The document summarizes the functional matrix theory of bone growth proposed by Melvin Moss. The theory states that bone growth occurs as a response to functional needs mediated by soft tissues, rather than bones growing independently. Growth involves periosteal matrices altering bone size in response to soft tissue demands, and capsular matrices passively translating bones during expansion. Experiments on rats supported the theory by showing bones altered in size and shape following muscle resection. Clinical implications include functional appliances altering bone growth by changing soft tissue pressures.

1. FUNCTIONAL MATRIX
THEORY
PRESENTED BY: ZYNUL JOHN
DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL
ORTHOPAEDICS

2. LEARNING OBJECTIVES
 Various theories of growth
 Functional matrix theory
 Clinical implications

3. CONTENTS
 Introduction
 Various theories of growth
 Functional matrix theory
 Drawbacks
 Clinical implications
 Summary
 reference

4. INTRODUCTION
 Growth is strongly influenced by genetic factors, but it
can also be significantly affected by the environment, in
the form of nutritional status, degree of physical activity,
health or illness and a no. of similar factors.
 Since a major part of the need for the orthodontic
treatment is created by disproportionate growth of the
jaws, it is necessary to learn how skeletal growth is
influenced and controlled to understand the etiologic
processes of malocclusion and dentofacial deformity

5. THEORIES OF BONE GROWTH
 Bone remodelling theory(Brash)
 Genetic theory(Brodie)
 Sutural theory(Sicher and Weinnman)
 Cartilaginous theory(James Scott )
 Functional matrix theory(Melvin Moss)
 Servo system theory(Alexandre Petrovic)
 Neurotrophism( Behrents)
 Enlows V principle of growth.

6. FUNCTIONAL MATRIX HYPOTHESIS
 Van der Klaaw was a professor of descriptive zoology whose
most important contribution is the introduction of new concept-
functional cranial component.
 Influenced by this work, Melvin Moss in 1960s put forward the
Functional Matrix Theory.
The origin, growth and maintenance of all skeletal tissues and
organs are always secondary, compensatory and obligatory to
temporally and operationally prior events or process that
occur in specifically related non-skeletal tissues, organs or
functional spaces (Functional matrices).”

7.  He theorizes that growth of the face occurs as a response
to functional needs and is mediated by soft tissues in
which jaws are embedded.
 In this conceptual view- the soft tissues grow and both
bone and cartilage react.
 Operationally, the head is a region within which certain
functions occur. Every function is completely carried out
by certain hard and soft tissues:
SKELETAL UNIT FUNCTIONAL MATRIX
TOTALITY OF SKELETAL, SOFT TISSUES AND FUNCTIONAL SPACES
NECESSARY TO CARRY OUT A FUNCTION IS “ FUNCTIONAL CRANIAL
COMPONENT

8. FUNCTIONAL CRANIAL COMPONENT
SKELETALUNIT FUNCTIONAL MATRIX
MICROSKELETAL
EG: CORONOID
PROCESS,
ANGULAR.
MACROSKELETAL
EG: MANDIBLE
MAXILLA
PERIOSTEAL
MATRIX
EG: TEETH
MUSCLES
CAPSULAR
MATRIX
EG: OROFACIAL

9. SKELETAL UNIT
 Bony structures that support functional matrix
 Skeletal unit provides necessary biochemical role of
providing protection and support to soft tissue
matrix
MICROSKELETAL UNIT MACROSKELETAL UNIT

10. MICROSKELETAL UNIT
 A single bone may be composed of number of
skeletal units, termed as microskeletal unit.
 Their growth is influenced by periosteal matrices.
coronoid
condyle
ramus
body
alveolar

11. MACROSKELETAL UNIT
 When adjoining portion of number of bones are
united to function as a single cranial component.
MAXILLA MANDIBLE

12. FUNCTIONAL MATRICES
 Functional matrix refers to all the soft tissues and
spaces that perform a given function.
PERIOSTEAL MATRIX CAPSULAR MATRIX

13. PERIOSTEAL MATRIX
 All non skeletal functional unit adjacent to skeletal
unit forms periosteal matrices.
 They act actively by means of osseous deposition
and resorption.
 They act to alter the size and shape of the bones.
The growth process is transformation.

