The development of mandible / dental crown & bridge courses

DEVELOPMENT OFDEVELOPMENT OF
MANDIBLEMANDIBLE
www.indiandentalacademy.comwww.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education

 IN ALL BIOLOGICAL SENSE DEVELOPMENT IS A PROCESSIN ALL BIOLOGICAL SENSE DEVELOPMENT IS A PROCESS
OF CONTINUOUS CHANGES OCCURING IN PREDETERMINEDOF CONTINUOUS CHANGES OCCURING IN PREDETERMINED
ORDERORDER..
 DEVELOPMENT IS AN INCERASE IN COMPLEXITY (TODD 1931)DEVELOPMENT IS AN INCERASE IN COMPLEXITY (TODD 1931)
 DEVELOPMENT IS USED TO INDICATE AN INCREASE IN SKILL ANDDEVELOPMENT IS USED TO INDICATE AN INCREASE IN SKILL AND
COMPLEXITY OF FUNCTION (LOWREY 1951)COMPLEXITY OF FUNCTION (LOWREY 1951)
 DEVELOPMENT REFERS TO ALL NATURALLY OCCURINGDEVELOPMENT REFERS TO ALL NATURALLY OCCURING
UNIDIRECTIONAL CHANGES IN LIFE OF AN INDIVIDUAL FROMUNIDIRECTIONAL CHANGES IN LIFE OF AN INDIVIDUAL FROM
ITS EXISTENCE AS A SINGLE CELL TO ITS ELABORATION ASITS EXISTENCE AS A SINGLE CELL TO ITS ELABORATION AS
MULTIFUNCTIONAL UNIT TERMINATING IN DEATH (MOYER 1981)MULTIFUNCTIONAL UNIT TERMINATING IN DEATH (MOYER 1981)
 THE ACT OR PROCESS OF NATURAL PROGESSION FROM ATHE ACT OR PROCESS OF NATURAL PROGESSION FROM A
PREVIOUS, LOWER OR EMBRYONIC STAGE, TO A LATER,MOREPREVIOUS, LOWER OR EMBRYONIC STAGE, TO A LATER,MORE
COMPLEX OR ADULT STAGE (STEDMAN 1990)COMPLEX OR ADULT STAGE (STEDMAN 1990)

 1. PRENATAL GROWTH AND DEVELOPMENT1. PRENATAL GROWTH AND DEVELOPMENT
 2. ROLE OF MECKEL’S CARTILAGE2. ROLE OF MECKEL’S CARTILAGE
 3. TYPES OF OSSIFICATION3. TYPES OF OSSIFICATION
 4. MECHANISMS OF BONE GROWTH4. MECHANISMS OF BONE GROWTH
 5. THEORIES OF GROWTH5. THEORIES OF GROWTH
 6. POSTNATAL GROWTH AND DEVELOPMENT6. POSTNATAL GROWTH AND DEVELOPMENT
 7. FACTORS AFFECTING GROWTH7. FACTORS AFFECTING GROWTH
 8. ANOMALIES OF MANDIBLE8. ANOMALIES OF MANDIBLE
 9. AGE CHANGES IN MANDIBLE9. AGE CHANGES IN MANDIBLE
 10. SUMMARY10. SUMMARY

PRENATAL GROWTH AND DEVELOPMENT
 IT IS A DYNAMIC PHASE WHICH IS DIVIDED INTO
1. PERIOD OF OVUM- FROM FERTILIZATION TO 14th
DAY
2. PERIOD OF EMBRYO- FROM 14TH
DAY TO 56TH
DAY
3. PERIOD OF FETUS- FROM 56TH
DAY TILL BIRTH
 THE MOST TYPICAL FEATURE IN THE DEVELOPMENT OF THE
HEAD IS THE FORMATION OF “PHARYNGEAL ARCHES”
 THEY APPEAR AT 4TH
– 5TH
WEEK OF DEVELOPMENT
 EACH PHARYNGEAL ARCH CONSISTS OF MESODERMAL CORE ,
COVERED ON OUTSIDE BY ECTODERMAL LAYER AND ON
INSIDE BY EPITHELIUM OF ENDODERMAL ORIGIN

