CHILDHOOD FACIAL GROWTH AND DEVELOPMENT
MATURATION- progress towards attainment of full growth and development.
GROWTH- process of increase in size by multiplication of cells and accretion of tissues.
DEVELOPMENT- all changes that takes place from conception to death. I.e. - a progression from a lower to higher state of complexity with corresponding changes in function. E.g. development of dentition – this begins with induction – matrix deposition- mineralization- eruption- emergence in the mouth- getting to occlusal level- wearing/ attrition- migration.
BASIS FOR HUMAN FACIAL FORMS
Human face is unusual when compared with the face of most other mammals. It posses a large rounded head with a rather bizarre combination of facial features.
FACTORS INFLUENCING GROWTH AND DEVELOPMENT
1 hereditary factors
2enviromental factors
HEREDITARY FACTORS- sex, race, family traits, chromosomal abnormality endocrines factor and inborn error of metabolism.
ENVIROMENTAL FACTORS- social economy factor, birth order, season, emotional and phycological factor, nutrition and diseases. For purpose of understanding, the skull has been divided into three regions
1 cranial vault
2 cranial base
3 face
FACIAL TYPES
There are two general types of faces
1Long and Narrow face (leptoprosopic)
2Rounds and Broad (euryprosopic)
Each facial type is associated with a tyre of head.
1 dolicho-cephalic head – this is relatively narrow and long
2 brachy cephalic head- this is wider and rounder.
Because the basicranium (cranial base) is the platform to which the facial bones articulate, the head forms provide the template that establishes a correspondingly narrow or broad facial skeleton.
These two skull configurations are associated with the characteristic facial features. The narrow facial type tends to have a convex profile with a prognatic ( protruding) upper part (maxilla) and a rethrognatic (retruding) lower part ( mandible). There is a lager frontal sinus than in broad facial type, the eye appears close set and the nose is correspondingly thin. The is typically prominent and quite long, and its point has tendency to tip downwards. The lower lip and mandibular are often set in a somewhat recessive position because the long dimensions of the nasal chambers causes a downward and backward rotational placements often lower jaw. The elolicephalic head form also has a more open cranial base flexture which also contributes to downward mandible rotation. The downward facial type is characterized by more upright and bulbous forehead. The upper nasal part of the face tends to be less prominent than in the doliocephalic face. The nasal chambers are horizontally shorter but wider in contrast to the the narrow but more prominent nasal region characterizing the dolicocephalic headform. The net capacity of the airways in both instances is thus equivalent. The eyes appear widely set and the cheek bones seem prominent because the nose and fore head are less prominent. Because the cranial base angle of the brachycephalic skull tends to more closed, the body and head posture tends to be more erect. There is a greater tendency towards an orthognathnic (straight jawed) profile. The Negroid (black) head form tends to be dolicocephalic, although a range of variation exists. The nose of black people is characterized by a lateral enlargement of its lower part. This produces a less prominent nose having a narrow upper bridge but with bilateral flaring of the algae and the lower part of the nasal chambers. Maxillary – mandibular alveolar dental protrusion is also a frequent characteristic feature among many black people. This characteristic result becomes the mandibular ramous tends to be quite broad and the resultant protrusion of the mandibular dental arch produces a labial inclination of the maxillary incisors and greatly reduces the incidence of protrution upper teeth in the black people.
FACIAL PROFILNS
There are three basic types of facial profiles-
1 straight jawed (orthognathic) type. This is the aesthetic ideal type in western society.
2 the retrognathic of profile- this has a retuding chin. This is the most commonly occurring profile among western Caucasian populations.
3 the prognathic profile- this is characterized by a bold lowers jaw and chin. To identify a person’s profile, imagine a line projecting horizontally from the orbit; drop a second line perpendicular to this just brushing the surface of the upper lip. If the chin just touches the vertical line, then the profile is orthognathic. If the chin lies ahead of the vertical line then the profile is prognathic. People with a dolicocephalic head forms have a greater tendency towards pronathism.
