-Presented by- Himanshu gorawat

“Prenatal and postnatal growth & development of maxilla and palate”

Content-• Introduction• Growth• Development• Importance of growth • Prenatal growth & development of maxilla• Prenatal growth & development of palate• Postnatal growth & development of maxilla• Postnatal growth & development of palate

INTRODUCTIONGrowth and development of an individual can be divided into pre-

natal and the post-natal periods. Pre-natal period of development

is a dynamic phase in the development of a human being.

GROWTH •Stewart – It may be defined as a developmental increase in mass.

In other words it is a process that leads to an increase in the physical

size of cells, tissues, organs or organisms as a whole.

•Proffit – an increase in size or number.

•Pinkham – an increase, expansion or extension

of a given tissue.

DEVELOPMENT•Moyers – all the naturally occurring unidirectional

changes in the life of an individual from its existence

as a single cell to its elaboration as a multifunctional

unit terminating in death.

•Todd – development means progress towards

maturity.

•Proffit – development is in complexity.

IMPORTANCE OF GROWTH• Indicator of general health.

• Identify unusual growth patterns at an early stage.

• Etiology and development of malocclusion.

• Identify abnormal occlusion – early stage.

• Poorly timed extractions – malocclusion.

• Growth - effects stability of occlusion.

• Use of growth spurts.

Prenatal development of maxilla

Pharyngeal arch

• During 4th week, lateral plate mesoderm of ventral foregut segments to form 5 bilateral mesenchyme swellings– pharyngeal arches

Each PHARYNGEAL ARCH consists of

Central cartilage rodMuscular componentVascular componentNervous element

• Around fourth week of intra uterine life a prominent bulge appears on ventral aspect of the embryo corresponding to the developing brain. Below the bulge the shallow depression , which corresponds to the primitive mouth appears called stomatodeum .

• Floor of stomatodeum is formed by buccopharyngeal membrane, which separates it form forgut.

• mesoderm covering the developing forebrain proliferates, and forms a downward projection that overlaps the upper part of the stomatodeum this downward projection is called the frontonasal process .

• The first branchial arch is called the mandibular arch and plays an important role in the development of the naso maxillary region.

• At this stage each mandibular arch forms the lateral wall of the stomatodeum . This arch gives off a bud from its dorsal end . This bud is called the maxillary process . It grows ventro- medially cranial to the main part of the arch which is now called mandibular process

• The ectoderm overlying the Fronto-nasal Process shows bilateral

localized thickenings above the stomatodeum. These are called the

Nasal Placodes.

• These Placodes soon sink and form the Nasal Pits.• Medial raised edge is called medial nasal process and lateral edge

is called the lateral nasal process.

• Each maxillary process now grows medially and fuses , first with the lateral nasal process and then with the medial nasal process .

• Medial and lateral process also fuse with each other in this way the nasal pit(external nares) are cut off from the stomatodeum .

• As the Maxillary Process undergoes growth the Fronto-nasal process becomes narrow so that the two Nasal Pits come closer.

• Mesodermal basis of the median part of the lip(called philtrum)is formed from the frontonasal process.

Development of nasal cavity- • Nasal cavity are formed by extension of nasal pits .soon the medial

and lateral processes fuse , and form a partition between the pit and the stomatodeum this is called primitive palate and is derived from the frontonasal process.

• The nasal pits now deepen to form the nasal sac . The dorsal part of this sac is , at first , separated from the stomatodeum by thin membrane called the bucconasal membrane or nasal fin this soon breaks down nasal sac now has a ventral orifice that opens on the face (anterior or external nares) and dorsal orifice that open into stomatodeum(primitive posterior nasal aperture)

• Frontonasal process becomes progressively narrower . This narrowing of the frontonasal process and the enlargement of the nasal cavities themselves being closer together the intervening tissue becomes much thinned to form the nasal septum ventrally attached to below the primitive palate and dorsally bucconasal membrane.

Prenatal development of palate

• The palate is formed by contributions of the-I. Maxillary process II. Palatal shelves given off by the maxillary process III. Fronto nasal process • The frontonasal process gives rise to the premaxillary region while the

palatal shelves grows medially , their union is prevented by the presence of the tongue, thus initially the developing palatal shelves grow vertically downward the floor of the mouth

• Sometimes during the seventh week of intrauterine life, a transformation in the position of the palatal shelves occurs. They change from a vertical to horizontal position.

• This transformation is believed to take place within hours.

