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4. Craniofacial growth
•
Genomic P
•
•
Craniofacial growthgenetically
predetermined
•
Orthodontic calvinismwendell w
•
•
•
Functional P
Emphasis on
functional factors
Plasticity of
craniofacial growth
Concentration – not on
skeletal tissues
5. Origin of the concept
Functional cranial component
Skeletal unit
Functional matrices
Macroskeletal Microskeletal
Periosteal
Capsular
eg-endocranial
surface Of calvaria
eg-teeth and
muscles
eg neural mass
eg-coronoid,
angular
6. Classic statement – 1981
• The functional matrix hypothesis claims that the origin ,
growth & maintenance of all skeletal tissues and organs are
always secondary , compensatory and obligatory
responses to temporally and operationally prior events or
processes that occur in specifically related non-skeletal
tissues, organs or functioning spaces
8. Why revisited FMH??
Measurement techniques –
eg – roentgenographic cephalometry
Method specific – not structurally detailed
FEM – quantitative aspect of localized cephalic
growth kinematics
9. Why revisited FMH??
• Hierarchical constraints
Downwards –cellular, subcellular or molecular
upwards – multicellular processes
“suspended” or “sandwiched” b/w two levels
10. Why revisited FMH??
• How epigenetic stimuli are transduced into signals by
bone cells??
• How individual bone cell signal brings about a
multicellular process??
12. Anatomic and conceptual basis
• Epigenetic primacy
• PFM considered only
cellular and molecular processes brings about the
triad of active skeletal adaptation.
Deposition
Resorption
maintenance
13. Anatomic and conceptual basis
• The developmental origin of all cranial skeletal
elements and all their subsequent changes in size,
shape and location, as well as their maintenance in
being, are always , without exception , secondary,
compensatory and mechanically obligatory responses
to the temporally and operationally prior demands of
their related cephalic non-skeletal cells, tissues,
organs and operational volumes.
14. FMH R1
• All vital cells – irritability
Mechanosensation
Mechanoreception
Mechanotransduction
Intracellular signal
16. Osseous mechanotransduction
Unique in 4 ways
1. Mechanosensory cells are cytologically specialized but
bone cells are not
2. 1 stimulus – 3 adaptational responses
3. Osseous signal transmission is Aneural
4. Adaptational processes are independent
17. Osseous mechanotransduction
• Important point
mechanotransduction translates the
informational content of PFM stimulus to skeletal
unit cell signal
Hierarchically downward
22. Bone as CCN
• PFM stimulus
transduced
Intracellular signal
Intercellular communication
Bone adaptation
Multicellular level
23. Bone as CCN
• All bone cells are interconnected – Gap Junctions
• Exception - osteoclasts
Connexin 43
Plasma membrane of canalicular processes meet
24. Bone as CCN
Gap jnc’ connects1. Osteons to interstitial regions
2. Superficial osteocytes – periosteal & endosteal
osteoblasts
3. Laterally connected
4. Periosteal osteoblasts – preosteoblastic
cells(interconnected)
25. Bone as CCN
•
Important points
1.
2.
3.
4.
5.
Extensive communication
CCN acts as a syncytium
Gap jns acts as electrical synapses
Permits bidirectional signal traffic
No role of secondary messengers
26. Bone as CCN
• Network theory
Cells are arranged in 3 layers
Initial input layer
Final output layer
Intermediate / hidden layer
27. Bone as CCN
• Network theory
Initial layer cells (loading);stimuli
“Weighted”input
summation
threshold
Intracellular signal (mechanotransduction)
Hidden layer cells (adj. Osteocytes)
Final layer cells (osteoblasts)
output
28. Bone as CCN
“The output determines the site, rate, direction,
magnitude and duration of specific adaptive
response i.e deposition, resorption or
maintenance of the skeletal tissue”.