MALE AND FEMALE FACES
Until about 12years of age boys and girls faces are essentially comparable. Shortly after puberty the female face has attained most of its size and structural maturity and growth cases. Growth and development of the male facial complex continues into the early 20s. This coninued development of the male skeletal superstructure brings about noticeable differences between male and female faces. Male and females, whether of the narrow or broad types, have a composite of keys to prographic characteristics. In general, male and female face tends to be noticeable more protuberant, and is much more knobby, bulky and coarse. The female face tends to be flatter, more delicate and less bumpy. Male face has a larger nose because of the requirements for a greater airway capacity. This is relatively wide and long male nose contrast with the thinner and less prominent female nose. There is also a major difference in the forehead profile between male and females. As there differences in the facial profile between long and broad head form types. Among the various differences between male and female faces and between narrow and broad faces many permutations exist. A female dolicocephalic, for example may present greater forehead slope a more prominent but thinner nose than a male brachy cephalic.
AGE CHANGES
Infant’s faces are round and white because lateral facial growth occurs earlier and to a greater extent than vertical growth. With increasing age and body size, vertical facial enlargement now exceeds the lateral facial growth because the nasal chambers progressively expand inferiorly to provide increased airway for the enlarging lungs. Baby’s face also appears rather flat because the nose is small relative to the broad but short face. Because forward growth of the face has not ysssset occurred, the forehead is upright and bulbons. Buccal and labial fat pads give a full appearance to the cheecks. Adult with a brachy cephalic head form usually have a rather juvenile facial character in comparism with the relatively angular and topographyically bolder adult dolicocephalic face. Subcutaneous adipose also tends to smooth out any age wrinkles and this further add to the illusion of youth. Any marked loss of facial adipose exaggerates an aged appearance because of consequent skin wrinkling. The effect is also seen in children who have undergone significant weight loss for any reason, as witnessed by the aged, sagging, wrinkled face of a child suffering severe malnutrition. The firm turgid velvet skin of youth becomes progressively replaced by the more open- pored leathery, spotted, crinkled and flabby skin of old age. Over exposure to the sun greatly hastens some of these changes. In middle age, the skin begins to sag and drop noticeably because the hypodermis becomes less firmly anchored to the underlying facial muscles and bone. This may be due to weight loss, but biochemical and physical alterations in the connective tissues of the dermis and hypodermis also exert an effect. These factors in turn, lead to the onset of facial hires and wrinkles, sunken eyes dropping bags and sub- orbital creases. Facial lines and furrows appear in characteristic locations. One of the first to appear and the one associated with middle age is the nasal labial furrow extending down along the sides of the nasal alae lateral to the corners of the mouth. This smile line can be seen at any age but become permanent in the late 30’s and early 40’s other permanent lines that appear with advancing age include the forehead furrows, suborbital, creases, crow’s feet at the face can become an expansive carpet of mobile ribbles, and may also be characterized by a loss of vertical dimension resulting from a loss of teeth.
BASIC CONCEPT OF FACIAL GROWTH
About half or more of the compact bone tissue of the facial and cranial bone is laid down by the endosteum, the inner membrane linking the medullary cavity. About half of the periosleum of most bone in the face and neurocranuim areresorptive in nature and about half are the pository. This is because a process of modellling is required to increase size of any bone. Three essential processes bring about the growth and development of the various cranial and facial bones- these are-
1 size increase
2 remodeling
3 displacements
Size increase and remodeling are closely related and they are produced simultaneously by a combination of bony resort ion and deposition.
The third process- displacement is a movement of all the bones away from one another at their articular junctions as each undergoes size increase.
SIZE INCREASE AND REMODELLING
A bone enlarges and remodeling the addition of new bone on one side of a cortical plate and removal of old bone from the opposite side of the same cortex. This process produces one of the two basic kinds of of growth movements termed relocation. The other form of growth movement is termed displacement. The cortex actually moves and it is the composite of all such changes throuout the bones that brings about it’s overall enlargement, simultaneously, internal regional remodeling adjustments are also made examples of the firt form of growth movement can be seen in the growth movement observe in the right and left zygomatic arches, the mandible and the palate.
