principles of growth
DESCRIPTION
Covers every thing in growth and devlopment...TRANSCRIPT
GROWTH & DEVELOPMENT1
Theories , Concept & principles
Dr.CHIRANJEEV SINGHPg 1st year ,RDCH
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CONTENTS1. Introduction
2. Goals
3. Objectives
4. Definitions
5. Theories
6. Types of growth
7. Themes of development
8. Methods of studying growth
9. Types of growth
10. Methods of gathering growth data
11. Mechanism of bone growth
12. Factors affecting growth
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Aim3
To understand the
1. basic growth concepts.
2. growth and development of the main
craniofacial components.
3. tissues involved in facial growth.
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4. differences in facial form and patterns.
5. major deformities of growth.
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6. why and how knowledge of facial and somatic growth and development is critical
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Definition of Growth8
“Growth usually refers to an increase in
size and number” – Proffit .1986
“Self multiplication of living substance”-
J.S.Huxley
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9 “Growth may be defined as the normal
change in the amount of living substance- moyers 1988
“Growth refers to increase in size” - Todd 1931
“Change in any morphological parameter which is measurable”- Moss.
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Definition of Development10
Development is a progress towards maturity” – Todd-
1931
“Development connotes a maturational process involving
progressive differentiation at the cellular and tissue
levels” - Enlow
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• “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
• Development is increase in complexity- Profitt 1986
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Key Definitions
Morphogenesis – “A biologic process having an underlying control at the cellular and tissue levels”
Differentiation – “It is a change from generalized cells or tissues to a more specialized kinds during development”
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•Maturation –
“It is the emergence of personal characteristics and behavioral
phenomenon through growth processes”
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14Theories
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The major theories explaining growth are
1.Genetic Theory
2.Sutural Theory
3.Cartilageneous Theory
4.Functional matrix Theory
5.Van Limborgh’s Theory
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Other theories related to craniofacial growth are –
Enlow’s expanding ‘V’ principle
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GENETIC theory
Growth is controlled by genetic influence and is preplanned.
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Sutural dominance theory
SICHER 1940 – stated that cranio facial growth occurs at sutures.
sutural growth is the proliferation of the connective tissue between the two bones.
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Growth of the cranial vault – expansive proliferative growth by sutural connective tissue that forces the bones of the vault away from each other.
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Points against sutural theory
1. Lack of innate growth
2. Growth takes place even in absence of
sutures .
CONCLUSION:
Sutures are growth sites not centers.
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The Irish anatomist, James H. Scott, proposed an explanation, the nasal septum theory or Scott's hypothesis
sutures play little or no direct role in the growth of the craniofacial skeleton.
Rather, sutures are secondary, and compensatory sites of bone formation and growth.
Scott concluded :- that the nasal septum is most active and important for craniofacial skeletal growth late prenatally and early post natally , through approximately three to four years of age in humans.
Cartilaginous theory21
SCOTT’S HYPOTHESIS: Intrinsic growth-controlling factors are
in cartilage & periosteum. Sutures are secondary & dependent on
extrasutural influences. Cartilaginous part of skull must be
recognized as primary centers of growth, with nasal septum being a major contributor in maxillary growth.
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Nasal septal cartilage
Primary mechanism for growth of nasomaxillary complex.
Experimental excision of the nasal septum affects the growth of the upper face considerably .
Nasal septum – acts as central support for the upper facial area, and its loss results in a predictable collapse in the area.
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Condylar cartilage Growth of the condylar
cartilage is responsible for the anteroposterior growth of the mandible- primary growth centre.
Growth of the mandible- a bent long bone, with the mandibular condyar cartilage being equivalent to the epiphyseal plates of long bones whose growth forces the mandible downward and forward, away from the cranial base
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Scott stated that :-
If the condylar cartilage is transplanted to a relatively nonfunctional site, such as the subcutaneous or brain tissue, it does not maintain its structure and does not behave like the condylar cartilage in situ.
Bilateral condylectomy, congenital absence of the cartilage appreciable effect on the growth of the rest of the mandible in humans.
