Pog

Orthodontics

1. Principles of Growth Dr. Priyal Billaiya

2. CONTENTS Introduction Growth & Development Terminologies Growth Pattern, Variability and Timing Methods of studying Growth Factors Affecting Growth Spurts Nature of Skeletal growth Conclusion References

3. History 594 – 593 BC – Solon . Divided Lifespan into 10 parts of 7 years period. Basis of 7 planets 460 BC – Hippocrates Stature and Strength is affected by AIR, Water and Place 384 – 322 BC – Aristotle – Mechanism of Growth 129 – 199 AD – Galen Used the term “ Genesis” 1728 – 1793 – John Hunter – Natural history of human teeth.

4. CEPHALIC & CAUUDAL LATERAL DORSO-VENTRAL

5. 1940 – Cohen determined 2 major reactions Governing factors Length or circumferential dimension Genetic Factor

6. Ref - Krogman WM. Growth Theory and Orthodontic Practice. Angle Orthodont . 1940; 10: 179-191

7. Introduction The current Orthodontics is about the early correction of malocclusion Maturational status can have considerable influence on diagnosis, treatment goals, treatment planning, and the eventual outcome of orthodontic treatment.

8. What is growth ? Change in Magnitude – Enlow Increase in size or number – Proffit S elf multiplication of living substance . - J.S. Huxley Increase in size, change in proportion and progressive complexity . - Krogman An increase in size . - Todd

9. Entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility. - Meridith Quantitative aspect of biologic development per unit of time . - Moyers Change in any morphological parameter which is measurable. - Moss

10. Negative Growth Concept Not always Enlargement Growth results in decrease in size. Thymus glands after puberty. Therefore growth may result in increase or decrease in size, change in form or proportion, complexity , texture

11. Development Biological development is a process of continuous changes occurring in a predetermined direction. It encompasses the normal sequential events between fertilization and death.

12. “ Development”, according to Todd, “Is progress towards maturity.” According to Proffit , “Is increase in complexity.” According to Moyers, “refers to all the naturally occurring unidirectional changes in the life of an individual from its existence as a single cell to its elaboration as a multifunctional unit terminating in death .”

13. According to Enlow , “ Maturational process involving progressive differentiation at the cellular and tissue levels” According to Salzmann, “ It is the sequences of changes from cell fertilization to maturity. It relates to cell division, growth, differentiation and maturation ”

14. Growth and Development Closely related , not synonymous William Proffit Growth is an anatomic phenomenon , whereas development is physiologic and behavioural . Todd Growth in an increase in size; development is progress toward maturity. Moyers Development = Growth + Differentiation + Translocation Ref - Proffit , Graber & Moyer

15. TERMINOLOGIES Growth Increase in size or number. ( Proffit ) Growth site A location at which growth occurs. ( Proffit ) Growth Center Location at which independent (genetically controlled) growth occurs. ( Proffit ) All growth centers are also sites, but the reverse is not true.

16. “Normal” – refers to the expected or typical. “ Morphogenesis” – “A biologic process having an underlying control at the cellular and tissue levels ”. “Differentiation” The change from generalized cells or tissues to more specialized kinds during development. The change in quality . “Maturation” Defined as the qualitative changes that occur with age. Translocation Change in position .

17. Differentiation Differentiation is the change from a generalized cell or tissue to one that is more specialized. A change in quality According to Todd Growth and development relies on influence of morphogenetic pattern; the threefold process works its miracles; self-multiplication, differentiation, organization - each according to its own kind! A fourth dimension is time.

18. Growth Pattern, Variability and Timing 3 Impotant concepts Pattern Variability Timing

19. Pattern ... implies predictability. Refers to the changes in spatial proportions over time Cephalocaudal gradient of growth Axis of increased growth extending from head to feet. Muscular and skeletal element grow faster than brain and CNS.