14. TEMPORALIS MUSCLE CORONOID PROCESS
LATERAL PTERYGOID CONDYLAR PROCESS
MASSETER AND ANGULAR PROCESS
MEDIAL PTERYGOID
TEETH ALVEOLAR BONE
INFERIOR ALVEOLAR
NEUROMUSCULAR TRIAD
BASAL BONE

15. FUNCTIONAL CRANIAL ANALYSIS OF CORONOID
PROCESS IN RAT
 63 Columbia-Sherman rats were used .
 All were operated on the 11th postnatal day &
sacrificed from 2 – 43 days, postoperatively at
intervals from 1 - 3 days.
 The middle & posterior fibers of left temporalis were
removed.
Source: Functional cranial analysis of coronoid process in
rat: MELVIN MOSS AND MARY-ANN MEEHAN

16. RESULTS
 First five postoperative days
- slight diminution in size, while form remained
unchanged.
- very slight reduction in trabeculae
 The 6th post operative day
- marked reduction in size
- upper surface of process affected
- trabeculae exposed
 In all later stages coronoid was markedly reduced,
now seen only as a slight bump

17.  In few cases, middle portion of muscle was not
completely removed . Though it showed reduction
in size and shape but it was recognisable.

18. The dependence of the coronoid process (skeletal unit) upon the
demands of its functional matrix (temporalis muscle) is shown in these
alterations in size and shape following unilateral muscle resection
14TH POST-OPERATIVE DAY
18TH POST-OPERATIVE DAY
23RD POSTOPERATIVE DAY

19.  So, the point is the coronoid process does NOT
grow first and thus provide a "platform" upon which
the temporalis muscle can then alter its functions.
 The total growth changes in all aspects of coronoid
process form (size and shape) are at all times a
direct and compensatory response to the
morphogenetically prior demands of the temporalis
muscle function.

20. CAPSULAR MATRIX
 Organs and spaces that occupy a broader anatomic
complex.
 Each capsule is an envelope that contains series of
functional cranial component, skeletal unit and their
related functional matrices.
 Capsular matrix do not act by process of active
resorption and deposition.
 They act passively on macroskeletal unit by
producing its secondary translation in space.
Eg: neurocranial space
orofacial space

21. OROFACIAL CAPSULE
CORONOID CONDYLAR
ALVEOLAR PROCESS
BASAL BONE
ANGULAR
LATERAL
PTERYGOIDTEMPORALIS
MEDIAL
PTERYG
OID
MASSETOR
TOOTH
BUD
ENLARGING
CAPSULE

22. NEUROCRANIAL CAPSULE
 As the capsule enlarges, whole of included and
enclosed periosteal matrices and microskeletal
units are carried outward in a passive manner.

23. OROFACIAL CAPSULE
OROFACIAL
CAPSULE
GROWS
PERIOSTEAL MATRIX RESPONDS TO THIS VOLUMETRIC EXPANSION
THIS THEN ELICITS CHANGES IN MICROSKELETAL UNIT
The growth of all orofacial skeletal units is a combination of the two types of
growth process discussed above – periosteal and capsular, transformative and
translative, changes in size and shape, and changes in spatial position.
GROWTH IN
RESPONSE TO
FUNCTIONAL NEEDS

24. FUNCTIONAL CRANIAL ANALYSIS OF MAXILLA
o Head is a composite structure, operationally
consisting a no.of independent functions :
Olfaction, Respiration, Vision, Digestion, Speech,
etc.
o The facial bones are passively carried outwards by
the primary expansion of the enclosed matrices.this
causes adaptive fill in response.
( e.g. : orbital, nasal, oral matrices ) .

25. ORBITAL, NASAL AND ORAL SPACE

26. There are three types of bone growth changes to be
observed in the maxilla :
1. First, those associated with passive motions of bone
associated with primary expansion of the orofacial
capsule.
2. Secondly , changes in bone morphology associated
with alterations in the absolute volume, size, shape or
spatial position of maxillary functional matrices, such
as the orbital mass.
3. Finally there are bone changes associated with the
maintenance of the form of the bone itself.