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FUNCTIONAL MATRIX HYPOTHESIS
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INTRODUCTION
Given by MELVIN MOSS IN 1969 and reviewed by him in 1990s
Worked on the concept put by VAN DER KLAAUW of FUNCTIONAL CRANIAL COMPONENT
The origin, growth and maintenance of all skeletal
tissues and organs are always secondary, compensatory and obligatory response to all the temporally and operational prior events and processes that occur in specifically related non-skeletal tissues, organs or functional spaces
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INTRODUCTION
MOSS said that head and neck region consist of number of functions
• Digestion
• Respiration
• Speech
• Olfaction
• Balance
• Vision
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INTRODUCTION Each of these function is completely carried out
by FUNCTIONAL CRANIAL COMPONENT
Each functional cranial component consists of all the tissues ,organs, spaces and skeletal parts necessary to carry out a given function.
The functional cranial component is divided into
1.functional matrix
2.skeletal unit.
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Skeletal unit
Composed of –bone, cartilage and tendinous tissue
MICROSKELETAL UNIT bones consisting of number of small skeletal unitsMAXILLA1. orbital 2. pneumatic3. palatal4. basalMANDIBLE-5. coronoid6. angular7. alveolar8. basal
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MACROSKELETAL UNIT- when adjoining portions of number of
neighboring bones carrying out a single function
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FUNCTIONAL MATRICES
This consist of soft tissue-muscle,gland,nerve,vessels,fat and teeth as well as non skeletal cartilages
DIVIDE INTO TWO TYPES- Periosteal matrices
Capsular matrices
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PERIOSTEAL MATRICES
All non skeletal functional units adjacent to
skeletal unit .
act by bringing transformation of the related
skeletal units .
Functional hypertrophy/hyperactivity-
increase in size and change in shape
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CAPSULAR MATRICES
consists of-
• NEURO CRANIAL
• ORO FACIAL
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Each of these capsules is an envelop
containing functional cranial component
Sandwiched between two covering layers
Capsules expands due to volumetric
increase of capsular matrix
This results in the translative movement
of the embedded bones
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NEUROCRAINAL CAPSULE
Sandwiched between-skin and dura mater Consists of-1. skin2. Connective tissue3. Apo neurotic layer4. Loose connective tissue5. Periosteum6. bone(base of skull)7. two layer dura mater
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The volumetric increase cause
compensatory expansion of surrounding
capsule.
Later the calvarial functional cranial
component as a whole are passively and
secondarily translated.
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ORO FACIAL MATRIX
Surround and protect oronasopharyngeal
space.
Surrounded by skin and mucous
membrane on either side.
Volumetric growth of these spaces is the
primary morphogenetic event in facial
skull growth
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Van Limborgh’s theory
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By Van Limborgh in 1970 He combines all the existing theories He supports the functional matrix theory ,
acknowledges some aspects of Sutural theory, and doesn’t rule out the genetic involvement .
Suggested the following five factors that he believed controls growth.
1. Intrinsic genetic factor.
2. Local epigenetic factor.
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3. General epigenetic factor.
4. Local environmental factor.
5. General environmental factor.
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Timing and sequential change a. Prenatal growth
b. Postnatal growth
c. Maturity
d .Old age
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Timing and sequential change
• Prenatal growth- rapid increase in cell no.
• Postnatal growth- till 20 yrs- growth starts declining & increasing maturation pickup speed.
• Maturity-period of stability
• Old age
• death
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GROWTH SPURTS44
Sudden increase in growth Is termed "growth spurt".
Periods whenA sudden acceleration
Of growth occurs.
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Physiological alteration inhormonal secretion cause for Growth Spurts.
TIMINGS OF GROWTH SPURTS.a. Just before birth b. One year after birth
c. Mixed dentition growth spurt Boys : 8-11 years Girls : 7-9 years
d. Pre-Pubertal growth spurt Boys : 14 - 16 years Girls : 11-13 years
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Different types of growth
Size change Positional change Proportional
change
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• Functional change• Maturational change
• Compositional change
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Proportional change
Eg-Head of the infant
Functional change
Eg- production of enzymes, hormones
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Size change- height, weight, volume
Positional change-
• Migration of neural crest cells
• Eruption of teeth
• Dropping of diaphragm
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49 Maturational change
stability and adulthood
Compositional change
Eye pigmentation
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Major themes of development50
Changing complexity
Shifts from competent to fixation
Shifts from dependent to independent
Ubiquity of genetic control modulated
by environment
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Changing complexity
At all level of organization i.e sub-cellular to whole organism
Complexity is increase in development
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Shifts from competent to fixation
Undifferentiated cells once differentiated become fixed.
Shifts from dependent to independent
Development brings independence at most levels of organization.
