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INDIAN DENTAL ACADEMY Leader in continuing dental education

Definition of 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” – Proffit

• “Change in any morphological parameter which is measurable”- Moss. • “Size development , progressive development (i.e, evolution, emergence, increase or expansion)”- Webster’s dictionary. • “Self multiplication of living substance”J.S.Huxley.

DIFFERENT KINDS OF GROWTH • Size change • Positional change • Proportional change • Functional change • Maturational change • Compositional change

• Timing and sequential change • a Prenatal growth •

b Postnatal growth • c Maturity • d Old age

Definition of 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 “Development connotes a maturational process

Major themes of development • • • •

Changing complexity Shifts from competent to fixation Shifts from dependent to independent Ubiquity of genetic control modulated by environment

Changing complexity • Takes place at all level of organisation from the sub-cellular to the whole organism • Normally complexity increases with development . • Most complex period of developing dentition is transition of dentitions.

Shifts from competent to fixation • Undifferentiated cells once differentiated become fixed.

Shifts from dependent to independent • Development brings greater independence at most levels of organisation.

Ubiquity of genetic control modulated by environment • Genetic control of development is constantly being modified by environmental interactions

Correlation between Growth & Development • Growth is basically anatomic phenomenon and quantitative in nature Development is basically physiologic phenomenon and qualitative in nature • Growth may not always be associated with increase in size, it may at times result in decrease in size, e.g. thymus gland after puberty Development on the other hand is a

Importance of growth and development to orthodontist • Serves as a backbone to understand the etiology of malocclusion • Helps to assess the health and nutrition of children • Allows comparison of growth of an individual child with the growth of other children • Helps to identify abnormal occlusal development at an earlier stage

• Makes available use of growth spurts • Surgery is done when facial growth is completed • Growth affects stability of occlusion hence retention regime should be planned accordingly.

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”

• Translocation – “It is a change in position”

• Maturation – “The term maturation is sometimes used to express qualitative changes which occur with ripening or ageing”

Normal features of Growth & Development • • • • •

Differential Growth Pattern Normality Variability Timing, rate & direction

DIFFERENTIAL GROWTH Different organs grow at different rates to a different amount and at different times. • •

Scammon’s curve of growth Cephalocaudal gradient of growth




PATTERN • 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. • Cephalocaudal gradient • An important aspect of pattern is predictablity

Predictability • 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. • In orthodontics, - Morphogenetic - Developmental

Variability • No two individuals with the exception of monozygotic twins are like. • Variability quantitatively is categorized in terms of deviations from the usual pattern, for which it is imp to understand the concept of normality.

Normality • Normality refers to that which is usually expected, is ordinarily seen or typical – Moyers • Normality may not necessarily be ideal. • Misuse of the concept of normality can lead to many problems in clinical orthodontics & •treatment planning.


Statistical Evolutionary Functional Esthetics Clinical

Growth charts

Applications of growth charts. • Location of an individual relative to the group can be established. • Can be used to follow a child over time and note for any unexpected change in growth pattern.

Timing of Growth • One of the factors for variablity in growth. • Timing variations arise because biologic clock of different individuals is different. • It is influenced by: genetic influence sex related differences physique related environmental influences

Distance curve Vs Velocity curve Distance curve


Velocity curve Distance Curve (cumulative curve): In this curve growth can be plotted in height or weight recorded at various ages. Age

Velocity Curve(incremental curve): In this by amount of change in any given interval that is growth increment

Growth spurts • Defined as periods of growth acceleration • Sex-linked – Normal spurts are • Infantile spurt – at 3 years age • Juvenile spurt – 7-8 years (females); 8-10 years (males) • Pubertal spurt – 10-11 years(females); 18-15 years (males)


Types of growth data

Methods of gathering growth data

Longitudinal growth studies

Methods of studying bone growth

Types of growth data.  Opinion  Observations.  Ratings and rankings.  Quantitative measurements. direct data.

Types of growth data. • Opinion It is a clever guess based on experience. they are the crudest form of scientific knowledge. • Observations: They are useful for studying all or none phenomenon.they are used in a limited way when more quantitative data is available.

• Ratings and rankings: certain data is difficult to quantify and thus may be compared to conventional rating scale .ratings make use of comparisons with such scales.rankings array data in ordered sequence according to value.

