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Post Natal growth and Devolopment Of Cranio Facial Complextheory class (1).pdf
- 1. Post Natal Growth andDevelopment of Craniofacial Complex
- 2. CONTENTS • Introduction • Factorsaffecting Physical Growth • Post natal cranial development • Concepts of growth • Theories of Growth and Development • Factors influencing growth & development • Mechanisms of skeletal growth • Osteogenesis • Cranio facial Growth Principles
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- 4. MECHANISMS OF SKELETAL GROWTH •Bone is a specialized structure of mesodermal origin, forming the structural framework of the body. • Normal bone contains 32-36% of organic matter. • Main mechanisms are: 1. Bone deposition and resorption 2. Cortical drift 3. Displacement
- 5. RESORPTIVE AND DEPOSITORY FIELDS •The Outside and the Inside surfaces of the bone is completely blanketed by Mosaic like pattern of GROWTH FIELDS. • About half of the External Periosteal surface has a characteristic arrangement of Resorptive Fields and a characteristic pattern of Depository Fields cover the remainder. ▪ Resorption /going inside ▪ Deposition /going outside
- 6. • If agiven Periosteal area has a resorptive type of field the opposite inside (endosteal) surface of the same area has a depository field. • Conversely, if the periosteal field is depository the endosteal field on the opposite side of the cortex is usually resorptive. Resorption>Deposition = Bone Loss
- 7. BONE REMODELLING • Remodelingis a process of reshaping and resizing each level (chip) within a growing bone as it is relocated sequentially into a succession of new levels. • A bone cannot simply grow by new addition keeping the same form. • The results are always dependent on: • Pattern of the fields of resorption & deposition • Boundaries between growth fields • Differential rates and amounts of deposition and resorption throughout each field. • Timing of the growth activities in various growth fields
- 8. MOVEMENT OF GROWTH- DRIFT ▪ Drift / Relocation : is sequential movements of component parts as a bone enlarges by remodeling of it’s own osteogenic tissue. ▪ The surface that faces towards the direction of movement is Depository. ▪ The Opposite surface facing away from the Growth direction is Restorative. ▪ If Resorption = Deposition the thickness of the cortex remains constant
- 9. MOVEMENT OF GROWTH- DISPLACEMENT ▪ Displacement : It is the physical movement of the whole Bone as a Unit. ▪ During the displacement process the whole bone is carried by mechanical force as it simultaneously enlarges. ▪ Two types:- 1. Primary displacement 2. Secondary displacement
- 10. PRIMARYDISPLACEMENT ▪ Happens/Occurs whenthe bone gets displaced as a result of it’s own growth. ▪ Provides the space within which the bone continues to enlarge. ▪ It is called primary because space comes first then bone fills the gap. Thus movement is needed first then the bone deposit back there to keep growing. E.g. – the maxillary sinuses get bigger as an individual grows from the age of 15 to 25. ▪ Amount of primary displacement = Amount of new bone formed.
- 11. SECONDARYDISPLACEMENT ▪ If thebone gets displaced as a result of growth and enlargement of adjacent bony structures , it is called secondary displacement. ▪ This can lead to a Domino Effect as the growth can be passed on from region to region to produce a secondary effect in areas quite distant. The effects can be cumulative.
