growth of maxilla & sinus
TRANSCRIPT
GROWTH AND DEVELOPMENT
OF MAXILLA AND THE MAXILLARY
SINUS.
•INTRODUCTION•DEFINITIONS•FACTORS AFFECTING GROWTH•GROWTH:CONCEPTS,METHODS OF GATHERING DATA AND STUDYING GROWTH•BONE DEVELOPMENT AND GROWTH•THEORIES OF GROWTH•PRENATAL GROWTH AND DEVELOPMENT OF MAXILLA•POST NATAL GROWTH AND DEVELOPMENT OF MAXILLA•DEVELOPMENT OF THE PALATE
DEFINITIONS OF GROWTH• J.S.Huxely: The self multiplication of living
substance.• Krogman:Increase in size, change in proportion
and progressive complexity.• Todd:An increase in size.• Meridith:Entire series of sequential anatomic and
phisiologic changes taking place from beginning of prenatal life to senility.
• Moyers:Quantitative aspect of biologic development per unit time.
• Moss: Change in any morphological parameter which is measurable.
DEFINITIONS OF DEVELOPEMENT
• Todd:Development is progress towards maturity.• Moyers: 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.
FACTORS AFFECTING PHYSICAL GROWTH• Heredity
• Nutrition• Illness• Race• Race• Socioeconomic factors• Family size and birth order• Secular trends• Climatic and seasonal effects• Psychological disturbances• Exercise
SOME CONCEPTS OF GROWTH
• Pattern
• Scammon’s Growth Curve
SCAMMON’S GROWTH CURVE
METHODS OF GATHERING GROWTH DATA
• Longitudinal studies
• Cross sectional studies
• Semi longitudinal studies
TYPES OF GROWTH DATA
• Opinion
• Observations
• Ratings and rankings
METHODS OF STUDYING GROWTH
• Measurement approaches• Craniometry • Anthropometry• Cephalometric radiology
• Experimental approachesVital stainingRadioisotopes ImplantsRadiographic techniquesNatural markersComparative anatomy
BONE DEVELOPMENT AND GROWTH
THEORIES OF GROWTH AND DEVELOPMENT
• Genetic theory
• Sutural theory
• Cartilagenous theory
• Functional matrix theory
• Van Limborgh’s theory
• Enlow’s expanding “V” principle
• Enlow’s Counterpart principle
PRENATAL DEVELOPMENT OF THE MAXILLA
The prenatal life may be divided into three periods :
The period of the ovum [fertilization to the end of fourteenth day]
The period of the embryo [14th to 56th day ]
The period of the foetus [56th to Birth ]
THE PERIOD OF OVUM:
This period consists primarily of cleavage of the ovum and attachment to the uterine wall . At the end of this period the ovum is only 1.5 mm in length and cephalad differention has not yet begun.
THE PERIOD OF THE EMBRYO:
This period is charecterised by the following events:
Formation of the three germ layers
Formation of the pharyngeal arches
Differentiation of the mesenchyme to signal beginning of endochondral and intramembranous bone formation
FORMATION OF THE THREE GERM LAYERS
The blastocyst [day 5 ] has cells arranged in two layers : 1.The outer cell mass which will form the trophoblast
2.The inner cell mass which will give rise to the embryo proper “embryoblast”
IMPLANTATION TAKES PLACE AT THE END OF 1ST
WEEK
--At the 8th day of development the trophoblast has differentiated into two layers:
Inner layer: CytotrophoblastOuter layer:Syncytiotrophoblast
The cells of embryoblast also differentiate into two layers:---A layer of small cuboidal cells : hypoblast---A layer of high columnar cells : epiblast
The hypoblast and the epiblast together constitute the bilaminar germ disc
--A small cavity is formed within the epiblast . This is called the AMNIOTIC CAVITY
--Around the 13th day of development the following structures are seen:
Secondary yolk sac
Extraembryonic coelom [ Chorionic cavity ]
Connecting stalk [ Future embryonic stalk ]
Prochordal plate [ Where the epiblast cells are firmly attached to the hypoblast cells ……The future Buccopharyngeal membrane ]
During the 3rd week there is appearance of the “primitive streak” with the “ primitive node”
In the region of the node and the streak, the epiblast cells invaginate a new cell layer between the hypoblast [ now called the ENDODERM ] and the epiblast [now called the ECTODERM] This third layer is called the MESODERM
The process of mesoderm formation is called the GASTRULATION
These cells form a tube like process called the NOTOCHORDAL PROCESS which gets filled in by cells to form the NOTOCHORD
Notochord forms the midline axis which serves as the basis
for axial skeleton . It extends from the prochordal plate in
the cephalic region to the cloacal membrane in the region
caudal to the primitive streak .
