GROWTH & DEVELOPMENT www.indiandentalacademy.com
INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
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Definitions • Growth • Development
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Growth • “Growth refers to increase in size” - Todd • “Growth may be defined as the normal change in the amount of living substance”Moyers
• “Growth usually refers to an increase in size and number” – Profitt
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Growth •“Growth is entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility” Meridith
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Development • “Development is a progress towards maturity” – Todd • “Development refers to all naturally occurring progressive, unidirectional, sequential changes in the life of an individual from it’s existence as a single cell to it’s elaboration as a multifunctional unit terminating in death” – Moyers www.indiandentalacademy.com
Development • “Development connotes a maturational process involving progressive differentiation at the cellular and tissue levelsâ€? - Enlow
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Theories of Growth • Various theories of growth are – • Genetic Theory • Sicher’s ‘Sutural Dominance Theory’ • Scott’s ‘Cartilaginous Theory’ • Functional Matrix Theory by Melvin Moss • Van Limborgh’s Multifactorial Theory of growth • Enlow’s Expanding ‘V’ Principle • Enlow’s Counterpart Principle • Theory of Neurotrophism • Petrovic’s Servosystem Theory www.indiandentalacademy.com
Genetic Theory • According to Genetic theory, growth of craniofacial region is solely dependent on genes, which is predetermined • But it is now clear that growth is not dependent solely on genetics, environmental factors also plays a role in growth
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Sicher’ s Sutural Dominance Theory • According to Sicher, sutures are primary growth centers and are under intrinsic genetic control and rest all factors are secondary • Primary event in sutural growth is proliferation of connective tissue between two bones which is then replaced by bone. • Connective tissue in sutures produces forces which separates the two bones, and the space created is then filled by bone. www.indiandentalacademy.com
Sicher’ s Sutural Dominance Theory • But it is clear now that sutures are not primary determinants of growth. Evidence supporting this are• When an area of suture between two facial bones is transplanted to another location, it does not grow, indicating that sutures lack innate growth potential. • It is seen that growth at sutures responds to outside influence. For e.g. if size of brain is small, cranial vault remains small in size. www.indiandentalacademy.com
Scott’ s Cartilaginous Theory • According to James Scott, primary growth centers of craniofacial region are cartilages, with sutures being secondary responders. • Cartilaginous portions of head, nasal septum, cranial base and mandible are under intrinsic genetic control.
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Scott’ s Cartilaginous Theory
Spheno-occipital Synchondrosis
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Scott’ s Cartilaginous Theory • Studies related to cartilaginous theory • Transplantation of various cartilages to another site showed that not all cartilage have innate growth potential • Epiphyseal plates has innate growth potential • Spheno-occipital synchondrosis also has some intrinsic growth potential but not as much as epiphyseal cartilage • Nasal septal cartilage also has little growth potential, similar to spheno-occipital synchondrosis • Mandibular condyles has little or none intrinsic growth potential
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Scott’ s Cartilaginous Theory • Studies related to cartilaginous theory • Experiments showed that removal of nasal septum severely affects the growth of midface, indicating that septal cartilage has some growth potential, whose loss makes a difference in maxillary growth.
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Functional Matrix Theory • This theory was proposed by Melvin Moss who was influenced by Van der Klaaus' ‘Functional Cranial Component’ concept • Moss claims that “the origin, form, position, growth and maintenance of all skeletal tissues and organs are secondary, compensatory and necessary responses to chronologically and morphologically prior events that occurs in specifically related non-skeletal tissues, organs or functional spaces. www.indiandentalacademy.com
Functional Matrix Theory • What is Functional Cranial Component? • Functional cranial components are those tissues, organs, spaces and skeletal parts which are necessary to carry out given function.
