphasizes the role of biological purpose, behavior, and the environment, i.e., “function” in the production of form . INTRINSIC vs EXTRINSIC FACTORS Intrinsic Genetically predetermined Extrinsic Systemic influences that are remote from the cells & tissues being considered, such as hormones,as well as effect of environment,like muscles www.indiandentalacademy.com
  7. 7.  GENOMIC & FUNCTIONAL PARADIGMS All biological cells & tissues have a degreeof plasticity at some stage of ontogeny during which they are capable of being influenced to a variable degree by factors extrinsic to the genome  EARLY CONCEPTS OF CRANIOFACIAL GROWTH Vital dye experiments www.indiandentalacademy.com
  8. 8. VARIOUS THEORIES OF GROWTH  REMODELLING THEORY OF GROWTH The flat membrane bones in the skull vault expand by accretion on the exposed surface and absorption on the intracranial surface. It was formerly supposed that the sutural lines represent the main region of growth, but this is by no means the case." SIR WILFRED LE CLARK(1939) www.indiandentalacademy.com
  9. 9. REMODELLING THEORY  Bone only grows appositionally at surfaces  Growth of the jaws is characterized by deposition of bone at the posteriorsurfaces of maxilla and mandible  Calvarial growth occurs via deposition bone endocranially www.indiandentalacademy.com
  10. 10. www.indiandentalacademy.com
  11. 11. ENLOW’S “V” PRINCIPLE www.indiandentalacademy.com
  12. 12. www.indiandentalacademy.com
  13. 13. THE SUTURAL THEORY  WEINMANN & SICHER ,1940s “ The role of proliferating sutural connective tissue in cranial growth…is identical to that of the proliferating cartilage in basal synchondroses” (Weinmann and Sicher, 1947 “The sutures, as well as the cartilages of the craniofacial skeleton, were essentially the locations of centers of bone growth at which the inherited pattern of craniofacial form and facial type, however determined, was expressed; and the pattern could not be www.indiandentalacademy.com changed” (Brodie, 1946).
  14. 14. THE NASAL SEPTUM THEORY  GIVEN BY JAMES H. SCOTT1953,54,56  The essential primary elements directing craniofacial skeletal growth are the cartilages found within the cranial base and, in particular, the anterior extension of the chondrocranium, the nasal septal cartilage. www.indiandentalacademy.com
  15. 15. EPIGENETIC  All the extrinsic(extraorganismal) factors impinging on vital structures , including mechanical loadings & electroelectric states  All intrinsic(intraorganismal)biophysical , biomechanical, biochemical ,bioelectric microenvironmental events occuring on ,in and between individual cells and extracellular substances. www.indiandentalacademy.com
  16. 16. CRANIAL DIFFERENTIATION  INTRINSIC GENETIC FACTORS  LOCAL EPIGENETIC FACTORS  GENERAL EPIGENETIC FACTORS  LOCAL ENVIRONMENTAL FACTORS  GENERAL ENVIRONMENTAL FACTORS www.indiandentalacademy.com
  17. 17. CONTROL OF SKULL GROWTH CHONDROCRANIAL GROWTH   INTRINSIC GENETIC FACTORS LOCAL ENVIRONMENTAL FACTORS DESMOCRANIAL GROWTH INTRINSIC GENETIC FACTORS LOCAL ENVIRONMENTAL FACTORS www.indiandentalacademy.com
  18. 18. SCOTT’S VEIW ON SKULL GROWTH CHONDROCRANIAL GROWTH INTRINSIC GENETIC FACTORS DESMOCRANIAL GROWTH SUTURAL GROWTH LOCAL EPIGE NETIC FACTORS LOCAL ENVIRON MENTAL FACTORS www.indiandentalacademy.com PERIOSTEAL GROWTH INTRINSIC GENETIC FACTORS
  19. 19. VAN LIMBORGH’S ESSENTIAL ELEMENTS  Growth of the synchondroses & the ensuing endrochondral ossification is exclusively controlled by intrinsic genetic factors.  The genetic factors controlling intramembranous bone growth are small in number & of a general nature  The cartilaginous skull parts must be seen as growth centers www.indiandentalacademy.com
  20. 20.  Extent of sutural growth is controlled both by the cartilaginous growth &the growth of the other head structures.  The extent of periosteal bone growth largely depends on growth of adjacent structures.  The intramembranous processes of bone formation can be additionally influenced by local environmental factors ,muscles inclusive. www.indiandentalacademy.com
  21. 21. CONTROL OF SKULL GROWTH (LIMBORGH) CHONDROCRANIAL GROWTH DESMOCRANIAL GROWTH Intrinsic genetic factors General epigenetic factors General environmental factors Intrinsic genetic Local epigenetic Local environmental General epigenetic General environmental www.indiandentalacademy.com