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- 13. Factors affecting Physical Growth •Heredity • Nutrition • Illness • Race • Socio-economic factors • Family size and birth orders • Secular trends • Climatic and seasonal effects • Psychological disturbances • Exercise
- 14. POST NATAL CRANIOFACIAL DEVELOPMENT •The development of the skull, comprising of both the cranium and the mandible is a blend of morphogenesis and growth of three main entities arising from neural crest and paraxial mesodermal tissues. 1. Desmocranium 2. Chondrocranium 3. Viscerocranium
- 16. CRANIAL VAULT ▪ Vault’sgrowth Pace = Growth of Skull ▪ Utilizes Suture system (sutures & sutural junctions) & Remodelling primarily around sutures ▪ Intramembranous Sutural Growth System replaces the 6 fontanelles present at birth. ▪ Post natal growth results in narrowing of sutures and elimination of fontanelles. 1. Anterolateral – closes 3 months after birth 2. Posterolateral – closes during 2nd year 3. Posterior – closes 2 months after birth 4. Anterior – closes during 2nd year
- 17. Growth ofcalvarial bones is a combination of sutural growth, surface apposition and resorption (remodelling) and centrifugal displacement by the expanding brain. The bones of the newborn calvaria are unilaminar and lack dilpoe. Growth till 4th year: predominantly sutural growth Growth after 4th year: Surface apposition
- 18. BASICRANIUM/CRANIAL BASE • Expansion ofcranial base takes place as a result of: 1. The growth of the cartilage remnants of the chondrocranium that persists between the bone. 2. The expansive forces that amanate from the growing brain, displacing the bones at the suture lines.
- 19. Closureofsynchondroses • Intra ethmoidaland intra sphenoidal- before birth • Intra occipital- <5 years • Spheno ethmoidal- 6 years • Spheno occipital- 13-15 years Spheno occipital being the major contributor postnatally, persisting into early adulthood. In addition to proliferative synchondrosal growth, the cranial base undergoes selective remodelling by resorption and deposition.
- 20. PARANASAL SINUSES • Maxillary,Sphenoidal, Frontal and Ethmoidal • The sinuses enlarge into bone (secondary pneumatization) from the initial small outpocketings, always retaining communication with the nasal fossae through ostea.
- 22. PALATE • Post natalossification: Hard palate: intra membraneous ossification Soft palate: no ossification • At birth: Length=Breadth of hard palate • Post natal increase in palatal length is due to appositional growth in the maxillary tuberosity region and to some extent at the transverse maxillo palatine suture. • Growth at mid palatal suture: Ceases between 1-2 years but no synostosis occurs. Posterior > Anterior
- 23. • Lateral appositionalgrowth – until 7 years of age • Posterior appositional growth - late childhood • The lateral process helps to form the antero posterior palatal furrow – well marked in the first year which flattens out into palatal arch after 3-4 years.
- 24. TONGUE • Lingual swellings+ Tuberculum Impar Anterior 2/3rd • Hypobranchial eminence Poserior 1/3rd • Entire tongue is within the mouth by birth. • Posterior 3rd descends into pharynx by 4 years of age. • Tongue doubles in length, breadth and thickness reaching near maximal size by about 8 years of age.
- 25. TEMPERO MANDIBULAR JOINT • Meckel’scartilage plays no part in the development of condyles but contributes in the formation of definitive TMJ. • At birth : mandibular fossae is almost flat and bears no articular tubercle.
- 26. • Only aftereruption of permanent dentition at 7 years – articular tubercle begin to become prominent. • Its development accelerates until 12 years of age. • In post natal life, as the articular tubercle grows, the disk changes in shape, becomes more compact, less cellular and more collagenous. • The mature disk is avascular and aneural in its central portion but is filled with vessels, nerves and elastic fibres posteriorly attaching it to the squamo tympanic suture.
- 27. NASOMAXILLARY COMPLEX ▪ Elongationof the frontal lobes causes elongation of the anterior cranial base & displaces midface forward. ▪ Deposition on the oral cortical plate and resorption on the nasal cortical plate causes the palate to grow downward. ▪ The surface below the vertex of Reversal Line is resorptive. Thus the anterior part of the maxilla moves inferiorly with the palatal vault
- 28. • The Nasomaxillarycomplex increases In overall size while being displaced inferiorly
- 29. MAXILLA ▪ Bone Depositionoccurs at the Posterior surface of maxillary tuberosity , endosteal anterior surface , and periosteal lateral surface of the Zygomatic process. ▪ Resorption occurs on the opposing surface. As a result the maxillary tuberosity grows In a posterior direction and the zygomatic arch grows posteriorly and laterally. ▪ Premaxilla exibits downward growth as Deposition occurs at it’s Endosteal surface and resorption at it’s periosteal surfaces.