• Functional Matrix and Skeletal Unit together make Functional Cranial Component
• Skeletal elements performing a given function are called as Skeletal Unit
• Soft tissues functionally related to a given skeletal unit are called as Functional Matrix www.indiandentalacademy.com
Functional Matrix Theory • Functional cranial component may consist of single or many bones depending on function to perform • For e.g. • Many cranial vault bones combine together to form single functional cranial component • Maxilla itself contains various functional cranial components performing many functions
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Functional Matrix Theory • Functional Matrix • These are the soft tissues within which Skeletal units are embedded
• It comprises of muscles, tendons, glands, neurovascular bundles, teeth and also empty spaces (e.g. Pharynx)]
• Functional Matrix is divided into Periosteal Matrix
Capsular Matrix
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Functional Matrix Theory • Periosteal Matrix • Periosteal matrix directly act on their related skeletal units • They mainly comprise of muscles, neurovascular bundles, glands
• Action of periosteal matrix causes deposition and resorption of bone
• Alteration in the functional demand of these matrices causes change in shape and size of their related skeletal units
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Functional Matrix Theory • Capsular Matrix • Capsular matrix acts indirectly and passively on their related skeletal units
• The skeletal units are passively and secondarily moved in spaces as the capsule is expanded. This kind of translative growth is not brought about by deposition and resorption
• Capsules of the craniofacial region are divided into Orofacial
Neurocranial
Capsule
Capsule
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Functional Matrix Theory Capsular Matrix Neurocranial capsule
Orofacial capsule
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Functional Matrix Theory • Capsular Matrix • Orofacial capsule forms an envelope around oral, pharyngeal and nasal space, thus regulating form and size of these structures.
• Alteration in spatial position of skeletal units are brought about by expansion of orofacial capsule within which facial bones arise, grow and are maintained
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Functional Matrix Theory • Capsular Matrix • Neurocranial capsule comprises of scalp on one side and two layers of Dura matter on other side
• Thus expansion of this capsule causes expansion of cranial vault
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Functional Matrix Theory • Skeletal Unit • Skeletal unit is or are bones related with given single function • Skeletal unit may comprise of single or multiple skeletal elements made up of bones or even cartilage
• Skeletal units are of two types Macroskeletal
Microskeletal
Unit
Unit
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Functional Matrix Theory • Macroskeletal Unit • When many bones, unite or combine together to perform a single function, they are called as Macroskeletal unit
• e.g. endocranial surfaces of Frontal, Parietal, Temporal, and Occipital bones form a macroskeletal unit
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Functional Matrix Theory • Microskeletal Unit • When single bone contains many skeletal units they are called as microskeletal units
• e.g. mandible has many microskeletal units such as alveolar, coronoid, condyloid and angular while maxilla has orbital, alveolar, nasal, palatal and external muscular
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Functional Matrix Theory • Microskeletal Unit MAXILLA
MANDIBLE
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Van Limborgh’ s Theory • Van Limborgh in 1970 proposed a multifactorial concept of growth • According to him, growth is a multifactorial process involving genetic, epigenetic and environmental factors • Limborgh suggested five growth controlling factors • Intrinsic genetic factors • Local epigenetic factors • General epigenetic factors • Local environmental factors www.indiandentalacademy.com factors • General environmental
Van Limborgh’ s Theory
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Van Limborgh’ s Theory • Limborgh listed the essential elements of Scott’s, Sicher’s, and Moss’ theories as follows • Growth of synchondroses and ensuing endochondral ossification is almost exclusively controlled by intrinsic growth factors
• Intrinsic factors controlling intramembranous bone growth are small in number and of genetic nature
• The cartilaginous skull parts must be seen as growth centers • Extent of sutural growth is controlled by both cartilaginous growth and growth of other head structures
• The extent of periosteal bone growth largely depends on the growth of adjacent structures
• The intramembranous processes of bone formation can be additionally influenced by local www.indiandentalacademy.com environmental factors, muscle inclusive
Enlow’ s Expanding ‘ V’ Principle • Many facial bones or their parts have a V shaped growth pattern • According to Enlow, bone growth takes place towards wider end of the ‘V’ by the process of remodelling • Bone deposition occurs on inner surface of ‘V’ while resorption occurs on outer surface • e.g. base of mandible, ends of long bone, palate
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Enlow’ s Expanding ‘ V’ Principle