The right and left zygomatic arches grow bilaterally to the right and left respectively. This growth increases the space between them and allows for the bilateral enlargement of the intervening brain and the remainder of the face and cranium. This relocation of the zygomatic arches is achieved through the combination of resopption and deposition. Because the extent of the depository actuty on one side of each bone cortex slightly exceeds the amount of resorption on the other side, the arch continiously increases in thickness as it moves (relocates) laterally.
The mandible – as the human mandibular increases in size, it remodels primarily in posterior and superior directors. It is a displacement movement that carries it downward and forward. The mandibular ramus relocates in a backward direction because the progressive amounts of bone addition on it’s backward facing surfaces slightly exceeds resorptive removal from it’s forward facing surfaces the ramus simultaneously enlarges as it moves slowly posteriorly over a period years. Because of the posterior manner of ramus relocation the body of the mandibular has space within which to elongate. It does this by remodeling. This is a continuos ongoing sequential process that proceeds from the early fetal period through the attainments of adults form and size.
The palent- in the young chill the level of the palate is only slightly inferior to the orbital floor. The nose expands through a growth process which involves the palate descending through remodeling. The palate has two corrticaal plates- one on the nasal side and one on the oral side, with a medullary space and canccllous bone between. One the nasal side the mucosal (periosteal) surface is resorptive and the medullary (endosteal) surface is depository. The periosted surface of the oral cortical plate of the hard palate is depository and its medullary surfaces are resortive. This combination produces a growth movement of the bony palate in a downward direction and the whole bony palate thereby relocates infairly to provides for a vertical expansion of the overlying growth site is used to designate some area or part has a note worthy role in the growth process e.g.- mandibular condyle
Nasal region- remodeling fields represents the morohogeneticactivity of the enclosing periostium, endosteum endother sofs tissue. The entire bone is involved in the growth process and not just a certain restricted growth sites or growth certies.
Displacement process
As all the various muscles, epithelia, connective tissues and other soft tissue of the head grow and expand, a separation effect occurs at the articular joints among the different bones, which are physically carried away from each other by the masses of enlarging soft tissues. These forces immediately trigger of the bones osteogenic membranes and cartilage to respond by producing an overall bone enlargement and remodeling. The bones grow by an amount proportionate to the increases in soft tissues mass. The displacement movement of the bone effect creates the space into which the bone grows. The mandibular becomes continuously disolaced in anterior and inferior direction but enlarges by equal amount posteriorly and superiorly. All the various bones of the naso maxillary complex also be one separated from ane another at their various structural junctions by displacement and the structural membrane deposit bone by amounts equal the displacement separation.
Bone and cartilage
Cartilage can exist without a surface rascular membrane its matrir is non rascular. It is also non calcified, turgid, and can grow interstitially; it therefore has the special capacity to function and grow while at the same time withstanding direct pressure.
Bone in contrast, is unable to withstanding any undue amount of direct pressure on its outer surface because of the compression closure of the vascular bed in the peristeum that results from such pressure. Because the matrix of bone is mineralized, it requires vascularization. The mineralized matrix also precludes interstitial growth, so that growth can occur only by appositionalactivities of its `surface membrane. The penosteum is, infact, structurally adapted to tension by vittue of its dense connective tissue designed, and the traction anchorage of muscles, tendons, ligament, and other soft tissues represents one of its principal functional roles. During postnatal growth and development, there are two modes of bones growth endochondral and intramembranes. In the growing face and cranium, there is an appropriate distribution of intramembrane and endochondral systems for growth. Endochondral growth sites in the child face and cranium involve prin cypally the mandibular cyndyles and the various synchordroses of the cranial base. (although some other localized endochondral growth sites also exist) all other areas in bones of face and cranium, as well as all remaining parts troughout the craniafacial skeleton, growth and remodel intramembranously by means of the periosteum, endosteum, periodontal membrane and structures.
Biomechanical pressures and tensions are believed to contribute to the stimulate that cause the membrane and cartilages to activate bone growth. Body mass and muscle actions cause bones or parts of bone to under go minute ‘bending’ actions, which creates very small bioelectrical potential (the piezoeffect) when a bone undergoes such slight distortions, pressure and tensions are produced within the fibrous matrix of the bone. The resultant negetive and positive bio electrical effects are in turn believed to generate corresponding osteoblastic and osteoclastic responses.
