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Growth and development of the mandible   /certified fixed orthodontic courses by Indian dental academy
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Growth and development of the mandible /certified fixed orthodontic courses by Indian dental academy




The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call



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    Growth and development of the mandible   /certified fixed orthodontic courses by Indian dental academy Growth and development of the mandible /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

    • GROWTH AND DEVELOPMENT OF THE MANDIBLE www.indiandentalacademy.com
    • INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    • Prenatal growth of the mandible www.indiandentalacademy.com
    • Neural crest cells Ist brachial arch Mandibular process Mandibular bone www.indiandentalacademy.com CT tissue
    • www.indiandentalacademy.com
    • 36 – 38 DAYS Ectomesenchymal condensation mandible Lateral to Meckels cartilage Osteogenic membrane www.indiandentalacademy.com
    • 6 th week www.indiandentalacademy.com
    • 10 – 12 weeks  Secondary accessory cartilages appear www.indiandentalacademy.com
    • 10 week - condylar cartilage   Appears in the Ramal region Endochondral bone (14 week) www.indiandentalacademy.com
    • Condylar Cartilage Serves as a growth site  Brings changes in the mandibular position and form  Growth increases during puberty  Peak 12 – 14 years  Ceases by 20 years  www.indiandentalacademy.com
    • 7 th month IUL    1 or 2 small cartilages appear in the future mental region Mental ossicles Incorporated into the intramembranous bone of symphsis www.indiandentalacademy.com
    • Features of neonatal mandible  Ascending Ramus low and wide Large Coronoid process  Body – open shell containing tooth buds and partially formed deciduous teeth  Mandibular canal that runs low in the body  www.indiandentalacademy.com
    • Features of neonatal mandible High Coronoid process Wide Ramus www.indiandentalacademy.com
    • Differential growth During fetal life    8 weeks - mandible > maxilla 11 weeks - mandible = maxilla 13 – 20 weeks maxilla > mandible At birth   Mandible tends to be retrognathic Early post natal life orthognathic www.indiandentalacademy.com
    • Post natal growth of the mandible www.indiandentalacademy.com
    • Main sites of post natal growth in the Mandible  Condylar cartilage  Posterior border of the Rami Width  Height length Alveolar ridges www.indiandentalacademy.com
    • Symphysis Menti   Limited growth till fusion No widening after fusion www.indiandentalacademy.com
    • Mental Foramen www.indiandentalacademy.com
    • Mental Foramen  Vertical relation within the body of the mandible www.indiandentalacademy.com
    • Mental Protuberance   Formed by mental ossicles from accessory cartilage and ventral end of Meckel’s cartilage Poorly developed in infants www.indiandentalacademy.com
    • Mental Protruberance Forms by osseous deposition during childhood  Prominence is accentuated by bone resorption above it  www.indiandentalacademy.com
    • Mental Protuberance    Reversal between 2 growth fields Concave convex Reversal line could be High or low www.indiandentalacademy.com
    • Alveolar process    Adds to the height and thickness of the mandibular body Teeth absent fails to develop Teeth extracted resorbs www.indiandentalacademy.com
    • Alveolar process    Acts as buffer zone Maintains vertical height Adaptive remodeling makes orthodontic tooth movement possible www.indiandentalacademy.com
    • Alveolar process Lingual movement of anteriors www.indiandentalacademy.com
    • Condylar cartilage   Secondary cartilage Important contribution to the overall length of the mandible www.indiandentalacademy.com
    • Condylar cartilage  ‘ v ‘ principle of Enlow www.indiandentalacademy.com
    • Is the Condylar cartilage the principle force that produces the displacement of the mandible ?  For many years considered primary growth center  FMH - Condyle absent yet mandible positioned normally  Considered secondary cartilage -no intrinsic growth potential www.indiandentalacademy.com
    •  PETROVIC ET AL – role of hormones  Experiments involving transplantation of the condyle  JOHNSTON ETAL detached condyle from the body of mandible in guinea pigs  Injection of papain –inhibition of chondrogenesis  RANCHOW MOSS - Condylectomy – immediate resumption of growth www.indiandentalacademy.com
    •    Condylar cartilage and functioning muscles translate the mandible and in the absence of one the other does best to compensate Integrity of periosteum is important When environment is changed compensatory contributions are enhanced www.indiandentalacademy.com
    • CURRENT CONCEPT   Condylar cartilage does have a measure of intrinsic genetic programming But extra condylar factors are needed to sustain this activity Physiologic inductors Intrinsic and extrinsic biomechanical forces ENLOW :   Increase pressure – growth inhibition Decrease pressure – stimulates growth www.indiandentalacademy.com based mainly on animal experiments
