EVOLUTION OF THEORIES

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INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com
Craniofacial biology as
“Normal Science”
David S. Carlson
• According to Kuhn(1970)
Normal science
Research firmly based u...
Paradigm
It is a conceptual scheme that
encompasses individual theories and
is accepted by a scientific
community as a mod...
EVOLUTION OF PARADIGM’S
www.indiandentalacademy.com
Various paradigms 1920-1940
• Development of the Genomic Paradigm
More emphasis on structure rather than function.
(Krogma...
Bookstein/Moyers
--The development and early use of
Radiographic cephalometry initiated a more
energetic period of data ac...
1940-1960
• Craniofacial biology saw an increased emphasis on

experimental animal research in an effort to account
for th...
Technological developments:• Use of Radioopaque Implants.
• Vital Dyes.
• Autoradiography.
• In-vivo and In-vitro transpla...
Comprehensive Approach:
-Continued with craniometrics but with more
Sophisticated hardware including radiographs,
cephalos...
--By the end of 1950’s the genomic paradigm was put
into question
--Periosteal and Sutural bone growth were removed
from t...
MAINLY DOMINATED
BY
GENOMIC PARADIGM

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1960-1980
--Formulation of an Alternative paradigm.
--Termed as the “Functional Paradigm” stated that the
Craniofacial com...
DEVELOPMENT OF AN ALTERNATIVE PARADIGM
www.indiandentalacademy.com
--Moss 10 yrs later released a third paper on the same.
--From then on the “Functional” hypothesis became a topic
of theor...
--Alexander Petrovic and Associates(1975)
•Proposed the cybernetic models of
mandibular growth.

1980-2000
• This period s...
Significant developments:
1. Functional Matrix Revisited (Moss-1997)
2. Von Limborg’s Conceptual Theory.

www.indiandental...
www.indiandentalacademy.com
Conclusion:
The 2 Paradigms present:
1.Genomic--Exists primarily on the strength of the
belief that facial growth and form...
FUNCTIONAL
MATRIX
REVISITED

PRESENT

www.indiandentalacademy.com
GROWTH CENTER vs GROWTH
SITE
• Cranial growth centers—facts or fallacies
Kalevi Koski (1968)AJO

www.indiandentalacademy.c...
According to BAUME:
Growth Center:
Is a site of endochondral ossification with
tissue separating force,contributing to the...
SUTURES
• On the basis of definition sutures cannot be called
growth centers.
• Histologically it is evident that sutures ...
Evidence in favor of the dependent role
of the sutural growth appears to be
accumulating

• Subcutaneous auto transplants ...
Thank you
www.indiandentalacademy.com
Leader in continuing dental education

www.indiandentalacademy.com
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Evolution of theories /certified fixed orthodontic courses by Indian dental academy