  22. 22. HEREDITY,GENETICS & THE GENE  The mechanisms by which traits are transmitted  The units of heredity  The mechanisms of action by those units of heredity  Mendel’s Laws of Inheritance: mechanism of inheritance & transmission of traits www.indiandentalacademy.com
  23. 23. Earlier Concepts  Bateson coined the term “genetics”as the new field of heredity in 1905  Weismann’s concept of “germplasm”:the cytoplasm found with germ cells is comprised of “determinants”that transmit traits from parents to offspring.  W.L.Johannsen used the term “GENE” to refer to the presumed unit of heredity in1909. www.indiandentalacademy.com
  24. 24.  Waddington thought of genes as organisers and evocators of development  Watson & Crick in 1953 discovered that DNA is arranged structurallyas a double helix gene replication  Operon Theory of Jacob &Monod(1963): genes and whole groups of genes operate within common regulatory sequencesthat can be turned on and turned off to control transcription of mRNA and gene expression www.indiandentalacademy.com
  25. 25. “The study of development transformed in large part into a study of how gene action underlies and governs developmental processes” www.indiandentalacademy.com
  26. 26. THE GENETIC CONTROL THEORY OF GROWTH  The whole plan of growth,the whole series of operations to be carried out ,the order and site of synthesis and their co-ordination are all written down in the nucleic acid message www.indiandentalacademy.com
  27. 27. Within the fertilized egg lies the information necessary to generate a diversity of cell types in the precise pattern of tissues and organs that comprises the vertebrate body All features (phenotype) are ultimately determined by the DNA sequence of the genome www.indiandentalacademy.com
  28. 28. THE GENOMIC THESIS The genome from the moment of fertilization contains all information to regulate i.e.cause,control,direct: 1.the intranuclear formation & transcription of mRNA 2. To regulate all of the intracellular& intercellular processes of subsequent,&structurally more complex,cells,tissues & organismal morphogenesis. www.indiandentalacademy.com
  29. 29. Morphogenesis is the predetermined reading out of an intrinsic and inherited genomic organismal blueprint where, in addition to molecular synthesis, the genome also regulates the geometric attributes of cell, tissue, organ, and organismal size,shape and location www.indiandentalacademy.com
  30. 30. GENOMIC REGULATIONS : 1.Psychological behaviour 2.Personality 3.Alcohol & drug abuse 4.Smoking 5.Obesity www.indiandentalacademy.com
  31. 31. THE BIOLOGIC BASIS FOR THE GENOMIC THESIS  The somatic cells of an individual inherit two classes of molecular information: 1. An identical diploid DNA 2. The maternal cytoplasmic constituents of the of the egg ,e.g.mitochondria,membranes www.indiandentalacademy.com
  32. 32.  Human genome has approx. 100,000 genes  Only 10% seems related to phenotypic ontogenesis  All somatic cells commonly share approximately 5000 different polypeptide chains  But ,each specific cell type is characterized only by approx. 100 specific proteins www.indiandentalacademy.com
  33. 33. Thus it is claimed that “these quantitative protein differences are related to differences in cell size ,shape and internal architechture” www.indiandentalacademy.com
  34. 34.  The encoding 10% of the DNA exists in two families : 1. “ housekeeping genes” : regulate (a)common energetic (metabolic,respiratory) activities of all cells and the specific activities of special cell types e.g. neurons, osteoblasts, ameloblasts etc (b)the synthesis of specific molecular gene products, whose presence,absence,or abnormal configuration are associated with the human pathologic conditions like marfan syndrome, achondroplasia,osteogenesis imperfecta etc 2. “ structural genes” : relatively nonabundant www.indiandentalacademy.com
  35. 35. THUS ,ALTERATIONS IN THE GENOMICALLY REGULATED PROCESSES OF MOLECULAR SYNTHESIS CAN PRODUCE AN EVENTUAL “STRUCTURAL COLLAPSE” AT THE HIERARCHICALLY HIGHER LEVEL OF A MACROSCOPIC BONE www.indiandentalacademy.com
  36. 36. HOMEOBOX GENES These are genes that contain within their coding regions a sequence of some 180 nucleotides called as HOMEOBOX  8 homeobox genes are linked in a cluster on one Drosophila chromosome.  All of them (Hox Cluster) : 1. Encode transcription factors 2. Act in sequential zones of the embryo in the same order that they occur on the chromosome. Approx. 60 aminoacids encoded by the homeobox www.indiandentalacademy.com are called a Homeodomain. 