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Enlow’ s Counterpart Principle • According to Donald Enlow, growth of any part of craniofacial region is related specifically to other parts • For maintenance of equilibrium, growth in parts and their counterparts should be in proper balance • Imbalances may be in the form of • Amount of growth • Direction of growth • Timing of growth www.indiandentalacademy.com
Enlow’ s Counterpart Principle • Examples of counterparts • Nasomaxillary complex – Anterior cranial fossa • Middle cranial fossa – Width of ramus • Middle cranial fossa – Anteroposterior dimension of pharynx • Maxilla – Body of mandible • Maxillary tuberosity – Lingual tuberosity
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Theory of Neurotrophism • According to Moss, neurotrophism is a non-impulsive transmittive 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
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Petrovic’ s Servosystem Theory • Charlier, Petrovic and Stutzmann researched on factorial quantitative analysis which led to Servosystem theory of processes controlling growth • According to this theory, the influence of the Somatotropic-stomatomedin complex on the growth of primary cartilage has a cybernetic form of command, while its effect on secondary cartilages comprises direct and indirect effects on cell multiplication www.indiandentalacademy.com
Petrovic’ s Servosystem Theory • Petrovic et al, during organ culture found that, • If growth results from cell division of differentiated chondroblasts, it appears to be subjected to general extrinsic factors and more specifically to somatotropic hormonestomatomedin complex
• These are primary cartilages and the effect of local biomechanic factors is reduced to modulation of the direction of growth with no effect on amount of growth
• e.g. of primary cartilages are, epiphyseal cartilage, cartilages of synchondroses of cranial base, cartilage of nasal septum www.indiandentalacademy.com
Petrovic’ s Servosystem Theory • Petrovic et al, during organ culture found that, • If growth results from cell division of prechondroblasts, it is subjected to local extrinsic factors
• These are secondary cartilages and the amount of growth can be modulated by appropriate orthopedic forces
• e.g. of secondary cartilages are, condylar cartilage, coronoid cartilage
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Petrovic’ s Servosystem Theory • Summary of servosystem theory • Upper dental arch is the constantly changing reference input and the lower arch is the controlled variable. i.e. variations in the maxillary growth controls the mandibular growth at condylar retrodiscal pad area through the activity of lateral pterygoid muscle.
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Post Natal Growth of Skull • Growth of skull is studied under two heads • Growth of Calvarium • Growth of Cranial base • Calvarium consists of flat bones like frontal, parietal, squamous temporal and squamous occipital bones • Cranial base consists of wings of sphenoid, body of sphenoid, petrous temporal bone and basi-occiput
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Post Natal Growth of Skull • Growth of calvarium • Growth of calvarium is mainly dependent on growth of brain
• • •
which is primary regulating factor As brain expands, bones of calvaria move outwards and there is deposition of bone in its various sutures, increasing the size of calvarium Width of calvarium increases by deposition of bone on both ectocranial and endocranial surfaces and resorption on endosteal surfaces of both inner and outer tables In early part of post natal life, however, selective resorption occurs on endocranial surface causing flattening of the calvarium www.indiandentalacademy.com
Post Natal Growth of Skull
Increase in Size of calvarium by deposition of bone in sutures www.indiandentalacademy.com
Post Natal Growth of Skull
Increase in thickness of calvarium
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Post Natal Growth of Skull • Growth of calvarium is accelerated during infancy, and by the end of fifth year of life over 90% of growth is achieved • It is recognized that there is actual translation as well as remodeling of the individual bone, with the structures being moved outward by growing brain • According to Davenport – • Brain case growth Birth ------------- 63% 6 months -------- 76% 1 year ------------ 82% 2 years ----------- 87% 3 years ----------- 89% 5 years ----------- 91% www.indiandentalacademy.com 15 years --------98%
Post Natal Growth of Skull • Growth of Cranial Base • Cranial base grow primarily by cartilaginous growth in the spheno-occipital, spheno-ethmoidal, intersphenoidal, intraoccipital synchondroses
• Some minor amount of growth also occurs by surface remodeling i.e. deposition on ectocranial and resorption on endocranial surface
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Post Natal Growth of Skull • Growth of Cranial Base Growth of Cranial Base by Endochondral Ossification in various Synchondroses
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Post Natal Growth of Skull • Growth of Cranial Base Growth of Cranial Base by Surface remodeling
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Post Natal Growth of Skull • Growth of Cranial Base • Spheno-occipital synchondrosis is major contributing factor for growth of cranial base
• According to Koski, spheno-occipital synchondrosis acts as growth center but not as effective as epiphysis
Spheno-occipital synchondrosis grows in upward direction, carrying anterior cranial fossa forwards www.indiandentalacademy.com