ECTODERM MESODERM ENDODERM
Central Nervous System Myotome {muscle} Epithelial lining for GIT, Respiratory tract and Bladder.
Peripheral Nervous System Sclerotome {Cartilage and Bone}
Parenchyma of tonsil, thyroid,parathyroid,thymus,liver and pancreas.
Sensory Epithelium of the Ear, Nose and Eye
Dermatome {Subcutaneous tissue of skin}
Epithelial lining of tympanic cavity and Eustachian tube
Skin, Hair, Nails Vascular System
Pituitary, Mammary and Sweat Glands
Uro-genital System {excluding the bladder}
Enamel of the Tooth Spleen and Supra Renal glands
THE NEURAL CREST CELLS
They give rise to
1. Sensory ganglia
2. Schawnn cells
3. Pigment cells
4. Odontoblasts
5. Meninges
6. Cartilage cells of branchial arches
They have a possible important function in the formation of face
When the embryo is 41/2 weeks old five mesenchymal swellings can be recognized:
The Mandibular Swellings [ 1st Pharyngeal Arch ]The Maxillary Swellings [ Dorsal portion of 1st Arch]The Frontal Prominence
Each Pharyngeal Arch is thus characterized by its own :
Muscular Component
Cranial Nerve Component
Arterial component
The mesenchyme of the maxillary process subsequently gives rise to the following:PremaxillaMaxillaZygomatic boneTemporal bone in part
All these bones undergo intramembranous ossification.
BRANCHIAL AND PHARYNGEAL ANOMOLIES
CONGENITAL AURICULAR SINUS AND CYSTS:They are found in a triangular area of skin anterior to ear. They are remnants of the 1st branchial groove.
BRANCHIAL SINUSES:Open on the side of the neck and result from the failure of the 2nd branchial groove to close. The blind pit or sinus that remains opens along the anterior border of the sternocleidomastoid.
FORMATION OF THE PHARYNGEAL ARCHES
The most typical feature in the development of the head and neck is formed by the BRANCHIAL or the PHARYNGEAL ARCHESThey appear in the 4th and 5th week of development and contribute greately to the characteristic appearance of the embryo.With this a number of outpocketings the PHARYNGEAL POUCHES appear along the lateral walls of the pharyngeal gut-the most cranial part of the foregut.At the end of 4th week the centre of the face is formed STOMODEUM ,surrounded by the first pair of pharyngeal arches .
When the embryo is 4 ½ weeks old, five mesenchymal swellings can be seen:
Two Mandibular Swellings [1st Pharyngeal Arch ]Two Maxillary Swellings[Dorsal Portion of the 1st Arch]The Frontal Prominence
BRANCHIAL FISTULA:It is a communication between the intratonsillar cleft and the side of the neck- persistence of the 2nd branchial groove and the 2nd pharyngeal pouch.
BRANCHIAL CYST:Remnants of part of cervical sinus and/or the 2nd branchial groove may persist and form this cyst …..it is located along the anterior border of the sternocleidomastoid.
FIRST ARCH SYNDROME:Due to insufficient migration of the neural crest cells into the 1st arch. Some of the more common are:
TREACHER COLLINS SYNDROME:Malar hypoplasiaAntimongoloid palpebral fissuresDefects of lower eyelidsDeformed external earsAbnormalities of middle and internal ears
PIEERE ROBIN SYNDROME:Hypoplasia of mandibleCleft palateDefects of the eye and the ear
DI GEORGE SYNDROME:HypoparathyroidismIncreased susceptibility to infectionsFish mouth deformityLow set notched earsThyroid hypoplasiaCardiac abnormalities
CONTROL PROCESSES AND FACTORS IN FACIAL GROWTH
VAN LIMBORGH’S CLASSIFICATIONIntrinsic genetic factors:Inherent in skeletal tissues themselves.They exert influence inside the cell to which they are inherent.