• Withdrawal of the embryonic face from against the heart prominence results

in slight jaw opening this results in slight withdrawal of the tongue from

between the palatal shelves and aids in elevation of the palatal shelves from a

vertical to a horizontal position

6th week– 2 lateral palatal shelves develop

Secondary nasal septum grows

7th week– palatal shelves grow & lie vertically

8th week

Stomatodeum enlarges

Tongue drops

Vertically inclined palatal shelves become

horizontal

Shelves contact each other in midline– forms

sec. palate

By 12th week, fusion of palatal processes is

complete

• The two palatal shelves by 8 ½ weeks of IU life are in close approximation with each other initially the two palatal shelves are covered by an epi. Lining . The connective tissue of the palatal shelves intermingle with each other resulting in their fusion.

• The entire palate doesn't fuse at same time • The mesial edge of the palatal processes fuse with the free lower

end of nasal septum and thus separates the two nasal cavities from each other and the oral cavity .

-Ossification-• Occurs from the 8th week of IU life. • Intramembranous type of ossification • The palatal ossifies from single centre derived from the maxilla• The most posterior part of the palate doesn't ossify this form soft

palate • The mid palatal suture ossifies by 12 – 14 years

Postnatal development of maxilla

• The growth of the naso-maxillary complex is produced by following mechanism-

I. DisplacementII. Growth at suturesIII. Surface remodeling

• Displacement – – It is the movement of whole bone as a unit.

Displacement

Primary

Secondary

Primary Displacement – When the bone gets displaced as a result of its own growth.

Secondary Displacement -If a bone gets displaced as a result of growth and enlargement of an adjacent bone.

Growth at sutures- • It is a complex system of sutures through which all the bones are in contact.

GROWTH AT SUTURE

• The maxilla is connected to the cranium and the cranial base by a number of sutures.

• These sutures include :

• a. Fronto - nasal suture.

• b. Fronto – maxillary suture.

• c. Zygomatico – maxillary suture.

• d. Pterygo – palatine suture.

• e. Zygomatico – temporal suture

• these sutures are all oblique and more or less parallel to each other. This allows the downward and forward positioning of the maxilla as growth occurs at this sutures.

• As the growth of the soft tissue occurs, the maxilla is carried downward and forward. This leads to opening up of space at the sutural attachments. New bone is formed on either side of the suture.

• Thus overall size of the bones increases on either side. Hence a tension related bone formation occurs at the sutures.

Surface remodeling-

• In addition to the growth occurring at the sutures , massive remodeling by bone deposition and resorption occurs to bring about –

I. Increase in sizeII. Change in shape of bone III. Change in functional relationship

• The following are the bone remodeling changes that are seen in the naso-maxillary complex-

1. Bone deposition occur along the posterior margin of the maxillary tuberosity they cause lengthening of dental arch and enlargement of antero – posterior dimension of the entire maxillary body this help to accommodate the erupting molars

2. Bone Resorption occurs on lateral wall of the nose leading to increase the size of nasal cavity.

3. Bone Resorption is seen on floor of nasal cavity to compensate deposition on palatal side thus net downward shift occurs leading to increase in maxillary height .

4. As the teeth start erupting bone deposition occurs at the alveolar margin increase maxillary height and depth of palate.

5. Entire wall of the sinus expect mesial wall undergoes Resorption this results in increases in size of the maxillary antrum

PALATE

• At birth breadth is equal to length.

• The post natal increase in length is by appositional growth in

maxillary tuberosity region and transverse maxillary-palatine

suture.

• Increase in width of palate is by midpalatal sutural growth and

appositional growth along lateral alveolar margins.

• Growth at the mid-palatal suture ceases at 1-2 years of age.

• Growth in the width of the suture is larger in its posterior part

than in its anterior part.

• Obliteration of growth starts in adolescence, but complete

fusion occurs usually till age of 20 years.

• Lateral appositional growth continues till 7

years of age, by this time palate reaches its

ultimate anterior width.

• Posterior appositional growth continues after

cesation of lateral appositional growth,

resulting in lengthening of palate.

The appositional

growth of alveolar

processes contributes

to deepening and

widening of palate.

DISPLACEMENT OF THE PALATE

• Bone Resorption occurs on the nasal side and deposition

occurs on the oral side thus displacing the palate in a

downward and forward direction.

Reference -

• Human embryology -7th edition – inderbir singh• Ten cate’s Oral Histology – 6th edition • Textbook Of Craniofacial Growth : MOYERS• Orthodontics art and science – S.I. BHALAJHI