THEORIES OF GROWTH, PRINCIPLE, ASSESSMENT,.pptx

Growth theories, definition ,principles factors and growth assessment parameters

1. THEORIES OF GROWTH, PRINCIPLE, ASSESSMENT, & FACTORS INFLUENCING GROWTH presented by- DR.Bhumika daheriya

2. CONTENTS 1. Definition of growth. 2. Theories of growth. 3. Principles of growth. 4. Factors influencing growth. 5. Growth assessment parameters. 6. Conclusion.

3. DEFINITION OF growth The self multiplication of living substance. - J.S. Huxley Growth refers to increase in size. - Todd(1931) Growth refers to increase in size or number. - Proffit (1986)

4. THEORIES OF GROWTH As it is well known concept that growth is strongly influenced by genetic factors but we must not forget the role of environment on the same. The theories of growth need to be evaluated in order to understand the etiological process of malocclusion & dentofacial deformities & to learn the influence on facial growth. Some of the major theories that have been postulated are –

5. Genetic theory – Brodie(1941) Scott’s cartilaginous theory – Scott(1953) Sutural dominance theory – Sicher (1955) Functional matrix theory – Moss(1962) Van Limbrog’s concept – Von Limborg (1970) Cybernatics – Petrovic , Stutzman(1974) Other theories of growth are : Enlow’s expanding ‘V’ principle. Neurotropic process in orofacial growth.

6. Genetic theory/Genetic Blue Print (Brodie,1941) This theory had proposed that genes control all the functions of growth & development. Epigenetic regulation can determine the behavioural growth activities of certain tissues. Examples to support this theory – - This implies that such tissues don’t entirely govern their own differentiation; rather their growth is controlled by genetic influence. - Inheritance is polygenic in nature; predisposition of an individual to Class III malocclusion.

7. Examples against this theory – - Relationship b/w genotype & phenotype of man & apes. - Large biological differences observed b/w 2 species with similar karyotypes.

8. 2. Scott’s Hypothesis/ Cartilaginous Theory/ Nasal Septum Theory (Scott,1953) James Scott, an Irish anatomist proposed that cartilaginous nasal septum has features & occupies a strategic position that might cause the midface region to displace rather than the sutures. Because the cartilage is more pressure tolerant it has more capacity to push the nasomaxillary complex downward & forward, thus giving rise to nasal septum theory. Therefore, this theory states that determinant of craniofacial growth is by growth of cartilages.

9. Examples to support this theory – - Although there is no cartilage in maxilla, there is a cartilage in nasal septum & this nasomaxillary complex grows as a unit. - Removal of nasal septum lead to midfacial deformities. Examples against this theory – - Mandibular condylar cartilage doesn’t grow in culture showing that there are some cartilages that are not growth centres but are just Sites of growth. - In case of injury mandibular condyle resorbs but if it is the growth stimulator, then it should grow back after injury.

10. 3. Sutural Dominance Theory/ Sicher’s Hypothesis (Sicher,1955) Sicher proposed that sutures cause most of craniofacial growth & to support this theory , he conducted some experiments using vital dyes. He said that primary event was proliferation of connective tissue b/w 2bones leading to appositional growth. Sicher felt that connective tissue in sutures of vault & nasomaxillary complex produced forces that separate the bones & cause expansion .

11. Examples to support this theory – - If sutures are pulled apart bone fills in & if sutures are compressed, then there is impeded growth. Examples against this theory – - Presence of forces triggers bone resorption & not deposition. - Growth can be seen in cases of untreated cleft palate patients even in Absence of sutures. - Thus, we can conclude that sutures are not primary determinants of growth & are just growth sites.

12. 4. Functional Matrix Theory/ Moss Hypothesis ( Moss ,1962) This theory was introduced by Melvin Moss based on functional cranial component by Van der klaaus . This theory claimed that the control for growth was not in cartilage or bone but in adjacent of soft tissues. He theorizes that growth of face occurs as a response to functional needs & is mediated by the soft tissues in which jaws are embedded. The functional matrix hypothesis claims that the origin, form, position, growth & maintenance of all skeletal tissues & organs are always secondary, compensatory, & morphologically prior events or processes that occurs in specifically related non skeletal tissues, organs or functioning spaces.