20. Cephalocudal Gradient of Growth HEAD TOWARDS FEET Head is 50% of body length Head is 30% Leg is 1/3 rd Head is 12% Leg is Half of Body length

21. Clinical Implication of Growth Pattern Morphological and Developmental aspect Prediction of Growth Facial Pattern – eg Class II (Morphological) Type of Growth – eg Vertical Growth Pattern (Developmental)

22. Variability ... deviation from usual pattern It is Nature’s Law No two individuals are identical (Except Monozygotic twins) Variation is response to environment

23. Variability Ref - Proffit

24. Concept of Normality Statistical Evolutionary Funtional Esthetic Clinical

25. Statistical Mean - an average value Median – value midway between greatest and smallest Mode – Most frequesnt measurement Standard Deviation – SD – A mathematical expression of distribution of individuals around mean.

26. Evolutionary All forms of life today have passed the critical test of survival. Abnormal forms which were unable to cope, have been lost Homeostasis with environment in order to adapt and survive Normal within a group is determined by culture Functional Esthetic

27. Clinical Based on tests and clinical evaluations Example – Length of Mandible and Maxilla according to age

28. Timing Same developmental events take place at different chronological age for different individual. Developmental Age Menarche as Reference Point Onset of Puberty is excellent indicator for skeletal maturity

29. Methods For Studying Physical Growth

30. Craniometry Involves measurement of skull found among human skeletal remains Dry skull Cross sectional Anthropometry Involves measuring skeletal dimensions on living individuals by using soft tissue points overlying these bony landmarks Study is longitudinal, where in the growth of an individual can be followed directly over a period of time with repeated measurement without damaging subject.

31.   Cephalometric Radiography Combines the advantage of both cranio and anthropometry Bony measurements as seen on the radiograph can be made over a period of time for the same individual Disadvantage: produces only two dimensional representation

32. Three Dimensional Imaging CBCT MRI CT scan

33. Vital staining: originated by John hunter in 18 th centuary Growth is studied by observing the pattern of stained mineralized tissues after the injection of the dyes into the animal. E.g. Alazarin was used for vital staining studies in animals. The gamma emitting isotope can be used to detect areas of rapid bone growth in humans.

34. Implant Radiographyused by : Bjork and co-workers• Inert pins made of titanium are inserted in bone anywhere in the skeleton including face and jaw. These pins are biocompatible super-imposing radiographs ( cephalograms in case of face) on the implants allow precise observation of both changes in position of bone relative to another and changes in external contour of the individual bone

35. Growth Data

36. Age Equivalence All individuals of given Chronological age , do not have same size, stage of maturation and development. Chronological Age – Years or months after birth Morphological Age Skeletal Age Dental Age Sexual Age

37. Morphologic Age: Is based on height & weight. This is determined, using growth charts for the particular population standards.

38. Skeletal Age A number of methods have been described to assess the skeletal maturity using hand-wrist radiographs . The following are the most commonly used methods: Atlas methods by Greulich and Pyle Bjork , Grave and Brown Method Fishman’s Skeletal Maturity Indicators Hagg and Taranger Methods

39. Dental age is determined from three characteristics The first is which teeth have erupted. The second - amount of resorption of the roots of primary teeth Third - amount of development of the permanent teeth. Dental Age

40. Average chronology of permanent tooth development. Tooth Calcification Begins Crown Completed Eruption Root Completed Max Mand Max Mand Max Mand Max Mand Central Incisor 3 M 3 M 4 ½ Y 3 ½ Y 7 ¼ Y 6 ¼ Y 10 ½ Y 9 ½ Y Lateral Incisor 11 M 3 M 5 ½ Y 4 Y 8 ¼ Y 7 ½ Y 11 Y 10 Y Canine 4 M 4 M 6 Y 5 ¾ Y 11 ½ Y 10 ½ Y 13 ½ Y 12 ¾ Y 1 st Premolar 20 M 22 M 7 Y 6 ¾ Y 10 ½ Y 10 ½ Y 13 ½ Y 13 ½ Y 2 nd Premolar 27 M 28 M 7 ¾ Y 7 ½ Y 11 Y 11 ¼ Y 14 ½ Y 15 Y 1 st Molar 32 W 32 W 4 ¼ Y 3 ¾ Y 6 ¼ Y 6 Y 10 ½ Y 10 ¾ Y 2 nd M olar 27 M 27 M 7 ¾ Y 7 ½ Y 12 ½ Y 12 Y 15 ¾ Y 16 Y 3 rd M olar 8 Y 9 Y 14 Y 14 Y 20 Y 20 Y 22 Y 22 Y

41. Dental Age : At dental age 10, approximately one half of the roots of the mandibular canine and mandibular first premolar have been completed, nearly half the root of the upper first premolar is complete, and there is significant root development of the mandibular second premolar, maxillary canine, and maxillary second premolar.

