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METHODS OF OSSIFICATION AND ASSESSMENT OF BONE GROWTH RECENT ADVANCES
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INTRODUCTION As with all practitioners in health arts,an Orthodontists primary objective is to describe and diagnose malocclusion he/she wishes to treat in confirmity with the primary dictim of medicine ,primum,non nocere (first ,do no harm) The diagnosis can dictate the treatment objectives and mechanotheraphy for a particular patient. The ability to predict patient’s facial growth early in life would enable the clinician to establish a correct diagnosis and identify the appropriate treatment www.indiandentalacademy.com
METHODS OF OSSIFICATION
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BONE FORMED BY TWO MECHANISMS Intramembranous ossification Endochondral ossification
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INTRAMEMBRANEOUS OSSIFICATION Within membranous,condensed plate of mesenchymal cells Mesenchymal cells lay down collagen – membrane formed. At initial site of ossification mesenchymal cells differentiate into osteoblasts Osteoblasts deposit osteoid Osteoblasts located in lacunae within matrix Collagen fibres – no preffered orientation – Woven bone www.indiandentalacademy.com
Osteoid calcifies – primitive trabecular bone Through reorganisation primitive trabecular bone & compact bone converted to mature bone
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ENDOCHONDRAL OSSIFICATION Formed by transformation of cartilage “bone models” Mesenchymal condensation – cells become chondroblasts,cells on surface of cartilage form perichondrium Intercellular substance calcify , nutrition cut off , cells die ,PRIMARY AREOLAE Periosteal bud invades cartilage model & progenitor cells enter cartilage www.indiandentalacademy.com
Periasteal bud eats away the calaified matrixlarge cavities – SECONDARY AREOLAE Osteogenic cells become osteoblasts , lay down osteoid Bone deposited– lamellar bone – primary ossification centre Secondary ossification centre – future epiphysis
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Periosteal collar – around shaft of cartilage model – woven bone
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Distinct zones close to the zone of ossifying cartilage Reserve cartilage – farthest from zone of ossification Zone of chondrocyte proliferation Zone of cartilage maturation and hypertrophy Zone of cartilage calcification www.indiandentalacademy.com
Between epiphysis and diaphysis – epiphyseal plate Epiphyseal plate – basis for rapid growth of length of bones Removed by continued production of bone from diaphyseal side
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Bone formation & resorption go hand in hand 1st deposited trabecular bone removed as zone of ossification moves in direction of future epiphysis Creates marrow cavity of the bones Bone removed from endosteal surface & deposited on periosteal surface of compact bone which forms diaphysis This results in growth of diameter of bone
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REORGANISATION OF BONE Change in size & shape of bone during growth Key players – osteoblasts & osteoclasts Cutting cone-Head of osteoclasts,Tail of osteoblasts New secondary osteons www.indiandentalacademy.com
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METHODS OF ASSESSMENT Direct measurements Osteometry vital staining implant markers histologic method
Indirect measurements Photographs models radiographs www.indiandentalacademy.com
Indirect measurments in combination X-ray + implants X-ray + metaphyseal bands Autoradiograhs 3D facial measurements Stereophotogrammetry Sassomis physioprint Rabey’s morphanalysis Holography Moire topography Contour photography www.indiandentalacademy.com
MEASUREMENT APPROACHES
Craniometry Anthropometry Animal experiments-1.Vital staining 2.Histology 3.Split line technique 4.Implants Radioactive tracers Auto radiographs Cephalometric roentgenography Photocephalometry Computerised cephalometry www.indiandentalacademy.com
Xeroradiography for cephalometric analysis Roentgen stereophotogrammetry
Medical photogrammetry Contour photography Silhouette method Study models Facial masks Laminagraphy Electromyography
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CRANIOMETRY Measurements of landmarks on skull Dried bones used Static cross-sectional study
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ANTHROPOMETRY
Measure skeletal dimensions on living subjects. Camphor,Morton ,Broca Longitudinal data John Hunter-first to apply anthropometry using mandible Mandible lengthened posteriorly Coronoid and condyle superiorly Resorption along anterior border of ramus Deposition along posterior border Increase in width of ramus www.indiandentalacademy.com
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ANIMAL EXPERIMENTS VITAL STAINING Madder feeding Leninus(1567)-staining property of root in bone Belchier(1736)-accurate account Duhannel(1742)-only newly formed bone stained Hunter-wide alternate red & white band of bone Brash – 5 pigs of different age www.indiandentalacademy.com
