Growth &development of   cranial vault & base   /fixed orthodontic courses
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Growth &development of cranial vault & base /fixed orthodontic courses




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    Growth &development of   cranial vault & base   /fixed orthodontic courses Growth &development of cranial vault & base /fixed orthodontic courses Presentation Transcript

    • INDIAN DENTAL ACADEMY Leader in continuing dental education
    • Skull  At Birth- 45 bony elements  In Adult- 22 bones Face- 14 bones Cranium- 8 bones
    • Cranium   Paired:- 1. parietal 2. temporal Unpaired 1. frontal 2. occipital 3. sphenoid 4. ethmoid
    • Four regions of the Craniofacial complex  The Cranial Vault  The Cranial Base  The Naso-maxillary complex  The Mandible
    • Further – Pre - natal and Post - natal growth Attention to:1. Site and location of growth 2. Type of growth occurring. 3. Determinant or controlling factors.
    • Anatomy  Norma Verticalis – Above  Norma Basalis – Below  Norma Lateralis – Side  Norma Occipitalis – Back  Norma Frontalis - Front
    •  Span –  Superciliary ridges & glabella of frontal bone upto & including Squamous occipital bone. Also includes part of Squamous temporal bone laterally.
    •    When viewed from above:a Ellipsoidal (roughly) b Bones –  Frontal  Parietal  Occipital  Temporal  Greater wing of sphenoid
    • c. Sutures  Frontal (metopic)  Coronal  Sagittal  Lambdoid  Bregma  Lambda
    • Neurocranium  Vault of skull(calvaria)  Phylogenetically-recent origin, to cover the newly expanded brain.  Formation- intramembranous bone of paraxial mesodermal & neural crest origin  Known a desmocranium.
    •  Cranial base  Derived phylogenetically –ancient cranial floor.  Associated with the capsular investments of nasal & auditory sense organs.  Neural crest origin.  Cartilaginous precursor-chondrocranium.
    • Development of calvaria Pre-natal growth Endomenix Ectomeninx Arachnoid Piamater Skull bone Duramater
    • Ossification centers of the skull Mesoderm – Frontal, Parietal, sphenoid, petrous temporal & occipital. Neural crest – Lacrimal, nasal, squamous temporal, zygomatic, maxilla & mandible
    • Ossification centers of the skull
    • Pre-Natal Growth  Frontal Bone  Primary centre ------ Superciliary arch(8 th wk)  Secondary centers ------ zygomatic process, (fusion 6-7 mts) nasal spine, trochlear fossae At birth- Metopic suture, fusion 2-7yrs
    • Pre-Natal Growth  Parietal bone   Occipital bone (Squamous part) 8th wk   Region of Parietal eminence 8th wk, fuse by 4th month. Just above superior nuchal line Temporal bone (Squamous part)  Root of zygoma
    • Frontanellae   Flat bones connected by loose connective tissue. Close at various times- 3 months to 2 years.
    • Fontenallae Time of closure -Anterior -2nd year -posterior -2 mts -Ant lateral -3mts -Post lateral -2nd year
    • Pre-Natal Growth -Control  Intrinsic genetic factors  Epigenetic factors  Environmental factors
    • Intrinsic Genetic control Local epigenetic factors Cranial Cranial differentiation differentiation General epigenetic factors Local Environmental factors General Environmental factors
    • Pre-Natal Growth -Control Shift of belief:Genetic influence Epigenetics Examples- Primordia of eye. - Brain.
    • Intrinsic Genetic control Local epigenetic factors Cranial Cranial differentiation differentiation General epigenetic factors Local Environmental factors General Environmental factors
    • Post-Natal Growth Various Theories of Growth, and how they relate to the cranial vault. Sicher’s Sutural dominance theory Scott’s Cartilaginous theory Moss’ FMH
    • Sutural Theory  Genetically determined  Growth at sutures  Mild effect of local factors ex- remodeling under the influence of muscles.