  1. 1. EVOLUTION OF THEORIES www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. Craniofacial biology as “Normal Science” David S. Carlson • According to Kuhn(1970) Normal science Research firmly based upon one or more past scientific achievements that Some particular scientific community acknowledges as supplying the foundation for its further practice www.indiandentalacademy.com
  4. 4. Paradigm It is a conceptual scheme that encompasses individual theories and is accepted by a scientific community as a model and foundation for further research. www.indiandentalacademy.com
  5. 5. EVOLUTION OF PARADIGM’S www.indiandentalacademy.com
  6. 6. Various paradigms 1920-1940 • Development of the Genomic Paradigm More emphasis on structure rather than function. (Krogman) Moss subdivided this period: 1. Preradiologic Phase-Emphasis placed on craniometry 2. Radiologic Phase www.indiandentalacademy.com
  7. 7. Bookstein/Moyers --The development and early use of Radiographic cephalometry initiated a more energetic period of data acquisition and Quantification of growth and form. Moss- “Classic Triad” 1. Sutures are primary growth sites 2. Growth of the cranial vault occurs only by periosteal deposition and endosteal resorption. 3. All cephalic cartilages are primary growth centers under direct genetic control www.indiandentalacademy.com
  8. 8. 1940-1960 • Craniofacial biology saw an increased emphasis on experimental animal research in an effort to account for the actual mechanism of facial growth. • Studies were more methodological and conceptual. • Investigators began to recognize that there is much more variation within the facial region and that this variation could be the result of modifying influences during Ontogeny. www.indiandentalacademy.com
  9. 9. Technological developments:• Use of Radioopaque Implants. • Vital Dyes. • Autoradiography. • In-vivo and In-vitro transplantations. By the end of 1950’s two similar approaches were seen within the single Genomic Paradigm: • Comprehensive Approach • Structurofuntional Approach www.indiandentalacademy.com
  10. 10. Comprehensive Approach: -Continued with craniometrics but with more Sophisticated hardware including radiographs, cephalostats and software in the form of statistical models. Structurofunctional Approach: -Concentrated more on “cause and effect relationships” Within and among the biologic systems of the Craniofacial complex. www.indiandentalacademy.com
  11. 11. --By the end of 1950’s the genomic paradigm was put into question --Periosteal and Sutural bone growth were removed from the genomic paradigm and given the status of secondary, compensatory or adaptive phenomena --But due to lack of evidence the genomic paradigm remained dominant and the alternative view that “Function” plays a major role continued to gather momentum. www.indiandentalacademy.com
  12. 12. MAINLY DOMINATED BY GENOMIC PARADIGM www.indiandentalacademy.com
  13. 13. 1960-1980 --Formulation of an Alternative paradigm. --Termed as the “Functional Paradigm” stated that the Craniofacial complex is highly adaptable to the functional demands placed on it and its developmental environment. --Melvin Moss’s “Functional Matrix Hypothesis” is believed by most craniofacial biologists to be the alternative paradigm (1960,American Journal Of Anthropology) --His second paper on Functional hypothesis was included in the Ist Vistas in Orthodontics in 1962. www.indiandentalacademy.com
  14. 14. DEVELOPMENT OF AN ALTERNATIVE PARADIGM www.indiandentalacademy.com
  15. 15. --Moss 10 yrs later released a third paper on the same. --From then on the “Functional” hypothesis became a topic of theoretical debate involving people like:• Moorrees(1972) • Johnston(1976) • Koski(1977) • Wayne Watson(1982) Debate focused on: • That cephalic cartilages have no intrinsic growth properties. • The mechanisms by which the capsular matrices(oral,nasal,pharyngeal)assert www.indiandentalacademy.com “morphogenic primacy”
  16. 16. --Alexander Petrovic and Associates(1975) •Proposed the cybernetic models of mandibular growth. 1980-2000 • This period saw a confluence of both the genomic and the functional paradigms. • A more focused view was developed and merits and demerits of each theory were considered. www.indiandentalacademy.com
  17. 17. Significant developments: 1. Functional Matrix Revisited (Moss-1997) 2. Von Limborg’s Conceptual Theory. www.indiandentalacademy.com
  18. 18. www.indiandentalacademy.com
  19. 19. Conclusion: The 2 Paradigms present: 1.Genomic--Exists primarily on the strength of the belief that facial growth and form should be encoded genetically. 2.Functional--Includes the Functional Matrix Hypothesis and its extension-The epigenetic hypothesis -- At the present time a confluence of these two paradigms is seen until a new one is proposed. www.indiandentalacademy.com
  20. 20. FUNCTIONAL MATRIX REVISITED PRESENT www.indiandentalacademy.com
  21. 21. GROWTH CENTER vs GROWTH SITE • Cranial growth centers—facts or fallacies Kalevi Koski (1968)AJO www.indiandentalacademy.com
  22. 22. According to BAUME: Growth Center: Is a site of endochondral ossification with tissue separating force,contributing to the increase of skeletal mass. Growth Site: Regions of Periosteal or suture bone formation and modeling resorption adaptive to environmental influences. www.indiandentalacademy.com
  23. 23. SUTURES • On the basis of definition sutures cannot be called growth centers. • Histologically it is evident that sutures are not similar to Epiphyseal growth plate. • The question remains. --whether there is an expansive force. --Is the growth in the sutural area of primary nature,that is does it have an independent growth potential OR is it of secondary nature,that is in response to some factor or factors. www.indiandentalacademy.com
  24. 24. Evidence in favor of the dependent role of the sutural growth appears to be accumulating • Subcutaneous auto transplants of the zygomatico-maxillary suture area in the guinea pig have not been found to grow. • An extripation of facial sutures appears to have no appreciable effect on the dimensional growth of the skeleton. • The shape of the sutures has been found to depend on functional stimuli,the closure of sutures appears extrinsically determined and it is possible to bring the sutural growth to halt by mechanical forces. www.indiandentalacademy.com
  25. 25. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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