42. Sexual Age: This is based on development of secondary sexual characters both boys and girls. This type of indicator is useful only for assessment of adolescent growth.

43. Girls Total Duration of Adolescent Growth : 3 ½ years period Stage 1 -Beginning of adolescent Growth. Appearance of breast buds, initial pubic hair. Stage 2 -(About 12 Months Later) Peak velocity physical growth (in height). Noticeable breast development, axillary hair, darker/more abundant pubic hair.  Stage 3 -(12-18 Months Later) Growth spurt ending. Menses, broadening of hips with adult fat distribution, breasts completed. Boys Boys Total Duration of Adolescent Growth : 5 years period Stage 1 -Beginning of adolescent Growth. “Fat spurt” weight gain, feminine fat distribution. Stage 2- (About 12 Months Later) Height spurt beginning. Redistribution/reduction in fat, pubic hair, growth of penis. Stage 3- (8-12 Months Later) Peak velocity in height. Facial hair appears on upper lip only, axillary hair, muscular growth with harder/more angular body form. Stage 4 - (15-24 Months Later) Growth spurt ending.  Facial hair on chin and lip, adult distribution/color of pubic and axillary hair, adult body form.

44. Factors affecting Growth Hereditary – Genetic Factor Hormones Nutrition Geologic Variation – Race Disease Ref – Robert Moyer : Handbook of Orthodontic

45. Climate and Seasonal Effect Socio - Economic F actor Exercise Family size and Birth order Secular Trend Psychological disturbances

46. Heredity – The basic control of growth, both in magnitude and timing is located in the genes. Interaction between the genetic potential and environment influences. Twin studies shown that body size, body shape, deposition of fat and pattern of growth are under genetic control than environmental.

47. Y chromosome allows grows males to grow longer period than females, therefore marking possible greater overall growth. XXY - Klinefelter’s syndrome have a growth pattern similar to males. Turner’s syndrome having only one X chromosome - female pattern of growth becoming more like a female

48. Hormones – The anterior lobe of the pituitary gland produces a hormone called growth hormone or somatotropin. proliferation of cartilage cells bone growth height growth Ineffective - when the epiphysal plates close. An excess of growth hormone produces a gigantism and a deficiency of the hormone produces a pituitary dwarf .

49. The anterior lobe of pituitary gland also secretes thyrotrophic hormone, which stimulating the thyroid gland to secrete the hormones thyroxine and tri- iodothyronine Bones , teeth and brain . Deficiency in childhood of the thyroid hormones produces a mentally retarded dwarf. Bone and dental growth from birth to the adolescent spurt are under thyroid control. At adolescence bones fall under increasing influence of the gonadal hormones .

50. Nutrition – Malnutrition may affect all aspects of growth including size of parts, body proportions, quality and texture of tissues, and onset of growth events . The effects of malnutrition are reversible to a certain extent as children have fine recuperative powers . Catch-up growth - If the adverse effects are not too severe, the growth process accelerates when proper nutrition is provided. 

51. Geologic Variation – Race Differences in growth among different races can be attributed to other Nutritional and environmental factors E.g.: In American blacks, calcification and eruption of teeth occurs almost a year earlier than their white counterpart .

52. Disease – After an illness - a catch up growth period usually brings the child back to the predetermined growth curve. Disease that slow growth Cartilage cell growth is stopped temporarily and is seen on x-rays as a line of arrested growth. Similar lines can be found in the teeth .

53. Climatic and seasonal effects. – Growth in height is faster in the spring than in autumn City children tend to mature faster than rural ones. Growth in height and eruption of teeth is greater at night than in the daytime Seasonal variation have been shown to affect adipose tissue content and the weight of new born babies.