    • Sichers Theory Intrinsic Genetic control Local epigenetic factors Desmocranial Desmocranial Growth Growth General epigenetic factors Local Environmental factors General Environmental factors
    • Cartilagenous theory     Intrinsic growth controlling factors – cartilage,periosteum. Sutures-secondary, dependent on extra skeletal influence. Cartilage-primary centers of growth. Nasal septum-major contributor in maxillary growth.
    • Post-Natal Growth Intrinsic Genetic control Chondrocranial Chondrocranial Growth Growth Local epigenetic factors General epigenetic factors Desmo- Sutures cranial Periosteal Growth growth Local Environmental factors General Environmental factors
    • Post-Natal Growth Moss’ FMH Intrinsic Genetic control Local epigenetic factors Desmocranial Desmocranial Growth Growth General epigenetic factors Local Environmental factors General Environmental factors
    • Post-Natal Growth Moss’ explanation for brain growth controlling growth of the cranium… Hydrocephalus, synostosis
    • Van Limborgh's Summarization:1. Intrinsic control of growth at synchondroses 2. Intrinsic control of sutural growth is less 3. Synchondroses 4. Sutural growth controlled in part by growth of cranial base Growth centre
    • 5. Periosteal bone growth (vault) controlled epigenetically by adjacent structures 6. Growth of cranial vault also controlled by local environmental factors (muscle forces inclusive)
    • Post-Natal Growth Growth of the cranial vault – direct influence of Neurocranial capsule
    •    As brain expands seperate bones of calvariadisplaced outwardly. Passive movement. Each separate bone is enmeshed within connective tissue stroma.
    •  Primary displacement- tension in sutural membranes.  Response-new bone deposition-sutural edges.  Each separate bone enlarges-circumference.  Endosteal surfaces-resorptive, overall thickness &expands medullary spaces.
    • Post-Natal Growth Thickening not uniform:Inner table Brain Outer table mechanical influences and functional stresses Growth of the frontal sinus (Benninghoff)
    • Post-Natal Growth 90% of cranial vault growth complete by 5-6 yrs In accordance with -Scammon’s curve - Cephalocaudal Gradient.
    • Clinical implications     Altered time closure of sutures-variable distortions of skull shape. Delayed midline ossification of frontal & sagital sutures –anterior frontanelle may remaine open. Cretinism,progeria,trisomy 21,cleidocranial dysostosis. Premature synostosis – Apert syndrome & crouzen syndrome.
    •    Conditions like hydrocephaly, microcephaly. Abnormal external forces during developmentdistort cranial morphology-bizzare shapes of skulls . Defect in closure of foramen caecum at the ethmoid-frontal suture herniation of cranial content into the facefrontal encephaloceles.
    •  1. 2. 3. Cranial growth is a combination of Sutural growth Surface deposition & resorption Centrifugal displacement by the expanding brain.
    • Cranial Base   Reasonably stable reference structure in cephalometric analysis Basis to compare and understand abnormal growth patterns
    • Functions  Supports & protects the brain & spinal cord  Articulation of skull with vertebral column , mandible & maxilla  Buffer zone between the brain, face & pharyngeal region
    • Anatomy  Anterior cranial fossa  Middle cranial fossa  Posterior cranial fossa
    • Anterior cranial fossa 1. 2. 3. Orbital part of frontal bone Cribriform plate of ethmoid Anterior part of the body of sphenoid & lesser wing
    • Middle cranial fossa It is deeper than the anterior fossa  It shaped like a butterfly. In front it is bounded by posterior borders of the lesser wing of sphenoid and the body of the sphenoid,  Behind by superior borders of the temporal bones & Dorsum sellae of sphenoid bone
    • Middle cranial fossa Centrally  Optic Canal  Hypophyseal Fossa Laterally  Superior Orbital Fissure  Foramen Rotundum  Foramen Ovale  Foramen Spinosum  Foramen Lacerum
    • Middle cranial fossa
    • Posterior cranial fossa  Largest and deepest of the cranial fossa.  Sorrounded by dorsum cella, posterior part of body of sphenoid bone & basilar part of occipital bone- anterior.  Posterior- lower portion of squamous part of occipital bone.