GROWTH- process of increase in size by multiplication of cells and accretion of tissues.
DEVELOPMENT- all changes that takes place from conception to death. I.e. - a progression from a lower to higher state of complexity with corresponding changes in function. E.g. development of dentition – this begins with induction – matrix deposition- mineralization- eruption- emergence in the mouth- getting to occlusal level- wearing/ attrition- migration.
BASIS FOR HUMAN FACIAL FORMS
Human face is unusual when compared with the face of most other mammals. It posses a large rounded head with a rather bizarre combination of facial features.
FACTORS INFLUENCING GROWTH AND DEVELOPMENT
1 hereditary factors
2enviromental factors
HEREDITARY FACTORS- sex, race, family traits, chromosomal abnormality endocrines factor and inborn error of metabolism.
ENVIROMENTAL FACTORS- social economy factor, birth order, season, emotional and phycological factor, nutrition and diseases. For purpose of understanding, the skull has been divided into three regions
1 cranial vault
2 cranial base
3 face
FACIAL TYPES
There are two general types of faces
1Long and Narrow face (leptoprosopic)
2Rounds and Broad (euryprosopic)
Each facial type is associated with a tyre of head.
1 dolicho-cephalic head – this is relatively narrow and long
2 brachy cephalic head- this is wider and rounder.
Because the basicranium (cranial base) is the platform to which the facial bones articulate, the head forms provide the template that establishes a correspondingly narrow or broad facial skeleton.
These two skull configurations are associated with the characteristic facial features. The narrow facial type tends to have a convex profile with a prognatic ( protruding) upper part (maxilla) and a rethrognatic (retruding) lower part ( mandible). There is a lager frontal sinus than in broad facial type, the eye appears close set and the nose is correspondingly thin. The is typically prominent and quite long, and its point has tendency to tip downwards. The lower lip and mandibular are often set in a somewhat recessive position because the long dimensions of the nasal chambers causes a downward and backward rotational placements often lower jaw. The elolicephalic head form also has a more open cranial base flexture which also contributes to downward mandible rotation. The downward facial type is characterized by more upright and bulbous forehead. The upper nasal part of the face tends to be less prominent than in the doliocephalic face. The nasal chambers are horizontally shorter but wider in contrast to the the narrow but more prominent nasal region characterizing the dolicocephalic headform. The net capacity of the airways in both instances is thus equivalent. The eyes appear widely set and the cheek bones seem prominent because the nose and fore head are less prominent. Because the cranial base angle of the brachycephalic skull tends to more closed, the body and head posture tends to be more erect. There is a greater tendency towards an orthognathnic (straight jawed) profile. The Negroid (black) head form tends to be dolicocephalic, although a range of variation exists. The nose of black people is characterized by a lateral enlargement of its lower part. This produces a less prominent nose having a narrow upper bridge but with bilateral flaring of the algae and the lower part of the nasal chambers. Maxillary – mandibular alveolar dental protrusion is also a frequent characteristic feature among many black people. This characteristic result becomes the mandibular ramous tends to be quite broad and the resultant protrusion of the mandibular dental arch produces a labial inclination of the maxillary incisors and greatly reduces the incidence of protrution upper teeth in the black people.
FACIAL PROFILNS
There are three basic types of facial profiles-
1 straight jawed (orthognathic) type. This is the aesthetic ideal type in western society.
2 the retrognathic of profile- this has a retuding chin. This is the most commonly occurring profile among western Caucasian populations.
3 the prognathic profile- this is characterized by a bold lowers jaw and chin. To identify a person’s profile, imagine a line projecting horizontally from the orbit; drop a second line perpendicular to this just brushing the surface of the upper lip. If the chin just touches the vertical line, then the profile is orthognathic. If the chin lies ahead of the vertical line then the profile is prognathic. People with a dolicocephalic head forms have a greater tendency towards pronathism.
