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INTRODUCION BASICS – Definitions – What is growth & development ? – Types of growth THEORIES OF CRANIOFACIAL GROWTH
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Krogman “Growth was conceived by an anatomist, born to biologist,delivered by a physician left on a chemist`s door step and adopted by a physiologist. At an early stage, she eloped with a statistician. Divorced him for a pschychologist, and is now being wooed alternately and concurrently by an endocrinologist, a biochemist, a physicist, a mathematician, an orthodontist, an eugenicist and the children`s bureau� www.indiandentalacademy.com
GROWTH •
Todd 1931 Growth refers to increase in size
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Profitt 1986 Growth usually refers to an increase in size and the number
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Moyers 1988 Growth may be defined as the normal changes in the amount of living substance. www.indiandentalacademy.com
Growth is basically anatomic phenomenon and quantitative in nature.
Development is basically physiologic phenomenon and qualitative in nature.
Correlation between growth & development
Development = growth + differentiation + translocation www.indiandentalacademy.com
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Cellular hyperplasia: increase in the number of cell.
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Cellular hypertrophy: increase in the size of individual cells. Interstitial: growth of softtissue occurs by combination of hyperplasia and hyperthrophy , these process go on every where in the tissue.[ it occurs all points with in the tissue]. Appositional :Direct addition of new bone to the surface of existing bone and does occur through the activity of cells in the periosteum.
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Pattern : – arrangement of parts,values,events, or relations among measurements. • Growth trends • Cephalocaudal gradient
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Variability : – Is the law of nature • Normality • Differential growth
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Timing : – Is variable & concerned with rate and division of growth • Growth spurts www.indiandentalacademy.com
Tweed employed four angles namely: IMPA,FMA,FMIA,ANB. TYPE A: Maxilla and mandibule grow downward & forward in union. No change in the size of ANB angle;25% of pts have this growth tendency. TYPE B: Although entire face grows downward & forward, maxilla grows more rapidly than mandible resulting in the increase of ANB angle; 15% pts fall under this category. TYPE C: Mandible grows rather downward & forward at a faster rate than middle third of face. This shows lessening of ANB angle in comparison of two standardized lateral ceph . These constitute 60%. www.indiandentalacademy.com
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CEPHALOCAUDAL GRADIENT
Thus “Cephalocaudal gradient of growth” , this simply means that there is an axis of increased growth extending from the head towards the feet. www.indiandentalacademy.com
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In fetal life, at about the third month of intrauterine development , the head takes up almost 50% of total body length. At this stage, the cranium is large relative to the face and represents more than half the total head . In contrast, the limbs are still rudimentary and the trunk is underdeveloped. By the time of birth, the trunk and limbs have grown faster than the head and face, so that the proportion of the entire body devoted to the head has decreased to about 30%. www.indiandentalacademy.com
The overall pattern of growth thereafter follows this course, with a progressive reduction of the relative size of the head to about 12% the adult. All of these changes,which are a part of the normal growth pattern, reflect the “cephalocaudal gradient of growth”. This simply means that there is an axis of increased growth extending from the head towards the feet.
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Normal refers to that which is usually expected , is ordinarily seen , or is typical. Normal – Range & Ideal – Fixed value On comparison with normal, a variable can be measured. CLINICAL IMPLICATION : Diagnosis of gross variations from central tendency of pathological condition or gross abnormal pattern of growth
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Not all tissue systems of the body grow at the same rate. Different tissues and in term different organs grow at different rates. This process is called differential growth.
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As the graph indicates, growth of the neural tissues is nearly complete by 6 or 7 years of age. General body tissue, including muscle, bone and viscera, show and S-shaped curve, with a definite slowing of the rate of growth during childhood and an acceleration at puberty. Lymphoid tissues proliferate far beyond the adult amount in late childhood, and then undergo involution at the same time that growth of the genital tissues accelerates rapidly around the onset of puberty. www.indiandentalacademy.com
scammons growth curve
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Just before birth
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One year after birth
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Mixed dentition period boys : 8 – 11 yrs girls : 7 – 9 yrs Pre pubertal period boys : 14 – 16 yrs girls : 11 – 13 yrs Pubertal period boys : till 25 yrs girls : 18 – 20 yrs
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Growth spurts serve as excellent indicators for timing of orthodontic treatment Correlation of a. Skeletal age, b. Dental age c. Chronological age. With on set of puberty. www.indiandentalacademy.com
Importance of Growth Spurts:  Pubertal increments offers best time for, determining the predictability, growth direction, patient management and total treatment time. 