Alizarin red injections Reveals rate,procedure,nature of calcification. Single i.p /i.v -2%solution of alizarin red Reacts strongly with calcium at sites of calcification. Invasive study Ground sections used Wet specimen is ground,cleaned ,dehydrated , xylene treated and mounted. www.indiandentalacademy.com
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HISTOLOGY Qualitative processes responsible for growth Direct measurements-Optical superimposition Indirect-Micro photographs Enlow-reconstructed 2Dimages of mandible Site ,direction &pattern of bone growth Localisation of enzymes,glycogen&glycoproteins Osteoclasts – Bone resorption Osteoblasts – Bone deposition www.indiandentalacademy.com
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SPLIT LINE TECHNIQUE
Benninghoff(1925)-superficial trabecular bone pattern Bones decalcified,penetrated with needle Indian ink diffuses to fix fine trabecular bone pattern www.indiandentalacademy.com
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IMPLANTS Duhamel(1742) – silver stylets Hunter(1770) – lead shots in tibia of pigs Au,Ag,Amalgam,SS,Vitalium,Tantalumpins,clips,pegs,screws,plates,wires 1st dental study – Humphery(1864) – pig mandible – wire loops around ramus - resorption in anterior border border
-deposition in posterior www.indiandentalacademy.com
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Indirect studies – using x-rays Grans Robinson,Sarnath – Silver amalgam implants Bjork – Tantalum pins & wires - serial x-rays taken Adv:
- no interference with diet - non invasive, - new bone formation&resorption measured
Disadv: - sum total is demonstrated - intervening changes not revealed www.indiandentalacademy.com
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RADIOACTIVE TRACERS Radiophosphorous,RadioNa,RadioCa,Stro ntium,RaFluoride,RaChloride,Iodine,Carb on,Plutonium, Americanum,Gallium Incorporated into tissue as a sort of vital stain. i.v.injection of isotope,detected by weak radiation it emits
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AUTORADIOGRAPHS
Placing tissue of an animal injected with radioactive substance close to a photographic emulsion Exposed to radiation in dark Distribution of radioactive material-dark.
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ROENTGENOGRAPHS
Superimposition of successive x-rays Krogman & Sassouni(1957)-measurments from shadows of bone &soft tissue landmarks on radiographic images 1922-Paccini –Teleradiographic image 1912 -Tandler- x-ray film in Anthropometry Serial hand wrist x-rays to detect growth changes Greulich&Pyle/ Tanner&Whitehousecomparing the stages with standard normsamount of growth left assessed. www.indiandentalacademy.com
CEPHALOMETRIC ROEOTGENOGRAPHY
1931-Broadbent &Hoffrath Krogman,Savara,Meridth,Popovitch,Bjork,& Woodside Longitudinal studies Stable anatomic base for superimposing Rate ,amount,&relative direction of bone growth Distinguish horizontal &vertical growth patterns Unilateral condylar hypoplasia-marked mandibular notching on the affected side Does not reveal sites or mode of growth Solow &Kreiborg-Multiprojection cephalometry EDP(Electronic data processing) Disadv-2D representation of a 3D structure PACeph projection-Moorees,Moyers Chierici&Faber. www.indiandentalacademy.com
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PHOTO CEPHALOMETRY Superimposition of co-ordinated head films with photographs Photo images on skin of patientaccurately superimposed on corresponding markers in a cephalogram Adv: Soft tissues seen
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COMPUTERISED CEPHALOMETRICS 1970 in U.S.A Computer fed with all data regarding norms & standards of all analysis Less time consuming,increased reliability by double digitization & easy storage of information
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XERORADIOGRAPH FOR CEPHALOMETRIC ANALYSIS
1971 Selenium containing plates in plastic cassette Reconstruction of cephalomatric planes &points made on tracing paper applied over the picture Adv:All densities displayed Edge enhancement effect www.indiandentalacademy.com
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CONTOUR PHOTOGRAPHY Cobb(1972),Lovesy (1974),Robertson(1976) Light sectioning technique Equal width grids projected on face producing contour pattern Convex telecentric lenses are placed in paths of projected beams & of recording camera www.indiandentalacademy.com
SILHOUETTE’S METHOD Light projected on patient from a predetermined distance Shadow on a smooth ,fixed screen Lontitudinal study
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STUDY MODELS
Duplication with plaster,thiokol,hydrocolloid,stone Permanent records,longtitudinal studies possible Model analysis done & growth changes measured
FACIAL MASKS
Impression of face taken at regular intervals Standard measurements – Zygoma-zygoma, Gonion-Gonion.