Post Natal Growth of Skull • Growth of Cranial Base • Activity of intersphenoidal synchondrosis disappears at birth • The intraoccipital synchondroses closes in 3-5 years • Spheno-ethmoidal closure has a range of 5-25 years • Spheno-occipital closes after 20 years of age • Timing of cranial base growth • By birth ----------- 55-60% • By 4-7 years ----- 94% • By 8-13 years --- 98% www.indiandentalacademy.com
Post Natal Growth of Maxilla • As Maxilla is attached to cranial base it is influenced by growth of cranium • Growth of maxilla has four contributing factors as follows • Surface remodeling Apposition
Resorption
• Translation or Displacement • Sutural • Cartilaginouswww.indiandentalacademy.com
Post Natal Growth of Maxilla • Growth of Maxilla by displacement Displacement of maxilla are of two types
• Primary Displacement • Secondary Displacement
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Post Natal Growth of Maxilla • Primary Displacement • Primary displacement of maxilla occurs by deposition of bone at maxillary tuberosity
• Although tuberosity grows in posterior direction, maxilla is displaced in anteriorly
• Secondary Displacement • As nasomaxillary complex is attached to cranial base, growth occurring at cranial base displaces the nasomaxillay complex downwards and forwards. This is Secondary displacement www.indiandentalacademy.com
Post Natal Growth of Maxilla • Growth of Maxilla by displacement •Secondary Displacement • Primary Displacement
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Post Natal Growth of Maxilla • Growth of Maxilla by Surface remodeling • Nasomaxillary complex increase in size by selective deposition and resorption on its surfaces such that overall size of nasomaxillary complex increases in all three dimensions, viz. transverse, vertical, and horizontal
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Post Natal Growth of Maxilla • Growth of Maxilla by Surface remodeling
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Post Natal Growth of Maxilla • Growth of Maxilla at Sutures • Maxilla is attached to cranium by various sutures such as • Frontomaxillary • Frontonasal • Zygomatico-temporal • Zygomatico-maxillary • Pterygopalatine
• Growth at these sutures, that are oblique and parallel, causes forward and downward displacement of nasomaxillary complex www.indiandentalacademy.com
Post Natal Growth of Maxilla Growth of Maxilla by Sutures
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Post Natal Growth of Maxilla • Growth of Maxilla by Cartilage • Nasal septal cartilage plays a role in mid facial development • Growth at cartilage pushes maxilla forwards and there occurs secondary bone formation within various maxillary sutures
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AT BIRTH
Post Natal Growth of Maxilla
Hard palate : length = width maxillary sinus : not visible radiographically 1 – 2 years Extensive remodeling descent of palate /enlargement of nasal cavity Mid palatine suture growth
ceases
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No synostosis
Post Natal Growth of Maxilla
THE MIXED DENTITION YEARS Inter canine width completed
12 yrs - females 18 yrs - males
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Post Natal Growth of Mandible • At birth the mandible is little more than a curved bar of bone and two sides are separated by a midline suture at symphysis menti • At first year of life there is closure of suture at symphysis menti • At birth chin is not prominent which becomes prominent as age advances. • At about 10 years of life intercanine width of mandible is completed www.indiandentalacademy.com
Post Natal Growth of Mandible • Growth of mandible is studied under following heads • Growth of condyle • Growth of coronoid process • Growth of ramus • Growth of body of mandible • Growth of alveolar processes • Growth of angle of mandible • Growth of lingual tuberosity • Growth of chin www.indiandentalacademy.com
Post Natal Growth of Mandible • Growth of mandible
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Post Natal Growth of Mandible • Growth of Condyle • Mandibular condyle has been recognized as an important site • The presence of condylar cartilage is an adaptation to withstand the compression occurring at joint
• Role of condyle may be— • Previously it was thought, Condyle grows towards the cranial base by bone deposition, displacing mandible away from cranium in downward and forward direction • Now it is believed, Growth of soft tissues carries the mandible away from crania base and there occurs secondary bone deposition at condyle to maintain contact with cranial base www.indiandentalacademy.com
Post Natal Growth of Mandible • Growth of Condyle Previous concept
Present concept
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Post Natal Growth of Mandible • Growth of Coronoid • Mandibular coronoid follows the enlarging ‘V’ principle • It is seen that, deposition occurs on the medial surfaces of coronoid process while resorption takes place on lateral surface
• The coronoid has a propeller like twist, so that its lingual side faces three general directions all at once i.e. posteriorly, superiorly, and medially
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Post Natal Growth of Mandible • Growth of Ramus • The ramus move progressively posterior by combination of deposition and resorption
• Resorption on anterior part while deposition on posterior region