Quantitative measurements: Includes expressing an idea or fact as a meaningful quantity or numbers. • Direct data: derived from measurements taken on living persons or cadaver with a measuring device. • Indirect data: derived from measurements taken from images or reproductions of the actual person. • Derived data: obtained by comparing at least two other measurements.

Methods of gathering growth data. • Longitudinal studies . • Cross sectional studies. • Overlapping or semi longitudinal studies.

Longitudinal studies. • These are measurements made of the same person or group at regular intervals through time. • Advantages: temporary temporal problems are smoothed with time, Variability in development within a group is put in proper perspective,serial comparison makes study of specific developmental pattern of individual possible. Disadvantages: time consuming, expensive, sample loss or attrition,averaging.

Cross sectional studies ADVANTAGES • Quicker • Less costly • Statistical treatment made easier • Allows repeating DISADVANTAGES • Variation in development amongst individuals within the sample cannot be studied

Semi longitudinal studies. • Longitudinal and cross sectional studies can be combined to to seek the advantages of this way one might compress 15 years of study into 3 years of gathering growth data.


Longitudinal growth studies • • • • • • •

Bolton brush growth study Burlington growth study Michigan growth study Denver child growth study Iowa child welfare study Forsyth twin study Meharry growth study

• • • • • • •

Montreal growth study Krogman philadelphia growth study Fels growth study Implant studies the mathews implant collection the hixon oregon implant study Cleft palate study

Bolton Brush growth study. • Initiated by Prof T Wingate Todd in 1926 • Aim- studying skeletal development . • Initiated concurrently by Dr Holly Broadbent Sr in 1929. • Aim- studying normal development of facial skeleton. • Sample size:5000 normal healthy children. • Records:series of x-rays,casts,dental and medical examination and psychological tests.

• The two collections merged officially in 1970.

• In 1975 the Bolton standards of dentofacial development growth were published by Dr Holly Broadbent jr. • These standards are a series of averages that represent optimum facial and developmental growth and form a baseline for understanding and assessing craniofacial growth.

Burlington growth study • AIM • Malcclusion • Evaluate preventive and interceptive orthodontic treatment. • Obtain a set of growth records as a database for future studies. • Sample size:1632 subjects followed longitudinally.

• Records :series of x-rays, casts,photographs,height and weight records and medical examination. • The original concept for the study was presented by Robert Moyers& the records were gathered under Frank Popovich.

Burlington growth study • More than 247 investigations & 322 studies are based on this growth study • Longitudinal studies by Thompson & Popovich to derive cephalometric norms of a representative sample was based on 210 children followed for 15 years at the Burlington growth center. • age sex and growth type specific craniofacial templates were derived and static and dynamic analysis were proposed on the basis of this study.

The Iowa child welfare study. • Sample size:it is a diminishing longitudinal study which began with 20 males and 15 female 4 year old subjects. Followed till 17 years of age. Non -orthodontically treated patients of entirely European origin were used. • Records:lateral and PA views and dental casts. • The study as done under Samir Bishara.

• Based on this study the changes in facial dimensions & relationships as well as in standing height were evaluated. • The dentofacial relationships of 3 normal facial types (long, average, short) from 5-25 yrs of age was described & compared.

CLEFT PALATE STUDIES. • LANCASTER PA:includes 850 record sets obtained annually from birth to 15 years. • HOSPITAL FOR SICK CHILDREN(Toronto):over 4000 subjects ranging in age from 5-20 years • .CENTER FOR CRANIOFACIAL ANOMALIES(Chicago);annual records of 1000 subjects. • Records include series of x-ray films, casts, medical and orthodontic treatment records. • All subjects had surgical repair and minor to extensive orthodontic treatment.

Methods of studying bone growth m e a s u re m e n t a p p ro a c h e s .

e x p e r im e n t a l a p p r o a c h e s .

c r a n io m e t r y .

a t m ic r o s c o p ic le v e l.

a t m a c r o s c o p ic le v e l.

a t b o t h le v e ls .

a n th ro p o m e try .

m in e r a lis e d s e c t io n s .

im p la n t m a r k e r s

v it a l s t a in in g .

c e p h a lo m e t r y .

m ic r o r a d io g r a p h y .

f in it e e le m e n t m o d e lin g .

c o m p a r a t iv e a n a t o m y .

f lu o r e s c e n t la b e ls . p o la r is e d lig h t . r a d io is o t o p e s . n u c le a r v o lu m e m o r p h o m e t r y . a u t o r a d io ra p h y .

n a tu ra l m a rk e rs .

