Growth & development of face/certified fixed orthodontic courses by Indian dental academy

CONTENTSCONTENTS INTRODUCTION EARLY EMBRYONIC DEVELOPMENT DEVELOPMENT OF FACE DEVELOPMENT OF BRANCHIAL ARCHES DEVELOPMENTAL ANOMALIES AND

CRANIOFACIAL ANOMALIES OF GENETIC ORIGIN GROWTH OF FACE ANATOMY OF FACE PROSTHODONTIC CONSIDERATIONS SUMMARY AND CONCLUSION REFERENCES

INDIAN DENTAL ACADEMYLeader in continuing Dental Education

www.indiandentalacademy.com

“A KNOWLEDGE OF DEVELOPMENT IS A PRECIOUS KEY TO A GRASP OF THE ANATOMICAL FINISHED PRODUCTS. ALTHOUGH THIS PRINCIPLE HOLDS FOR ALL PARTS OF THE BODY ,IT IS PROBABLY TRUE TO SAY THAT IT IS MOST VALID FOR THE HEAD AND NECK.”


INTRODUCTIONINTRODUCTION

An individual spends 9 months/ 38 weeks/266 days or nearly 383040minutes of his life in his mother’s womb. Human development is a continuous process and does not stop at birth.

Anatomical structures are more diverse in the mouth than in any other region.


The development of the dentofacial complex is dependent primarily upon the following:

1. Genetic endowment.

2. Environmental factors.

3. Functional forces.


DEFINITION OF DEFINITION OF DEVELOPEMENTDEVELOPEMENT

•Development refers to all the naturally occuring unidirectional changes in the life of an individual from its existence as a single cell to its elobaration as a multifunctional unit terminating in death. Thus it encompasses the normal sequential events between fertilization and death.


EARLY EMBRYONIC DEVELOPMENTEARLY EMBRYONIC DEVELOPMENT

a) Preimplantation period (first 7 days).

b) Embryonic period (next 7 weeks).

c) Fetal period (next 7 months).


PREIMPLANTAION PERIODPREIMPLANTAION PERIOD



PERIOD OF EMBRYOPERIOD OF EMBRYO

It’s divided into 3 periods they are:

1) PRESOMITE(8-21days)

2) SOMITE(21-31days)

3) POSTSOMITE(32-56days)


FORMATION OF GERM LAYERSFORMATION OF GERM LAYERS

There are three germ layers in the human embryo:

•Ectoderm

•Endoderm

•Mesoderm




Primitive streak


Primitive streak showing migration of the cells(mesodermal)



Fetal periodFetal period

Last 7 months of fetal life are devoted to very rapid growth and repositioning of body components, with little further organogenesis or tissue differentiation.

- By 3rd month sex of fetus is known- 4 months human face is seen - Last 2 months of fetal life fat is deposited

subcutaneously.


FORMATION OF PHARYNGEAL ARCHES

Pharyngeal archeswww.indiandentalacademy.com

DEVELOPMENT OF BRANCHIAL DEVELOPMENT OF BRANCHIAL ARCHESARCHES

During the 4th week of i.u. the mesoderm of foregut region becomes segmented to form a series of five distinct bilateral mesenchymal swellings the branchial arches.

The neural crest tissue surrounds the mesodermal core.

Skeletal and connective tissue muscle myoblast



• Cartilage component :

Adapt to form Bony, Cartilagenous or Ligamentous structures

• Muscle component :

Give rise to special visceral muscles composed of straited muscle fibers.

• Vascular component :

Provides necessary blood supply

Branchial arches


• Enter mesoderm of branchial arches

• Initiate muscle development in the mesoderm

• Nerve component

Branchial arches


1st BRANCHIAL ARCH

(Mandibular arch)

Branchial arches

• Precursor of both the jaws:

Maxilla + Mandible

• Initially gives rise to a large mandibular prominence.

• Gives rise to a small maxillary prominence which extends cranioventrally

Maxillawww.indiandentalacademy.com


COMPONENTS OF 1st ARCH

Cartilage : MECKEL’S CARTILAGE

--Arises 41st – 45th Day I.U

--It provides a template for subsequent development of the mandible.

Branchial arches


Derivatives of Meckel’s Cartilage

-- Mental Ossicle (Endochondral Oss.)

-- Head and neck of Malleus.

-- Short crus of the Incus.

-- Ant. Ligament of the Malleus.

-- Sphenomandibular Ligament

Branchial arches


2. Musculature Derived from 1st arch:

-- Muscles of Mastication.

-- Mylohyoid Muscle.

-- Ant. Belly of Digastric.