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LAMINAGRAPHY Assess peri-chondroblastic activity of secondary cartilage in reaction to stress on mandibular condyle,by using lamina &examined under microscope
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ELECTROMYOGRAPHY Assess electric potentials in response to external stimuli of muscle spindles Deep & surface electrodes Kinesograph-movements of muscle spindles Principle – bone yields to muscle pressure Studying the role of muscle influence on bone growth Caliberated metre – records the potential elicited during movements www.indiandentalacademy.com
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SKELETAL INDICATORS OF MATURITY Hand wrist radiographs Cervical vertebrae Canine calcification
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HAND WRIST RADIOGRAPHS P-A radiograph of left hand & wrist Todd , followed by Greulich & Pyle – Atlas of standard hand & wrist films at various ages Systematic comparison of left hand & wrist to atlas standards Bones assessed in regular order Each centre is given a skeletal age , an overall average age is determined Good index of overall biologic maturation www.indiandentalacademy.com
Tanner & Whitehouse method – “maturity points”,scores given Bjork – capping of epiphysis of 3rd middle phalanx closely related to P.H.V
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GREULICH & PYLE METHOD – Comparison with standard x-rays TANNER & WHITEHOUSE METHOD – “Maturity points”,scores given ANTHROPOMETRIC METHOD U/L Segment ratio www.indiandentalacademy.com
Tanner & Whitehouse method 3 methods 1.RUS 2.Carpal bone method 3.TW2 method – each growth centre – maturity rating on a scale of 8 ( A toH) except Radius ( A to I) Numerical score for each centre Total gives overall maturity rating www.indiandentalacademy.com
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OSSIFICATION OF ABDUCTOR SESAMOID & MP3 Taranger &Hass Sesamoid usually attained during acceleration period of pubertal growth spurt MP3 – third finger middle phalanx
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Chapman – Standard size dental films to assess development of 1st metacarpal joint Abductor sesamoid ossification – beginning of adolescent spurt in height Bjork,Holm – 7 Maturational events -Bone development to growth velocity www.indiandentalacademy.com
CERVICAL VERTEBRAE Sato – appearance of epiphyseal plate of odontoid process – indicator of growth peak Lampraski – atlas that stimulated morphologic changes in cervical vertebral bodies in puberty Hassel & Farman , Garcia – Fernandez – pubertal growth based on cephalometric radiographs O Rielly & Yaniello (1998) – increase in corpus length , ramus height & mandibular length during stages of cervical vertebral maturation www.indiandentalacademy.com
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CANINE CALCIFICATION Garn,Engstrom & co workers – relationship between tooth mineralisation & skeletal development Mandibular canine - to estimate timing of pubertal growth spurt Assessed according to Demirjian’s stage of dental calcification Maturity of mandibular canine is more closely related to PHV than other
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A.Initial cusp
D.Formed upto CEJ
G. Apex still open
B.Cusp coalesence
E.Root smaller than crown
H.Fully erupted
C.Crown 他th formed
F.Root & crown equal
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MORPH ANALYSIS Centroid-based pattern of orientation Dental,skeletal & soft tissues identified by non-numeric graphic approach CGA-centro graphic analysis – cephalometric radiograph to demonstrate growth changes Facial centroid axis was formulated to provide a better , stable reference plane www.indiandentalacademy.com