 EACH OF THE FIVE ARCHES CONTAIN
1. A CENTRAL CARTILAGE THAT FORMS SKELETON OF
ARCH
2. MUSCULAR COMPONENT OR BRANCHIOMERE
3. VASCULAR COMPONENT
4. NEURAL ELEMENT
 MANDIBLE IS THE DERIVATIVE OF THE FIRST
PHARYNGEAL ARCH
 DORSAL PORTION IS KNOWN AS MAXILLARY PROCESS
 VENTRAL PORTION KNOWN AS MANDIBULAR PROCESS
OR MECKEL’S CARTILAGE
 DEVELOPMENT OF MANDIBLE STARTS AT 4TH
WEEK I.U.L
 CENTER OF FACE FORMED BY STOMODEUM,
SURROUNDED BY FIRST PAIR OF PHARYNGEAL ARCHESwww.indiandentalacademy.comwww.indiandentalacademy.com

4 ½ week embryowww.indiandentalacademy.comwww.indiandentalacademy.com

ROLE OF MECKEL’S CARTILAGE
DERIVED FROM FIRST PHARYNGEAL ARCH AROUND
41TH
– 45TH
DAY I.U.L
EXTENDS FROM OTIC CAPSULE -THE MIDLINE OR SYMPHYSIS
FIRST OSSIFICATION CENTER ARISES AT 6TH
WEEK I.U.L IN
THE REGION OF BIFURCATION OF THE INFERIOR ALVEOLAR
NERVE
THE CENTER IS LOCATED LATERAL TO THE MECKEL’S
CARTILAGE
FROM THIS “PRIMARY CENTER”- OSSIFICATION SPREADS
“BELOW AND AROUND” THE INFERIOR ALVEOLAR NERVE
AND THEN MOVES “UPWARDS”
OSSIFICATION THEN SPREADS “DORSALLY AND
VENTRALLY” TO FORM RAMUS AND THE BODY OF MANDIBLE
AS OSSIFICATION CONTINUES MECKEL’S CARTILAGE BECOMES
SURROUNDED BY BONE

REMANANTS OF MECKEL’S CARTILAGE:
MAJOR PART OF THE MECKEL’S CARTILAGE DISAPPEARS
DURING GROWTH
1. MENTAL OSSICLES
2. INCUS AND MALLEUS
3. SPINE OF SPHENOID
4. ANTERIOR LIGAMENT OF MALLEUS
5. SPHENOMANDIBULAR LIGAMENT

TYPES OF OSSIFICATION:
MANDIBLE IS THE SECOND BONE IN THE BODY TO BE
OSSIFIED
THERE ARE TWO TYPES OF OSSIFICATION :
1. INTRAMEMBRANOUS TYPE :
FORMATION OF BONE IS NOT PRECEDED BY FORMATION
OF CARTILAGENOUS MODEL
BONE IS DIRECTLY LAID INTO FIBROUS MEMBRANE
THERE IS CONDENSATION OF MESENCHYMAL CELLS
SOME CELLS FORM OSTEOBLAST AND SECRETE OSTEIOD
DEPOSITION OF CALCIUM SALTS INTO THE OSTEOID LEADS
TO CONVERSION OF OSTEOID INTO LAMELLA

2. CARTILAGENOUS TYPE:
FORMATION OF BONE IS PRECEDED BY FORMATION OF
CARTILAGENOUS MODEL
CONDENSATION OF MESENCHYMAL CELLS TO FORM
CHONDROBLASTS-- LAY DOWN HYALINE CARTILAGE
CARTILAGE IS SURROUNDED BY PERICHONDRIUM —
VASCULAR AND CONTAINS OSTEOGENIC CELLS
INTERCELLULAR CELLS SURROUNDING CARTILAGE CELLS
CALCIFY DUE TO THE ACTION OF ALKALINE PHOSPHATASE
NUTRITION TO THE CELLS IS CUT– LEADING TO DEATH---
FORMATION OF EMPTY SPACES— PRIMARY AREOLAE
BLOOD VESSELS AND OSTEOGENIC CELLS INVADE THE
CALCIFIED CARTILAGENOUS MATRIX WHICH IS NOW REDUCED
TO BARS OR WALLS– FORMATION OF LARGER SPACES----
SECONDARY AREOLAE