-- Tensor Tympani.

-- Tensor Veli Palatini Muscles.

3. Arterial Component:

-- Part of Maxillary and Ext.Carotid.Art

Branchial arches


4. Nerve components:

-- Mandibular division of Trigeminal.N

( Vth Cranial Nerve)

-- Sensory component supplies

: Mandible and covering mucosa.

: Mandibular teeth including Gingiva.

: Mucosa of ant. 2/3 of Tongue.

: Floor of the mouth.

: Skin of the lower third of Face

Branchial arches


22ndnd BRANCHIAL ARCH BRANCHIAL ARCH (Hyoid Arch)

•Components: 1. Cartilage : Reichert’s Cartilage

(45th – 48th I.U)

-- Greater part of the third ear ossicle.

-- Stapes .

-- Styloid process of the temporal bone.

-- Stylohyoid ligament.

-- Lesser horn and

-- Cranial part - Body of Hyoid.

-- Segments of the facial canal.

Branchial arches


2. Muscles :

-- Stapedius

-- Stylohyoid

-- Post. Belly of Digastric.

-- Muscles of facial expression.

-- Levator Veli Palatini.

Branchial arches


3. Nerve :

-- Facial / VII Cranial nerve.

-- Special sensory component

- Chorda tympani nerve

(Ant 2/3rd of Tongue)

4. Artery :

-- Stapedial artery

- Transient i.e. disappears during fetal life.

Branchial arches



•Pharyngeal arch I •Cranial nerve - Maxillary and mandibular division of trigeminal nerve (cranial nerve V) •Artery - Maxillary (terminal branch) •Muscles - Muscles of mastication (ie, temporalis, masseter, pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini •Skeleton - Maxillary cartilage (incus, alisphenoid), mandibular or Meckel cartilage (malleus), arch dermal mesenchyme (maxilla, zygomatic, squamous portion of temporal bone, mandible)

A summary of the derivatives of the first and second pharyngeal (ie, branchial) arches is as follows:


•Pharyngeal arch II (hyoid) •Facial nerve - Cranial nerve VII •Artery - Stapedial •Muscles - Muscles of facial expression (ie, orbicularis oculi, orbicularis oris, risorius, buccinator, platysma, auricularis, frontalis), stapedius muscle, posterior belly of digastric, stylohyoid muscle •Skeleton - Stapes, styloid process, stylohyoid ligament, lesser cornu of hyoid, upper part of the body of the hyoid bone


Anomalies associated with branchial arches

•Deficient development of the branchial arches result in syndromes according to the arch involved.

•First arch anomalies

- Agnathia

- Microstomia

- Treacher Collins syndrome (mandibular dysostosis)

- Pierre Robin syndrome (micrognathia+cleft palate)

Branchial arches


Pharyngeal pouches and branchial Pharyngeal pouches and branchial groovesgrooves

Primitive pharynx project a series of pouches internally between the branchial arches called pharyngeal pouches.

Intervening between the branchial arches externally are branchial grooves


First branchial groove deepens to form the external acoustic meatus and the membrane in the depth of groove forms the tympanic membrane.

3rd and 4th branchial groove may form cervical sinus.

Failure to obliterate completely these grooves may result in branchial fistula or sinus.


1st pharyngeal pouch Ventral portion obliterated by the developing

tongue. Dorsal portion deepens as tubotympanic recess to

form auditory tube.2nd pharyngeal pouch Forms tonsillar fossa and palatine tonsil.3rd pharyngeal pouch Forms thymus and inferior parathyroid gland.4th pharyngeal pouch Forms superior parathyroid gland.5th pharyngeal pouch Forms the ultimobrachial bodyCommon anomaly is DiGeorge Syndromewww.indiandentalacademy.com

DEVELOPMENT OF FACEDEVELOPMENT OF FACE

Development of face depends upon the inductive activities of organizing centres

Procencephalic Rhombencephalic

Induces the inner ear apparatus and upper third of face

Induces the middle and external ear apparatus and the middle and lower third of face



Oral development in embryo is demarcated extremely early in life by the appearance of the prechordal plate

with

Endodermal Thickening forms

Oropharyngeal Membrane



Face develops from 5 prominences that surround the stomatodeum

- Frontonasal- Paired maxillary processes.- Paired mandibular processes.


Frontonasal prominence formed by proliferation of mesenchyme ventral to the forebrain. It forms

- Lateral optic diverticula eyes - Forehead (between the eyes)- Nasal placodes


Mesenchyme proliferates around the placodes producing medial and lateral nasal prominences

Lateral nasal prominence separated from maxillary process by nasolacrimal groove



Fusion of medial nasal prominences and the maxillary and lateral nasal prominences requires disintegration of nasal fin.