Understanding the growth, predictability of future growth of maxilla, mandible and alveolar process helps in diagnosing and achieving excellent results of the malocclusion. www.indiandentalacademy.com
Large number of cases for the orthodontic and orthopedic correction of Maxilla and Mandible. Growth spurts serve as excellent indicators for timing of orthodontic treatment. For eg: orthognathic surgeries after growth spurt completion. Growth spurt is the best period for Interceptive orthodontics. www.indiandentalacademy.com
For ex: classII malocclusion with mandibular retrognathism can be managed by activator thearpy.
classII malocclusion with maxillary prognathism can be managed by the use of headgear.
classIII malocclusion with mandibular prognathism can be controlled by chincap and headgrear.
classIII malocclusion with maxillary retrognathism can be managed by nakamuras applince which promotes the growth of maxilla. www.indiandentalacademy.com
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Malocclusion of dental arches can be treated taking Advantage of growth spurts during the active growth periods.
Arch expansion & rapid skeletal expansion can be undertaken during periods of maximum growth. www.indiandentalacademy.com
Theories of Growth and Development
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Genetic theory – brodie 1941
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Sutural theory – sicher 1955
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Cartilaginous theory – scott’s 1956 Funtionalmatrix theory – melvin moss 1962 Enlow’s expanding “v” principle – enlow 1963 Enlow’s counterpart principle Van Limborgh’s theory - 1970 Servosystem – petrovic hypothesis - 1974
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Mainly based on observations
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No evident scientific data
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Lacked scientific understanding and soon replaced by other theories.
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Sutural theory Proposed by Sicher in 1955: According to Sicher
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“The primary event in sutural growth is the proliferation of the connective tissue between the two bones. If sutural tissue proliferates, it creates the space for appositional growth at the border of the bones”.
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We now know that functions of suture are :
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Unite the bone
2.
Absorb the forces,
3.
Act as a joint
4.
Act as a growth site and not growth centre www.indiandentalacademy.com
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Evidences Against Sicher’s Theory:
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Auto transplants of sutures fail to grow in cultural medium though provided with same environment and conditions.
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Extripation of sutures has no appreciable effect on growth of skeletal.
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The shape and growth within sutures is dependent on external stimuli.
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It is possible to bring the sutural growth to halt by mechanical stress applied across the sutures. www.indiandentalacademy.com
Cartilagenous Theory (James Scott-1956)
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The fact that, for many bones of the hand and legs, cartilage does the growing while bone merely replaces it makes this theory attractive for the bones of the jaws.
According the Scott:-
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Spheno-occipital synchondrosis cartilage -responsible for the growth of cranial base.
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Nasal septal cartilage – Responsible for the growth of maxilla
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Condylar cartilage – Responsible for the growth of mandible www.indiandentalacademy.com
1. Spheno ethmoidal 2. Inter-sphenoidal 3. Spheno-occipital
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Important growth center of craniofacial skeleton, especially cranial base.
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Cartilage of Nasal Septum:
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Spheno-occipital Synchodrosis:
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Growth of maxilla is difficult to explain on the cartilage theory. Proponents of the cartilage theory hypothesize that the cartilaginous nasal septum serves as a pacemaker for other aspects of maxillary growth.
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• Removal of a segment of the Nasal Septal Cartilage in humans and rabbits showed mid-facial deformities.
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Two kinds of experiments have been carried out to test the idea that cartilage can serve as a true growth center.
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1. Transplanting nasal cartilage to cultural medium or any other place did not give equivocal results, that is sometime it grew, sometimes it did not. Indicating doubtful growth potential of the nasal septal cartilage whereas, if a piece of the epiphyseal plate of a long bone is transplanted, it will continue to grow in a new location or in culture, indicating that these cartilages do have innate potential. www.indiandentalacademy.com
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Since longtime, its being hypothesized that condylar cartilage is the growth center for the growth of mandible.
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Experiments of transplanting condylar cartilage showed little or No growth potential.
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It is no clear that condylar cartilage is secondary cartilage, which grows by appositions and not by intestitial deposition. Whereas, epiphyseal cartilage is primary cartilage.mandibular condylar thus do not have innate growth potential and not a growth center. www.indiandentalacademy.com
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The fact that after the condylar fracture in children do not all together inhibit growth of mandible indicates that condyle is not a growth center.