29. Bone as CCN
Attributes of CCN
1. Developmentally – untrained, self- organized,
epigenetically regulated
2. Operationally – stable, dynamic system – oscillatory
behaviour
3. Structurally – non modular, i.e variation in
organization permits discrete processing of signals
30. Bone as CCN
Important points
1. Information is not stored discretely in CCN
2. CCN shows oscillations
3. Phenotypically similar osteoblasts – open gap jns
4. Dissimilar osteoblasts – sharp histological
discontinuities
31. Bone as CCN
Attributes of strain
1. Dynamic loadings – better response
2. Frequency – osteocytes are tuned to the frequencies
of muscle function
3. Magnitude of the strain
32. Bone as CCN
• conclusion
New version –
explanatory chain extending from the
epigenetic event of skeletal muscle contraction,
hierarchically downward , through the cellular and
molecular levels to the bone cell genome and then
upwards again through histologic levels to the event of
gross bone form adaptational changes.
33. FMH R3 & FMH R4
The controversy
•
•
•
•
•
Genetic Vs epigenetic
Dichotomy
How to solve dichotomy????
Dialectic analysis….
A method of examining and discussing ideas in order
to find the truth
35. Genomic thesis
• The plan of growth – written down in nucleic acid
message
Jacob.F (Logic Of Life)
• Within the fertilized egg, all information is present
for growth
Kessler and Melton
• Genes make us, body and mind
Dawkins ( The selfish gene)
36. Biologic bases for genomic thesis
• Only 10% of genome is related to ontogenesis
Housekeeping
Genes
Structural
Genes
• Regulate metabolic and resp activity of all cells
• Regulate specific activity of special cell
(neurons, osteoblasts)
37. Biologic bases for genomic thesis
• Defect in the gene
Disorders…..
Marfans syndrome
O Imperfecta
Achondroplasia
Physical analogy – construction of building
38. Genomic thesis in orofacial biology
• Classic article on prenatal craniofacial dev
Johnston. MC & Bronsky. PT
Craniofacial development
Initial regulatory homeobox
gene activity
Subsequent activity of 2
mol. groups
Growth factor
families
steroid/thyroid
Retinoic acid
Super family
39. Orthodontic implication of genomic thesis
• Defect in the regulatory activity of genes or gene
expression governing the size of the teeth and jaws
Malocclusion and dentofacial deformities
40. The other side of the coin
• FMH supports the concept of epigenetic primacy
• Epigenetic processes and mechanisms has the
capability of regulating the genomic activity
Epigenetic antithesis
• Odontogenic eg. Of genomic / epigenetic dichotomy
41. The other side of the coin
Mechanical forces
Epigenetic signals
Dental papilla cells
Control of genetic expression of differential tooth form
43. Epigenetics
• All the extrinsic factors impinging on the vital
structures – mechanical loadings / electrical signals
+
All intrinsic events occuring in the cell and between the cell
44. Hierarchy
• Levels of organization
• Sub atomic
atom
organism
organ
molecule
tissue
Genomic thesis
Epigenetic antithesis
subcellular
cell
45. Emergence
• Appearance of attributes at each successive higher
level
• Changes in attributes – cannot be predicted
Osteocytes and bone tissue
Emergence is not genomically controlled
46. Causation
• How the attributes of a given biologic
structural level cause (control, regulate and
determine) the attributes of next higher level
Genomic thesis
Epigenetic antithesis
Coronoid and temporalis
47. Classification of causation
Material (what is acted upon?)
Intrinsic ;prior causes
Formal (by what rules?)
Efficient (what was the immediate preceding event?)
Extrinsic ; proximate
Final (why?)
49. Conclusion
• Morphogenesis is regulated by both genomic and
epigenetic processes, mechanisms
• Both are necessary causes, neither alone are sufficient
causes.
• Their integrated activities provide the necessary and
sufficient causes for growth and development
50. References
• Moss, Primary role of functional matrix in facial growth- Am J Orthod,
1969 June:(20-31)
• James Scott, The doctrine of functional matrices- Am J Orthod, 1969
July:(56)
• Moss, The capsular matrix- Am J Orthod, 1969 nov:(56)
• Moss, Twenty years of functional cranial analysis- Am J Orthod, 1972
may:(61)
• Moss, Genetics, epigenetics and causation- Am J Orthod, 1981oct:
(366-75)
• Moss, Functional matrix hypothesis revisited- Am J Orthod Dentofac
Orthop, 1997 july-oct.