MALE AND FEMALE FACES
Until about 12years of age boys and girls faces are essentially comparable. Shortly after puberty the female face has attained most of its size and structural maturity and growth cases. Growth and development of the male facial complex continues into the early 20s. This coninued development of the male skeletal superstructure brings about noticeable differences between male and female faces. Male and females, whether of the narrow or broad types, have a composite of keys to prographic characteristics. In general, male and female face tends to be noticeable more protuberant, and is much more knobby, bulky and coarse. The female face tends to be flatter, more delicate and less bumpy. Male face has a larger nose because of the requirements for a greater airway capacity. This is relatively wide and long male nose contrast with the thinner and less prominent female nose. There is also a major difference in the forehead profile between male and females. As there differences in the facial profile between long and broad head form types. Among the various differences between male and female faces and between narrow and broad faces many permutations exist. A female dolicocephalic, for example may present greater forehead slope a more prominent but thinner nose than a male brachy cephalic.
AGE CHANGES
Infant’s faces are round and white because lateral facial growth occurs earlier and to a greater extent than vertical growth. With increasing age and body size, vertical facial enlargement now exceeds the lateral facial growth because the nasal chambers progressively expand inferiorly to provide increased airway for the enlarging lungs. Baby’s face also appears rather flat because the nose is small relative to the broad but short face. Because forward growth of the face has not ysssset occurred, the forehead is upright and bulbons. Buccal and labial fat pads give a full appearance to the cheecks. Adult with a brachy cephalic head form usually have a rather juvenile facial character in comparism with the relatively angular and topographyically bolder adult dolicocephalic face. Subcutaneous adipose also tends to smooth out any age wrinkles and this further add to the illusion of youth. Any marked loss of facial adipose exaggerates an aged appearance because of consequent skin wrinkling. The effect is also seen in children who have undergone significant weight loss for any reason, as witnessed by the aged, sagging, wrinkled face of a child suffering severe malnutrition. The firm turgid velvet skin of youth becomes progressively replaced by the more open- pored leathery, spotted, crinkled and flabby skin of old age. Over exposure to the sun greatly hastens some of these changes. In middle age, the skin begins to sag and drop noticeably because the hypodermis becomes less firmly anchored to the underlying facial muscles and bone. This may be due to weight loss, but biochemical and physical alterations in the connective tissues of the dermis and hypodermis also exert an effect. These factors in turn, lead to the onset of facial hires and wrinkles, sunken eyes dropping bags and sub- orbital creases. Facial lines and furrows appear in characteristic locations. One of the first to appear and the one associated with middle age is the nasal labial furrow extending down along the sides of the nasal alae lateral to the corners of the mouth. This smile line can be seen at any age but become permanent in the late 30’s and early 40’s other permanent lines that appear with advancing age include the forehead furrows, suborbital, creases, crow’s feet at the face can become an expansive carpet of mobile ribbles, and may also be characterized by a loss of vertical dimension resulting from a loss of teeth.
BASIC CONCEPT OF FACIAL GROWTH
About half or more of the compact bone tissue of the facial and cranial bone is laid down by the endosteum, the inner membrane linking the medullary cavity. About half of the periosleum of most bone in the face and neurocranuim areresorptive in nature and about half are the pository. This is because a process of modellling is required to increase size of any bone. Three essential processes bring about the growth and development of the various cranial and facial bones- these are-
1 size increase
2 remodeling
3 displacements
Size increase and remodeling are closely related and they are produced simultaneously by a combination of bony resort ion and deposition.
The third process- displacement is a movement of all the bones away from one another at their articular junctions as each undergoes size increase.
SIZE INCREASE AND REMODELLING
A bone enlarges and remodeling the addition of new bone on one side of a cortical plate and removal of old bone from the opposite side of the same cortex. This process produces one of the two basic kinds of of growth movements termed relocation. The other form of growth movement is termed displacement. The cortex actually moves and it is the composite of all such changes throuout the bones that brings about it’s overall enlargement, simultaneously, internal regional remodeling adjustments are also made examples of the firt form of growth movement can be seen in the growth movement observe in the right and left zygomatic arches, the mandible and the palate.
The right and left zygomatic arches grow bilaterally to the right and left respectively. This growth increases the space between them and allows for the bilateral enlargement of the intervening brain and the remainder of the face and cranium. This relocation of the zygomatic arches is achieved through the combination of resopption and deposition. Because the extent of the depository actuty on one side of each bone cortex slightly exceeds the amount of resorption on the other side, the arch continiously increases in thickness as it moves (relocates) laterally.