  37. 37. THE HOX CLUSTER Mice & Humans have 4 Hox clusters located on four different chromosomes Genes in the mammalian Hox clusters show strong sequence homology to equivalent genes in Drosophila www.indiandentalacademy.com
  38. 38. HOMEODOMAIN  www.indiandentalacademy.com
  39. 39. DROSOPHILA(Fruit Fly) THORAX SEGMENTS: T1 T2:- a single pair of wings T3:- halteres(balance) Each carries a pair of legs  www.indiandentalacademy.com
  40. 40. DROSOPHILA HOMEOBOX GENES  Ultrabithorax : acts within the cells of T3 to suppress the formation of wings  Antennapedia : is normally turned “on” in the thorax and turned “off” in the cells of the head. These genes are called as selector genes or master switches as they regulate the expression of other genes. www.indiandentalacademy.com
  41. 41. Mutations in a single gene were able to cause the reprogramming of the building of T3 and the Head of the Drosophila. Human Dlx5 and Dlx6 genes have been identified as homeobox genes Inactivation of these genes in the mice results in severe CRANIOFACIAL,axial ,and appendicular skeletal abnormalities,leadind to perinatal lethality. These genes are also believed as possible candidate genes for the autosomal dominant form of the split-hand/split-foot malformation,characterized by missing central digits and claw-like distal extremeties www.indiandentalacademy.com
  42. 42. ROLE OF HOMEOBOX GENES IN CRANIOFACIAL DEVELOPMENT  It is believed that “homeobox genes coordinate the development of complex craniofacial structures and in both normal and abnormal development,much of the regulation of the development of virtually all of the skeletal and connective tissue of the face is dependent on a cascade of overlapping activity of homeobox genes” www.indiandentalacademy.com
  43. 43. FUNCTIONAL MATRIX HYPOTHESIS “The origin,growth and maintainence of all skeletal tissues and organs are always secondary,compensatory,and obligatory responses to temporally and operationally prior events for processes that occur in specifically related non-skeletal tissues, organs or functioning spaces” www.indiandentalacademy.com
  44. 44. THE FUNCTIONAL MATRIX HYPOTHESIS  MELVIN MOSS ,1962,68,69 FUNCTIONAL CRANIALCOMPONENT FUNCTIONAL MATRIX SKELETAL UNIT www.indiandentalacademy.com
  45. 45. FUNCTIONAL MATRIX PERIOSTEAL MATRIX CAPSULAR MATRIX (muscles,blood (organs & spaces e.g. vessels,nerves) brain,globes of eyes,oropharynx) www.indiandentalacademy.com
  46. 46. CAPSULAR MATRIX  NEUROCRANIAL CAPSULAR MATRIX  OROFACIAL CAPSULAR MATRIX www.indiandentalacademy.com
  47. 47. SKELETAL UNIT MICROSKELETAL UNITS (tuberosities,coronoid process of mandible,other muscle attachment ridges) MACROSKELETAL UNITS (neurocranium, maxillomandibular complex) www.indiandentalacademy.com
  48. 48. SKELETAL UNIT       Condylar process:-Lateral pterygoid muscle Coronoid :-Temporalis Alveolar process:- Teeth Angular process: Massetor,medial pterygoid Symphysis :- Mentalis, geniohyoid, genioglossus Basal portion:- blood vessels,nerves in IA canal www.indiandentalacademy.com
  49. 49. FUNCTIONAL MATRIX REVISITED those portions that are retained, extended or discarded which prior deficiencies are now resolved The new revision deals mainly with the responses to periosteal matrices www.indiandentalacademy.com
  50. 50. CONSTRAINTS OF FMH METHODOLOGIC CONSTRAINT Macroscopic measurements used e.g. roengenographic cephalometry Removed by use of FEM continuum mechanic techniques HIERARCHICAL CONSTRAINT The prior FMH could not establish a link between the signals given to cells and the responses by individual cells;thus no link could be given between the hierarchical levels www.indiandentalacademy.com
  51. 51. Actively adapting osseous tissues demonstrate that : 1. Adjacent adaptational tissue surfaces simultaneously show deposition,resorption, and maintenance 2. Adaptation is a tissue process.Deposition and maintenance are functions of relatively large groups of osteoblasts,never single cells 3. A sharp demarcation exists between adjacent cohorts of active,depository,and quiescent (resting) osteoblasts www.indiandentalacademy.com
  52. 52.  Attributes of successively higher levels are not simply the sum of lower level attributes  Rather at each higher level,new and more complex structural and operational attributes arise that cannot be predicted, even from a complete knowledge of those of the lower levels. www.indiandentalacademy.com