- 30. PRIMARY & SECONDARYDISPACEMENT OF MAXILLA ▪ The maxilla increases in length & displaced anteriorly simultaneously. Both changes take place in the same amount. ▪ Secondary displacement of the maxilla results from enlargement of the middle cranial fossa.
- 31. MANDIBLE ▪ Some ofthe main areas of deposition are the posterior surfaces of the rami and at the condyles. ▪ Resorption occurs on the opposing surfaces on the anterior surfaces of rami & angle of the mandible ▪ Result is growth in a posterior and superior direction
- 32. REMODELLING OF THE MANDIBLE Themandibular corpus lengthens by an amount that equals the enlargement of the maxillary arch which is it’s structural counterpart The body of the mandible elongates posteriorly due to resorption and remodeling of the anterior border of ramus.
- 33. ▪ The remodellingprocess of the ramus must take place towards the posterior. The body of the mandible becomes lengthened. Part of condyar head is converted to neck of condyle ▪ Remodelling is based on relocation & is a secondary result of displacement process.
- 34. PRIMARY DISPLACEMENT MANDIBLE • Thisprocess is stimulated by the posterior growth of the condyles & the posterior border of the ramus. Posterior depository & anterior resorptive activity are equal • Elongation of the mandibular corpus and the anterior displacement of the mandible take place simultaneously.
- 35. SECONDARY DISPLACEMENT MANDIBLE • Themandible is displaced forward & downward by the enlargement of the middle cranial base • As the middle cranial fossa growth Is mostly located anterior to the condyles, secondary displacement in the mandible is not as pronounced as in the maxilla.
- 36. HORIZONTAL GROWTH OFRAMUS OF MANDIBLE ▪ Ramus is displaced posteriorly until it’s horizontal dimension corresponds to those of middle cranial fossa. Simultaneously condylar Growth which takes place diagonally upward and backward causes anterior displacement of the mandible at the same time ▪ This compensates for upper and lower jaw discrepancy and displaces the occlusal plane inferiorly.
- 37. AGE CHANGES INTHE MANDIBLE At Birth - 1800 0-6 yrs. - 1400 15-30 yrs. – 90 - 1100 Age changes in location of mandibular foramen • 3 yrs …….. 4.12 mm below (mandibular occlusal plane) • 9 yrs …….. At level • Adult ……. 4.16 mm above • Old age ….. Further increases
- 38. Concepts of Growth 1.Concept of Normality • Normal refers to that which is usually expected, is ordinarily seen or is typical. • Craniofacial growth normality changes with age. What normally is seen or expected for a particular age group may not be necessarily normal for a different age group. 2. Rhythm of Growth • Human growth is not a steady and uniform process wherein all parts of the body enlarge at the same rate and increments of one year are equal to that of preceeding or succeeding year.
- 39. • First waveof growth – 5th or 6th year • Slower increase in boys about 10th-12th year and in girls by 10th year • Accelerated growth corresponding to adolescence completed in boys about 16th-18th year and in girls about 14th-16th year • Final period of slow growth completed by 25th year in boys and 18th – 20th year in girls
- 40. 3. Growth Spurts •The sudden increase in growth in periods when a sudden acceleration of growth occurs. • Due to physiological alteration in hormonal secretion. a) Just before birth b) One year after birth c) Mixed dentition growth spurt – boys:8-11 years and girls:7- 9 years d) Pre pubertal growth spurt – boys:14-16 years and girls: 11- 13 years
- 41. 4. Differential Growth Thehuman body does not grow at the same rate throughout the life. Different organs grow at different rates to a different amount and at different times. • Scammons growth curve • Cephalo caudal gradient of growth
- 44. THEORIES OF GROWTHAND DEVELOPMENT • Developmental theories provide a set of guiding principles and concepts that describe and explain human development.
- 45. GENETIC THEORY ▪ Simplysaid that ‘Genes determine all’ ▪ It says growth is controlled by genetic influence and is pre planned. ▪ One of the earliest theories to be put forward but general assumptions were found to be flawed.