13. A large number of functions are carried out independently in craniofacial region (respiration, olfaction, hearing, chewing, etc.) Each of these is carried out by a functional cranial component which can be divided into functional matrix & skeletal unit.

14. Functional cranial component Functional matrix Skeletal unit Periosteal matrix Capsular matrix Macroskeletal unit Microskeletal unit All nonskeletal Units adjacent to Maxilla Mandible Skeletal unit. Neurocranial capsule Orofacial capsule

15. Functional Matrix – this consists of teeth, organs, glands, muscles, nerves & vessels as well as non skeletal cartilages. It is divided into periosteal matrix & capsular matrix. Periosteal matrix - all non skeletal units adjacent to skeletal units. - act directly & actively upon their related skeletal units producing a secondary compensatory mechanism. 2. Capsular matrix – a) Neurocranial capsule : b/w skin & dura mater. - Act indirectly & passively upon their related skeletal units producing a secondary compensatory translation. - Expansion of capsule takes place & the skeletal units move in expanded capsule thus giving translative growth without deposition & resorption.

16. b) Orofacial capsule – surround & protect oronasopharyngeal space. - Volumetric growth of these spaces is the primary morphogenic even in facial growth. Skeletal Unit – may be comprised of bone, cartilage, or tendon. All skeletal tissues are related to a specific functional matrix that is all skeletal tissues are associated with a single function. - It is divided into :

17. a) Microskeletal Unit – bones consisting of number of skeletal units . - When a combination of several bones make up this unit is called micro- skeletal unit like mandible. b) Macroskeletal unit – when there is a contribution of parts of many adjacent bones such a unit is called macroskeletal unit like maxilla. Examples to support this theory – - Growth of cranial vault is directly a response of growth of brain. Examples against this theory – In hydrocephalic patients, the sites of brain is small but the cranial vault is bigger.

18. 5. VAN LIMBORG’S CONCEPT ( VAN LIMBORG’S, 1970) According to him, all the previous theories were not complete & acceptable but each had some elements of significance that can’t be denied. This made him to postulate multifactorial theory -

19. Genome Intrinsic genetic factor Epigenetic factor genetic control of skeletal units. Local General Environment Local factors General factors nongenetic factors nongenetic factors like habits, factors like muscle force. Nutrition, oxygen.

20. 6. CYBERNATICS (PETROVIC, STUTZMAN, 1974) Cybernatics is the science dealing with comparative study of operations of complex computers of nervous system. According to this theory, control of primary cartilage takes a cybernatics form of a command whereas control of secondary cartilage is comprised of secondary cartilage is comprised of indirect & direct effects of cell’s multiplication.

21. 7. NEUROTROPISM (BEHRENT, MOSS,1976) The physiology of neurotropism is based on the fact that nervous system apart from conducting efferent & afferents is also concerned with integrity of body structures. Nerve control of skeletal growth by transmission of a substance through its axons is called neurotropism.

22. 8. ENLOW’S EXPANDING ‘V’ PRINCIPLE This is the most basic & useful concept of growth . Many facial & cranial bones have V-shaped pattern of growth & the expansion of these occurs along the ends of V as a result selective bone resorption & deposition. The pattern of growth is such that there is deposition along the inner side & wide ends of V & resorption on the outer aspect. Some of the bones which grow according to this pattern are end of long bones, base of mandible, mandibular body & palate.

23. Enlow’s Counterpart Principle – - This states that growth of facial or cranial part relates specifically to other structural & geometric counterparts in face & cranium. Body part & their geometric counterparts – 1. Nasomaxillary complex = Anterior cranial fossa. 2. Maxillary arch = Mandibular arch. 3. Bony Maxilla = Corpus of mandible. 4. Maxillary Tuberosity = Lingual tuberosity.

