bone growth in oral physiology

8/12/2019 Bone Growth in Oral Physiology

http://slidepdf.com/reader/full/bone-growth-in-oral-physiology 1/51

Bone Growth

Presented to you by

Armil O. Purificacion



Bone ResorptionOsteoclasts resorb bone

How?1. Anchor themselves to surface

of bone

2. Create a sealed zone andwithin zone create acidic

environment which dissolve

mineral content from bone

3. Enzymes are released fromosteoclasts which remove

collagenous bone matrix



Bone Formationn

-Some active osteoblast get trapped in the matrix they

secrete and become osteocytes

-other osteocytes will undergo apoptosis or revert back

to lining cells which cover surface of bone



Bone formation by osteoblast

Bone modelingBone formation by osteoblast occur without prior bone

resorption by osteoclast

- Increase in bone mass

- Important for maintaining bone strength

- Optimizing growing structure

- After age 30, most people experience gradual loss ofbone mass due to relative decrease of osteoblast

compared with osteoclast



Growth Development of the

Maxilla



• Forms within maxillary prominences extending

ventrally from dorsal aspect

• Ossification of maxilla begins slightly later than in

mandible

Development of the Maxilla



• Palatogenesis begins towards endof 5th week

• Completed by 12th week

• Palate develops from 2 primordia*

• Primary Palate

• Secondary Palate

Development of the Palate

Primordia –

An organ at its earliest stageof development



• Primary Plate

• Finishes at 5th week

• Develops from deep part of intermaxillary segment

of maxilla

• Internal merging of medial nasal prominences

• Represents only small part of adult hard palate

• Secondary Plate• Primordium of hard/solft palate posterior to incisive

forament

• Begins to develop in 6th

week, from shelf likestructure called Lateral Palatine Process



• The processes fuse in midline w/ Nasal Septum and

posterior part of Primary Plate

• Palate begins anteriorly during 9th week and

completed posteriorly by 12th week

• Posterior part of palatal process remains unossified



Post Natal Growth of Maxilla



Growth movements

1. Drift: movement of bone surface cauesd by deposition and

resorption towards depository surface. AKA

Transformation

2. Displacement: growth of bone as whole unit, so that bone

is taken away from its articulation w/ other bones. AKA

Translation

1. Primary/Active Displacement: movementn due to

growth of bone itself

2. Secondary Displacement: movement of one bone due

to growth of other bones.



• Maxillae articulates w/ surrounding bone with help of

sutures:

1. Zygomaticomaxillary

2. Frontomaxillary

3. Pterygopalatine

4. Zygomaticotemporal

• Growth at these paired parallel sutures will move

maxilla Downward and Forward



Translation

• Process by which specific local areas come to occupynew positions as entire bone enlarges

• Active: growth at tuberosity of maxilla pushes maxilla

forward

• Passive: when maxilla grows downward and forward

by spheno-occipital synchondrosis

• When maxillary bone is translated in space by growthof corresponding capsular matricdes

• Capsules (3): Orbital, nasal and oral capsule



Remodeling

• Simultaneous resorption and deposition moves surfaces of

maxilla while maintaining integrity and shape of bone



Maxillary Growth

• Matures first in

• Width

• Depth

• Length



Maxillary Width

• Nasal Cavity

• Faces anterior, lateral and superior direction

• Growth proceeds in same direction

• Surface removal: periostium lining inner aspect of nasalcavity

• Deposition: enndosteal surface, allows expansion of cavity

• Orbital Part of Maxilla

• Orbital floor faces laterally, anteriorly and superiorly• Growth proceeds in same direction by deposition and

resorption on lateral surface of orbital rim



Anteroposterior/Depth

• Zygomatic Bone• Moves: posteriorly and laterally

• Deposition in posterior and lateral surface

• Resporption in medial surface• In anteroposterior direction: appositional growth I

posterior tuberosity area, for space for permanent

teeth

• Zygomatic bone moves in posterior direction tokeep its relation w/ maxilla, via resorption in

anterior surface and deposition I posterior surface



Maxillary Height

• Maxillary bones increase I height by apposition along alveolar

processes

• Increase is seen as long as teeth erupt

• Resorption along nasal floor

• Deposition along palatal roof



Growth of the Mandible

M dibl i th l bl b f ll b i



• Mandible is the only movable bone of all bones in

face

• Horeshoe shaped w/ the followings parts

1. Body of mandible

2. Ramus

3. Codnylar process

4. Coronoid Process5. Alveolar Process

Condylar Process



G th D l t f th



Growth Develpmt of the

Mandible- Primary cartilage of 1st Pharyngeal arch is the

Meckel’s cartilage, helps in formation of lower jaw



Meckel’s Cartilage

- Meckel’s cartilage appears at 6th week of IUL

- Provides template for development of mandible

G th D l t f th



Growth Development of the

Mandible- Ossification starts at the division of mental and

incisive branch of inferior alveolar nerve lateral to

Meckel’s cartilage around 6th week IUL

- Fate of Meckel’s Cartilage- Greater part of Meckel’s cartilage degenerate w/o

contributing formation of mandible by 24th week

D l f h M dibl



Development of the Mandible

• 5th week of IUL: mandibular process of both sides

approach easchother and are fused• Meckel’s cartilage extends from area of future ear to

midline of fused mandibular processes

• 6th week: cartilaginous rods begin chondrifying

(change into cartilage), rods support forming skeletal

framework of mandible

• Part of mandible mesial to mental foramen:

Endochondral ossification• Lateral to foramen undergoes intramembranous

ossification



Development of the Mandible

• 10th week: formation of condylar process begins

• 14th week: Ossification begins except region of tip of

head of condyle superiorly. Maintained till teens for

future growth• Once condyle finished: TMJ jointt is shifted anteriorly

• 16th week: ossification of ramus

• 7th

month of IUL: 1 or 2 cartilaginous fragments inregion of mental foramen ossify and fuse w/ bone

• Failure of fusion of both mandibular process from

both sides leads to Midline cleft



Postnatal Growth of Mandible

• At Birth

• Ramus short horizontal & w/ obtuse gonial angle

• Angle of mandible – obtuse around 140 degrees+

• Condyles: low, at position of occlusal plane



Mandibular Growth in the 1st Year

• Growth at symphyseal suture

• Lateral expansion of anterior region to

accommodate erupting anterior teeth

• Suited for suckling activity since condyle

and glenoid fossa is flat

• Helps in anteroposterior movement of

mandible



Mandible in the Adult

• Ramus: longer• Gonial Angle: Less obtuse

• Bone is larger on the whole

• Condyle: is well-developed- Condylar growth rate increases at

puberty

- Peaks between 12 to 14yrs of age

- Normally ceases about 20 years

of age



V-Principle of Growth in Mandible

All these changes take place w/ the growth of the

mandible in the form of an expanding V

Al l P



Alveolar Process

- Alveolar growth occurs around tooth buds

- As teeth develops & begins to erupt, alveolar

process inncreases in size and height

- Continnued growth of alveolar bone increases height

of mandibular body

- Alveolar process grows

Upwards and outwards

On expanding arch-Permits dental arch to

Accommodate larger

Permanennt teeth



Length of the Mandible

• Anteroposterior growth: deposition at posterior surface of

ramus

• Resorption of the leading edge anterior surface

• Helps lengthen mandible so anterior part of the ramus is

occupied by posterior part of body in future and to

accommodate the developing permanent molars



Length of the Mandible

• As mandible grows posteriorly, it’s displaced anteriorly

• Articulation of the condyle to the glenoid fossa is

constant, and change in length can only take place by

anterior displacement



Width of the Mandible

• Deposition, lateral surface of ramus

• Resorption, lingual surface below mylohyoid

ridge

• Coronoid pprocess, undergoes apposition atmedial surface, and resorption at lateral

surface. This expands mandible like a V

• Condyle undergoes reduction on lateral aspect

of neck, deposition corresponding to the V

makes condyle longer at neck



Height of the Mandible

• Alveolar process height corelate well w/ eruption of teeth

• Bone deposition taking place in lower border of mandible also

contribute to increase in height of mandible



Thumb Sucking

• Thumb Sucking: Placing the thumb into variousdepths into the mouth

• Commonly seen habits

• Observed in intrauterine life• Sucking- 1st co-coordinated muscular activity in

the infant



Thumb Sucking

• Normal TS

• 1st & 2nd Year of Life

• DON’T GENERATE ANY MAOCCLUSION

• Abnormal TS

• Can cause malocclusion



Thumb Sucking



Mouth Breathing



• Mouth breather usually has lips open most of

the time

• Causes facial development narrow and long



• tongue usually presses forward between teeth which

do not contact when swallowing

• Tongue action prevents arch development

• Narrow V-shaped upper arch w/ crowding is result



• Class II Division 1 w/ open bite is created by action of

tongue

• Class II: Distocclusion (retrognathism, overjet) In this situation,

the upper molars are placed not in the mesiobuccal groove butanteriorly to it. Usually the mesiobuccal cusp rests in between

the first mandibular molars and second premolars. There are

two subtypes:

• Class II Division 1: The molar

relationships are like that of

Class II and the anterior teeth

are protruded.



• Backward movemtn when swallowing compreses

TMJ causing TMJ problems



References

• Prep Manual for Undergraduates:

orthodonticsc, Premkumar, Sridhar. 2008

Elsevier

• http://www.slideshare.net/dr_abi/growth-

development-of-maxilla-and-mandible

• http://orthocj.com/2009/06/a-camouflage-

treatment-of-class-ii-division-malocclusion/

http://www.slideshare.net/dr_abi/growth-development-of-maxilla-and-mandible


http://orthocj.com/2009/06/a-camouflage-treatment-of-class-ii-division-malocclusion/





























bone growth in oral physiology

Documents