- 46. SUTURAL THEORY/ SICHER’S HYPOTHESIS ▪Sicher believed that Craniofacial Growth occurs at sutures. ▪ He said: the primary event in sutural growth is the proliferation of the connective tissue between the two bones. ▪ He felt connective tissue between these sutures produced forces which separated the bones. ▪ He stated about the mandible that it can grow both interstitially as epihyseal plates and appositionally as bone grows under periosteum.
- 47. ▪ Points raisedagainst this theory: ▪ When an area of suture is transplanted to another location , the tissue doesn’t continue to grow thus lacking innate growth potential. ▪ Growth takes place in untreated cases of cleft palate even in absence of sutures.
- 48. CARTILAGENOUS THEORY/ SCOTT’S HYPOTHESIS ▪Put forward by James Scott. ▪ According to Scott, the nasal septal cartilage is the PaceMaker for Growth of the entire NasoMaxillary Complex ▪ According to him, intrinsic growth controlling factors are present in cartilage and periosteum with sutures only being secondary. ▪ He considered mandible as the Diaphysis of a long bone bent into a Horse Shoe shape with Epiphysis removed so that there Is cartilage constituting half an epiphyseal plate at it’s ends which are represented by condyles.
- 49. Pointsinfavourofcartilaginoustheory 1. In manybones cartilage growth occurs and bone merely replaces it. 2. If a part of the Epiphyseal plate is transplanted on to a different location, it will continue to grow in the new location, thus indicates innate potential for growth. 3. Nasal septal cartilage also shows innate growth potential on being transplanted to another site. 4. Experiments on rabbit involving removal of nasal septal cartilage demonstrated retarded mid-face development.
- 50. FUNCTIONAL MATRIX THEORY •By Melvin Moss • It attempts to comprehend the relationship between form and function. • A number of relatively independant functions are carried out in the cranio-facial region of the human body. Some of the functions like respiration, olfaction, vision, hearing, balance, chewing, digestion, swallowing, speech and neural integration are carried out.
- 51. Concept: • The origin,form, position, growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related non skeletal tissues, organs or functioning spaces (functional matrices)
- 52. Functional Cranial Component •The Skeletal Unit bone, cartilage, tendinous tissue a. Micro skeletal units - when a bone is comprised of several contiguous skeletal units. Eg: Maxilla, mandible b. Macro skeletal units - when adjoining portions of a number of neighbouring bones are united to form a single cranial component. Eg: the entire endocranial surface of the calvarium. The Functional Matrix Consists of muscles, glands, nerves, vessels, fat, teeth and functioning spaces a. Periosteal Matrices • Act directly and actively upon their related skeletal units • Includes muscles, blood vessels, nerves, glands, etc b. Capsular Matrices • Act indirectly and passively on their related skeletal units producing a secondary translation in space.
- 53. Neuro-cranial complex 1. Thecovers consist of skin and dura mater 2. Surrounds and protects the nuero- cranial capsular functional matrix(brain, leptomeninges and CSF) Oro-facial complex 1. The covers consist of skin and mucosa 2. Surrounds and protects the oro- nasopharyngeal spaces 3. The growth of the facial skull is influenzed by the volume and patency of these spaces
- 54. The functional matrixhypothesis revisited Where the original FMH version offered only verbal descriptions of periosteal matrix function and skeletal unit response, the addition to the FMH have the concepts of • Mechanotransduction • Osseous connected cellular network • The genomic thesis • The epigenetic antithesis
- 55. VAN LIMBORG’S THEORY ▪Multifactorial theory put forward by Van Limborg in 1970. ▪ He divided factors controlling skeletal morphogenesis into 5 groups: 1. Intrinsic Genetic factors. 2. Local Epigenetic factors. E.g. Brain, eyes 3. General Epigenetic factors. E.g. GH, sex hormones 4. Local Environmental factors. E.g. Habits, Muscle force 5. General Environmental factors. E.g Nutrition, Oxygen
- 56. ▪ The viewsexpressed can be summarised as : 1. Chondrocranial growth is controlled mainly by intrinsic genetic factors. 2. Desmocranial growth is controlled by a few intrinsic genetic factors. 3. The cartilagenous part of the skull must be considered as Growth centre. 4. Sutural growth is mainly controlled ye influences originating from the skull cartilages and the from adjacent skull structures. 5. Periosteal growth largely depends on growth of adjacent structures. 6. Sutural & periosteal growth are additionally governed by local non genetic environmental Influence.