CRANIOMETRY. Involves measurements of skull used to study the Neanderthal and Cro-magnon skull. give information of extinct population and pattern of growth

Advantages: Precise measurements. Disadvantages:All growth data must be cross sectional.

ANTHROPOMETRY: • measurements using soft tissue points overlying bony landmarks in living individuals. • can also be done on dried skulls but variation in soft tissue thickness would produce different results. • Possible to follow the growth of an individual directly.

• CEPHALOMETRIC RADIOGRAPHY: • allows direct measurement of bony skeletal dimensions and follow up of the same individual over time .

• Disadvantages •:Depends upon precise orientation of head and precise control of magnification. • 2D representation of 3D structure

Mineralized sections. • Fully mineralized sections are superior to demineralized specimens as there is less processing distortions and both organic and inorganic matrix can be studied simultaneously. • Cellular details and resolutions can be enhanced by reducing the thickness of the sections. • Specific stains can be used to enhance both cellular and extra cellular details. • Thin sections can however quench more rapidly

Microradiography. • High resolution of images of bone sections • Differential density between primary and secondary bone. • Strength of the bone-proportional to degree of mineralisation. • secondary bone has more strength than primary bone. • Secondary mineralisation process takes about 8 months to form and hence the minimum retention period after active orthodontic correction should be 6-8 months.

Fluorescent labels. • Administered 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 commonly used labels.

Radioisotopes. • • •

Radioisotopes of certain elements or compounds are often used as in vivo markers for studying bone growth. Such labeled material is injected and after some time located within the growing bone by means of autoradiographic techniques. Commonly used markers are : 1. 2. 3.

Technetium 99 Calcium 45 Potassium 32

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.

Quantitative and qualitative assessment of the label uptake is a physiologic index of cell activity.

• • • •

Commonly used autoradiographic labels are: A. 3 H thymidine. B. 3 H proline. C. Bromodeoxyuridine.

Polarized light. • indicates the orientation of collagen fibers within the bone matrix. • Most lamellar bone consists of collagen fibers oriented at right angles. • However 2 other configurations can also be noted:longitudinally aligned(L osteons).

• And mixed fiber pattern.(both L and A osteons). • Loading condition at the time of bone formation dictate the orientation of collagen fibers . Thus bone formation can adapt to different loading conditions by changing the internal lamellar organization of bone tissue.

Nuclear volume morphometry. • cytomorphometric procedure to measures the nuclear size for assessing the stages of differentiation of osteoblastic precursor cells. • Pre osteoblasts have significantly larger nuclei than their precursors. • used in determining the relative differentiation of PDL and other bone living cells.

Teleradiology. • Introduced in 1982 at international conference of PACS. • Universal method of storing and transporting digital images . • Currently American college of radiology have developed DICOM to allow the transmisssion of images over the internet.

Vital staining • reported by Belchier in 1796 • John Hunter- alizarin dye • Alizarin reacts with calcium at sites of bone calcification i.e. sites of active skeletal growth thus marking these locations • Other dyes : tetracyline trypon blue lead acetate procion

• Vital staining aids in studying: Manner in which bone is laid down site of bone growth the direction and amount of growth and the timing and relative duration of growth at different sites.

Natural markers. • The persistence of certain developmental features has led to their use as natural markers by means of serial radiography. • Eg: trabaculae,nutrient canals and lines of arrested growth can be used for reference to study deposition, resorption and remodeling. • Certain natural markers are used as cephalometric landmarks.

Implant markers. • Bjork devised a method of implanting tiny bits of tantalum or biologically inert alloys into growing bone which served as 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.

Mechanism of growth • 3 mechanisms at the cellular level – Hyperplasia – Hypertrophy – Secretion of extracellular matter

Mechanism of growth in soft tissues

• In soft tissues growth occurs by a combination of two mechanisms namely: • hyperplasia and hypertrophy • These result in interstitial growth.

Mechanism of growth in hard tissues. • The craniofascial skeleton grows by three unique processes: • Chondrogenesis: formation of cartilage • Endochondral bone formation: process of converting cartilage into bone • Intramembranous bone formation: process of bone formation from undifferentitaed mesenchymal tissue.