Local Epigenetic factors:Epigenesis includes the sum total of all biochemical and biophysical events produced by the functioning of the cells and organs ……Petrovic
General Epigenetic factorsLocal environmental factorsGeneral environmental factors
L O C A LG en etic con tro l o rig in a tin g
from ad jacen t s tru c tu re an d p rovid e loca l ac tion s E xam p le :E m b ryon ic in d u c tion in flu en ces sk . g row th B ra in ,eye
G E N E R A LG en etic con tro l o rig in a tin g from d is tan t s tru c tu re
an d p rovid e g en era l ac tion sE xam p le : H orm on es
E P IG E N E TIC F A C TO R S
LO C ALN on g en e tic in flu en ce evoked b y s tim u li
o rig in a tin g from exte rn a l en viron m en tE xam p le :h ab its ,fo rces o f m u sc .con trac tion
G EN ER ALTh ese a re G en era l n on g en e tic
in flu en cesE xam p le :N u trit ion ,food ,oxyg en .
EN VIR O N MEN T AL FAC T O R S
THE CONTROL PROCESSES
THE GENETIC BLUE PRINT:Genes have a fundamental and perhaps an overriding influence in establishing basic facial pattern but they are NOT exclusive determinants of all growth parameters.
BIOCHEMICAL FORCES:The play of physical forces acting on a bone to regulate its development, morphologic configuration, histological structure and physical properties.
WOLFF’S LAW: The architecture of bone is such that it can best resist the forces that are brought to bear upon it with the use of as little tissue as possible. It has a flaw in that the law doesn’t distinguish between physical forces acting on a bone and forces acting on the osteogenic connective tissue that actually produce any remodelling of the bone.
SUTURES,CONDYLES AND SYNCHONDROSES: Growth,form and dimensions of a bone are governed by intrinsic genetic programming residing within that bone’s own bone –producing cells of periosteum,sutures and bone related cartilages –provide inclusive growth regulation for each of the whole bones they serve. Modern research discounts such a concept .
CONTROL MESSENGERS: Growth control is essentially a localised developmental process working with local function as it responds to multiple developmental interplay with other growing parts.
FORCE/PRESSURE/TENSION
BIOPHYSICAL REACTIONS-Bone deformation,compression
of periodontal ligament,tissue injury
PRODUCTION OF FIRST MESSENGERS Hormones[PTH],Prostaglandins,Neurotransmitters
PRODUCTION OF 2nd MESSENGERS[Camp,Cgmp,Ca]
INCREASE IN CELLS OF RESORPTION/DEPOSITION
POSTNATAL GROWTH AND DEVELOPMENT OF
MAXILLAThe growth of maxilla depends on influence of several functional matrices that act upon different areas of the bone thus allowing its subdivision into skeletal units:
The BASAL BODY beneath the INFRAORBITAL NERVE, later surrounding it to form the infraorbital canal.
The ORBITAL UNIT responds to the growth of the eyeball
The NASAL UNIT depends on the SEPTAL CARTILAGE for its growth.
The TEETH provide the functional matrix for the ALVEOLAR UNIT
The PNEUMATIC UNIT reflects maxillary sinus expansion,which is more a responder than a determiner of the skeletal unit.
THE 3 PRINCIPLE REGIONS OF FACIAL AND NEUROCRANIAL
DEVELOPMENT
THE BRAIN AND THE BASICRANIUM:The above said determines the persons headform and typeEx:A long and narrow basicranium gives rise to dolicocephalic facial form while a brachycephalic facial form gives a wider facial configurationBASICRANIUM is the template that establishes the shape and perimeter of the facial growth field.
THE AIRWAY:The configuration and dimensions of the airway are a product
of the composite growth of many hard and soft tissues along its pathway from nares to glottis. These parts are again dependent upon the airway for maintanance of their own functional and anatomic position. It functions as a key stone for the face.
THE ORAL REGION: Compensatory adjustments by the remodelling process occur throughout growth and development in many ways. The oral region is one of the areas around which these changes take place.
A CORNERSTONE OF GROWTH PROCESS
RemodellingDisplacement
REMODELLING:Refers to a process where bone deposition and resorption occur so as to bring about change in size , shape and relationship of the bone .
FUNCTIONS OF REMODELLING:Progressively create the changing size of bone
Sequentially relocate each of the component regions of the whole bone to allow for overall enlargement.Shape the bone to accommodate its various functionsProvide fine tune fitting of all the separate bones to each other and to their contiguous soft tissues.