- 57. THE ENLOW’s ‘V’PRINCIPLE • According to this concept, bone is deposited in the inner surface of the V shaped bone & resorbed on the outer surface. Thus the ‘V’ moves away from it’s narrow end & enlarges in overall size. • Longitudnal section through the right & left coronoid process. The processes are enlarged during growth in accordance to the V principle. Bone is deposited on the inner lingual surfaces & resorbed from the opposing buccal surfaces. The structures increase in height & the tips of the coronoid process diverge further & their bony bases converge. Vertical Expansion
- 58. • The mandibularconfiguration of a 5 yr. old and an adult as viewed from above. • The mandible as viewed from above including a horizontal section through the base of the coronoid process. • Bone is deposited on the lingual side of the mandibular structures upto the ramal level. Thus the coronoid process move despite bone depositition on the inner surface in the backward direction, & the posterior parts of the mandible widen. Horizontal Expansion
- 59. ENLOW’S COUNTERPART PRINCIPLE • Itstates that the growth of any given facial or cranial part relates specifically to other structural and geometric "counterparts" in the face and cranium. • These are regional relationships throughout the whole face and cranium. If each regional part and its particular counterpart enlarge to the same extent, balanced growth occurs. • Different parts and their counterparts: 1. Nasomaxillary complex-anterior cranial fossa 2. Horizontal dimension of the pharyngeal space-middle cranial fossa 3. Middle cranial fossa-breadth of ramus 4. Maxillary and mandibular arches 5. Bony maxilla – body of mandible 6. Maxillary tuberosity- lingual tuberosity
- 60. NEUROTROPHIC GROWTH PROCESS INORO-FACIAL GROWTH • Neurotrophism is a non-impulse transmitting neural function that involves axoplasmic transport and provides for long term interaction between neurons and innervated tissues. • The different types of neurotrophic mechanisms are: 1. Neuro-epithelial trophism: Epithelial mitosis and synthesis are neurotrophically controlled. The normal epithelial growth is controlled by release of certain neurotrophic substances by nerve synapses. If this neurotrophic process is lacking or defficient, abnormal epithelial growth, oro-facial hypoplasia and malformation, etc occurs.
- 61. 2. Neuro-muscular trophism:Embryogenic myogenesis is independant of neural innervation and trophic control. Approximately at the myoblast stage of differentiation the neural innervation is established without which further myogenesis cannot continue. 3. Neuro-visceral trophism: The salivary glands, fat tissue and other organs trophically related, at least in part.
- 62. FACTORS INFLUENCING GROWTH& DEVELOPMENT 1. GENETIC FACTORS 2. NEURAL CONTROL 3. HORMONAL CONTROL 4. NUTRITION 5. SECULAR TREND 6. SEASON & CIRCARDIAN RHYTYM 7. DISEASE
- 63. GENETIC FACTORS ▪ Thepotential for growth is genetic. ▪ Both magnitude and timings are located in the genes. ▪ Actual outcome depends on interaction between genetic potential and environmental influences. ▪ Genetic factors play a major role in male-female growth differences. ▪ E.g. delayed growth in males because of Y chromosome. ▪ E.g. Klinefelters vs Turners syndrome.