24. PRINCIPLES OF GROWTH Bone grows by adding new bone on one side of bony cortex & taking it away from the other side due to which bone drift occurs. The inner & outer surface of bone are covered with mosaic type appearance of growth fields, which can be resorptive or depository. If bone is resorptive on one side then it will be depository on other. Bone has 2 layers : endosteal & periosteal. Control of growth is done by the soft tissue matrix present around the bone. The various growth sites don’t show same rate of growth. Remodelling is basic part of growth process. Growth process leads to primary or secondary displacement.

25. The human body doesn’t grow at the same rate throughout life. Different organs grow at different rates at a different amount & at different sites known as Differential Growth. Scammon’s growth curve for growth : Scammon’s proposed that the growth of different tissues & systems could be summerized in 4 patterns or curves of growth. - Body tissues namely lymphoid, general, neural, & genital grow at different rates at different times.

26. General tissue : exhibits ‘S’ shaped curve. Lymphoid tissue: increases rapidly in late childhood & reaches almost 200% of its adult size. Neural tissue: grows very rapidly & reaches adult size by 6-7yrs. Genital tissue: this shows negligible growth until puberty but, grows rapidly on reaching puberty till adult level is achieved.

27. General tissue : the general curve describes the the growth of the body as whole & most of its parts – growth pattern of stature, weight & most external dimensions of body. This consists of bones, muscles, & other organ systems. -These exhibits ‘S’ shapes curve with rapid growth upto 2-3yrs of age followed by a slow phase till 10yrs. Then growth again enters rapid phase in the 10 th yr & continues till, terminating about 18-20yrs. 2. Neural tissue : the neural curve characterizes the growth of brain, nervous system & associated structures(eyes, upper face, & parts of skull). -These tissues experience rapid growth early in postnatal life, so that about 95% of total increment in size of CNS b/w birth & 20yrs is already attained by about 7yrs of age.

28. 3. Lymphoid tissue : lymphoid curve describes the growth of lymph glands, thymus gland, appendix & lymphoid patches in intestine. These tissues are involve in general with child’s developing immunological capacities, including resistance to infectious disease. It increases rapidly in late childhood & reaches almost 200% of its adult size. This is due to fact that children are more prone to infection. By 18 yrs the lymphoid tissue undergoes involution. 4 . Genital tissue : genital curve characterizes the the growth pattern of primary & secondary sexual characters. This shows negligible growth until puberty but, grows rapidly on reaching puberty till adult level is achieved.

29. Growth pattern, Variability & Timing concept : The physical arrangement of the body at any one time is a pattern of proportioned parts. It can be seen as the overall change in body proportions that occur during normal growth & development. Primary Concept = in fetal life at about 1/3 rd month of intrauterine development, the head takes up almost 50% of total body length. -The cranium is large relative to face & represents more than half of total head, whereas the limbs are still rudimentary & the trunk is underdeveloped. -By the time of birth, trunk & limbs have grown faster than head & face so that the proportions of entire body devoted to head has decreased by 30% . -There is more growth of lower limbs than upper limbs during postnatal life. This means there is an axis of increased growth extending towards feet. This is k/a Cephalocaudal Gradient Growth.

30. Second Concept = variability -Since everybody is not alike it is very difficult but, very imp. to decide whether an individual is merely at the extreme level of normal variation or falls outside the normal range. Final Concept = Timing -Variation from timing arises because the same event happens for different individuals at different times. - Eg :- some children grow rapidly & mature early thereby being on the high side of developmental charts.

31. FACTORS INFLUENCING GROWTH Genetic factors. Extracranial & Intracranial pressure. Maternal factors. Socioeconomic factors. Nutrition. Muscular function. Growth factors. Race. 9. Illness. 10. Climate & seasonal effect. 11. Adult physique. 12. Exercise. 13. Family size & birth order. 14. Secular trend. 15. Psychological disturbance. 16. Hormonal factors.