PARTS OF MANDIBLE DERIVED FROM
1. INTRAMEMBRANOUS OSSIFICATION
i) WHOLE BODY OF MANDIBLE EXCEPT THE ANTERIOR
PART
Ii) RAMUS OF MANDIBLE AS FAR AS MANDIBULAR
FORAMEN
2. ENDOCHONDRAL OSSIFICATION
i) ANTERIOR PORTION OF THE MANDIBLE (SYMPHYSIS)
ii) PART OF RAMUS ABOVE THE MANDIBULAR FORAMEN
Iii) CORONOID PROCESS
iv) CONDYLAR PROCESS

MECHANISMS OF BONE GROWTH
GROWTH OF THE MANDIBLE PRIMARILY INVOLVES
1. BONE REMODELLING
PROCESS OF BONE DEPOSITION AND RESORPTION
2. CORTICAL DRIFT
COMBINATION OF BONE DEPOSITION AND RESORPTION
RESULTING IN GROWTH MOVEMENT TOWARDS DEPOSITION
SURFACE
3. DISPLACEMENT
MOVEMENT OF WHOLE BONE AS A UNIT
i) PRIMARY DISPLACEMENT
ii) SECONDARY DISPLACEMENT

THEORIES OF GROWTH

OTHER THEORIES
ENLOW’S “V” PRINCIPLE
THE GROWTH AND ENLARGEMENT OF BONES OCCUR
TOWARDS WIDE END OF ‘V’ DUE TO DIFFERENTIAL
DEPOSITION AND RESORPTION
 ENLOW’S COUNTERPART PRINCIPLE
GROWTH OF ANY FACIAL OR CRANIAL PART RELATES
SPECIFICALLY TO OTHER STRUCTURAL AND GEOMETRIC
COUNTERPARTS

POST NATAL GROWTH AND DEVELOPMENT
GROWTH TIMING
 GROWTH OF WIDTH OF MANDIBLE IS COMPLETED FIRST,
THEN GROWTH IN LENGTH AND FINALLY GROWTH IN HEIGHT
WIDTH OF MANDIBLE
GROWTH IN WIDTH IS COMPLETED BEFORE ADOLESCENT
GROWTH SPURT
 INTERCANINE WIDTH DOES INCREASE AFTER 12 YEARS
BOTH MOLAR AND BICONDYLAR WIDTH SHOWS SMALL
INCREASE UNTIL GROWTH IN LENGTH ENDS
GROWTH IN LENGTH
GROWTH IN LENGTH CONTINUES THROUGH PUBERTY
GIRLS—14-15 YEARS
BOYS---18-19 YEARS www.indiandentalacademy.comwww.indiandentalacademy.com

GROWTH IN HEIGHT
CONTINUES IN BOTH THE SEXES FOR LONGER PERIOD
GROWTH INCREASE OCCURS WITH CONCOMITANT ERUPTION
OF TEETH AND CONTINUES TO INCREASE THROUGH OUT LIFE
AND DECREASES IN ADULT LIFE

1. RAMUS OF MANDIBLE
 RAMUS MOVES PROGRESSIVELY POSTERIOR BY A
COMBINATION OF DEPOSITION AND RESORPTION
 RESORPTION OCCURS ON THE ANTERIOR PART AND THE
DEPOSITION OCCURS ON THE POSTERIOR PART---DRIFT

2. BODY OF THE MANDIBLE
 THE INCREASE IN WIDTH OF THE MANDIBLE OCCURS
PRIMARILY DUE TO RESORPTION ON THE INSIDE AND
DEPOSITION ON THE OUTSIDE
INCREASE IN LENGTH OCCURSS DUE TO DRIFT OF THE
RAMUS POSTERIORLY
INCREASE IN HEIGTH OCCURS CUE TO ERUPTION OF THE
TEETH

3. ANGLE OF THE MANDIBLE
ON THE LINGUAL SIDE, RESORPTION TAKES PLACE ON THE
POSTEROINFERIOR ASPECT,WHILE DEPOSITION OCCURS ON
THE ANTEROSUPERIOR ASPECT
ON THE BUCCAL SIDE ,RESORPTION OCCURS ON
ANTEROSUPERIOR PART WHILE RESORPTION OCCURS ON
POSTEROINFERIOR