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Ubiquity of genetic control modulated by environment
Genetic control of development is constantly being modified by environmental interactions
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Importance of growth and development to orthodontist
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Etiology of malocclusion
Health and nutrition of children
comparison of growth
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identification - abnormal occlusal development at an earlier stage
use of growth spurts
Surgery initiation
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Normal features of Growth & Development
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pattern-Differential Growth -cephalocaudal gradient of growth
Variability Predictability Normality Timing, rate & direction
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PATTERN57
Pattern in growth represents proportionality .It refers not
just to a set of proportional relationships at a point in
time but to change in these proportional relationships
over time
In orthodontics , use of word pattern has both a
morphological and a developmental application
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DIFFERENTIAL GROWTH58
Different organs grow at different rates amount and at different times.
Scammon’s curve of growth-Richard scammon
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SCAMMON’S CURVE OF GROWTH59
LYMPHOID NEURAL GENERAL GENITAL
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conclusion60
Each tissue grows at different rate
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CEPHALOCAUDAL GRADIENTOF GROWTH
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• Axis of increased growth
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CEPHALOCAUDAL GRADIENTOF GROWTH
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Growth of head and face63
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• It illustrates the change in overall body proportions during normal growth and development.
• Imp aspect of pattern is its predictability.
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Predictability65
Predictability of growth pattern is a specific kind of proportionality that exists at a particular time and progresses towards another, at the next time frame with slight variations.
Change in growth pattern indicates some alteration in the expected changes in body proportions.
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Variability66
No two individuals with the exception
of siamese twins are like.
Hence it is important to have a
“normal variability” before
categorizing people as normal or
abnormal.
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Normality67 Normality refers to that which is usually expected, is ordinarily seen or typical –
Moyers
Normality may not necessarily be ideal.
•
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TYPES OF NORMALITY68
STATISTICAL
EVOLUTIONARY
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FUNCTIONAL
ESTHETICAL
CLINICAL
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Timing of growth
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One of the factors for variability in growth.
Timing variations arise because biologic clock of different individuals is different.
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It is influenced by: genetics sex related differences physique related environmental influences
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GROWTH STUDIES AND METHODS OF
STUDYING GROWTH.
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• Longitudinal growth studies
• Methods of studying bone growth
• Types of growth data
• Methods of gathering growth data
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OpinionObservations.Ratings and rankings.Quantitative measurements.
direct data.
indirect data.
derived data.
Types of growth data74
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Types of growth data.
• Opinion clever guess based on experience. crudest form of scientific knowledge.• Observations: for studying all or none phenomenon limited use . quantitative data is needed.
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RATING - comparison
RANKING -value
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Quantitative measurements Includes expressing a fact as a meaningful
quantity or numbers.
• Direct data: measurements ,living persons or cadaver -measuring device.
• Indirect data: images or reproductions of actual person.
• Derived data comparing at least two measurements.
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Methods of gathering growth data.
• Longitudinal studies .• Cross sectional studies.• Overlapping or semi longitudinal studies.
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Longitudinal studies.• measurements of same person or group-
regular intervals through time. • Advantage: temp. problems are smoothed with
time, Variability, serial comparison makes study of
specific developmental pattern of individual possible.
Disadvantages: time consuming, expensive, sample loss or attrition, averaging.
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Cross sectional studies80
Measurment of different individuals or different samples & studied at different periods
ADVANTAGES repeating Quicker Less costly Statistical treatment made easier
DISADVANTAGES
Variation amongst individuals cannot be studied
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Semi longitudinal studies.
Merger of either studies
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METHODS OF STUDYING GROWTH
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CRANIOMETRY.
• measurements of skull
• Neanderthal and Cro-Magnon skull.
• Found in 18th century in Europe
• information of extinct population ,growth pattern.
Advantages: Precise measurements.
Disadvantages: All data is cross sectional.
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ANTHROPOMETRY:
• soft tissue pts over bony landmarks- living individuals.
• variation in soft tissue thickness –leads to different results
• Measured at a point at the bridge of nose to a point at the greatest convexity of the rear of skull
• individual growth directly measured• Produce longitudinal data
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• CEPHALOMETRIC RADIOGRAPHY: • direct measurement - bony skeletal dimensions
follow up same individual over time .
• Disadvantages• precise orientation of head ,precise control of
magnification.• 2D of 3D structure
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Mineralized sections.
• Special stains
• Thin sections- quench- rapidly
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Micro radiography.
• High resolution of images of bone sections
• Differential density between primary and
secondary bone.