27. FUNCTIONALCRANIAL ANALYSIS OF MANDIBLE
 The mandible is not a unitary biological object, but
rather a composite of several unitary & relatively
independent functional cranial components. The
skeletal units corresponding to these mandibular
functional components include :
1. Alveolar process
2. Coronoid process
3. Condylar process
4. Angular process
5. Body
6. Chin

28.  The mandibular cranial components arise & exist
completely embedded within the capsule, they all
are passively & secondarily translated in space to a
new position as the capsule expands.
 Such passive translations of mandibular functional
cranial components as a whole, also alters the
individual periosteal matrices.
 This causes direct changes in the size &/or shape
of their various skeletal units.
 A longitudinal series of cephalometric radiographs
were taken by Moss & the following structures were
traced:
1. Anterior cranial base
2. External surface of mandible
3. Mental foramina

29.  First , 2 tracings were
superimposed on the
cranial base, Moss
observed the total
growth changes of the
mandibular complex
during this period.

 Moss termed this is a
Inter-Osseous Growth,
i.e total growth relative
to fixed anterior cranial
base.

30.  Similarly a second tracing
was made superimposing
the mandibular tracings
on the mental foramen.
 We now observe the
changes in shape or size
of several mandibular
units which occur
independently of the
changes in spatial position
of these same units with
time.
 This is termed as Intra-
osseous Growth.

31.  Finally a third composite
tracing was made in
which both the previous
composite tracings were
taken & superimposed on
the outlines of the oldest
mandibles.
 Downward and forward
motion of the mandible
primarily is passive
translation, active
transformation produces
minor changes anteriorly
and inferiorly and the
posterior and upward
compensatory growth of
the condylar process.

32. 3 IMPORTANT CONCEPTS IN MANDIBULAR
GROWTH - MOSS
 Constancy of relative growth of mandible

33.  Absolute migration of dention through alveolar
bone- the migration is pronounced during eruption
of permanent dentition

34.  Change in direction of mental foramen

35. Periosteal Matrix ------------> Skeletal Unit
[Teeth] [Alveolar Bone]
CLINICALIMPLICATIONS
Capsular Matrix -------------> Multiple Skeletal Units
[Functional Appliances] [Jaw Bones]

36. FRANKEL APPLIANCE
 The Frankel Regulator buccal shields prevent the
pressure of the buccinator being exerted on the
dento alveolar area both during deglutition and at
rest. The net effect is outward expansion to the
“ought-to-be” acrylic shield functional matrix.

37. DRAWBACKS.
 No clarification on as to how functional needs are
transmitted to tissues -PROFFITT
 In AJO-May 1972, Moss stated that investigations
are still going to find out various means and
process by which morphogenetic stimuli are
transmitted to their skeletal unit ,mode of
transmission, Its reception and translation.

38.  How the functional matrix is involved in its own
growth and development on how it is controlled.
That is, how much genome and how do the
provocative ideas of complexity and self-
organization play into this? –
• Donald Enlow

39. FUNCTIONAL MATRIX HYPOTHESIS -
REVISITED 1997
FMH 1- Role of Mechanotransduction
FMH 2 - Role of Osseous Connected Cellular
Network
FMH 3 - The Genomic Thesis
FMH 4 - The Epigenetic Antithesis and the
Resolving Synthesis
Am J Orthod Dentofac Orthop 1997;112

40. SUMMARY
 According to functional matrix hypothesis, apart
from initiating the process of development, heredity
and genetics play no active role in growth of
skeletal structures.
 Bones do not grow, bones are grown.
 Expansion of soft tissue matrix is the primary
response

41. REFERENCE
 Textbook of craniofacial growth- Sridhar
Premkumar
 Text book of orthodontics-T.M Graber
 The capslar matrix-melvin moss
 The functional cranial analysis of mandible
 The primary role of functional matrices in facial
growth- melvin moss

42. Thank You