32. 1. Genetic factors :- Genetic control influence the size of organism to a great extent & the rate of onset of growth event. Bayley emphasizes the resemblance of the child to the parent in stature & in performance becoming ever closer with increasing growth thus indicating the genetic background size of newborn baby. 2. Extracranial & Intracranial pressure :- Any factor affecting physical growth is expected to be associated with effect on size & shape of cranial vault. Eg :- raised intracranial pressure during infancy results in an increased cranial circumference; if pressure is longstanding sutural margin develop interdigitation with spiky appearance & so when sutures are closed it leads to excessive resorption of inner table of cranial vault.

33. 3. Socioeconomic factors :- These factors play role as a growth factor. Children living in favourable socioeconomic conditions tend to display different types of growth, & show variations in timing of growth. 4. Nutrition :- Raw materials for growth & biosynthesis are essential for normal growth. Lack of nutrition delays growth, affects size of body part, & texture of some tissues. Eg :- iodine deficient diet retards craniofacial growth.

34. 5. Hormones :- Group I - Hormone influencing skeletal bone growth. Growth hormone, Insulin, Thyrotropic hormone. They stimulates production of proteins. Excess or deficiency may cause dwarfism, cretinism, acromegaly, or gigantism. Group II – Hormones responsible for ossification of long bones. Parathormone. It increases bone resorption by intensifying osteoclastic activity & facilitates conversion of vitamin D & calcium absorption.

35. Group III – Hormones responsible for pubertal growth spurt. Androgen, Progesterone, Estrogen . -These hormones are responsible for development of secondary sexual characteristics, Sex differentiation, Making muscle bulkier, Growth of female genital tract & breasts, Behavioural changes on puberty. Group IV –Miscellaneous. - Prolactin. (secretion of milk).

36. 6. Muscular function :- The close relation b/w muscles & bone growth is seen due to the fact that muscles influence the growth both as tissue affecting vascular supply & as a force element. The increased loading of jaws leads to increased sutural growth & bone apposition resulting in transverse growth of maxilla & broader base of dental arches. 7. Growth factors :- These are peptides that transmit signals within & b/w cells & play a comprehensive role in modulation of tissue growth & development. These factors regulate a number of mechanism like gene regulations, migration & differentiation.

37. 8. Race :- There are various factors like nutrition & environment that may lead to difference in growth in different races. 9. Illness :- Any systemic diseases or prolonged debilitating disease has a profound affect on the growth process of a child. 10. Exercise :- Exercise is useful for fitness & increase in muscle mass but has no relation with linear growth.

38. 11. Climate & Seasonal effect :- Large amount of skeletal variations are associated with seasonal & climatic variations & these may affect the growth rate & weight of newborn. Growth also varies according to seasons like it is faster in springs, & summers & comparatively slower in winters. 12. Adult physique :- There exists a definite relation b/w physique & development according to somatotypes. Eg :- tall women mature at a later age as compared to the other women of their age groups.

39. 13. Family size & Birth order :- In a family, there is always exist a difference b/w the various members of a family with respect to their individual sizes, maturation level & intelligence. Data also supports the fact that 1 st borns usually weigh less at birth, have less stature & higher IQ. 14. Secular trend :- Size & maturational changes in large population can be shown to occur with time. Eg :- 15yr old boys nowadays are 5inches taller than 15yr old 50yr back.

40. 15. Psychological Disturbance :- These can lead to inhibition of growth depending upon the severity of psychological disturbances. This is due to the fact that in stressful conditions children will display inhibition of growth hormone.

41. Growth Assessment Parameters The correct knowledge of facial age, developmental age, chronologic age etc. is very necessary for formulating treatment plan. Various assessment parameters are – i ) Somatotypic Age. ii) Chronologic Age. iii) Height & Weight Age. iv) Sexual Age. v) Facial Age. vi ) Skeletal Age.