Failure of normal disintegration of nasal fin cause cleft of upper lip and anterior palate.


Midline merging of medial nasal processMidline merging of medial nasal process

Forms:- Philtrum of upper lip.- Tip of the nose.- Primary palate.

Merging of medial nasal and maxillary Merging of medial nasal and maxillary processprocess

Continuity of the upper jaw and lip.Causes separation of nasal pits from stomodeum



Merging of mandibular process in midlineMerging of mandibular process in midline

Forms lower jaws and lips



DEVELOPMENT OF NOSEDEVELOPMENT OF NOSE

The nose is a complex of contributions from:

- Frontal prominence The bridge.

- Medial nasal prominence Median ridge and tip

- Lateral nasal prominence The alae

- The cartilage of nasal capsule the septum and nasal conchae



A summary of the derivatives of the prominences is as follows: •Frontonasal prominence - Forehead and the dorsum apex of the nose •Lateral nasal prominences - Sides (alae) of the nose •Medial nasal prominences - Nasal septum •Maxillary prominences - Upper cheek region and most of the upper lip •Mandibular prominences - Chin, lower lip, and lower cheek regions •Mesenchyme in the facial prominences - Fleshy derivatives and various bones


Paranasal SinusesParanasal Sinuses

Paranasal sinuses develop during late fetal life the remainder develops after birth.

They form as outgrowths or diverticula of the walls of the nasal cavities and become air filled extensions of the nasal cavities in the adjacent bone.– Frontal – Ethmoidal– Maxillary – Sphenoidal



Time of development of Time of development of paranasal sinusesparanasal sinuses

•Maxillary sinus: Develops at 10

weeks.

•Sphenoidal sinus. At 4 months i.u.

•Ethmoidal sinus. At 4 months i.u.

•Frontal sinus. 3 to 4 months I.U.


Expand in nasal fossae by growth of mucous membrane sacs- primary pneumatization

Enlarged by secondary pneumatization

Retain communication with nasal fossae through ostia


DEVELOPMENT OF PALATEDEVELOPMENT OF PALATE

Palatogenesis begins towards the end of 5 th week and is completed by about 12th week.

The palate develops from two primordia.– Primary palate– Secondary palate




DEVELOPMENT OF THE EARDEVELOPMENT OF THE EAR

Ear consists of 3 anatomical parts:Internal earMiddle earExternal ear


External ear:External acoustic meatus:

– Develops by deepening of the dorsal end of the 1st pharyngeal groove

Pinna or Auricle:– Six mesenchymal hillocks –

Auricular hillocks develop from the 1st and 2nd pharyngeal arch.


Middle ear: Develops from the tubotympanic recess i.e. derived

from the 1st pharyngeal pouch.

Tympanic cavity- Distal portion of the tubotympanic recess expands.

Tympanic membrane: - Ectodermal lining from 1st pharyngeal groove

-Mesodermal lining from 1st and 2nd arch

-Endodermal lining from tubotympanic recess


Ear ossicles:1st bone to attain ultimate size.

Maleus and Incus develop from the 1st arch.

Stapes develop from 2nd arch.

Ossification begins in the 16th week and

continues up to the 25th week.


Internal Ear:

•Otic Placode

•Otic Pit

•Otic Vesicle

•Primordium for Membrane labyrinth


•Otic vesicle

•Saccular part

•Utricle•Semicircular ducts

•Endolymphatic duct

•Saccule•Cochlear duct

•Otic vesicle

•Articular part


DEVELOPMENT OF EYEDEVELOPMENT OF EYE

Eyes develop from three sources:

Neuroectoderm of the forebrain retina,optic n.

Surface ectoderm of the headlens

Mesoderm between these layers eye muscle

and vascular tissues

1st indication of eye formation is optic sulcus which is

formed in the 4th week.www.indiandentalacademy.com

•Optic sulcus

•Optic vesicle

•Lens placode

•Lens pit •Lens vesicle

•Optic cup

•Retina•Contact surface ectoderm



ANATOMY OF FACEANATOMY OF FACE

SKIN Vascular Rich in sebaceous and sweat glands Laxity facilitates spread of edema Elastic and thick due to insertion of muscles.