54. Socio - economic factors – Children brought up in affluent and favorable socio-economic conditions show Earlier onset of growth events. Grow to a larger size than children living in unfavorable socio-economic environment .  

55. Exercise – Exercises are essential for a healthy body, Strenuous and regular exercises have not been associated with more favorable growth. Certain aspects of growth such as development of some motor skills and increase in muscle mass is found to be influenced by exercise. 

56. Family size and birth order . – First born babies tend to weigh less at birth and have smaller stature but higher I. Q. The smaller the family size, the better would be the nutrition and other favorable conditions. 

57. Secular Trend Although children are growing at a faster rate they are also stopping Growth sooner. The adolescent height spurt is earlier now, but not more accentuated today than in past. An interesting feature of secular trend is the progressive advancement in the timing of menarche .

58. Psychological disturbances. – Children experiencing stressful conditions display an inhibition of growth hormone secretion. Psychological disturbances of prolonged duration can hence markedly retard growth.

59. Growth Spurts Sudden increase in growth is termed Growth S purt . Growth Spurt Periods when a sudden acceleration of growth occurs . P hysiological alteration in hormonal secretion is a cause for Growth Spurt . There is a period of rapid increase of growth just before birth and another just before, and at beginning of puberty.

60. Woodside (1968 ) in his study of Burlington study Group Toronto, showed Name of growth spurt Girls Boys Infantile/childhood growth spurt 3 yrs 3 yrs Juvenile/mixed growth Spurt 6-7yrs 7-9yrs Pre Pubertal/adolescent growth spurt 11-12yrs 14-15yrs

61. Modified by Bjork ( 1975) Prenatal -- Just before birth. Postnatal One year after birth. Mixed dentition growth spurt Females : 7- 9 years. Males : 8-11 years. Pre Pubertal growth spurt Females : 11-13 years. Males : 14-16 years.

62. Timing Of Puberty Velocity curves for growth at adolescence shows difference in timing between boys and girls. Pubertal growth spurt occurs on an average nearly 2 years earlier in girls than boys. When the growth velocity curves for early (M1), average (M2), and late(M3) maturing girls are compared, the marked differences in size between these girls during growth are apparent.

63. Thus during the rapid growth at adolescence, the cartilage is used up faster than it is replaced. Toward the end of adolescence, the last of the cartilage is transformed into bone, and the epiphyseal plates close . At this point growth potential is lost and growth stops.   Early cessation of growth in girls.

64. Growth in width is completed first, then in length, and finally height. Growth in width of both jaws, including the width of the dental arches, tends to be completed before adolescent growth spurt. Growth in width at the palatal suture occurs during the first 5 years of age, mostly at the inter-maxillary and inter-palatine suture. Inter-canine width more likely to decrease than increase after age 12 .  

65. According to Graber Percentage of craniofacial growth completed at different stages . Cranium Maxilla Mandible 1 to 5 Years 85% 45% 40% 5 to 10 Years 11% 20% 25% 10 to 20 Years 4% 35% 35%

66. Mandibular length changes Growth of the mandible continues at a relatively steady rate before puberty. On the average, ramus height increases 1 to 2 mm per year and body length increases 2 to 3 mm per year. 

67. Age Body Length Increase (mm) ( Gonion - Pogonion ) Ramus Height Increase (mm) ( Condylion - Gonion ) Male Female Male Female 7 2.8 1.7 0.8 1.2 8 1.7 2.5 1.4 1.4 9 1.9 1.1 1.5 0.3 10 2.0 2.5 1.2 0.7 11 2.2 1.7 1.8 0.9 12 1.3 0.8 1.4 2.2 13 2.0 1.8 2.2 0.5 14 2.5 1.1 2.2 1.7 15 1.6 1.1 1.1 2.3 16 2.3 1.0 3.4 1.6

68. Mandibular length changes Growth in length and height of both jaws continues through the period of puberty. In girls, the maxilla grows slowly downward and forward to age 14 to 15 on the average (more accurately, by 2 to 3 years after first menstruation), then tends to grow slightly more almost straight forward . In both sexes, growth in vertical height of the face continues longer than growth in length, with the late vertical growth primarily in the mandible.