42. i ) Somatotypic Age : Sheldon defined somatotype by a series of 17 anthropometric measurements & is not related to nutritional status. Endomorph – stocky abundant subcutaneous fat, digestive viscera are highly developed. Mesomorph – upright, sturdy, athletic, muscle bone, & connective tissue predominate. Ectomorph – tall, thin & fragile with minimal subcutaneous fat & muscle tissue. # In terms of chronologic age Ectomorph is a late maturer whereas Endomorph is an early maturer . # Somatotype may tell about child’s developmental pattern but it is not an accurate predictor of growth.

43. ii) Chronologic Age : This is the most easily determined developmental age parameter, which is figured from child’s date of birth. The might be difference in children of same chronologic age due to difference in thing of maturation, diseases, & various environmental factors. Although it is easy to determine but, chronologic age is not accurate predictor of growth.

44. iii) Height & Weight Age : Height has been commonly employed as determinant of developmental age. The standard growth curve commonly employed to characterize a child’s height compared, to that of children of same chronologic age is used to assess developmental age. Growth of all children upto puberty follows nearly the same curves but the difference in adolescent growth spurts change the growth curves during & after puberty greatly. Height of each child is related to genetic as well as environmental factors. Weight & age are corelated well with each other, so height or weight age alone is poor indicator, if growth or developmental age owing to a large number of variation.

45. Clinical implications of this age are that earlier the spurt occurs shorter it is & therefore late maturers are taller which also accounts for the difference in males & females.

46. iv) Sexual Age : At puberty differential hormones actions yield characteristic body changes. These changes are classified into 5 stages according to Reynolds EL, Wines JV & Tanner JM.

47. v) Facial Age : Aim is to identify whether they are on their own facial growth curve & to use this as a predictor of growth. Various methods used for measurement of facial age & prediction of craniofacial growth are anthropometric measurements, facial growth velocity curve & cephalometric radiographs.

48. Vi) Skeletal Age : Skeletal age is the very important aspect of assessing developmental age of child as skeletal age was found to more highly correlate with the developmental age than any other parameter. Any of the skeletal growth centres can be used for skeletal age assessment but hand & wrist have been most commonly used for assessment of pubertal maturation. Advantages – a)Readily recognisable stage of ossification b)Regular sequence of developmental changes occurring from birth to childhood. c)Characteristic pattern of progression of ossification of epiphyseal centres can be identified.

49. Hand wrist Radiographs – Handwrist region is made up of numerous small bones which show a predictable & scheduled pattern of appearance, ossification & union from birth to maturity. Thus by comparing a patients’ radiograph with the standards that represent different skeletal ages, we find out the skeletal maturation status of that individual. Anatomy of hand-wrist radiographs : this region is made up of 4 groups of bones i ) Forearm. ii) Carpals. iii) Metacarpals. iv) Phalanges.

50. APA view of radiograph of left hand & wrist are considered to be standard for determining skeletal age. For determination of skeletal age, one compares the radiograph of left hand-wrist region of the child with the atlas standard beginning with same sex & nearest chronological age. The hand-wrist standard that superficially resembles the child’s radiograph is chosen for more detailed comparison. All the bones are assessed & each center is given a skeletal age of standard. An overall age then determined.

51. CONCLUSION Growth is always an increase in size. Functional matrix theory given by Melvin Moss explains that the origin, form, position, growth & maintenance of all skeletal tissues & organs are always secondary, compensatory & necessary response to chronologically & morphologically prior events or processes that occur in specifically related nonskeletal tissues, organs or functioning space. All the factors of growth are equally responsible for growth & development. Chronological age is the most obvious & easily determined age parameter, figured from child’s date of birth Skeletal age assessment done by Hand-wrist Radiograph is the most reliable method of age assessment.

52. REFERENCE Nikhil Marwah (Textbook of Paediatric Dentistry) 4 th Edition. Shobha Tandon (Textbook of Paedodontics ) 3 rd Edition. Bhalajhi (Textbook of Orthodontics) 5 th Edition.