Comparison of physiologic properties of bone and cartilage • Characteristic


• • • • • •


Calcification Non calcified Vascularity Avascular Surface membrane Nonessential Pressure resistance Tolerant Rigidity Flexible Modes of growth Interstitial Appositional and appositional

Calcified Vascular Essential Sensitive Inflexible

Endochondral bone formation • Definition:It is the process of converting cartilage into bone.

• Occurs in regions exposed to high levels of compression • In craniofacial region it is seen in areas like • Synchondrosis at the cranial base • Condylar cartilage • Nasal septal cartilage

Steps of chondrogenesis • Chodroblasts produce matrix • Cells become encased in matrix • Chondrocytes enlarge,divide and produce matrix • Matrix remains uncalcified • Membrane covers the surface but is not essential

Steps of endochondral bone formation • hypertrophy of chondrocytes and matrix calcifies • Invasion of blood vessels and connective tissue cells. • osteoblasts differentiate and produce osteoid tissue. • osteoblast tissue calcifies.

Intramembranous bone formation Definition: it is the process of bone formation from undifferentiated mesenchymal tissue • Derived from neural crest cells • Occurs in areas exposed to tension • It differs from endochondral bone formation by formation of bone directly from mesenchymal tissue

–Seen in areas like: – Cranial vault • Maxilla • Mandible except condylar cartilage

Steps of intramembranous bone formation • Osteoblasts produce osteoid tissue. • Cells and blood vessels are encased. • Osteoid tissue is produced by membrane cells. • Osteoid calcifies. • Essential membrane covers bone.

Bone metabolism • Bone is the primary calcium reservoir of the body

(99% stored in skeleton) •Bone structure is sacrificed to maintain the critical serum calcium levels at 10mg %

Bone metabolism

Calcium homeostasis is supported by 3 mechanisms : 1. Rapid instantaneous flux of calcium from bonefluid (seconds) by selective transfer of calcium ions into and out of bone fluid. 2. Shorterm control of serum calcium levels affects rates of bone . formation $ resorption

3. Longterm regulation of metabolism- have effects on skeleton

TYPE OF BONES • • • • • • •

Lamellar bone Non lamellar bone Fine cancellous bone Coarse cancellous bone Woven bone Bundle bone Composite bone

LAMELLAR BONE • Comprises 99% of human skeleton • Strong highly mineralised • Mineralised in two stages: • primary mineralisation • secondary mineralisation

Clinical significance • Full strength of lamellar bone supporting an orthodontically moved tooth is not attained for upto a year after completion of active treatment.

Non Lamellar bone • Makes up fine cancellous bone tissue • No distinct stratification in fibre orientation

Woven bone • Type of non lamellar bone • Weak , disorganised, poorly mineralised • Not found in adult human skeleton under normal conditions • First bone formed in response to orthodontic loading.

Bundle bone • Present adjacent to periodontal ligament • Presence of perpendicular striations called sharpey’s fibres. • Formed on depository side of socket, laid dowm in the direction toward the moving tooth root.

Composite bone • Predominant bone type during early retention phase • Most rapid means of producing strong bone • Formed by deposition of lamellar bone within a woven bone lattice.

Fine cancellous bone tissue • Formed by periosteum and endosteum • Marrow spaces are fine • It is located in cortex e.g. posterior border of a growing ramus in a child • Fastest growing of all bone types

Coarse cancellous bone • Produced by endosteum only • Irregular marrow spaces containing red or yellow marrow • Irregularly arranged trabeculae • Present in medulla

Mechanisms of bone growth • • • • •

Deposition and resorption Growth fields Modelling Remodelling Growth movements drift displacement

Deposition and resorption • Bone sides which face the direction of growth are subject to deposition (+) and those opposite to it undergo resorption(-) ‌surface principal

Deposition and resorption • Bone produced by covering membraneperiosteal bone comprises about half of the cortical bone tissue: bone laid down by the lining membrane-endosteal bone makes up the other half.

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.

Transverse histologic section of bone: A.Periosteal surface reorptive,endosteal surface depository. B.New endosteal bone addedon inner surface. C.Endosteal layer produced covered by periosteal layer following outward reversal. D.Cortex made entirely of periosteal bone‌.outer surface depository inner surface resorptive.

Example with V oriented vertically • When bone added on lingual side of coronoid process,growth proceeds and this part of the ramus increases in vertical dimension.