• Bone strength -proportional to degree of
mineralization.
• secondary bone has more strength than primary
bone.
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M R IMagnetic Resonance Imaging
Depicts- soft tissue growth
contrast with hard tissue.
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Bimetric tests E.g. Skeletal maturation & ossification
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Fluorescent labels.• in vivo calcium binding labels • anabolic time markers of bone formation.• Mechanism of bone growth determined by
analysis of label incidence and interlabel distance.• Sequential use of different colored labels assess
bone growth, healing and functional adaptation.• Tetracycline,calcein green,xylenol orange, alizarin
complexone,demeclocycline and oxytetracycline
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Radioisotopes.
• Radioisotopes of certain elements or compounds are often used as in vivo markers
• labeled material injected and located within the growing bone by auto radiographic techniques.
1. Technetium 992. Calcium 453. Potassium 32
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Autoradiography.
• Histological sections are coated with a nuclear track emulsion to detect radiographic precursor for structural and metabolic material.
• Specific radioactive labels for protein carbohydrates or nucleic acids are injected.
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• Commonly used auto radiographic labels are:• A. 3 H thymidine.• B. 3 H proline.• C. Bromodeoxyuridine.
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Vital staining
• John Hunter- alizarin dye
• Other dyes : tetracycline
trypon blue
lead acetate
procion
lead acetate
alizarin red 5
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• Vital staining aids in studying:
• Manner in which bone is laid down
• site of bone growth
• the direction and amount of growth
• the timing and relative duration of
growth at different sites.
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Natural markers.
• developmental features - serial radiography.
• cephalometric landmarks.
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Implant markers.
• By arne bjork at royal dental college in
copenhagen
• biologically inert alloys into growing bone –
• radiographic reference markers for serial
cephalometric study.
• The method allows precise orientation of serial
cephalograms and information on the amount and
sites of bone growth.
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Mechanisms of bone growth
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Deposition and resorption Growth fields Modelling Remodelling Growth movements drift displacement
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Deposition and resorption Bone sides which face the direction
of growth are subject to deposition (+) and those opposite to it undergo
resorption(-)
The surface principal The surface facing towards the
direction of progressive growth receives new bone deposition & surface facing away undergoes resorption. The result is the process termed cortical drift, a gradual movement of the growing area of the bone.
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Deposition and resorption Changes are:-a. Change in shape b. Change in sizec. Change in
proportiond. Change in
relationship of the bone with adjacent structures
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Growth fields
Inside and outside of every bone is covered by growth fields which control the bone growth.
They are both resorptive and depository types..
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About one half of the bone is periosteal and the other half endosteal. If endosteal surface is resorptive then periosteal surface would be depository.
it provides two growth functions:
1. Enlargement of any given bone.
2. Remodelling of any given bone.
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Growth sites
Growth fields having special role in the growth of the particular bone(grows fast) are called growth sites ;
e.g. mandibular condyle, maxillary tuberosity, synchondrosis of the basicranium, sutures and the alveolar process.
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Growth sites105
Growth centers
Special areas which are believed to control the overall growth of the bone e.g.mandibular condyle.
Force, energy or motor for a bone resides primarily within its growth centre.
But according to recent studies these centers do not control the whole growth process.
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MODELING107
Bone modeling involves
independent sites of
resorption and formation
that change the size and
shape of a bone.
Remodelling
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Required differential growth activity required for bone shaping.
It involves deposition and resorption occurring on opposite ends
Four types Biochemical remodelling Haversian remodelling Pathologic remodelling Growth remodelling
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1. Biomechanical- continuous deposition & removal of ions to maintain mineral homeostasis
2. Growth remodelling- constant replacement of bone during childhood
3. Haversian remodelling- secondary process of
cortical reconstruction as primary vascular bone is replaced.
4. Pathologic remodelling- regeneration & reconstruction of bone during & following trauma.
E.g. The ramus moves posteriorly by the combination of deposition and resorption.
so the anterior part of the ramus gets remodeled into a new addition for the mandibular corpus.
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Functions of Remodeling111 1. Progressively change the size of whole
bone
2. Sequentially relocate each component of the whole bone
3. Progressively change the shape of the bone to accommodate its various functions
112 4. Progressive fine tune fitting of all the
separate bones to each other and to
their contiguous ,growing, functioning
soft tissues
5. Carry out continuous structural
adjustments to adapt to the intrinsic
and extrinsic changes in conditions .