- 64. NEURAL CONTROL ▪ Itis thought that growth centre exists in region of hypothalamus. ▪ During the first 2 years of post natal growth the neural system has got the child on it’s pre determined genetic curve. ▪ After birth those children destined to become large, experience a growth activity which levels off during the first 2 years of life. ▪ It is thought that hypothalamus sends message to the pituitary through an elaborate feedback mechanism. ▪ Evidence is that P.N.S plays a role in growth mechanism exhibiting a Nutritive or trophic effect. ▪ E.g : if a somatic nerve is denervated, it atrophies.
- 65. HORMONAL CONTROL ▪ Thetiming sequence of maturation is definitely under hormonal control. ▪ Probably the endocrine glands influence Growth. GROWTH HORMONE • Detected at the end of 2nd fetal month, produced by Anterior lobe of Pituitary. ▪ Not very essential in fetal growth but essential in growth from birth onwards. ▪ Maintains the normal rate of protein synthesis and inhibits synthesis of fat and oxidation of carbohydrates ▪ Necessary for proliferation of cartilage cells and it’s effect ceases as epiphysis closes.
- 66. HORMONAL CONTROL T.S.H. /THYROID STIMULATING HORMONE • Produced by the anterior lobe of pituitary. • Thyroxine & Thiodonine both stimulate general metabolism & are important for growth of cells, bones, teeth & brain. • Iodine deficiency reduces production of these hormones. Deficiency in childhood would result in a mentally retarded dwarf. • Thyroid secretion reduces from birth to adolescence & then increases for the duration of adolescence spurt. • Bone and dental growth from birth to adolescence spurt are under thyroid control.
- 67. ANDROGENS • Produced bythe Suprarenal cortex which is controlled by ACTH produced in the pituitary • They play a major role in adolescent growth in both the sexes. • Gonadotropin hormone stimulates the production of Testosterone in males and estrogen & Progesterone in females. • Testosterone stimulates growth of muscle , bone and R.B.C.s & secondary sexual characters in males. • Ovarian secretion have less generalised effect on growth but do control secondary sex changes including alterations in body shape. • At Adolescence bones fall apart under increasing influence of gonadal hormones.
- 68. ▪ Parathyroid secretions, Parathormone & Calcitonin control the amount of calcium in the blood and it’s interchange in calcium with the bone. ▪ The 2 hormones are mutually antagonistic affect bone growth.
- 69. NUTRITION ▪ Sufficient intakeof nutritious food is essential for normal growth. ▪ Under-nutrition tends to accentuate normal differential growth of body tissues. ▪ Growth of teeth takes precedence over bone growth. Bones grow better than soft tissues. ▪ Starvation alters composition of body. Protein is depleted & ECF is increased. ▪ All 9 Amino acids are essential for growth. Absence of any one results in disordered growth. ▪ Ca, P, Mn, Mg are essential for proper bone growth and tooth growth. ▪ Fe is needed for Heame production. ▪ Vit. A, D & C are required for proper growth of bones and connective tissue. ▪ Oxygen is essential for normal healthy growth. Stunted growth in children with heart defects ▪ Gross malnutrition affects craniofacial growth in humans.
- 70. SECULAR TREND ▪ Today’schildren are growing faster than children in the past. ▪ Probably this is the result of better balanced diet , reduced illness , & improved health care ▪ The adolescent growth is sooner now, So children although they are growing at a faster rate will stop growth sooner. ▪ Another feature is the progressive advancement of menarche that may be related to better nutrition.
- 71. SEASON & CIRCARDIANRHYTHM ▪ Growth is faster in the spring than in the autumn for height. ▪ Weight growth proceeds faster in the autumn than spring. ▪ There is evidence that growth in height and eruption of teeth is greater in night than daytime. ▪ The reason for this/these differences is probably related to fluctuations in hormonal release.
- 72. DISEASE ▪ Has similareffects like malnutrition. ▪ Females compensate better than males following illness. ▪ Diseases that slow growth probably have an effect of reducing growth hormone production as a result of increased release of cortisone during illness. ▪ Cartilage cell growth is stopped temporarily & is seen on x rays as a line of arrested growth. Similar lines can be found on teeth.