69. It is important clinically to carefully asses physiologic age, to plan orthodontic treatment According to P roffit , growth modifications must begin in girls during mixed dentition period. Since adolescent growth spurt often precedes the final transition of dentition, so by the time second premolars and molars erupt growth get completed . In slow maturing boys - dentition can be relatively complete while a considerable amount of physical growth remains .

70. Principles of Growth Contd ….. Dr. Priyal Billaiya

71. Nature of growth

72. Osteogenesis APPOSITION: Formation of new cells in periosteum , extra cellular material secreted, get mineralized and new bone formed. e.g.: BASAL PART OF THE SKULL,TRUNK & LIMBS  

73. INTRAMEMBRANOUS OSSIFICATION Transformation of mesenchymal connective tissue into membranous sheets to osseous tissue Example: Calvarium , clavicles, body of mandible ENDOCHONDRAL OSSIFICATION Conversion of hyaline cartilage prototype into bone Example: base of skull

74. Long Bones End of long bones -epiphysis. The newly formed bone – metaphysis Matured bone - diaphysis . The epiphysis initially forms a cartilage tissue which later ossifies and fuses with the metaphysis as it matures.

75. How Facial Growth operates ?

76. DISPLACEMENT : Movement of the whole bone as a unit – PRIMARY : Displacement in conjunction with its own growth. SECONDARY : Displacement of bone as result of growth and enlargement of adjacent bone

77. Bone Growth Bone Displacement

78. Bone grows by adding new bone on one side of bony cortex The inner and outer surface of the bone are covered with mosaic type appearance of growth fields, which can be resorptive or depository CORTICAL DRIFT: Growth movement towards the depository surface by a combination of resorption and deposition

79. Mandible moves Posteriorly by series of Deposition And Resorption Anterior part of Ramus remodelled to accommodate Mandibular Corpus

80. ENLOWS COUNTERPART PRINCIPLE It explains that, growth of one bone has influence on its adjuvant bone which is called counter part, and this controls the growth and proportional relationship with its counterpart . E.g .: Maxillary arch is counter part of mandibular arch.

81. ENLOWS EXPANDING “V” PRINCPLE It says that most of craniofacial bones especially intramembranous have v shape eg : maxilla , mandible , palate ,nasal etc. And growth movement occurs towards wide end of V deposition of bone is seen in inner side and resorption is seen in outer surface

82. NEUROTROPHISM Nervous control of skeletal growth by transmission of substance through axons of nerves is called neurotrophism non-impulse transmitting neural function involves axoplasmic transport long term interactions between neurons and innervated tissue Homeostatically regulate the morphological , compositional and functional integrity if those tissues Moss indicates three general categories : Neuro-epitelial trophism . Neuro -visceral trophism . Neuro -muscular trophism

83. Growth activity in one region is invariably accompanied by complementary growth in other regions. Imbalance can be seen in: Amount of growth Direction of growth Time of growth Clinical decisions regarding use of extra oral traction forces, functional appliances, extraction versus non-extraction treatment, or orthognathic surgery are based on growth considerations. Conclusion

84.  JUST AS THE CLINICIAN NEEDS THE MEDICAL HISTORY TO MAKE A LOGICAL DIAGNOSIS. THE GROWTH AND DEVELOPMENT OF FACE IS ESSENTIAL FOR A LOGICAL EXPLANATION OF ANY STRUCTURAL GROWTH

85. REFERENCES Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics. 5 th ed. Elsevier, India; 2014 Krogman WM. Growth Theory and Orthodontic Practice. Angle Orthodont . 1940; 10: 179-191 Essentials of Facial Growth-Donald H.Enlow , Mark G.Hans Handbook of Orthodontics-Robert E.Moyers Textbook of Orthodontics-Graber Textbook of Craniofacial Growth-Sridhar Premkumar Dentofacial Orthopedics with Functional Appliances-GRP

86. A History of the Study of Human Growth, James Mourilyan Tanner, 1981: Cambridge University Press