Wounds tend to gape


Muscles of the Face

Develop from 2nd branchial arch and supplied by facial nerve

Grouped under1. Ms. of scalp2. Ms. of the auricle3. Ms. of the eyelid4. Ms. of nose5. Ms. around mouth6. Ms. of the neck


Common facial expressions and muscles producing them-

1. Smiling and laughing- zygomaticus major

2. Sadness- levator labii superioris, levator anguli oris

3. Grief- depressor anguli oris

4. Anger- dilator naris, depressor septii

5. Frowning- corrugator supercilli, procerus


Nerve supply of faceNerve supply of face


Arteries of faceArteries of faceVeins of faceVeins of face


Danger area of face and lymphatic Danger area of face and lymphatic drainagedrainage


Growth of FaceGrowth of Face Growth usually refers to increase in size or

number (Todd). Development is progress towards maturity (Todd). Growth is largely an anatomic whereas

development is physiologic. Differential growth can be described by - Scammons curve- Cephalocaudal gradient


THEORIES OF GROWTHTHEORIES OF GROWTH

1. GENETIC THEORY

2. SUTURAL THEORY

3. CARTILAGENOUS THEORY

4. FUNCTIONAL MATRIX THEORY

5. VAN LIMBORGH’S THEORY

6. ENLOWS EXPANDING MASS PRINCIPLE

7. ENLOWS COUNTERPART PRINCIPLE


Factors Affecting GrowthFactors Affecting Growth

1. Hereditary 2. Nutrition3. Illness4. Race5. Socioeconomic factors6. Family size7. Climatic and seasonal affects8. Psychological disturbances9. Exercise


Growth patterns in the Dentofacial complexGrowth patterns in the Dentofacial complex

Growth of nasomaxillary complex.

1. Passive displacement.

2. Growth at sutures.

3. Surface remodelling.


Growth in mandible is seen as a series of bone remodelling process by the deposition and resorptive processes.

GROWTH IN MANDIBLEGROWTH IN MANDIBLE


Anomalies of Development Anomalies of Development Defects of facial development are the result

of various etiological factors.The study of these anomalies constitute

teratology.– Defective brain development– Acephaly– Acrania– Acalvaria– Holoprosencephaly


Otomandibular Syndrome

- Agnathia

- Synotia

- Micrognathia

- Mandibulofacial dysostosis


Failure of facial prominences to merge results in developmental clefts.

1. Oblique facial cleft.2. Microstomia.3. Macrostomia.


Cleft lip and Palate Cleft lip results from the failure of the maxillary prominence

to unite with the mesial nasal prominences. Unilateral or bilateral.


Cleft palateUnilateral and bilateral cleft palate can be

classified into – Cleft of the anterior palate– Clefts of the posterior palate– Clefts of anterior and posterior palate.



Anomalies of Genetic OriginAnomalies of Genetic Origin

AchondroplasiaCleidocranial dysostosisProgeriaDown’s syndromeMandibulofacial dysostosis



Maxillofacial prosthodontics focuses on optimizing the rudimentary functions of speech and swallowing. Although the primary goal is the restoration of these functions but patient esthetics and mastication is important and also has an psychological effect on the patient.


Nasal prosthesis Nasal prosthesis

Orbital prosthesis Orbital prosthesis

Ear prosthesis Ear prosthesis


ObturatorObturator

An obturator prosthesis is required for patients who undergo resection of the maxilla for various reasons like neoplasms

Types: Surgical obturator. Interim obturator. Definitive obturator.


Various factors to be considered during complete denture construction

Lip support.Lip thickness.Tone of facial tissues.


Summary & ConclusionSummary & Conclusion

Development of the vertebrate face is a dynamic multiple-step process, which starts with the formation of neural crest cells in the developing brain and their subsequent migration to form, together with mesodermal cells, the facial primordia. Signaling interactions coordinate the outgrowth of the facial primordia from buds of undifferentiated mesenchyme into the intricate series of bones and cartilage structures that, together with muscle and other tissues, form the adult face. www.indiandentalacademy.com

ReferencesReferences

Keith L. Moore “The developing human”. 4th edition.

T.W. Saddler “Langman’s Medical Embryology”. 5th edition.

G.H. Sperber “Craniofacial embryology”. 4th edition.

Moore, Persuad “Color atlast of clinical embryology”. 2nd edition.

W.R. Proffit “Contemporary orthodontics”. 3rd edition.

S.I. Balaji “Orthodontics the art and science”. 2nd edition.


A.R. Tencate “Oral histology”. 5th edition. Shafer “A textbook of Oral pathology”. 4th edition. B.D. Chaurasia “Human anatomy Head and neck”.

3rd edition. Snell “Clinical anatomy for medical students”. Zarb Bolender “Prosthodontic treatment for

edentulous patients”. 12th edition. Keith F. Thomas “ Prosthetic Rehabilitation”.


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