Paradigm and theories

 EVOLUTION OF THEORIESEVOLUTION OF THEORIES
 DIFFERENCES BETWEENDIFFERENCES BETWEEN
GROWTH SITES AND GROWTHGROWTH SITES AND GROWTH
CENTRESCENTRES
 SUTURAL DOMINANCESUTURAL DOMINANCE
THEORYTHEORY
 CARTILAGENOUS THEORYCARTILAGENOUS THEORY
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EVOLUTION OFEVOLUTION OF
THEORIESTHEORIES
New vistas in orthodonticsNew vistas in orthodontics
-DAVID.S.CARLSON-DAVID.S.CARLSON

Craniofacial biology as “NormalCraniofacial biology as “Normal
Science”Science”
David S. CarlsonDavid S. Carlson
 Craniofacial biologyCraniofacial biology
 Normal scienceNormal science
 ParadigmParadigm
 Scientific RevolutionScientific Revolution

CRANIOFACIAL BIOLOGYCRANIOFACIAL BIOLOGY
 Study of growth, function and adaptation of theStudy of growth, function and adaptation of the
craniofacial skeleton and related structures.craniofacial skeleton and related structures.

ACCORDING TO KUHNACCORDING TO KUHN
Normal scienceNormal science
Research firmly based upon one or more pastResearch firmly based upon one or more past
scientific achievements that some particularscientific achievements that some particular
scientific community acknowledges as supplyingscientific community acknowledges as supplying
the foundation for its further practice.the foundation for its further practice.

PARADIGM
 Paradigm provides a coherent conceptualParadigm provides a coherent conceptual
scheme to organize observations and ideas,scheme to organize observations and ideas,
determining which are relevant, whichdetermining which are relevant, which
problems are legitimate and indicating howproblems are legitimate and indicating how
these problems may be solved.these problems may be solved.
 A single paradigm may be the basis for manyA single paradigm may be the basis for many
theories and certainly for numeroustheories and certainly for numerous
hypothesis, even if they are in conflict withhypothesis, even if they are in conflict with
each other.each other.

EVOLUTION OF PARADIGMS
Normal science-Scientific revolution-Normal scienceNormal science-Scientific revolution-Normal science

1920-19401920-1940
 Early research -study of structure of theEarly research -study of structure of the
craniofacial skeletoncraniofacial skeleton
 No consideration to the functionNo consideration to the function
 This was done byThis was done by
--Anthropologic craniometryAnthropologic craniometry
--Racial analysisRacial analysis
--Comparative anatomyComparative anatomy

 Two periods by MossTwo periods by Moss
- Pre radiologic - craniometry- Pre radiologic - craniometry
-Radiologic-Radiologic
 Dominant paradigm was –Dominant paradigm was –GENOMICGENOMIC
PARADIGMPARADIGM
 Focus-----dentoalveolar changes------not onFocus-----dentoalveolar changes------not on
skeletal modificationskeletal modification

1940-19601940-1960
 Period of increased animal researchPeriod of increased animal research
-Radio opaque implants-Radio opaque implants
-Vital dyes-Vital dyes
-Autoradiography-Autoradiography
 Mid 1950’ also called –Mid 1950’ also called – PRE REVOLUTIONARY PERIODPRE REVOLUTIONARY PERIOD

 KUHN SAYSKUHN SAYS
-Pre revolutionary periods are characterised by-Pre revolutionary periods are characterised by
growing disenchantment with the currentgrowing disenchantment with the current
paradigm, which leads to the development of aparadigm, which leads to the development of a
new paradigm.new paradigm.

 MOSSMOSS
-Did experiments on sutures and concluded-Did experiments on sutures and concluded
that sutures are site of active but compensatorythat sutures are site of active but compensatory
growthgrowth

 Moss- “Classic Triad”
 Sutures are primary growth sites
 Growth of the cranial vault occurs only by
periosteal deposition and endosteal resorption.
 All cephalic cartilages are primary
growth centers under direct genetic
control

 By end of 1950s there were mutuallyBy end of 1950s there were mutually
acceptable approaches within genomicacceptable approaches within genomic
paradigmparadigm
--Comprehensive approachComprehensive approach
--Structurofunctional approachStructurofunctional approach
 Sutures - adaptive phenomenaSutures - adaptive phenomena
 Function as affecting growth gainedFunction as affecting growth gained
momentummomentum

1960-19801960-1980
 Saw the coming of a new paradigm-Saw the coming of a new paradigm-
FUNCTIONAL PARADIGMFUNCTIONAL PARADIGM
 Moss gave theMoss gave the functional matrix hypothesisfunctional matrix hypothesis
 Genetic influence not deniedGenetic influence not denied

•Van LimborghVan Limborgh
theorytheory
•FunctionalFunctional
matrix revisitedmatrix revisited

Van Limborghs theoryVan Limborghs theory

CONCLUSIONCONCLUSION
 Genetic paradigmGenetic paradigm cannot be rejectedcannot be rejected as suchas such
 Both genetic and functional paradigmBoth genetic and functional paradigm have to coexisthave to coexist
and be applicable for the benefit of the patient.and be applicable for the benefit of the patient.
 Functional matrix hypothesis isFunctional matrix hypothesis is not synonymousnot synonymous withwith
functional paradigm. It is an extreme but legitimate wayfunctional paradigm. It is an extreme but legitimate way
of expressing the functional paradigm.of expressing the functional paradigm.
 Experimental design andExperimental design and results are influencedresults are influenced by theby the
paradigm maintained by the investigator.paradigm maintained by the investigator.

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