• Remodeling of ramus occurs • To accommodate the increasing mass of masticatory muscles • To accommodate enlarged breadth of pharyngeal space (Enlow’s Counterpart Principle) • To accommodate the erupting molars www.indiandentalacademy.com
Post Natal Growth of Mandible • Growth of Ramus
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Post Natal Growth of Mandible • Growth of Body of Mandible • Displacement of the ramus posteriorly results in conversion of ramus to corpus of mandible
• In this manner mandibular body lengthens
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Post Natal Growth of Mandible • Growth of Alveolar process • Alveolar processes develops in response to the presence of tooth buds
• As the teeth erupts, alveolar processes increases in height causing increase in height and thickness of the body of mandible
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Post Natal Growth of Mandible • Growth of Angle of mandible • On lingual side, resorption takes place on the posterio-inferior aspect while deposition occurs on the antero-superior aspect
• On buccal side, resorption occur on antero-superior part while deposition on postero-superior part
• This results in flaring of mandible as age advances
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Post Natal Growth of Mandible • Growth of Lingual tuberosity • Lingual tuberosity forms the major site of growth for the lower bony arch (counter part to Maxillary tuberosity)
• It move posteriorly by deposition on its posterior surface • Combination of resorption in the lingual fossa and deposition on the medial surface of tuberosity causes accentuation of prominence of lingual tuberosity
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Post Natal Growth of Mandible • Growth of Chin • Chin is a specific human characteristic • In infancy, chin is underdeveloped • Chin prominence is formed by bone deposition in childhood • The chin prominence is accentuated by bone resorption occurring in the alveolar region above it
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Dynamics of Growth • Differential Growth • Pattern • Normality • Variability • Growth Spurts
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Dynamics of Growth Differential Growth Not all the tissue system of body grow at same rate Neural tissue growth is completed by 6 – 7 years Lymphoid tissue growth is completed in late childhood and growth of genital tissues accelerates at the same time. General Body tissue follows S-Shaped curve. www.indiandentalacademy.com
Scammon’s curves Depicting differential growth
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Pattern
Dynamics of Growth
It is a set of constraints operating to preserve the integration of parts under varying conditions or through time – Changes in overall body proportions – Changes in proportion of cranio-facial region
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Normality
Dynamics of Growth
Normality refers to that which is usually expected is ordinarily seen or typical - Moyers Two standard deviations On either side of mean Is normal Misuse of the concept of normality can lead to many problems in clinical orthodontics & treatment planning.
Standard deviation
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Variability
Dynamics of Growth
• No two individuals with the exception of monozygotic twins are like
• Variability quantitatively is categorized in terms of deviations from the usual pattern, which is done using standard growth charts
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Dynamics of Growth
Growth Spurts
• Not all the tissues or organs grow at same time and uniformly, there are certain periods of acceleration which are in spurts called as growth spurts
• Sex-linked – Normal spurts are
• Just before Birth • One year after birth • Juvenile spurt – 7-9 years (females); 8-11 years (males)
• Pubertal spurt – 11-13 years(females); 14-16years (males)
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Factors Affecting Growth • Accelerating Factors • Familial trait • Favorable environment • Endocrine Disorders like hyperpituitarism • Periods of growth spurts
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Factors Affecting Growth • Retarding Factors • Endocrine disorders like Hypopituiterism, hypothyroidism • Juvenile diabetes • Deficiency of vitamins A, B complex , C, and D • Infantile Syphilis • Renal Insufficiency • Nutritional disorders • Chronic Infectious diseases www.indiandentalacademy.com
Methods of Assessing Growth • Measurement Approach • Anthropometry • Craniometry • Cephalometry • Natural Markers • Hand Wrist radiographs • CVMI index • Growth Curve • Comparative anatomy www.indiandentalacademy.com
Methods of Assessing Growth • Experimental Approach • Vital staining • Radioisotopes • Implants
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Importance of study of growth • Knowledge of growth is important to the pedodontist and orthodontist • Many growth changes and timing of growth determines the treatment plan • For e.g. if mandible needs to be expanded in anterior area, it has to be done before 10 yrs of age as mandibular intercanine width is completed by 9-10yrs of age • Growth also affects the prognosis of the treatment. www.indiandentalacademy.com
An accurate estimate of an individual’s state of development is essential in planning orthodontic treatment. Malocclusion and dentofacial deformity arise through variations in the normal developmental process, and so must be evaluated against a perspective of normal development.
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