DEVELOPMENT AFTER BIRTH

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DEVELOPMENT AFTER BIRTH
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• The general pattern of physical development
  after birth is a continuation of the pattern of
  the late fetal period
• rapid growth continues with a relatively steady
  increase in height and weight.
• But birth is a traumatic process and requires a
  dramatic set of physiologic adaptations. For a
  short period, growth stops and there is a small
  decrease in weight during the first 7 to 10 days
  of life.

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• An interruption in growth produces an effect
  in skeletal tissues that are forming at the time
  - the result is a noticeable line across both
  bones and teeth neonatal line. Its location
  across the surface of the primary teeth varies
  from tooth to tooth, depending on the stage of
  development at birth.

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• Primary as well as permanent teeth can be
  affected by
• illnesses during infancy and early childhood. The
  more severe is illness, the greater the impact
  and the more chronic the illness, the greater
  cumulative impact.
• chronically inadequate nutrition, has an effect
  similar to chronic illness.

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MATURATION OF THE ORAL FUNCTION

• During the eruption of primary dentition also
  the maturation of oral functions take place.
• The principal physiologic functions of the oral
  cavity are
• the respiration
• swallowing
• mastication
• speech

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THE RESPIRATION

• Newborn infants are obligatory nasal breathers
  and may not survive if the nasal passage is
  blocked at birth.
• Later, breathing through the mouth becomes
  physiologically possible.
• At all times during life, respiratory needs can
  alter posture of mandible and tongue and so the
  basis from which oral activities begin.

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THE RESPIRATION

• The nasal passage may be reduced by
• tonsilar hyperthrophy
• deviation of nasal septum

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THE RESPIRATION

• nasal polyps
• adenoids

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THE RESPIRATION

• This situation can alter oral function and the
  result is
• alteration of growth of the facial skeleton
• the characteristic appearance of the face and
• resulting malocclusion.

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THE SWALLOWING

• Next physiologic priority of the newborn child
  is to obtain milk and transfer it into the
  gastrointestinal system. This is accomplished by
  two maneuvers
• suckling (not sucking) and
• swallowing

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THE SWALLOWING

• The milk ducts of the mammals are surrounded by
  smooth muscle which contracts to force out the
  milk.
• To obtain milk, the infant doesnt have to suck
  it from the mothers breast.
• Instead, the infants role is to stimulate the
  smooth muscle to contract. This is done by
  suckling, consisting of small nibbling movements
  of the lips, a reflex action in infants.

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THE SWALLOWING

• In infants the anterior oral seal is created by
  contact of the tongue with lower lip. At this
  stage of development, tongue to- lower lip
  contact is maintained most of the time.
• Infant swallowing is characterized by active
  contraction of the lips, a tongue tip brought
  forward in to contact with lover lip and little
  activity of the posterior tongue or pharyngeal
  muscles.

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THE SWALLOWING

• As the infant matures, there is increasing
  activation of the elevator muscles of the
  mandible as the child swallows.
• As semisolid and solid foods are added to the
  diet, it is necessary for the child to use the
  tongue in a more complex way to transport food
  posteriorly.
• The suckling reflex and infant swallowing normaly
  disappear during the first year of life.
• After the eruption of the primary molars, during
  the second year, drinking from a cup replaces
  drinking from a bottle or continued nursing at
  the mothers breast.
• A transition in the pattern of swallow leads to
  the acquisition of an adult pattern. This type is
  characterized by relaxed lips, the placement of
  the tongue tip against the alveolar process
  behind the upper incisors and posterior teeth
  brought into occlusion.

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THE SWALLOWING

• If some sort of sucking habit (thumb sucking,
  finger or similary shaped object sucking)
  persist, there will not be a total transition to
  the adult swallow. After sucking habit is
  stopped, a complete transition to the adult
  swallowing may require some month.

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THE SWALLOWING

• An anterior open bite or proclination of the
  upper incisors (which may be present if sucking
  habit persists a long time) can delay this
  transition.
• It is because of the physiologic need to seal
  the anterior space during swallowing.

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THE CHEWING PATTERN

• The chewing movements of a young child typically
  involve moving the mandible laterally as it
  opens, then bringing it back towards the midline
  and closing, to bring the teeth into contact with
  food.
• An adult typically opens straight down, then
  moves the jaw laterally and brings the teeth into
  contact. The transition from the juvenile to
  adult chewing pattern appears to develop in
  conjunction with eruption of the permanent
  canines, at about age 12.

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THE GENRAL PATTERN OF MATURATION

• Maturation of oral functions can be
  characterized in general as following from
  anterior to posterior.
• At birth, the lips are relatively mature,
  whereas more posterior structures are quite
  immature.
• As the time passes, greater activity by the
  posterior parts of the tongue and more complex
  motion of the pharyngeal structures are required.

