Current concepts in functional matrix hypothesis

CURRENT CONCEPTS IN
FUNCTIONAL MATRIX HYPOTHESIS
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Introduction:

Theories of growth:

determine all. According to this theory the basic
control of growth, both in magnitude and timing is
located in the genes. The potential for growth is
genetic. Although called a theory it was more
assumed than proven.

1.The independence of the skull growth
cannot be consistently demonstrated.
• Scott hypothesis emphasizes that the intrinsic growth controlling
factors are present in the cartilage and in the periosteum, with the
sutures being only secondary and dependent on extrasutural
influences. According to this theory, the determinant of craniofacial
growth is growth of cartilages. He specifically emphasized the role of
cartilage of the nasal septum during the growth of the maxilla. Sutural
growth, Scott felt, came in response to the growth of the other
structures including cartilaginous elements, brain, the eyes and so
forth. Sutural growth is responsive to synchondrosis proliferation and
local environmental factors that is, sutures are passive and secondary.

Drawbacks:
• It appears that epiphyseal and the cranial base synchondrosis can and do act
as independently growing centers, as can the nasal septum (perhaps to a
lesser extent). Neither transplantation experiments not experiments in which
the condyle is removed lend any support to the idea that the cartilage of the
mandibular condyle is an important center. It appears that the growth at the
mandibular condyles is much more analogous to growth at the sutures of the
maxilla-entirely reactive than to growth at an epiphyseal plate.
• Though the cartilaginous theory was successful in explaining the growth of
the cranial base and to a great extent maxilla too, it could not explain the
growth of mandible and relate the growth of mandible to the condylar
cartilage satisfactorily.
• Functional matrix theory:

Based on the original concepts of Van der Klaauw,
his own experimental work and that of others,
combined with clinical interpretations and
experiences, Melvin L. Moss has formulated the
functional matrix theory in1960s.

He theorizes that growth of the face occurs as a
response to functional needs and neurotrophic
influences and is initiated by the soft tissue in
which the jaws are embedded. If the soft tissue
grows, both bone and cartilage react.

STATEMENT OF HYPOTHESIS:

There is no direct genetic influence on the size,
shape or position of skeletal tissues, only the
initiation or ossification. All genetic skeletogenic
activity is primarily based upon the embryonic
functional matrices.

Growth of face occurs as a response to the
functional needs and neurotrophic influences and
is initiated by the soft tissues in which the jaws
are embedded

Functional cranial analysis:

Functional Components & Skeletal units

According to Moss, the head is a structure
designed to carryout functions, e.g. neural
integration respiration, digestion, hearing,
olfaction & speech.

termed a functional cranial component. Each
component consists of all of the tissues, organs,
spaces and skeletal parts necessary to carryout a
given function completely. Thus, the component
handling speech would consist of the lips, teeth,
tongue and oral cavity, nasal cavity etc- any aspect
of the head that enables a person to speak is part
of this functional component.

Moss divides these components into 2 parts,

i. Functional Matrix:

Consisting of the soft tissue and space that
completely performs a particular function.

ii. Skeletal Unit:

A related skeletal unit that acts biomechanically to
protect and or support its functional matrix.

implication of this relationship is that the skeletal
unit is subordinate to and supportive of the
functional matrix. The bone tissue assumes a size
and shape that best enables the matrix to perform
its function. As a consequence, the cells of the
bone need not have genetic information for
morphologic orientation; the functional matrix
will provide the direction.

In essence, the head consists of a number of
functional matrices, (which are operational
components), all of which are rendered
morphologically and spatially secure by their
specifically associated skeletal units.

To better understand how the matrix can influence
the form (size & shape) of bone, it is
advantageous to think in terms of two types of
functional matrices and two types of skeletal
units.

One
function

Functional
cranial component

THE FUNCTIONAL MATRIX BY
REGIONS

With these definitions the growth of the head can
be analyzed from a new perspective. The
functional matrix theory is probably the dominant
theory in craniofacial biology, even though every
aspect of it is not universally accepted.

Neurocranial Growth:
• In the case of neural skull, it is quite easy to visualize the calvarial bones as lying within a neurocranial capsule. The composition of
this capsule in the adult is easily stated: these are the so-called ‘five layers’ of the scalp, then the bone itself, and finally, the two
layers duramater and cerebrospinal fluid. The calvarial bone consists of a number of contiguous Skeletal Units: Outer table, inner
table, diploic space (and variably sinuses). Each of these microsleletal units obviously has its specific periosteal matrix, muscles and
vessels. Taken as a functioning whole, the neurocranial capsular matrix is identical with the volume of this neural mass.
• Facial Skeletal Growth:
• Functioning Spaces
• Mandibular Growth
• Moss, Rankow – AO 1968
• Mandibular growth (as well as neurocranial growth) is seen now to be a combination of the morphologic effects of both capsular
and periosteal matrices. The capsular matrix growth causes an expansion of the capsule as a whole. The enclosed and embedded
macroskeletal unit (the "mandible" as a whole), accordingly, is passively and secondarily translated in space to successively new
positions. In normal conditions the periosteal matrices related to the constituent mandibular microskeletal units also respond to this
volumetric expansion. Such an alteration in their spatial position inevitably causes them to grow; that is, causes changes in their
functional demands. These now call forth direct alterations in the size and shape of their microskeletal units. The sum of translation
plus changes in form comprises the totality of mandibular growth.

CLINICALAPPLICATIONS OF
FUNCTIONAL MATRIX HYPOTHESIS

FUNCTIONAL MATRIX REVISITED
(MOSS 1997)

Basic terminologies

ring (the event observed). Prior to the act of
pushing, the building and streets must be
intrinsically wired and a generator must be
constructed and connected (material). Further,
electrical blueprints and the "laws'' of electricity
(for example, Ohm's law) must exist (formal).
Clearly while both extrinsic and intrinsic causes
are necessary, neither alone is sufficient; only their
combination can cause a bell to ring.

Osseous mechanotransduction
• ELECTRICAL PROCESSES
• MECHANICAL PROCESSES
• GAP JUNCTIONS
• Connected cellular network
• Epigenetic genomic problem is a dichotomy
• GENOMIC THESIS
• Biologic basis for genomic thesis
• Structural genes

Genomic thesis for orofacial growth

Orthodontic implications of genomic thesis

EPIGENETIC ANTITHESIS
• Strengths against genomic thesis

1.Gene is a unit of heredity(DNA sequences
incorporate information needed for the generation
of a RNA)

a. Integrative- clarifies the causal chain
between genome and phenotype.
• WHAT IS EPIGENETICS

EPIGENETIC THESIS

EPIGENETIC REGULATION OF
HIGHER STRUCTURAL LEVELS
• RESOLVING SYNTHESIS

COMPLEXITY THEORY

CONCLUSION

Current concepts in functional matrix hypothesis

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