• Lysle E.Johnston Jr - Factors affecting the growth of the midface –
The functional matrix hypothesis : Reflections in a jaundiced eye
• David S. Carlson – craniofacial biology as normal science
51. HUMAN TOOTH MOVEMENT IN
RESPONSE TO CONTINUOUS STRESS
OF LOW MAGNITUDE
Laura R. Iwasaki
James E. Haack
Jeffery C. Nickel
John Morton
AJODO 2000
53. • Current project –
• Translation can occur without lag phase
• Low force magnitude
• Translation can occur at velocities that are clinically
significant
54. •
•
•
•
7 subjects
84 day study
18 g and 60 g
Compressive stresses on distal aspect of canine was
4 kPa and 13 kPa
• M/F ratio – 9-13
• Tooth movement in 3 linear and 3 rotational
dimensions was measured
• Dental casts – at 14 day interval
55. Subjects and method
• 7 Healthy patients from the graduate orthodontic
clinic at the university of nebraska medical center
• 2 males and 5 females (12y 3m to 16 y 3m)
• Good oral hygiene
• Maxillary 1st premolars extracted
• NSAIDs avoided
56. Subjects and method
• Each subject was scheduled for 9 appt
• Day 0 , 1 , 3 and then after every 14 day for a total of
84 day
•
•
•
•
One week before day 0 – orthodontic appliance
Chlorhexidine mouth wash
Oral hygiene evaluated
Impressions made
57. Subjects and method
• Maximum posterior anchorage was required
• Nance app or combination of nance/
transpalatal arch
• Upper 2nd molars involved
• Segments were made
of 19 x 25 ss
58. Subjects and method
•
•
•
•
•
Canine retraction
17x25 or 16x22 ss
Vertical height – 9-13 mm
Cres – 0.24(Lr)
Activation of loop – NiTi
closed coil spring
59. Subjects and method
• 2 retraction forces
• Distributed randomly to
Rt and Lt canines
• Force (spring)= k(ΔL)
• Spring attachment
60. Subjects and method
• Between appointments – canines moved
• Springs adjusted or changed to maintain the desired
force magnitude
• The forces and countermoment delivered were
measured with 2 calibrated clinical instruments
62. Subjects and method
•
•
The compressive stresses applied were 4kpa and 13
kpa
These values were chosen for 3 reasons
1. 2 stresses were different enough to bring different
rates of tooth movement
2. Both stresses were of low magnitude
3. Pilot work demonstrated sufficiency for canine
retraction
63. Subjects and method
• To produce the desired compressive stresses
Distal root surface area
Root morphology
64. Subjects and method
• Impressions were made at each appt.
Posterior anchorage segment
was stable
3 axis measuring microscope
65. Subjects and method
• Results
2.41 mm
Canines retracted at low stresses
Canines retracted at high stresses
3.52mm
72. • Conclusion
• Effective canine retraction can be brought about,
without a detectable lag phase and with minimal
unwanted linear or angular tooth movements
• Continuous stresses of 13 kpa (60g force) produced
distal tooth velocity of 1.27mm/ month
• 4kpa – 0.87mm/month
• Segmental retraction showed controlled and
determinate tooth movement
73. Optimum force magnitude for
orthodontic tooth movement : A systemic
literature review
Yijin Ren
Jaap C. Maltha
Angle Orthod 2003
74. Materials and methods
• Meta analysis of force magnitude
•
•
•
•
Medline was searched from 1966 – 2001
Over 400 articles collected
Animal studies
Human trials
75. Materials and methods
•
•
•
•
•
•
•
•
Exclusion criteria
No quantification of orthodontic force magnitude
No quantification of rate of tooth movement
No control group or split mouth design
Number of experimental sites </= 5
Use of extaoral or functional app
Observation period </= 1 week
Medication or surgical intervention.
76. Materials and methods
• 161 articles on animal studies - 17
• 305 articles on human studies – 12
• Articles tabulated
80. Conclusion
• It is not possible to perform a meta analysis of the
relation between force magnitude and rate of tooth
movement from current literature
• No evidence based force level could be
recommended for optimal efficiency in clinical
orthodontics
• Well controlled clinical studies with standardized set
up are required for better understanding on optimal
forces.