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THE SPEECH

• This principle of the front-to-back maturation
  is particularly well illustrated by the
  development of speech.
• The first speech sounds are bilabial sounds (p)
  and (b), so the usual first word is likely to be
  mama or papa.
• Somewhat later, tongue tip consonants like (t)
  and (d) appear.
• The sibilant (s) and (z) sounds, which require
  that the tongue tip is placed close to palate
  come later.
• The last sound (r) requires precise positioning
  of the posterior tongue.

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ERUPTION OF PERMANENT TEETH

• The eruption of any tooth can be divided into
  several stages. The nature of eruption and its
  control before emergence of the tooth into the
  mouth are somewhat different from eruption after
  emergence.
• Preemergent eruption
• Postemergent eruption

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Preemergent eruption

• Preemergent eruption eruptive movement begins
  soon after the root begins to form. This supports
  the idea that metabolic activity within the
  periodontal ligament is the major part of, if not
  the only mechanism for, eruption. Two processes
  are necessary.
• 1. there must be resorption of bone and primary
  tooth roots
• 2. the eruption mechanism itself then must move
  the tooth in the direction where the path has
  been cleared.

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Preemergent eruption

• Although the two mechanisms normally operate
  together, in some circumstances they dont. The
  bone resorption and the rate of tooth eruption
  are not controlled by the same mechanism.
• Failure of teeth eruption because of defective
  bone resorption occurs in the syndrome of
  cleidocranial dysplasia. (there is also heavy
  fibrous gingiva and multiple supernumerary teeth)

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Preemergent eruption

• In a rare but now well documented human syndrome
  called primary failure of eruption affected
  posterior teeth fail to erupt because of the
  defect in the eruption mechanism. Bone resorption
  apparently proceeds normally, but the teeth
  simply do not follow the path that has been
  cleared.

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Preemergent eruption

• Normally, the rate of eruption is such that the
  apical area remains at the same place, while the
  crown moves occlusally, but if eruption is
  mechanically blocked, the proliferating apical
  area will move in the opposite direction. (lack
  of space within the dental arch, supernumerary
  tooth, cyst, tumor )

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Postemergent eruption

• Postemergent eruption once a tooth emerges
  into the mouth, it erupts rapidly until it
  approaches the occlusal level and is subjected to
  the forces of mastication. At that point its
  eruption slows and then as it reached the
  occlusal level of other teeth and is in complete
  function eruption stops.

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Postemergent eruption

• After that teeth erupt at a rate that parallels
  the vertical growth of the mandibular ramus. As
  the mandible continues to grow, it moves away
  from maxilla, creating a space into which the
  teeth erupt.
• Exactly how eruption is controlled so that it
  matches mandibular growth is not known.
• some of the more difficult orthodontic problems
  arise when eruption does not coincide with
  growth.

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Postemergent eruption

• The amount of eruption necessary to compensate
  for jaw growth can be best visible in observing
  an ankylosed tooth. It appears to submerge
  because it remains at the same vertical level
  while the other teeth continue to erupt. It may
  be covered over again by the gingiva.

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Postemergent eruption

• During the adult life, teeth continue to erupt at
  an extremely slow rate. If an antagonist is lost
  at any age, a tooth can again erupt more rapidly,
  demonstrating that the eruption mechanism remains
  active.

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ERUPTION OF PERMANENT TEETH

• A change in the sequence of eruption is much more
  reliable sign of a disturbance in the development
  than a generalized delay or acceleration.
• For example, a delay in eruption of maxillary
  canines to the age 14 is within normal if the
  second premolars are also delayed. But if the
  second premolars have erupted at 12 and the
  canines have not, something is probably wrong.

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ERUPTION OF PERMANENT TEETH

• Several reasonably normal variations in eruption
  sequence have clinical significance and should be
  recognized
• 1. Eruption of second molars ahead of second
  premolars in mandibular arch.
• Early eruption of second molars can be
  unfortunate in the dental arch where room to
  permanent teeth is marginal. It tends to decrease
  the space for the second premolars and may lead
  to displacement or retention of premolars.

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ERUPTION OF PERMANENT TEETH

• 2. Eruption of canines ahead of first
  premolars in maxilla. If maxillary canines erupt
  at about same time as first premolars, the
  canines probably will be forced labially.

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ERUPTION OF PERMANENT TEETH

• 3. As a general rule, if a permanent tooth in
  one side erupts but its counterpart on the other
  side doesnt within 6 month, a radiograph shold
  be taken to investigate the cause of the problem.

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