Methods of study bone growth /certified fixed orthodontic courses by Indian dental academy

Methods of studying bone
growth
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


Bone growth ?
Bone = bone cells(osteoblasts ,osteocytes ,osteoclasts)
+matrix (collagen + calcium hydroxyapatite 65-70%)
Woven bone
Lamellar bone (compact bone)
Composite bone (cancellous bone)
Bundle bone
Vitamin-D
PTH

9-11mg/dl
Serum Ca++

Calcitonin

Passion & controversy may have a place in discussion &
interpretation but certainly not in study of rigorously
collected biomedical &clinical data
A. G. Petrovic

Study
Acquisition of knowledge by investigation.

Collection
of data

Explanation

Analysis of
this data

Presentation
of data


Source of data
Census
Registration of vital events
Hospital records & other health records
Survey of population
Health interview survey (opinion)
Health examination survey
Health record survey
mailed question survey

Types of data
Opinion :it is a clever guess .
Observation :Done to see presence or
absence of certain
phenomena
Rating & ranking.
Measurements :Most scientific approch
direct data
indirect data
derived data


Methods of collecting data
Cross sectional method :based on single

examination of a cross-section of population at
one point in time .

Longitudinal method :observations period
are repeated in the same population over a
prolonged of time by means of follow up
examination.

Semi-longitudinal method :

Cross-sectional method
ADVANTAGES
easy & quick
less expensive
no attrition of sample
various factors acting
at that time can be
analyzed
can be repeated

DISADVANTAGES
variability with in
the sample
larger size of
sample
factors acting at
various time period
cannot be analyzed


Longitudinal method
ADVANTAGES
more specific
factors acting at
different time can be
analyzed
less no of subjects
individual variations

DISADVANTAGES
more expensive
difficulty in maintaining
lab & data
more time
attrition of samples
cannot be repeated

Eg Bolton Brush study ,Michigan study ,Iova child welfare study

Semi-longitudinal method
ADVANTAGES
Tries to combine advantages of both
longitudinal & cross-sectional method.
Data of 15 yrs of study obtained in 3 yrs
DISADVANTAGES
Not as authentic as longitudinal study


Approach for analysis of
obtained data.
MEASUREMENT
APPROACH
Here animals & humans
are measured without
inducing any change in
them.
Dead/alive
Longitudinal/crosssectional

EXPERIMENTAL
APPROACH
Here growth is
manipulated and
observations are
made.
More detailed study.
Mainly animal study.
Longitudinal/crosssectional

Methods of presenting data
Simple tables
Graphs (special
curves)
Charts
Bar charts
Histograms
Pie charts
Pictograms
Diagrams (pictures)

Explanation concerning craniofacial
growth in current literature
Deductive:logically explained consequence of certain
premises.

Deductivoprobabilistic: tries to relate various items
explained by the deductive explanation with
certain assumptions.Forms basis of D/D
&prognosis.

Functional: Based on single assumption.Generally

Noncolinear relations are seen here .

Phylogenetic:Growth trends explained based on
evolutionary trends.

Methods of studying bone
growth.
Mineralized sections
Polarized light birefringence
Craniometry
Fluorescent labels
Comparative
Micro radiography
anatomy
Auto radiography
Anthropometry
nuclear volume morphometry
Cell kinetics
Radiology/Imaging
Micro electrodes
Finite element modeling
EXPERIMENTAL
Vital staining
Metallic implants

MEASUREMENT

Craniometry
Measurement of skull of human skeleton.
Broca (1875) defined landmarks &
instruments used for measurements.
Congress of German anthropological
society held at Frankfurt in 1882.

Comparative anatomy

Anthropometry
Measurement of skeletal dimensions on
living individuals
Physical anthropology :Study of mans
biologic behavior in time and space
Special instruments are used
ADV :Longitudinal study
No harm to subjects
DISADV :Soft tissue error
Operator error

Radiology /Imaging
Conventional radiographs
Nature and production of x-rays
How does it detect bone growth ?
Films :composition
size: 22*35 24*40 32*41 57*76 mm 8*10” :Image
formation ,developing & fixing

Intensifying screens (calcium tungstate & rare earth)
Grids (parallel ,focused &Potter Bucky grids.80-100lines/Inch)

Techniques of
conventional radiography
Intra oral
IOPA

Extra oral

paralleling technique
Bisecting angle

Bite wing
occlusal projection

Posterio-anterior
Walters occipitofrontal
Riverse-Towne
sub mento vertex
Lateral oblique mand
Lateral skull
Pt position
Cephalostat
Cephalometry


Broadbent-Bolton cephalometer


Cephalometry
ADVANTAGES
Combines advantages of anthropometry
and craniometry that is direct bony
measurement & study of same individual
DISADVANTAGES
2-dimensional
Head position critical
Direction of growth not clear
Panoramic