Example of V oriented horizontally • Same deposits of bone also bring about a posterior direction of growth movement. • 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 as in fig 1. • Hence, the wider part undergoes relocation into a more narrow part as the whole v moves towards the wide part (fig 2)

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..

About one half of the bone is periosteal and the other half endosteal.If endosteal surface is resorptive then periosteal surface would be depository. • Provides two growth functions: Enlargement of any given bone Remodelling of any given bone •

Growth sites • Growth fields having special role in the growth of the particular bone are called growth sites • e.g. mandibular condyle, maxillary tuberosity, synchondrosis of the basicranium, sutures and the alveolar process.

Growth sites – Such special sites do not out the entire carry growth process but the entire bone takes part

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. • Now believed that these centers do not control the whole growth process.


Bone modeling involves independent sites of resorption and formation that change the size and shape of a bone.

CONTROL FACTORS FOR BONE MODELING – Mechanical load in Micro strain. 1. Disuse atrophy 2. Bone Maintenance —2500. 3. Physiological Hypertrophy —4000. 4. Pathological Overload >4000. •

Peak <200. 200 2500

â&#x20AC;˘ Endocrine. 1.Bone metabolic hormones-PTH,Vit D,Calcitonin. 2.Growth Hormones-Somatotropin,IGF 1,IGF 2. 3.Sex steroids-Testosterone,Estrogen.

Remodelling • Required differential growth activity required for bone shaping. • It involves deposition and resorption occuring on opposite ends • Four types – – – –

Biochemical remodelling Haversian remodelling Pathologic remodelling Growth remodelling

â&#x20AC;˘ E.g. The ramus moves posteriorly by the combination of deposition and resorption. â&#x20AC;˘ so the anterior part of the ramus gets remodeled into a new addition for the mandibular corpus.

Functions of Remodeling 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

Functions of Remodeling 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

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 â&#x20AC;˘ It is remodeling process and a combination of deposition and resorption. â&#x20AC;˘ If an implant is placed on depository side it gets embedded.eventually marker becomes translocated from one side of cortex to

Displacement â&#x20AC;˘ Displacement is a physical movement of the whole bone as it remodels â&#x20AC;˘ Two types: primary displacement secondary displacement

Primary displacement â&#x20AC;˘ It is a physical movement of a whole bone and occurs while the bone grows and remodels by resorption deposition â&#x20AC;˘ E.g. in maxilla

Secondary displacement â&#x20AC;˘ It is the movement of a whole bone caused by the separate enlargement of other bones

Combination of remodeling & displacement • Both these mechanisms carries out two general functions • Positions each bone • Designs and constructs each bone

Rotation • According to Enlow, growth rotation is due to diagonally placed areas of deposition and resorption • Two types – Remodelling rotations – Displacement rotations

Principle of â&#x20AC;&#x2DC;Area relocationâ&#x20AC;&#x2122; Both remodeling and displacement together cause a shift in existing position of a particular structures with reference to another


Counter part principle • “Growth of any given facial or cranial part relates specifically to other structural and geometric counterparts in the face and cranium” Enlow

Growth equivalent principle This principle proposed by Hunter & Enlow relates the effects of cranial base growth on the facial bone Growth.

REFERENCES: • Proffit:contemporary orthodontics. • Moyers:handbook of orthodontics. • An inventory of United states and Canadian growth record sets.S.Hunter , Baumrind S AJO 1993. • Craniofacial imaging in orthodontics :S Kapila et al AO 1999:69 • Essays in honour of Robert moyers CFGS.monograph 24.

References • Bone biodynamics in orthodontics:CFGS.27 • Atlas of craniofacial growth in Americans of African descent CFGS.26 • Growth changes in the nasal profile from 7-8 yrs AJO 1988:94 Meng H ,R Nanda • Longitudinal changes in 3 normal facial types .S Bishara,AJO1985:88 • S Bishara,J R Peterson, changes in the facial dimensions & relationships between the ages 5-25yrs.AJO 1984:85

References • Lewis A B, Roche AF pubertal spurts in cranial base & mandible AJO 1985:55 • Popovich.Thompson. Craniofacial templates for orthodontic case analysis. • Baumrind S,Korn EL,quantitation of maxillary remodeling. AJO 1987:91 • Atlas of craniofacial growth CFGS monograph 2. • Moyers,Van Der Linden standards of human occlusal development CFGS:5 • B Grayson 3D cephalogram theory,technique and clinical application.

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