methods of study bone growth / orthodontic courses by indian dental academy

Methods of studying bone growth

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

www.indiandentalacademy.com

Bone growth ?

Bone = bone cells(osteoblasts ,osteocytes ,osteoclasts) +matrix (collagen + calcium hydroxyapatite 65-70%)

Woven boneLamellar bone (compact bone)Composite bone (cancellous bone)Bundle bone

Vitamin-D 9-11mg/dl CalcitoninPTH Serum Ca++


Study Acquisition of knowledge by investigation.

Collection of data

Analysis of this data

Presentation of data

Explanation

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


Source of data

CensusRegistration of vital eventsHospital records & other health recordsSurvey of population

Health interview survey (opinion)Health examination surveyHealth record surveymailed question survey


Types of dataOpinion :it is a clever guess .Observation :Done to see presence or

absence of certain phenomenaRating & ranking.Measurements :Most scientific approch

direct dataindirect dataderived data


Methods of collecting dataCross 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 :www.indiandentalacademy.com

Cross-sectional method

ADVANTAGESeasy & quickless expensiveno attrition of samplevarious factors

acting at that time can be analyzed

can be repeated

DISADVANTAGESvariability with in

the samplelarger size of

samplefactors acting at

various time period cannot be analyzed


Longitudinal method

ADVANTAGESmore specificfactors acting at

different time can be analyzed

less no of subjectsindividual

variations

DISADVANTAGESmore expensivedifficulty in

maintaining lab & data

more timeattrition of samplescannot be repeated

Eg Bolton Brush study ,Michigan study ,Iova child welfare studywww.indiandentalacademy.com

Semi-longitudinal methodADVANTAGESTries to combine advantages of both

longitudinal & cross-sectional method.

Data of 15 yrs of study obtained in 3 yrs

DISADVANTAGESNot 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/aliveLongitudinal/cross-

sectional

EXPERIMENTAL APPROACH

Here growth is manipulated and observations are made.

More detailed study.Mainly animal study.Longitudinal/cross-

sectionalwww.indiandentalacademy.com

Methods of presenting dataSimple tablesGraphs (special

curves)Charts

Bar charts Histograms Pie charts Pictograms

Diagrams (pictures)www.indiandentalacademy.com

Explanation concerning craniofacial growth in current literatureDeductive: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 Fluorescent labels Micro radiography Auto radiography nuclear volume

morphometry Cell kinetics Micro electrodes Finite element modeling Vital staining Metallic implants

MEASUREMENT Craniometry Comparative

anatomy Anthropometry Radiology/Imaging

EXPERIMENTAL


CraniometryMeasurement of skull of human skeleton.Broca (1875) defined landmarks &

instruments used for measurements. Congress of German anthropological

society held at Frankfurt in 1882.

Comparative anatomywww.indiandentalacademy.com

AnthropometryMeasurement of skeletal dimensions on

living individualsPhysical anthropology :Study of mans

biologic behavior in time and spaceSpecial instruments are usedADV :Longitudinal study

No harm to subjects

DISADV :Soft tissue error Operator error


Radiology /ImagingConventional radiographs Nature and production of x-raysHow 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 radiographyIntra oralIOPA

paralleling technique

Bisecting angle Bite wingocclusal projection

Extra oral Posterio-anterior Walters

occipitofrontal Riverse-Towne sub mento vertex Lateral oblique mand Lateral skull

Pt positionCephalostatCephalometry


Broadbent-Bolton cephalometer


CephalometryADVANTAGESCombines advantages of anthropometry

and craniometry that is direct bony measurement & study of same individual

DISADVANTAGES2-dimensional Head position criticalDirection of growth not clear

Panoramic www.indiandentalacademy.com

Specialized radiographic techniqueDigital imaging (CCD -voltage-bits 0-255)

Direct digital radiography (R V G )Indirect digital radiographyDigital subtraction radiography Digitized image interpretation

Computed tomographyMagnetic resonanceRadionuclide imagingUltrasoundElectronic thermography


3-D Imaging3-D analysis would be the ideal way of

analyzing soft/hard tissue profileSource 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

Mineralized sections Polarized light Fluorescent labelsMicro radiographyAuto radiographynuclear volume morphometryCell kineticsMicro electrodes

Finite element modelingVital stainingMetallic implants


Histopathological techniquePreparation of tissues for microscopySoft tissue embedded in paraffin

Fixationprocessing

colloidal embedding - hard tissues(decalcified)

Acid treatmentchelationHydrolysis

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


Mineralized sectionsCritical analysis of tissues as there is less

distortion during processingBoth inorganic mineral & organic matrix can

be studied100um -tissue level details25um-Enhanced cellular details

Bone labels quench rapidly Tissue density inadequate for microradiography


Polarized light birefringenceFringe pattern indicate collagen

orientation within boneLoading conditions during bone

formation dictates orientation of collagen

Longitudinal alignment -TensionTransverse alignment -compression


Fluorescent labelsIn vivo administration of Cl binders act

as time markers of bone formationSix fluorescent bone labels are used

Tetracycline -bright yellow Calcein - green Xylenol- orange Alizarin- complexone red Demeclocyclin- gold Oxytetracycline- greenish yellow


MicroradiographyHigher resolution images of polished 100um

mineralized sections obtained1 week primary mineralization8 months secondary mineralizationExperimental animals analyzed by both

microradiography & using fluoroscentlabels midfacial sutures PDL Alveolar process Mandibular condyle temporal fossa


AutoradiographySpecific 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 kineticsBy 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


MicroelectrodesTungsten or glass electrodes are

inserted atraumatically into PDL in live animals via gingival sulcus

changes in electric potential are notedWidened areas have a negative chargeCompressed areas have positive chargeThis coincides with the age old principle,

that bone forms near cathode & resorbs at anode


Finite element modelingFinite 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 must be considered


Vital stainingReported 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 humanswww.indiandentalacademy.com

Metallic implantsMethod 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 growthwww.indiandentalacademy.com

ConclusionTooth 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


ReferencesEnlow;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 www.indiandentalacademy.com

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

References ctd

Xwww.indiandentalacademy.com

Thank you

For more details please visit www.indiandentalacademy.com


methods of study bone growth / orthodontic courses by indian dental academy

Documents