Drift
It is remodeling process and a combination of deposition and resorption.
If an implant is placed on depository side it gets embedded. Eventually marker becomes translocated from one side of cortex to other.
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Displacement114
Displacement is a physical movement of the whole bone as it remodels caused due to surrounding physical forces
Two types:
1. primary displacement
2. secondary displacement
Primary displacement
It is a physical movement of a whole bone and occurs while the bone grows and remodels by resorption deposition. As the bone enlarges it is simultaneously carried away from the other bones in direct contact with it.
E.g. in maxilla
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Secondary displacement
It is the movement of a whole bone caused by the separate enlargement of other bones.
Example- growth in the middle cranial fossa results in the movement of the maxillary complex anteriorly & inferiorly
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Rotation According to Enlow, growth
rotation is due to diagonally placed areas of deposition and resorption
Two types Remodelling rotations
Displacement rotations
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Principle of ‘Area relocation’
Both remodeling and displacement together cause a shift in existing
position of a particular structures with reference to
another
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Enlow’s V principal Most useful and
basic concept in facial growth as many facial and cranial bones have a V- shaped configuration.
Bone deposition(+) occurs on the inner side and resorption (-) occurs on the outer surface.
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Example with V oriented vertically
bone deposition
on lingual side of
coronoid
process , growth
proceeds and
this part of the
ramus increases
in vertical
dimension.
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V oriented horizontally
Same deposits of bone also bring about a posterior direction of growth movement.
.
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This produces a backward movement of coronoid processes even though deposit is on the lingual side
Same deposits carry base of bone in medial direction .
So, the wider part undergoes relocation into a more narrow part as the whole v moves towards the wide part .
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VARIOUS FACTORS AFFECTING GROWTH AND DEVELOPMENT-pre-natal factors
Causing INTRAUTERINE GROWTH RETARDATION
(IUGR)-
1. Chromosomal abnormalities2. Teratogens – a. Infectious agents b. Physical agents c. Chemical agents d. Hormones
3. Congenital infections- a. Rubella
b. Toxoplasmosis
c. Syphilis
d. HSV, HIV
4. Poor Maternal health- hypertension, renal & cardiac disease
5. Mother’s nutritional status/ Socioeconomic status
6. Mother’s use of alcohol, cigarettes, drugs etc
7. Placental insufficiency
8. Multiple births
Developmental anomalies CLEFT LIP & CLEFT PALATE CLEIDOCRANIAL DYSOSTOSIS CRANIOFACIAL DYSOSTOSIS (Crouzon’s
disease) MANDIBULOFACIAL DYSOSTOSIS (Treacher-
Collins Syndrome) PIERRE ROBIN SYNDROME FACIAL HEMIHYPERTROPHY ECTODERMAL DYSPLASIA
CLEFT LIP
Natal causes127
Growth can be affected by injuries during birth-
1. Intrauterine molding Arm pressed against the face
-maxillary deficiency
Head flexed against the chest- mandibular deficiency.
2. Trauma to mandible during birth process – forceps delivery
Post-natal factors GENETICS/HEREDITY:
GENERAL EPIGENETIC FACTORS: a. Hormonal factors b. Neural control c. General body growth LOCAL EPIGENETIC FACTORS: a. Function b. Muscles
GENERAL ENVIRONMENTAL FACTORS:
a. Nutrition
b. Illness
c. Race
d. Climate and seasonal effects
e. Exercise
f. Family size & birth order
g. Psychological disturbance
h. Socioeconomic factors
LOCAL ENVIRONMENTAL FACTORS:
a. Habits
Genetic / hereditary factors
Potential for growth is genetic.
Actual outcome of growth - Genetic potential combined with Environmental influences
Advanced rate of maturity in females than males – delaying action of ‘Y’- chromosome.