82. Implants
• Preserving anchorage in total is a major problem
• Conventional orthodontics
IOA
Anchor loss
EOA
Patient compliance
83. Implants
• Treatment options start getting limited or the end
results compromised
• Pioneering studies by Dr. Branemarke on Osseo
integrated implants
• Implants – Absolute anchors
Indirect anchorage
True stationary anchorage
True skeletal anchorage
84. Implants
• Definition
• Implants are alloplastic devices which are surgically
inserted into or onto the jaw bones
• Osseo integration – an intimate structural contact at
the implant surface and adjacent vital bone devoid of
any intervening fibrous tissue
88. Implants
• Based on configuration design
Root form implant
Blade / Plate implant
• Based on surface structure
Threaded or Non Threaded
Porous or Non Porous
89. Implants
• Based on the composition
SS
Ti
Co - Cr – Mo
Ceramic
Miscellaneous – Vitreous carbon and composites
90. Implants
• Early reports of implant usage
• Grainesforth and Highely (1945)
Vitallium screws in Ramal area
Immediately loaded For canine
retraction
92. Implants
• Orthopedic changes
Maxillary protraction
Maxillary expansion
• Shapiro and kokich (1984) used ankylosed teeth as
pseudoimpant
• Intentional ankylosis of deciduous canines
93. Implants
• Smalley et al (1988)
Insertion of titanium
implants into maxilla,
zygoma, orbital and occipital
bones of monkeys
12-16mm widening of sutures
with 5-7mm increase in
overjet
94. Implants
• Andrew , Parr et al (1997)
• Conducted experiments on nasal expansion using
endosseous Ti screws
• Sample – 3 groups
• 1 N and 3 N force force applied
• 5.2 mm and 6.8 mm expansion
95. Implants
• Orthodontic changes
• Creekmore (1983)
• Unloading period of 10
days
• Within 1 yr – 6 mm of
intrusion and 25ºof
lingual root torque
96. Implants
• Southard (1995) compared the efficacy of Ti
implants with that of teeth in dogs
• Unloading period of 3 months
• Intrusive force of 50 – 60 g
97. Implants
• Eugene Roberts: use of retromolar implants for space
closure
Size of implant: 3.8mm width and 6.9mm length
98. Implants
•
Drawbacks of Retromolar implants
1.
2.
3.
4.
•
Bulky
Long waiting period
Anatomic limitations
Expensive
Since 1995 , around 10 implant systems have
evolved
100. Implants
• Osseous implants
• Placed in dense bones – zygoma, body or ramus, mid
palatal area
Skeletal anchorage system
Orthosystem implant
Graz implant supported system
Zygoma anchor system
101. Implants
• Skeletal anchorage system (SAS)
• Developed by Umemori and Sugawara
• Ti miniplates stabilized using screws (2 - 2.5 mm in
dia)
• Design – L type
T type
105. Implants
• Zygoma anchor system
• Hugo De Clerck and Geerinckx (2002)
• Curved Ti miniplate with provision of 3
screws
• Lower end projects outward and has a
vertical slot
• Placed in zygomaticomax buttress area
107. Implants
• Interdental implants
• Rely on mechanical retention rather than Osseo
integration
• Simple to place under LA
Mini implant
Aarhus implant
Micro implant anchorage
110. Implants
• Microimplant
anchorage (MIA)
• Dev by a team of korean
orthodontists
• Maxillary implants are
longer
• Ti implants
• Drill – 0.2 mm smaller
than the implant size
112. Implants
• Stability of the implant
• Miyawaki et al analyzed the stability of screw and
plate implant
• Sample – 51 patients
• 134 screw implants(1,1.5, 2.3 mm dia)
• 17 miniplate
113. Implants
• Results
• 1mm dia – high failure rate
• 1.5 and 2.3mm dia – success rate of 84%and
86%respectively
• Miniplates – showed best stability
• Peri implant hygiene major criteria for success