    • Posterior cranial fossa
    • Posterior cranial fossa Various foramina  Foramen magnum  Jugular foramen  Internal acoustic meatus  Facial canal  Hypoglossal canal
    • Pre-natal growth Cranium  Neurocranium-protects, supports;brain, sense organs Viscerocranium-alimentary, respiratory tracts, face, maxilla & mandible Basicranium - both
    • Prenatal growth Chodrification  Mesenchyme derived from paraxial mesoderm and neural crest .  Form ectomeningeal capsule.   Earliest evidence of skull formation. Mesenchyme starts converting into Cartilage Starting on day 40 i.u. Cartilage
    • cartilages  parachordal cartilage  Hypophyseal cartilage  Otic capsule.  Nasal capsule
    • Parachordal cartilage  Chondrification centers forming around the cranial end of the notochord  Parachordal cartilages fuse with the sclerotomes arising from occipital somites surrounding the neural tube
    • Parachordal cartilage
    • Hypophyseal cartilage 2 Hypophyseal cartilages - Post sphenoid Sella turcica Body of the sphenoid (post. Part)
    • 2 Pre sphenoid cartilage- Pre sphenoid bone Body of the sphenoid bone (ant. Part)
    • Most anteriorly- presphenoid cartilagesMesethmoid Ossifies into perpendicular plate of ethmoid Upper edge forms crista galli
    •   Orbito sphenoid  Lesser wing Alisphenoid  Greater wing
    • Otic capsule Mastoid and petrous portions of the temporal bones Otic capsule does not chondrify.
    • Nasal capsule- 2nd month i.u Cartilages of nostrils and the nasal septal cartilage  Functional matrix- downward & forward growth  Transfer’s compressive forces from incisor region to the sphenoid region
    • Primordial cartilage
    • Chondrocranial ossification 110 ossification centers –embryonic human skull.  Ossification starts in the 4 months. Unossified chondrocranial remnents: Alae & septum of the nose  Spheno-occipital & spheno-petrous junctions.  Apex of the petrous bone  Between the separate parts of occipital bone. 
    • Chondrocranial ossification
    • Occipital bone  7 ossification centers - 2 intramembranous 5 endochondral  Sq portion above sup nuchal line –ossify from pair of i.m ossi centers 8th i.u week  Infranuchally – pair of endochondral centers 10th i.u week
    •  Single median endochondral ossi center at 11 th week ant to foramen magnum & ant 3rd occipital condyle.  pair of endochondral ossification centers at 12 th week from exoccipital bone lateral to magnum including 2/3rd occi condyle.
    • Temporal bone  21 ossi centers  squamous & tympanic portion – ossify i.m  Petrosal & styloid elements - endochondrally
    •  Sq portion – single center at 8th i.u week.  Tympanic ring- 4 centers at 3rd i.u month.  Petrosal part- 14 centers; appear at 16 th week, fuse 6th i.u month  Styloid process- 2 centers upper center- just before birth lower center- just after birth
    • Ethmoid bone – 3 centres  A single median center -Perpendicular plate & crista galli  Lateral labyrinths in the nasal cartilages- 2 endochondral centers
    • Ossification-sphenoid bone Intramembranous ossification centres  Medial pterygoid plates – 2  Lateral pterygoid plates -2 Endochondral ossification centres  Presphenoid – 3  Postsphenoid – 4  Orbitosphenoids - 2  Alisphenoids - 2  Pterygoid hamuli - 2
    • Ossification Bone Site & number of ossification Intramembranous Occipital - supra nuchal squamous (2) Temporal - Endochondral squamous (1) tympanic (4) Ethmoid - - infra nuchal squamous(2) Basilar (1) Exoccipital (2) petrosal (14) styloid (2) lateral labarynths (2) perpendicular plate; crista (1)
    • Bone Site & number of ossification Intramembranous Vomer Sphenoid - Endochondral Alae (2) Medial pterygoid pre sphenoid (3) plates (2) post sphenoid (4) Lateral pterygoid orbitosphenoid (2) plates (2) elisphenoids (2) pterygoid hamulus (2) sphenoidal conchae( 2) Inferior nasal conchae lamina (1)
    • Cranial base angulation Angle at the hypophyseal fossa where prechordal & chordal parts meet each other