Genetic control seen in- a. body size, shape, deposition of fat b. patterns & rate of growth c. onset of growth events- menarche, -eruption of teeth, -ossification of bones, -beginning of adolescent
growth spurt
Hormonal factors
HORMONES LOCAL
GENERAL(ENDOCRINE)
Ex. Acetyl choline NON-SPECIFIC SPECIFIC
Secretin (all body cells) (target) organs)
ex. Growth hormone ex. ACTH
Thyroid hormones LH, FSH
Insulin
Hormones affecting growth
1. Growth Hormone2. Thyroid Hormones3. Parathyroid Hormone4. Calcitonin5. Insulin6. Adrenocortical hormones
Growth hormone/ somatotropin
Secreted by- ACTIONS
Protein synthesis synthesis & secretion
Lipolysis of IGF
Protein breakdown Use of glucose for ATP production
Increases size & number of cells Converts chondrocytes into osteogenic
cells Deposition of proteins by chondrocytic and
osteogenic cells
INDIRECT DIRECT
nutrition Proteins ( 9 essential amino acids),
carbohydrates, fats. Ca, Mg, Mn, , Vit D – bone & tooth Fe- Hb formation Vit A- activities of osteoblasts & osteoclasts Vit B complex- DNA formation & cell
maturation Vit C- collagen formation Oxygen – cardiac anomalies – stunted growth Teeth- bone- soft tissues
Effects of malnutrition
Delays growth, adolescent spurt
Affects size of body parts, proportions &
chemistry
Quality & texture of tissues – bone &
teeth
If period of malnutrition short – “catch-
up growth”
Girls better buffered against malnutrition
& illness.
illness Minor childhood illnesses – not much
effect.
Serious, prolonged, illnesses – marked
effect
Disease decreased GH.
Cartilage cell growth stopped temporarily.
Catch up growth – brings child back on
predetermined genetic curve.
Race
Racial differences-climatic, nutritional or
socioeconomic.
Gene pool differences – North American
blacks are ahead of whites in skeletal
maturity at birth & for at least first 2 yrs
of life.
Calcification & eruption of teeth 1 yr
earlier than whites.
Climate & seasonal effects
Cold climates- increased adipose tissue.
Increased height – in spring than autumn.
Increased weight - in autumn than spring.
Growth in height & eruption of teeth – more at
night than day.
Fluctuations in hormone release.
Family size & birth order First-born children – weigh less at
birth, ultimately less stature.
Sizes, maturation, intelligence of individuals- has no correlation with size of family.
EXERCISE Effects on growth is not proved. but Development of motor skills, in
muscle mass, fitness, general well-being.
Psychological disturbances Psychological abuse adversely affects
growth- accidental discovery in 1948 by German
physician. Ht. & wt. gain of children in 2 German
orphanages for 1 yr. Orphanage governed by harsh
headmistress – grew less in ht. & wt. though 20% extra calories.
Because of Inhibition of growth hormone. Catch-up growth.
Socioeconomic factors
Favorable socioeconomic status-
-different type of growth
-variation in timing of growth
Positive relationship associated with
socioeconomic “class” ; not family income.
Habits
Habits are learned patterns of muscle contraction of a very complex nature.
1. Thumb-sucking 2. Tongue-thrusting3. Mouth-breathing
Thumb-sucking Begins at birth and outgrown by 3-4 years.
Through sucking child obtains- feelings of euphoria, sense of security and feeling of warmth.
Maxillary constriction- not due to negative pressure.
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Mandible positioned in a downward manner to accommodate the interposed thumb- causing increased eruption of posterior teeth.
Tongue is lowered which decreases the pressure on the upper posterior teeth.
Imbalance between tongue & cheek pressures.
Cheek pressure increased as buccinator muscle contracts during suckling
Tongue-thrusting Tongue thrust is forward placement of
the tongue between the anterior teeth & against the lower lip during swallowing- Schneider (1982).
Tongue thrusting results due to lack of anterior seal.
Skeletal open bite Steep mandibular plane. Increased anterior facial height.
Mouth-breathing Breathing through
the mouth alters equilibrium of the jaws & teeth.
Lowering of the mandible & tongue & extension of the head is seen.
‘Adenoid facies’-separated lips, small nose, nostrils poorly developed, pout in the lower lip, vacant facial expression.
downward & backward rotation of mandible & increased lower facial height.
REFERENCES:149 Proffit:contemporary orthodontics.
T.M.Graber: Orthodontics Principles And Practice 3rd edition
Moyers:handbook of orthodontics. Donald H. enlow: facial growth 2nd
edition An inventory of United states and
Canadian growth record sets.S.Hunter , Baumrind S AJO 1993.
References150
Growth changes in the nasal profile from 7-8 yrs AJO 1988:94 Meng H ,R Nanda
Lewis A B, Roche AF pubertal spurts in cranial base & mandible AJO 1985:55
Baumrind S,Korn EL,quantitation of maxillary remodeling. AJO 1987:91
10.Sarnat: Growth pattern of the mandible; AJO-DO 1986: 90;221-233
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