4. ALVEOLAR PROCESS
DEVELOPS IN RESPONSE TO PRESENCE OF TOOTH BUDS
IT INCREASES IN HEIGHT AS THE TEETH ERUPTS
THIS INCREASES THE HEIGTH AND THICKNESS OF THE BODY OF
MANDIBLE
5.CHIN
PROMINENCE OF THE MENTAL PROTRUBERANCE IS ACCENTUATED
BY BONE RESORPTION THAT OCCURS ABOVE THE ALVEOLAR
PROCESS—CREATING A CONCAVITY

6.CONDYLE
IT HAS BEEN RECOGNISED AS AN IMPORTANT GROWTH SITE
THERE ARE TWO SCHOOLS OF THOUGHT
i) GROWTH AT THE CONDYLE PUSHES IT TOWARDS THE
CRANIAL BASE, THIS LEADS TO DISPLACEMENT OF THE
MANDIBLE “FORWARDS AND DOWNWARDS”
RAYMOND.C.BERNABEI AND LYSLE.E.JOHNSTON (1978) FOUND THAT
CONDYLAR CARTILAGE IS NEEDED FOR NORMAL GROWTH
ii) IT IS NOW BELIEVED THAT GROWTH OF SOFT TISSUES
SURROUNDING THE MANDIBLE CARRIES IT AWAY FROM THE
CRANIAL BASE AND GROWTH OCCURS AT CONDYLE TO
MAINTAIN CONSTANT CONTACT
ROSARIO.BERRAQUERO et al (1992) FOUND THAT CONDYLAR CARTILAGE IS
A SECONDARY GROWTH CENTER AND NOT A PRIMARY GROWTH CENTER

RONNING.O OBSERVED THAT THERE WAS NO GROWTH OF THE CONDYLAR
CARTILAGE AFTER INTRACEREBRAL IMPLANTATION
JANSEN.H.W AND DUTERLOO.H.S (1986) STATED THAT CONDYLAR CARTILAGE
SHOWED SIGNIFICANTLY LESS GROWTH THAN OTHERS, SO THE CONDYLE DOES
NOT ACT AS A GROWTH CENTER

7. CORONOID PROCESS
IT FOLLOWS ENLARGING “V PRINCIPLE”
IN LONGITUDINAL SECTION, DEPOSITION OCCURS ON
LINGUAL SIDE OF BOTH LEFT AND RIGHT CORONOID
PROCESS
GENERAL GROWTH IS “POSTERIORLY,SUPERIORLY AND
MEDIALLY”

GROWTH ROTATION
i) REMODELLING
ii) DISPLACEMENT
THE RAMUS UNDERGOES REMODELLING ROTATION
TO DECREASE THE GONIAL ANGLE---THIS PRODUCES
DISPLACEMENT ROTATION OF THE MANDIBLE AS A
WHOLE

 BJORK AND COWORKERS DESCRIBED TWO TYPES
 1. INTERNAL ROTATION
ROTATION THAT OCCURS AROUND THE CORE OF THE
MANDIBLE THAT SURROUNDS THE INFERIOR ALVEOLAR
NERVE
i) MATRIX ROTATION– ROTATION AROUND THE CONDYLE
ii) INTRAMATRIX ROTATION— ROTATION AROUND THE BODY
 2. EXTERNAL ROTATION
SURFACE CHANGES DUE TO RESORPTION AND
DEPOSITION

OVERALL CHANGES IN ORIENTATION OF JAW RESULTS
FROM THE COMBINATION OF INTERNAL AND EXTERNAL
ROTATION
THE CORE OF MANDIBLE DURING GROWTH ROTATES IN
SUCH A WAY THAT TENDS TO DECREASE THE MANDIBULAR
PLANE ANGLE i.e UP ANTERIORLY AND DOWN POSTERIORLY

THE ROTATION IS CONSIDERED “FORWARD” IF GROWTH IS
MORE POSTERIORLY THAN ANTERIORLY
THE ROTATION IS “BACKWARD” IF ANTERIOR GROWTH IS
MORE THAN POSTERIOR
INDIVIDUALS OF “SHORT FACE” TYPE HAVE EXCESSIVE
FORWARD GROWTH OF MANDIBLE. THEY HAVE DECREASED
MANDIBULAR AND GONIAL PLANE ANGLE– SQUARE JAW
“LONG FACE” INDIVIDUALS HAVE EXCESSIVE BACKWARD
ROTATION OF MANDIBLE AND HAVE INCREASED MANDIBULAR
PLANE ANGLE
IN GENERAL, MALES HAVE SLIGHT FORWARD GROWTH AND
DECREASED MANDIBULAR PLANE ANGLE
 FEMALES HAVE SLIGHT BACKWARD ROTATION OF
MANDIBLE AND INCREASED MANDIBULAR PLANE ANGLE