    •  Highly Uneven  Anterior cranial base increases its length and width by 7 folds between the 10th and 40thweek of I.U life  Posterior cranial base grows only 5 fold
    • Post natal growth Expansion of cranial base occurs by   Growth of the cartilage remnants of the chondrocranium- basicranial bones Forces from growing brain
    •  Cranial base acts as a template from which the face develops  The endocranial surface of the basicranium is resorptive in most areas  Remodeling is required to accommodate the massively enlarged human brain
    • Fossa enlargement
    •  Bony elevations b/w fossae, divide fossa into various compartments  Middle & post fossae by petrous elevation  Olfactory fossae by crista galli  Rt & left mid cranial fossae by midline sphenoidal elevation  Rt & left ant & post cranial fossae by longi midline bony ridge
    •   Fossa expands outward by resorption, Partitions between them enlarge inward by deposition
    • synchondrosis    Bands of cartilage remain at the junction of various bones. Regarded as growth center & pacemaker of cranial base. Present in midline part of basicranium
    •  Synchondrosis at the base  Spheno-occipital synchondrosis  Inter-sphenoidal synchondrosis  Spheno-ethmoidal synchondrosis  Intra-occipital synchondrosis
    • Synchondrosis of cranial base
    • Spheno-occipital synchondrosis     Major contributor in the post natal growth. Fuses at 12 to 13 years in girls & 14 to 15 years in boys. Ossifies at 20 years of age. Pressure adapted bone growth mechanism.
    • Structure of synchondrosis Zones of cartilage Familiar reserve zone  Cell division zone  Hypertropic zone  Calcified zone
    •   Endochondral bone growth – primary displacement of bones involved. Sphenoid & occipital bones moved apartprimary displacement processes Two major directions of linear growth
    • Hunter-Enlow growth equivalents concept
    •  Frontal lobe growth completes by 5years.  Temporal lobes continue to enlarge for several more years and displaces the frontal lobe forward.
    • Clinical implications Configuration of neurocranium(& brain) determines a person’s head form type - Dolicocephalic - Brachycephalic - Mesocephalic
    • Cranial base growth for Dutch boys and girls – Monique Henneberke & Birte Prahl Andersen (AJO 1994 ) Hypothesis that there is no difference in the cranial base growth between children with or   without ortho treatment- was tested S-N 153(boys)and 167 (girls) N-Ba and S-Ba 116 (boys) and 116 (girls), 714 yrs Mixed longitudinal study
    • Results 1. The effect of orthodontic therapy on cranial base was not significant 2. The cranial base displayed sexual dimorphism in absolute size, timing and amount of growth. 3. Girls did not show growth spurts where as boys showed growth spurts for S-N and NBa.
    • Achondroplasia  Deficient growth at synchondrosis.  Disturbance in endochondral bone formation  Maxilla is not translated forward  This results in abnormal depression of the bridge of the nose  Relative midface deficiency
    •   Premature ossification or synostosis of the suture between the presphaenoid and postsphenoid parts of the spheno-occipital suture depressed nasal bridge and dished face
    •  Anomalous development of the presphenoidal elements Excessive separation of orbits and abnormally broad nasal bridge  Hypertelorism  Anecephaly (Absence of calvaria ) Retain acute cranial base flexure
    •  Cliedocranial disostosis Abnormalities of the skull, teeth, jaws and shoulder girdle  Afflictions of cartilage growth cranial base with angulation-achondroplasia ,critinism, down’s syndrome
    • REFERENCES 1. Craniofacial Embryology G.H.SPERBER 2. Essencials Of Facial Growth D.H.ENLOW 3. Contemporary orthodontics W.R.PROFFIT 4. Orthodontics principles and practice T.M. GRABER 5. Anatomy –Gray
    • 6. Cranial Base Growth For Dutch Boys & Girls – M.Herneberke,b.P. Andersen (AjoNovember; 1994 ) 7. Grants Atlas
    • Thank you Leader in continuing dental education