DISPLACEMENT:It is the physical movement of the whole bone and occurs while the bone simultaneously remodels by resorption and deposition.Bone deposition doesn’t push the articular contact surface of another bone and provide growth….rather bone is carried by the expansive force of all growing soft tissues around it and attached to it by anchoring fibres.
DISPLACEMENT : THE GREAT CONTROVERSY
PRIMARY DISPLACEMENT: Movement of a bone because of its own growth .
SECONDARY DISPLACEMENT: Movement of a bone passively or secondary to growth of contiguous bone/s.
DRIFT: The combination of bone deposition and resorption resulting in a growth movement towards the depositing surface is called drift.
RELOCATION: The progressive sequential movement of component parts as a bone enlarges is relocation.
THE GROWTH AND DEVELOPMENT OF THE NASOMAXILLARY COMPLEX
The maxillary tuberosity and arch lengetheningThe lacrimal suture-a key growth mediator.The maxillary tuberosity and the key ridgeThe vertical drift of teethThe nasal airwayPalatal remodellingDownward maxillary displacementThe cheekbone and the zygomatic archOrbital growth
THE MAXILLARY TUBEROSITY AND ARCH LENGETHINING:The horizontal lengethening of maxilla is produced by remodelling at the maxillary tuberosityBack facing periosteum of tuberosity has continuous deposits of new bone as long as srowth in this part continues.The lateral surface is also depositiory …the arch widens.The endosteal side of the cortex is resorptive …the maxillary sinus expands as a result.The whole maxilla undergoes primary displacement in an anterior and inferior direction as it grows.
THE LACRIMAL SUTURE A KEY GROWTH MEDIATORThe lacrimal bone is a diminutive flake of a bony island which is surrounded by sutural connective tissue.The sutural system of the lacrimal bone provides for the slippage of multiple bones along sutural interfaces with the pivotal lacrimal as they all enlarge differentially.The lacrimal sutures allow maxilla to slide downward along its orbital contacts which facilitates inferior displacement of the maxilla.
THE MAXILLARY TUBEROSITY AND THE KEY RIDGE:Major change occurs in surface contour along the vertical crest below malar protruberance called the key ridge. A reversal occurs here where by external surface of maxillary arch anterior to it is resorptive.Similarly reversal is seen at Point A as well.
THE VERTICAL DRIFT OF TEETH: AN IMPORTANT CLINICAL CONSIDERATION
The term vertical drift denotes the displacement of the whole tooth along with its alveolar housing in an occlusal direction.
As the jaws grow the dentition drifts both vertically and horizontally to keep phase in the respective anatomic positions.
THE NASAL AIRWAY
The lining surfaces of the bony walls and floor of the nasal chambers are resorptive accept for the nasal side of the olfactory fossae.
This produces a lateral and anteiror expansion of the nasal chamber and a downward relocation of the palate.
The breadth of the nasal bridge in the region just below
the frontonasal sutures does not markedly increase from
childhood to adult hood. More inferiorly in the inter
orbital area the medial wall of each orbit expands and
balloons out considerably in a lateral direction.
PALATAL REMODELING
Even though the labial side of the whole anterior part of
the maxillary arch is resorptive, the arch none the less
increases in width and the palate becomes wider (the ‘V’
principle).
DOWNWARD MAXILLARY DISPLACEMENT
The primary displacement of the whole ethmomaxillary
complex in a downward direction is accompanied by
simultaneous remodeling in all areas.
New bone added at the following sutures
-Frontomaxillary -Zygotemporal -Zygosphenoidal -Zygomaxillary-Ethmomaxillary-Ethmofrontal-Nasomaxillary-Nasofrontal -Frontolacrimal-Palatine-Vomerine
THE CHEEK BONE AND ZYGOMATIC ARCH
The posterior side of malar protuberance within the temporal fossae is deposited in while the anterior surface is resorptive. Thus the cheek bone relocate posteriorly as it enlarges.
This results in a protrusive appearing nose and an anteroposteriorly much deeper face.
ORBITAL GROWTH The remodeling changes in orbit are complex as it
comprises of a number of bones including1. Maxilla2. Ethmoid3. Lacrymal4. Frontal 5. Zygomatic6. Greater and lesser wings of sphenoid There is bone deposition along much of the walls of
the orbit except the lateral wall which is resorptive. The orbit also grows by ‘V’ principle, so that the
cone shaped orbital cavity moves in a direction towards its wide opening.