FACTORS AFFECTING GROWTH
A) SYSTEMIC FACTORS
1. GENETIC
2. HORMONAL IMBALANCE
3. NUTRITION
4. SYSTEMIC ILLNESS OR CHRONIC ILLNESS
5. LOCALISED ALTERATION/ DISEASES OF UTERUS
6. SYSTEMIC ILLNESS IN MOTHER
7. DRUGS

B) LOCAL FACTORS
1. VASCULAR ABNORMALITY
2. LYMPHATIC DISTURBANCE
3. NEUROLOGIC DISEASE
4. LOCAL INFECTION
5. EAR INFECTION OR MASTOIDITIS
6. ANKYLOSIS
7. TRAUMA OR FRACTURE
8. BIRTH INJURY
9. HABITS

ANOMALIES OF MANDIBLE
 SOME OF THE SYNDROMES ASSOCIATED WITH
MANDIBULAR ABNORMALITY
i) DOWN’S SYNDROME
ii) MARFAN SYNDROME
iii) TURNER SYNDROME
iv) KLINFELTER SYNDROME
v) PIERRE-ROBIN SYNDROME
vi) TREACHER- COLLINS SYNDROME

1. CONGENITAL
i) AGNATHIA
ii) MICROGNATHIA
iii) MACROGNATHIA
iv) FACIAL HEMIHYPERTROPHY
v) FACIAL HEMIATROPY
2. DEVELOPMENTAL
i) INFANTILE CORTICAL HYPEROSTOSIS
ii) ACHONDROPLASIA
iii) TORUS MANDIBULARIS
iv) STAFNE’S CYST
v) ODONTOGENIC CYST
vi) ODONTOGENIC TUMOURwww.indiandentalacademy.comwww.indiandentalacademy.com

ROBERT. CANTOR AND THOMAS. CURTIS BASED ON THE AMOUNT
OF RESECTION OF THE MANDIBLE DEFINED SIX POSTSURGICAL
ANATOMIC CATEGORIES
 CLASS I; RADICAL ALVEOLECTOMY WITH PRESERVATION OF THE
MANDIBULAR CONTINUITY

CLASS II: LATERAL RESECTION OF THE MANDIBLE DISTAL TO
THE CUSPID

CLASS III: LATERAL RESECTION OF THE MANDIBLE TO THE
MIDLINE

CLASS IV: LATERAL BONE GRAFT SURGICAL
RECONSTUCTION

CLASS V: ANTERIOR BONE GRAFT SURGICAL
RECONSTRUCTION
 CLASS VI: RESECTION OF ANTERIOR PORTION WITHOUT
RECONSTRUCTION

AGE CHANGES OF THE MANDIBLE

SUMMARY
MANDIBLE DEVELOPS FROM FIRST PHARYNGEAL ARCH
SEVERAL CHANGES OCCUR IN THE MANDIBLE DURING THE
DEVELOPMENTAL PERIOD
ANY DISTURBANCE DURING THE NORMAL GROWTH OF THE
MANDIBLE REFLECTS AS A ANOMALY

REFERENCES:
 Langman’s medical embryology – T.W. Sadler, 5th Edition.
 Oral histology, development, structure and function – A.R. Ten Cate,
4th Edition
 The essentials of facial growth – Enlow and Hans, 1st Edition.
 Contemporary Orthodontics – William R. Proffit.
 Textbook of Pedodontics –Shobha Tandon
 Textbook of oral pathology– William Shafer, 4th
Edition
 Handbook of Osteology – S.Poddar,8th
Edition
 Growth in situ of isolated mandibular segments.
Raymond.c.Bernabei AJO-1978;73-74;24-35
 Role of condylar cartilage in mandibular growth-Rosario. Berraquero
et al AJO-1992;102;220-6www.indiandentalacademy.comwww.indiandentalacademy.com

The development of mandible / dental crown & bridge courses

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