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Studies carried out in Scndinavia in 1960’s demonstrated that after the fracture of mandibular condyle in child, there was an excellent chance that the
condylar
process
would
regenerate
to
approximately its original size and small chance that it would overgrow after the injury.
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FUNCTIONAL MATRIX CONCEPT (MELVIN MOSS)
This concept attempts to comprehend the relation between form & function.
This concept claims that origin, form, position, growth & maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary
response
to
chronologically
&
morphologically prior events or processes that occur in specifically related non-skeletal t
issues, organs or www.indiandentalacademy.com functioning space .
Functional cranial component
Skeletal unit
Functional matrices
Macroskeletal
Microskeletal
Eg-coronoid, angular
Eg-endocranial surface Of calvaria
Periosteal
Eg-teeth and muscles
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Capsular
Eg-orofacial, neurocranial
a) Skeletal unit – it protects &/or support its specific functional matrices. b) Functional matrix – which carries out the function.
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Skeletal unit: 
All skeletal tissues associated with a single function are called skeletal unit.
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The skeletal unit may be comprised of bone, cartilage and tendinous tissue.
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MACRO SKELETAL UNIT Adjoining portions of number of neighbouring bones carrying out a single function eg- endocrainal surface of calvaria
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MICROSKELETAL UNIT Bones consisting of number of small skeletal units MAXILLA-orbital -pneumatic -palatal -basal MANDIBLE-coronoid -angular -alveolar -basal www.indiandentalacademy.com
The Functional matrix Divided into: 1. Periosteal matrix 2. Capsular matrix Periosteal matrices
Act directly & actively upon their related skeletal units. Alterations in their functional demands produce a secondary compensatory transformation of the size or shape of their skeletal units Such transformations are brought about by the inter related process of bone deposition and resorption. www.indiandentalacademy.com
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Best explanation – coronoid process and temporalis muscle ,removal denervation and post infectively decrease in the size or total disappearance , hence in simple terms it can be stated coronoid process does not grow itself first and thus provide a platform upon which the temporalis muscle can alter its function but it is the opposite which is true
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Capsular matrices ď ś
Act indirectly and passively on their related skeletal units producing a secondary compensatory translation in space.
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The skeletal units are passively & secondarily moved in the space as their enveloping capsule is expanded. This kind of translative growth is not brought about bywww.indiandentalacademy.com deposition and resorption.
FOUR CAPSULES ARE PRESENT NEURO CRANIAL ORO FACIAL OTIC ORBITAL
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Each of these capsules is an envelop containing functional cranial component Sandwitched 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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Surrounded by skin and mucous membrane , Surrounds and protects oro-naso-pharyngeal space on either side. Originates by process of enclosure. Volumetric growth of these spaces is the primary morphogenetic event in facial skull growth
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Orofacial Capsule
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Primary function is maintaining airway this is accomplished by “AIRWAY MAINTENANCE SYSTEM”-BOSMA
Growth of functional spaces-increase in the size of capsule
Followed by passive movement of functional cranial component www.indiandentalacademy.com
Functional matrix theory revisited Melwin Moss in 1997 proposed continuation of his classical functional matrix theory with the new concept. He published series of articles in American Journal of Orthodontics in 1997. This has lead to the inclusion of two topics: i.The Mechanisms of Cellular Mechanotransduction ii.Biologic Network Theory www.indiandentalacademy.com
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According to this concept the mechanical stimulus is pursued by the specialized cells by process called as mechanoperception. Then these signals are transmitted through the tissues by way mechanoconduction or mechanotrasmision. Finally, these signals are transmitted to the genome of the bone were protein synthesis is taking place.
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These signals alter the protein metabolism depending upon the severity and longativity of the mechanical stimulus. In short the earlier concept of FMH theory remained same as form is determine by the function.
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Moss also recognizes the important role of genetics and human genome in determining the ultimate size and shape of the craniofacial skeleton. He quotes reference of human genome project which is being carried in a mega scale allover the world. According to the human genome project human chromosomes contain the genetic informations www.indiandentalacademy.com necessary for buildingup of entire human body.
Genes now beyond doubt have been proved to effect
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the physical growth of the person, behavior of person and
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psychology of person.