In the child the floor of nasal and orbital cavities are at about the same level. But in the adult the nasal cavity is located much lower than the orbital.
SEX DIFFERENCES
The females have
1. More upright and bulbous forehead
2. Lesser eyebrow ridges
3. Small and less protrusive nose
4. Lower nasal bridge
5. A more rounded nasal tip
6. Flatter face
7. Wider appearing face with more prominent appearing cheek bones.
8. Vertically shorter midface.
DEVELOPMENT OF PALATE
The palate is formed from three components
a) The two palatal process
b) The primitive palate formed from frontonasal process.
The definitive palate is found by the fusion of these three parts
The transition from vertical to horizontal position is completed within hours.
Some of the mechanisms are
- Biochemical transformation in the physical consistency of the connective tissue matrix of the shelves.
- Variation in vasculature and blood flow to this structures
- The sudden increase in tissue turgor
- Intrinsic shelf force
- Muscular movements
ANAMOLIES OF PALATAL DEVELOPMENT
Epstein’s pearls and Bohn’s nodules
The entrapment of epithelial rests or pearls in the
line of fusion of the palatal shelves may give rise
to median palatal rests cysts.
II. Dental lamina cysts
Epithelial remnants of dental lamina that develop
on the crest of alveolar ridge.
III. Torus palatinus:
IV. Oblique facial cleft
Failure of maxillary swelling to merge with its corresponding lateral nasal swelling results in this deformity.
V. Cleft lip and Palate
Successful fusion of the three embryonic components of the palate involves complicated synchronization of
1. Shelf movements with growth
2. Withdrawal of the tongue
3. Growth of the mandible and head
CLASSIFICATION OF CLEFT LIP AND PALATE
Davis and Ritchi (1922) and Veau (1931) have given the following classification
Class I – Cleft of soft palate only
Class II – Cleft of hard and soft palate till the incisive foramen
Class III – Complete unilateral cleft of the soft palate, hard palate, the alveolar ridge and the lip on one side.
Class IV – Complete cleft of soft palate, hard palate, alveolar ridge and the lip on both sides.
INCIDENCE
Cleft lip : 1:1000 Births, More in males
Cleft palate : 1:2500 Births, More in females
PROSTHODONTIC TREATMENT
If it is decided the surgery will be unsuccessful for the treatment of cleft soft palate then the first obturator is given at 2 years
There are three types:
1. Fixed pharyngeal
2. Hinged pharyngeal
3. Meatal
The cleft of hard palate can be so easily covered by means of a simple acrylic or metallic palate.
PHARYNGEAL ARCH
NERVE MUSCLES SKELETON
Mandibular V-Mandibular div. Muscles of mastication, Ant. Belly of Digastric,Tensor Palatini,Tensor Tympani.
Incus,Malleus, Ant. Ligament of Malleus,Sphenomandibular ligament ,Portion of mandible.
Hyoid VII-Facial Muscles of facial expression, Post. Belly of Digastric, Stylohyoid,Stapedius.
Stapes,Styloid process,Stylohyoid Ligament, Smaller horn and Superior body of Hyoid.
III IX-Glossopharyngeal Stylopharyngeus Greater horn, Lower part of Body of Hyoid.
IV-VI Sup.Laryngeal, Rec.Laryngeal.
Muscles of Pharynx, Soft Palate and Larynx.
Laryngeal Cartilages.
ENDODERMAL POUCH DERIVATIVES
I Tubo tympanic recess-Auditory tube,middle ear cavity,tympanic antrum.
II Tonsil.
III Inferior Parathyroids,Thymus.
IV Sup.parathyroids.
V Ultimo Branchial body-Parafollicular cells of thyroid.
TIMING OF PRIMARY CLEFT LIP AND PALATE PROCEDURES.{After Delaire}
CLEFT LIP ALONE
UNILATERAL
One operation at 5-6 months.
BILATERAL
One operation at 5-6 months.
CLEFT PALATE ALONE
SOFT PALATE ALONE
One operation at 5-6 months.
SOFT + HARD PALATE
Two operations
Soft palate –6 months
Hard palate- 12- 15 months
CLEFT LIP AND PALATE
UNILATERAL
Two operations
Cleft lip + soft palate – 5-6 months
Hard palate + gum pad +/- lip revision – 12-15 months
BILATERAL
Two operations
Cleft lip + soft palate – 5-6months
Hard palate + gum pad +/- lip revision – 12-15 months