CO-ORDINATE GRIDS FOR 3D FACIAL MEASURMENTS Leivesley(1983) Volumetric measurements & rectangular coordinates Two grids availableUniformly spaced grids with predetermined interval Proportionally spaced grids www.indiandentalacademy.com
Superimposition – measurement in those areas lacking natural landmark Grid intersections – used to define artificial , constructed landmarks
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FOURIER ANALYSIS Mathematical method , allows quantitative analysis of shape and it’s changes Reconstruct outlines , landmark identification and fourier analysis of these outlines through a set of equations enables detection of variations in soft tissues and growth changes over a period of time
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NMR SPECTROSCOPY New method of obtaining 3D cross sectional pictures of thin slices of human head - using resonance of hydrogen nuclei Radio tracers of P,Na,Mg - growth studies on non invasive plane 
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COMPUTER AIDED TOMOGRAPHY Image of the subject is processed by a computer , assessing cranio facial growth and numerical investigations regarding growth
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COMPUTER LASER SCAN SYSTEMS Regular cephalostat for taking cephalograms with specialised coated films He & Ne Lasers used to activate Delinate hard & www.indiandentalacademy.com
LASER Rapid 3D for facial morphology study Scan face in 6 seconds,gives image in 4 min Adv:contact free , data memory,rapidity Dis adv:costly www.indiandentalacademy.com
DIGIGRAPH Sonic digitizing probe Pressing button – sound elicited & land mark recorded by microphone array Dolphin imaging systems(California,USA)
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Electronic circuitory Head holder 2 video camera
Lighthly touching the probe to patient’s skin www.indiandentalacademy.com
Ceph measurements recorded by microphone array in X-Y-Z coordinate Calculating time between sonic wave emission & detection 
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FINITE ELEMENT ANALYSIS In 1985, Melvin moss ,introduced a method to analyse a cephalogram that uses partial differential equations to asign loading values for intermediary points in irregular structures by dividing into a set of regular geometric shapes Generate a mathematical matrix of transformation related to both size & shape Finite element for analysis of serial,lateral cephalometric radiographs Useful tool for morphometric analysis in www.indiandentalacademy.com
By reducing the structure to a group of appropriately connected small elements of known mechanical behaviour,the response of entire structure to loading can be estimated 
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ANTEGONIAL NOTCH FOR GROWTH PREDICTION Singer , Mamandras & Hunter Presence of prominent antegonial notch-arrested growth of mandibular condyles Apposition Forward rotating
symphysis
Backward rotating Angle
Resorption Angle Symphysis
So deep antegonial notch – Backward rotating mandible. www.indiandentalacademy.com
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FRONTAL SINUS & MANDIBULAR GROWTH PREDICTION(AJO DO 1991 DEC)
Rassouw,Lombard & Harris
Correlation between max & mand length, symphysis width,condylar length & frontal sinus on lateral ceph Frontal sinus bud present at birth in ethmoid region Rapid growth to adult size at 12 years Tunner-Annual height growth increments reached a plataeu at ages when frontal sinus enlargement ceased www.indiandentalacademy.com
Brown,Molleson & Chinn – study on lateral ceph The surface area(sq.mm) of frontal sinus – assessed by summagraphic decoder linked to a microcomputer Negative ANB angle – small maxilla & large mandible coincided with large frontal sinus Frontal sinus size though influenced by external environment & muscle attachments is a valuable indicator of excessive mandibular growth.