Specialized radiographic
technique
Digital imaging (CCD -voltage-bits 0-255)
Direct digital radiography (R V G )
Indirect digital radiography
Digital subtraction radiography
Digitized image interpretation

Computed tomography
Magnetic resonance
Radionuclide imaging
Ultrasound
Electronic thermography

3-D Imaging
3-D analysis would be the ideal way of
analyzing soft/hard tissue profile
Source of data
Multiple video imaging
Sonic digitizing
Laser scanning

Disadv: Pt movement during digitizing
Primitive soft ware not very accurate
Norms & data not extensive

Specific experimental
method
Polarized light
Vital staining
Fluorescent labels
Metallic implants
Micro radiography
Auto radiography
nuclear volume morphometry
Cell kinetics
Micro electrodes

Histopathological technique
Preparation of tissues for microscopy
Soft tissue embedded in paraffin
Fixation
processing

colloidal embedding - hard tissues(decalcified)
Acid treatment
chelation
Hydrolysis

Ground sections- hard tissues(undecalcified)
Frozen sections for immediate examination

Critical analysis of tissues as there is less
distortion during processing
Both inorganic mineral & organic matrix can
be studied
100um -tissue level details
25um-Enhanced cellular details
Bone labels quench rapidly
Tissue density inadequate for microradiography

Polarized light birefringence
Fringe pattern indicate collagen
orientation within bone
Loading conditions during bone formation
dictates orientation of collagen
Longitudinal alignment -Tension
Transverse alignment -compression


Fluorescent labels
In vivo administration of Cl binders act as
time markers of bone formation
Six fluorescent bone labels are used
Tetracycline -bright yellow
Calcein - green
Xylenol- orange
Alizarin- complexone red
Demeclocyclin- gold
Oxytetracycline- greenish yellow

Microradiography
Higher resolution images of polished 100um
mineralized sections obtained
1 week primary mineralization
8 months secondary mineralization
Experimental animals analyzed by both
microradiography & using fluoroscentlabels
midfacial sutures PDL
Alveolar process Mandibular condyle
temporal fossa

Autoradiography
Specific radioactive labels for proteins
carbohydrates ,& nucleic acids are injected at
known intervals before sampling
Detected by coating histologic sections with
nuclear track emulsion
3H thymidine labels DNA synthesis
3H Proline for bone matrix

Nuclear volume
morphometry
Cytomorphometric procedure for accessing the
size of osteoblastic precursor cells
Mechanism of osteogenesis in orthodontically
activated PDL
Preosteoblasts have larger nucleus than
committed osteoprogenitor cells and their
precursors


Cell kinetics
By noting the -increase in nuclear volume
or labeling S-phase cells in vivo using
Bromodeoxyuridine (BDU) cell movement
& differentiation is noted
Generally done in PDL
under normal conditions
under metabolic stimuli
mechanical stimuli

Microelectrodes
Tungsten or glass electrodes are inserted
atraumatically into PDL in live animals via
gingival sulcus
changes in electric potential are noted
Widened areas have a negative charge
Compressed areas have positive charge
This coincides with the age old principle,
that bone forms near cathode & resorbs at
anode

Finite element modeling is a branch of
mechanical engineering where in the stress &
strain of mechanically loaded structures are
analyzed.
Initial stress for periodontium are derived by
assuming linear elastic properties
For complex tissues like periodontium with
viscoelastic properties both solid & fluid
mechanics mustwww.indiandentalacademy.com
be considered

Vital staining
Reported initially by Belchier (1796) &
John Hunter where in they attributed
staining to alizarin
This method reveals the site ,manner,
amount , direction ,timing & duration of
bone growth
Tetracycline stains in humans

Metallic implants
Method of study used extensively by Prof
Bjork & coworkers R D C Copenhagen
They gave new dimension to study of
dentofacial growth.
Remodeling changes in the contours of
jaws was better understood
Rotational pattern of jaw growth

Conclusion
Tooth movement has been
possible because bone
behaves dynamically
Better understanding of
physiology of bone PDL
interface is necessary
All these methods have
given us the tool for further
study it is up to us to use it

References
Enlow;Hand book of facial growth, W B Saunders
Company,1982
Orbans:Oral histology &embryology,Delhi, C B S
publishers,1990
Rakosi ,Jones & Graber:Colour atlas of orthodontic
diagnosis,New York,Thieme medical publishers,1993
Farkas L G:Anthropometry of head &face, New York,
Raven press,1994
Jacobson :Radiographic cephalometry,quintessence
books,1995

References ctd
Goaz & White:Oral radiology, St Louis,C V Mosby,
1994
K Park : Preventive &social medicine, Jabalpur , M/S
Banarsidas Bhanot,1997
Profitt W R:Contemporary orthodontics,St Louis,C V
Mosby,1997
Graber,Rakosi,Petrovic:Dentofacial orthopedics with
functional appliances, 1997
Graber Vanarsdall:Orthodontics current principles
&technique, St Louis,C V Mosby,2000.

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