  53. 53. The new FMH version includes two complementary concepts :1. Mechanotransduction occurs in single bone cells 2. Bone cells are computational elements that function multicellularly as a connected cellular network www.indiandentalacademy.com
  54. 54.  Gap junctions are found where the plasma membranes of a pair of markedly overlapping canalicular processes meet.  Gap junctions also connect superficial osteocytes to periosteal and endosteal osteoblasts  All osteoblasts are similarly interconnected laterally  Vertically,gap junctions connect periosteal osteoblasts with preosteoblastic cells which are in turn similarly interconnected www.indiandentalacademy.com
  55. 55. MECHANOTRANSDUCTION Mechanosensing processes enable a cell to sense and to respond to extrinsic loadings by using two processes:1.Mechanoreception:-transmits an extracellular physical stimulus into a receptor cell . 2.Mechanotransduction:-transduces or transforms the stimulus’s energetic and/or informational content into an intracellular signal.E.g. mechanoelectrical, mechanochemical www.indiandentalacademy.com
  56. 56. OSSEOUS MECHANOTRANSDUCTION It is unique in four ways:  Most other mechanosensory cells are cytologically specialized, but bone cells are not  One bone-loading stimulus can evoke three adaptational responses  Osseous signal transmission is aneural  The evoked bone adaptational responses are confined within each “bone organ” independently so there is no “interbone” or organismal involvement www.indiandentalacademy.com
  57. 57. Types of Mechanotransduction 1.IONIC OR ELECTRICAL:(a) Strech-activated channels (b) Electromechanical (c) Electrokinetic (d) Electric field 2. MECHANICAL www.indiandentalacademy.com
  58. 58. MECHANOTRANSDUCTION: A TENTATIVE SYNTHESIS  Normal muscle function strains attached bone tissue intermittently  The dynamics of skeletal muscle contraction fit rather nicely with the energetic requirements for bone cell responsiveness  The range of specific strain-frequency harmonics of muscle dynamics are also those found to be morphogenetically competent i.e. osteoregulatory  Normal skeletal muscle activity produces intraosseous electric fields on the orderof extrinsic fields found to be similarly morphogenetic  Bone cells may be stimulated by two mechanismsdirectly by SA plasma membrane channels and www.indiandentalacademy.com
  59. 59. BONE AS AN OSSEOUS CONNECTED CELLULAR NETWORK (CCN)  All bone cells (except osteoclasts) are interconnected by gap junctions that form an osseous CCN  Connexin 43 is the major protein  Each osteocyte,enclosed within its mineralized lacuna, has many cytoplasmic processes(15mic m)long that interconnect with similar processes of up to 12 neighbouring cells.  These processes are arrayed three-dimensionally  They lie within mineralized bone matrix channels www.indiandentalacademy.com
  60. 60. GAP JUNCTIONS  Permit the intercellular transmission of ions and small molecules  Exhibit both electrical and fluorescent dye transmission  Gap junctions are electrical synapses thus bidirectional www.indiandentalacademy.com
  61. 61. THE CONNECTIONIST THEORY A CCN is operationally analogous to an “artificial neural network” in which massively parallel or parallel-distributed signal processing occurs  It computationally processes the intercellular signals created by an electrical type of machanotransduction of periosteal functional matrix stimuli  Computed output signals move hierarcally upward to regulate the skeletal unit adaptational responses of the osteoblasts www.indiandentalacademy.com
  62. 62.  Initial input(loadings) all loadings are weighted inputs they are summed if exceeds threshold value an intracellular signal is generated signal is transmitted to adjacent osteocytes until final osteoblastis layer which responds to the stimulus  The CCNs show oscillations i.e. interactive reciporcal signalling between layers.This enables them to adjustively self organise .This behaviour is relayed to the fact that biologic CCNs are not pre-programmed rather they learn by unsupervised or epigenetic training. www.indiandentalacademy.com