The mandible – as the human mandibular increases in size, it remodels primarily in posterior and superior directors. It is a displacement movement that carries it downward and forward. The mandibular ramus relocates in a backward direction because the progressive amounts of bone addition on it’s backward facing surfaces slightly exceeds resorptive removal from it’s forward facing surfaces the ramus simultaneously enlarges as it moves slowly posteriorly over a period years. Because of the posterior manner of ramus relocation the body of the mandibular has space within which to elongate. It does this by remodeling. This is a continuos ongoing sequential process that proceeds from the early fetal period through the attainments of adults form and size.
The palent- in the young chill the level of the palate is only slightly inferior to the orbital floor. The nose expands through a growth process which involves the palate descending through remodeling. The palate has two corrticaal plates- one on the nasal side and one on the oral side, with a medullary space and canccllous bone between. One the nasal side the mucosal (periosteal) surface is resorptive and the medullary (endosteal) surface is depository. The periosted surface of the oral cortical plate of the hard palate is depository and its medullary surfaces are resortive. This combination produces a growth movement of the bony palate in a downward direction and the whole bony palate thereby relocates infairly to provides for a vertical expansion of the overlying growth site is used to designate some area or part has a note worthy role in the growth process e.g.- mandibular condyle
Nasal region- remodeling fields represents the morohogeneticactivity of the enclosing periostium, endosteum endother sofs tissue. The entire bone is involved in the growth process and not just a certain restricted growth sites or growth certies.
Displacement process
As all the various muscles, epithelia, connective tissues and other soft tissue of the head grow and expand, a separation effect occurs at the articular joints among the different bones, which are physically carried away from each other by the masses of enlarging soft tissues. These forces immediately trigger of the bones osteogenic membranes and cartilage to respond by producing an overall bone enlargement and remodeling. The bones grow by an amount proportionate to the increases in soft tissues mass. The displacement movement of the bone effect creates the space into which the bone grows. The mandibular becomes continuously disolaced in anterior and inferior direction but enlarges by equal amount posteriorly and superiorly. All the various bones of the naso maxillary complex also be one separated from ane another at their various structural junctions by displacement and the structural membrane deposit bone by amounts equal the displacement separation.
Bone and cartilage
Cartilage can exist without a surface rascular membrane its matrir is non rascular. It is also non calcified, turgid, and can grow interstitially; it therefore has the special capacity to function and grow while at the same time withstanding direct pressure.
Bone in contrast, is unable to withstanding any undue amount of direct pressure on its outer surface because of the compression closure of the vascular bed in the peristeum that results from such pressure. Because the matrix of bone is mineralized, it requires vascularization. The mineralized matrix also precludes interstitial growth, so that growth can occur only by appositionalactivities of its `surface membrane. The penosteum is, infact, structurally adapted to tension by vittue of its dense connective tissue designed, and the traction anchorage of muscles, tendons, ligament, and other soft tissues represents one of its principal functional roles. During postnatal growth and development, there are two modes of bones growth endochondral and intramembranes. In the growing face and cranium, there is an appropriate distribution of intramembrane and endochondral systems for growth. Endochondral growth sites in the child face and cranium involve prin cypally the mandibular cyndyles and the various synchordroses of the cranial base. (although some other localized endochondral growth sites also exist) all other areas in bones of face and cranium, as well as all remaining parts troughout the craniafacial skeleton, growth and remodel intramembranously by means of the periosteum, endosteum, periodontal membrane and structures.
Biomechanical pressures and tensions are believed to contribute to the stimulate that cause the membrane and cartilages to activate bone growth. Body mass and muscle actions cause bones or parts of bone to under go minute ‘bending’ actions, which creates very small bioelectrical potential (the piezoeffect) when a bone undergoes such slight distortions, pressure and tensions are produced within the fibrous matrix of the bone. The resultant negetive and positive bio electrical effects are in turn believed to generate corresponding osteoblastic and osteoclastic responses.
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