    • Lingual Tuberosity   Grows posterior and medial by deposition Resorptive field belowLingual fossa www.indiandentalacademy.com
    • Coronoid Process  POSTERIOR Lingual surface SUPERIOR MEDIALLY  Follows ‘v’ principle www.indiandentalacademy.com
    • Coronoid Process  ‘’V’ PRINCIPLE OF ENLOW www.indiandentalacademy.com
    • Coronoid Process  Deposition on lingual side MEDIAL  Resorption INCREASES VERTICAL LENGTH POSTERIOR GROWTH - buccal surface www.indiandentalacademy.com
    • RAMUS   Posterior border deposition Anterior border resorption www.indiandentalacademy.com
    • Ramus   Superior part of ramus below sigmoid notch Lower part of ramus below the Coronoid process LINGUAL -DEPOSITION BUCCAL RESORPTION BUCCAL DEPOSITION LINGUAL RESORPTION www.indiandentalacademy.com
    • Ramus www.indiandentalacademy.com
    • Posterior border of Ramus   Depository and keeps pace with condylar growth Angle of growth vertical  horizontal Posterior margin below condyle --resorptive field www.indiandentalacademy.com
    • Ramus Uprighting Posterior border – deposition Inferior > superior  Anterior border – resorption Inferior >superior  Condylar growth more vertical www.indiandentalacademy.com
    • Age related differences in mandibular growth MARK HANS , DONALD ENLOW AJO DEC 1995     30 well preserved human mandibles from dental ages 1 – 13 years Ground and polished microscopic sections were obtained from the Ramus Distribution of various types of resorptive vs depository surfaces were recorded 2 additional patterns of Ramal remodeling were noted www.indiandentalacademy.com
    • Type A – Classical Pattern www.indiandentalacademy.com
    • Type B – Vertical Variation  www.indiandentalacademy.com
    • Type C - Rotation Variation www.indiandentalacademy.com
    • Conclusions    All 3 patterns cause downward & forward displacement but to varying degree ENLOW’S original description of general body growth & remodeling type A most common but one pattern of remodeling is incomplete The difference in pattern were large enough to influence orthodontic treatment www.indiandentalacademy.com
    • Ramus corpus junction   Inferior Border of junction resorption Forms Antegonial notch www.indiandentalacademy.com
    • Gonial region  Anatomically variable B - Resorption  Gonial flares inwardly outwardly L - deposition B -deposition L - resorption  Depends upon growth direction of ramus and condyle www.indiandentalacademy.com
    • Mandibular foramen    Ramus -- posterior and superior direction Mandibular foramen drifts in backward & upward direction Maintains constant position -[A-P] www.indiandentalacademy.com
    • Condylar neck     Anterior margin deposition Posterior margin Lingual and buccal margin Rotation – posterior border resorption Periosteal resorption Endosteal deposition www.indiandentalacademy.com
    • Ramal growth     Backward transportation of entire ramus – elongation of mandibular body Displacement of corpus –anterior direction Vertical lengthening of ramus as mandible is displaced Movable articulation during various growth changes www.indiandentalacademy.com
    • Role of muscles in Mandibular growth MOSS    CORONOID GONIAL ANGLE Medial CONDYLE Temporalis Masseter & pterygoid internal pterygoid www.indiandentalacademy.com
    • Skeletal units of mandible www.indiandentalacademy.com
    • Role of muscles in Mandibular growth  Decrease muscle activity Flattening of Gonial angle Reduction of Coronoid process www.indiandentalacademy.com
    • Growth of mandible during pubescence ARTHUR LEWIS , ALEX ROCHE AJO OCT 1982    Spurts in the mandible were analyzed in 67 subjects from Fels longitudinal study Spurts in Ar-Go , Ar-Gn , Go-Gn A spurt was defined as an annual increment exceeding the immediately preceding annual increment by at least 1 mm www.indiandentalacademy.com
    • Growth of mandible during pubescence www.indiandentalacademy.com
    • Growth of mandible during pubescence conclusion      Spurts in mandibular dimensions are common but not universal More common in boys 1.5 yrs earlier in girls 1st pubertal spurt usually occurs before PHV Almost all 1st pubertal spurts occur one year after US ossification and before menarche www.indiandentalacademy.com
    • Anomalies of development  AGNATHIA – deficiency of neural crest cells in lower part of the face DOWNS  MICROGNATHIA - TREACHER COLLINS PIERRE ROBIN www.indiandentalacademy.com
    • Anomalies of development  BIFID /DOUBLE CONDYLE  MACROGNATHIA  MICROGENIA  TORUS MANDIBULARIS www.indiandentalacademy.com
    • References        Craniofacial embryology – SPERBER Facial growth – ENLOW Contemporary orthodontics – PROFFIT Handbook of orthodontics – MOYERS Principles and practice of orthodontics – GRABER Growth of mandible during pubescence – ROCHE,LEWIS AO OCT 1982 Age related differences in Ramus growth – ENLOW,HANS AJO DEC 1995 www.indiandentalacademy.com
    • Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com