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GROWTH OF MANDIBLE

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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

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GROWTH OF MANDIBLE

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PRE NATAL GROWTH OF MANDIBLE  EMBRYONAL

 FETAL

PERIOD

PERIOD

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FETAL PERIOD The alveolar plate lengthens more rapidly than does the ramus  The ratio of the alveolar plate length to total mandibular length is reasonably constant  The width of the alveolar plate shows a more rapid increase than does total width  The ratio of the width between the mandibular angle to total width is relatively constant during fetal life 

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STRUCTURES RELATED TO DEVELOPING MANDIBLE  INFERIOR

DENTAL NERVE

 MECKEL’S  TOOTH

CARTILAGE

GERMS

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DEVELOPMENTAL ELEMENTS RELATED TO THE MANDIBLE  NEURAL  ALVEOLAR  RAMAL  MUSCULAR  CARTILAGENOUS

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DEVELOPMENT OF THE MANDIBLE

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ANATOMY OF THE MANDIBLE

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MEDIAL ASPECT

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LINGUAL VIEW

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SKELETAL UNITS

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TEMPORALIS MUSCLE

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MUSCLES OF THE TMJ

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PRIMARY &SECONDARY CARTILAGE

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Variation in tissue arrangement adjacent to endochondral bone formation

a.bone b.prechondroblasts c.chondroblasts d.resting cartilage e.mature cartilage f.transitional zone g.dense fibrous connective tissue h.bone & marrow of epiphysis i. Articular cartilage www.indiandentalacademy.com


CONDYLAR CARTILAGE a. b.

c. d.

Capsular layer(densely fibrous) Layer of prechondroblastic cellscellular proliferation New developing cartilage Continually forming endochondral bone

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CONDYLAR REMODELLING   

 

PERIOSTEAL RESORPION ENDOSTEAL DEPOSITION CONDYLE MOVES IN A SUPEROPOSTERIOR COURSE NECK IS NARROWED DOWN NECK IS LOCATED IN POSITION OF CONDYLE

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ENLOW’S “V” PRINCIPLE

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CONDYLAR RESECTION IN RHESUS MONKEY     

Facial height is less in A than in B Accentuation of anti gonial notch Shorter,wide anteriorly positioned ramus Larger and heavier coronoid process Reduced facial height on operated side

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OSTEOCHONDRAL RIB TRANSPLANT  

Each precursor chondroblast divides 35-50 times Each progenitor chondroblast divides 8-11 times

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The chondroblasts issuing from a progenitor chondroblast produce a pyramid-like structure that is a component of the primary growth cartilage of the rib

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RIB TRANSPLANT EXPERIMENT OBSERVATIONS

Intracellular concentrations of Na+ tended to decrease  Intracellular concentrations of Ca++ & H+ ions tended to increase  Intracellular pH was lowered  Na+ & K+ -ATPase activity was intensified  Ca++, Mg++ - ATPase ,and H+ - ATPase activities were diminished  The numbers of cell divisions declined slightly and demonstrated a significant slowing of growth rate  Similar variations were observed in condylar cartilage of rats and humans www.indiandentalacademy.com 


Differentiation rate of the precursor chondroblast into progenitor chondroblast is submitted not only to the command represented by genetic,hormonal, humoral factors but also to epigenetic biomechanic factors Also autologous osteochondral rib transplant is preferable in treatment of TMJ ankylosis than metatarsal cartilage transplant www.indiandentalacademy.com


Sectioning of mandible into parts for study

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TRANSVERSE SECTION OF CONDYLAR NECK Lingual surface A has received periosteal deposits  B is composed of endosteal compacted cancellous bone produced during condylar neck reduction  C has received periosteal depositsas post.border of neck grows in post.direction  D buccal area growing in endosteal direction lller to B  E is undergoing resorption as ant.part of neck grows in a www.indiandentalacademy.com cephalic direction towards side A 


Remodelling Process

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Coronoid Process & Ramus

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Remodelling at the lingual tuberosity

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The posterior growth of the tuberosity is accomplised by continued new deposits of bone on its posteriorfacing exposure. Part of the ramus just behind the tuberosity remodels medially www.indiandentalacademy.com


LOGARITHMIC CURVE FOR MANDIBULAR GROWTH

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CONCLUSION The spatial movements of the mandible, and of the mental foramen, related to the “rotation� of this logarithmic spiral are clear indications of the passive translation of the macro-skeletal unit within the expanding oro-facial capsule,which is a response to the primary morphogenetic enlargement of the oro-nasal functioning spaces. The posterior and upward movements of the mandibular foramen ,on the other hand, accurately reflect the active transformative growth changes of the several mandibular microskeletal units due to deposition and resorption of bone brought about www.indiandentalacademy.com by the action of periosteal matrices


RAT INCISORS

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Logarithmic spiral applied to rat incisors

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OSTEOCLAST

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ď ś

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AGE CHANGES IN THE MANDIBLE

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