Thus Moss FMH revisited theory states the ultimate
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growth controlling factor of the craniofacial skeleton depends on two factors.
1.
Genetic factors
2.
Environment factors. www.indiandentalacademy.com
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Morphogenesis is regulated by both genomic and epigenetic processes and mechanisms both are necessary causes, neither alone are sufficient causes.
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Their integrated activities provide the necessary and sufficient causes for growth and development
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ENLOWS EXPANDING ‘V’ PRINCIPLE Growth
movements
&
enlargements of these bones occur towards the wide ends of the
‘V’
differential
as
a
result
deposition
of &
selective resorption of bone Bone deposition occurs on the inner side of the ‘V’ and bone resorption surface.
on
the
outer
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Deposition also takes place at the end of two arms of the ‘V’
resulting in growth movement towards the ends.
The ‘V’ pattern occurs in a number of regions such as base of the mandible, ends of long bones , mandibular body, palate etc.
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The growth of any given facial or cranial part specifically to other structural and geometric counterparts in the face and cranium There are regional relationships through out the whole face and cranium. If each regional part and its particular counterpart enlarge to the same extent, balanced growth occurs.
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Antr – cranialbase ----- maxilla middle – cranialbase --- pharyngealspace middle – cranialbase ----- width of ramus Maxilla ---------- mandible Maxilla tuberosity ----- lingual tuberosity
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VAN LIMBORGH’S THEORY
Process of growth & development in a view that combines all the 3 existing theories.
He suggested following 5 factors[multifactorial theory] Intrinsic genetic factors
They are the genetic control of the skeletal units themselves. Local epigenetic factors
Bone growth is determined by genetic control originating from adjacent structures like brain,eyes etc… www.indiandentalacademy.com
General epigenetic factors They are genetic factors determining growth from distant structures. e.g. sex hormones, growth hormone etc…
Local environmental factors They are non genetic factors from local external environment. e.g. habits, muscle force etc.
General environmental factors They are general non-genetic influences such as www.indiandentalacademy.com
ď ś
The views expressed by Van Limborgh’s can be summarized in 6 points 1. Chondrocranial growth is controlled mainly by the intrinsic genetic factors. Eg; Base of the skull 2.Desmocranial growth is controlled by a few intrinsic genetic factors. Eg; calvaria. 3. The cartilaginous parts of the skull must be considered growth centers. www.indiandentalacademy.com
4 .Sutural growth is controlled mainly by influences originating from the skull cartilages & from other adjacent skull structures. 5.Periosteal growth largely depends upon growth of adjacent structures. 6.Sutural & periosteal growth are additionally governed by local non genetic environmental influence www.indiandentalacademy.com
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Proposed by petrovic accordingly, the growth of maxilla and mandible and cranial base depends upon cybernetic control.
This cybernetic control is
mainly by Secretion of hormones. These hormones mainly include growth hormone - somatomedin, testosterone and estrogen.
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Author describes the secretion of hormones is by the signal established independed of the feedback system.
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This signal secretion is described as COMMAND .
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This signal is transmitted to the Reference input elements. In maxilla they include septal cartilage, septopremaxillary frenum, the labionarinary muscles and the maxillary bones. In mandible reference input elements include muscle attachments to the mandible that is lateral pterygoid, medial pterygoid and tempralis muscles. www.indiandentalacademy.com
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The commanding signal is first established in the maxilla through the above quoted reference input elements and thus maxilla grows in sagittal and vertical direction. The corresponding actuating signal followed to the above process is felt in the mandible through the reference input elements and mandible growth occurs.
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Neurotrophism is a non impulse transmitting neural function that involves axoplasmic transport and provides for longterm interaction between neurons and innervated tissues that homeostatically regulates the morphological, compositional ,functional integrity of those tissue.
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Neuro-epithelial trophism:Epithelial mitosis and synthesis are neurotropiclly controlled by release of neurotrophic substances by the nerve synapses. Ex;taste buds sensation. neuro-muscular trophism:Embryonic myogenesis is independent of neural innervation and trophic control. Neuro-visceral trophism:The salivary glands,fat tissue and other organs are trophically regulated.
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Contemporary Orthodontics ---William R.Proffit Orthodontics Practice and Principles– TM Graber Orthodontics The Art and science-S.I. Bhalaji Textbook of Orthodontics --Gurkeerat singh
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www.indiandentalacademy.com Leader in continuing dental education
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