  63. 63. NEUROTROPISM It is a non- impulse transmitted neurofunction, involving axoplasmic transport , providing for the long term interactions between neurons and innervated tissues which homeostatically regulate the morphological, compositional and functional integrity of those tissues. The nature of neurotropic substances & the process of their introduction into the target tissue are unknown at present www.indiandentalacademy.com
  64. 64. THREE GENERAL CATEGORIES  Neuro-epithelial Trophism  Neuro-visceral Trophism  Neuro-muscular Trophism www.indiandentalacademy.com
  65. 65. NEURO-EPITHILIAL TROPHISM The mitotic activity necessary for normal epithelial turnover of taste buds,their maintenance, the expression of their genomic potential in such processes as DNA,and enzymatic synthesis are all under the direct and continuous afferent gustatory neurotrophic control. www.indiandentalacademy.com
  66. 66. NEUROVISCERAL TROPHISM  Experimental data have shown an increase and decrease of mature salivary glands under trophic influence  There is a consensus developing that normal rate of growth , expressed in part as regulation of cell size and number ,is under neurotrophic control www.indiandentalacademy.com
  67. 67. NEUROMUSCULAR TROPHISM  “Skeletal muscle ontogenesis requires motorneuron innervation to proceed past the stage of myotubes”  Cross innervation experiments show that significant morphologic,biomechanical,and functional parameters of re-innervated muscle come to more closely resemble those of the muscle formerly innervated by now ectopically implanted nerve i.e. these parameters of skeletal muscle are nerve specific not muscle specific. www.indiandentalacademy.com
  68. 68. SERVOSYSTEM THEORY  INPUT – orthodontic appliances  BLACK BOX – genetically determined and cybernetically organized biologic features of phenomena characterising,inducing,or controlling spontaneous & appliance modulated growth eg: maxilla lengthening,mandible lengthening  OUTPUT – correction of malocclusion and intermaxillary relation  OPEN & CLOSED LOOP SYSTEM  PERIPHERAL AND CENTRAL COMPARATOR www.indiandentalacademy.com
  69. 69. command Reference input elements Actuator Controller Coupling System (amplifier) Controlled System X Performance Analysing elements Performance www.indiandentalacademy.com
  70. 70. Fwd traction by septopremaxillary ligament Forward growth Of septal cartilage Fwd traction by labionarinary muscles Growth of premaxillo maxillary suture Protrusion of upper incisors STM somatomedine Increase of Tongue volume Outward growth of lateral mass of ethmoid Growth of Cartilage B/w greater Wings, and body Of sphenoid Appositional growth of ant premaxillary extremity Posteroanterior shift of premaxillary bones GROWTH OF LENGTH OF UPPER JAW Growth of maxillopalatine suture Protrrusion of lower incisors Outward shift of alveolar border & upper molar groups Transverse separation of two premaxillary bones Growth of interpremaxillary suture Growth of midpalatal suture Transverse separation of horizontal maxillary and palatine plates Outward growth of two maxillary bones www.indiandentalacademy.com Outward appositional bone growth GROWTH OF WIDTH OF UPPER JAW
  71. 71. GROWTH HORMONE Septal cartilage growth Somatomedin & Other GHmediators Other Masticatory muscles X Activity of lateral pterygoid muscle GROWTH OF CONDYLAR CARTILAGE X Appositional Growth of Posterior border Of ramus Local Biomechanical factors Center for Command of Mandibular movements MOVEMENTS OF MANDIBLE C CENTRAL NERVOUS SYSTEM Direct thrust LabioNarinary muscles Forward Growth of Maxilla Shape Reference (mandible) Iterative activity Of retrodiscal pad Superior head Number of sarcomeres in series Inferior head Superior Labial frenum And septoPremaxillary ligament Tongue Position of upper dental Arch (constantly changing Reference input) Mandibular angle CondyleDental arch distance Forward growth Of mandible Sagittal Position of Lower Dental arch (controlled Variable) X SAGITTAL POSITION OF MANDIBLE Detectors of occlusal Adjustment (perodontal, dental, Articular, and muscular) www.indiandentalacademy.com Occlusal Adjustment Location Of teeth
  72. 72. Interaction between STH, testosterone &LPM on condylar cartilage growth c4 c2 retrogn M grw rotation www.indiandentalacademy.com c3 progn
  73. 73. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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