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ROENTGEN STEREOPHOTOGRAMMETRY
Selvik(1974)
Davidson,Hedley & Payne – 3D localisation procedures from radiopgraph Bone markers – Tantalum spheres,balls or pins Aromo,Selvik & Holst – implantation instruments with a needle & adjustable stop clock 2 markers – longitudinal growth registration 3 markers – kinetic studies Growth is calculated from distance
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Distance changes - from 3D co-ordinates of implants using the 3D pythogorean theorem Biologic mechanism of growth – spatial co-ordination from 2D film co-ordinates RAD – below normal New & exact information on skeletal growth No technical problems – differential enlargement , definition of landmarks , image interpretation problems , orientation errors Skull cephalostats avoided www.indiandentalacademy.com
CASMAS - COMPUTER AIDED SKELETAL MATURITY ASSESSMENT SYSTEM Digital hand atlas with large set of normal set of hand & wrist images that reflect skeletal maturity , race , sex difference & current child development Digital hand atlas will be used for computer aided bone age assessment via web Medical university California designed and partially implemented a computer aided diagnostic system for web based bone age assessment www.indiandentalacademy.com
The system consists of digital hand atlas , a relational image data base & web based interface The digital atlas is based on a large set of normal hand & wrist images with extracted bone objects & quantitative features The image database uses a content based indexing to organise the hand images & their attributes & present to user in a structural way Allows users to interact with hand image data base from browsers
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Quantitative features on the examined image, which can reflect the skeletal maturity will be extracted & compared with patterns from atlas database to assess the bone age The relevant reference images and the final assessment report will be sent back to user’s browser via web 
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THREE DIMENSIONAL FACIAL GROWTH STUDIED BY OPTICAL SURFACE SCANNING The optical scanner – rapid accurate data collection in 3D Assosiated software creates a visual image Dis adv – high cost Recently,video-capture stereoscopic method of imaging 2 pairs of stereo camera – curved facial www.indiandentalacademy.com structures are imaged
The system allows photo realistic image generation of the face that can be viewed from any direction Study the 3D alterations in the facial morphology with increasing age 
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CONCLUSION Dynamics of growth is a complex process The Orthodontist , if he is to evaluate properly the role he plays in correcting malocclusion must have the opportunity to examine the conditions over which he has the least control , namely growth & development during correction of malocclusion With the use of the recent techniques available accurate information about growth can be obtained
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REFERENCES 1.Profitt – Contemporary Orthodontics 2.White & Goaz – The Dental Radiology 3. Athanasiou – Orthodontic Cephalometry 4.Thomas Rakosi – Cephalometric Radiography 5.Inderbir Singh – Textbook of human histology 6.Hassel & Farman – Skeletal maturation evaluation using skeletal vertebra- AJO DO 1995,107,pg:58-66 7.Bernard G. Sarnath – Growth pattern of mandible – AJO DO 1986 pg:221-233 8.Garcia – fernandez,The cervical vertebra as Maturational indicator- JCO April 1998 9.Leivesly – Reliability of Contour Photography for facial measurements- BJO 1983, pg:34-37
10.Tashinaro Mito & Sato – Cervical vertebral bone age in girls – AJO DO
12.Nute & Moss – 3D facial growth studied by optical scanning – JO 2000 vol 2002,122,pg:380-385 27,pg:31-38 11.Hagg & Taranger – Maturity &Pubertal growth spurts – AJO 1982,82,pg:299-309 www.indiandentalacademy.com
13.Chertkow – Tooth mineralisation as an indicator of the pubertal growth spurt – AJO DO 1980 ,pg:79-91 14.Sato & Mito – An accurate method of predicting mandibular growth potential based on bone maturity – AJO DO 2001 , 120, pg :286-290 15.Sierra – Assessment of dental & skeletal maturity – A new approach,AO 1987,pg:194 –208 16.Abdul Khadher – The potential of dental didital Radiography in recording adductor sesamoid & MP3 – BJO 1999,VOL:26,291-293 17.Kolodziej,southard – Evaluation of Ante gonial notch depth for growth prediction – AJO DO 2002,121,pg:357-363 18.Melesio.r.Leite, O’Rielly – Skeletal assessment using 1sty , 2 nd & 3rd fingers of hand – AJO DO – 1987,pg:492-498 19.Sandro Coutinno – relationship between mandibular canine calcification stages & skeletal maturity – AJO DO 1993, pg:262 -268
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