PRIMARY DENTITION

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PRIMARY DENTITION

• It takes from 2 to 3 years for the primary
  dentition to be completed .
• Calcification of the primary teeth begins in
  utero 13 and 16 weeks

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• By 18-20 weeks post fertilization, all the
  primary teeth have begun to calcify, beginning
  with the initial calcification of the primary
  central incisor to the completion of the roots of
  the primary second molar.

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PERMANENT TOOTH

• Each permanent tooth takes 8-14 years to complete
  if the third molar is considered.

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• Normally at birth no teeth are visible in the
  mouth
• however, occasionally infants are born with
  erupted mandibular incisors.

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• Investigations of the chronology of emergence of
  the primary teeth in different racial and ethnic
  groups reflect considerable variation, and there
  is very little information available on tooth
  formation in nonwhite/non-European-derived
  populations

6
World population differences in tooth standards
suggest that there are patterned differences that
may not be large. Tooth size or tooth morphology,
as well as tooth formation, is highly
inheritable. There are few definitive
correlations between primary tooth emergence and
other physiologic parameters such as skeletal
maturation, size, and sex
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values for eruption are presented as the mean age
and a range of variation based on plus or minus
one standard deviation, after rounding all values
to the nearest month.
8
1 year

• The eruption or emergence of primary mandibular
  central incisors through the gingiva occurs at a
  mean age of eight months.
• The eruption of these teeth is followed about two
  months later by the maxillary central incisors at
  a mean age of 10 months, and then by the
  mandibular lateral incisors at a mean age of 13
  months.
• In some instances babies may display four
  mandibular incisors before the maxillary teeth
  erupt.

9
2 years

• At a mean age of 16 months the primary first
  molars erupt with the maxillary molar tending
  most often to erupt earlier than the mandibular
  first molar.
• There is some evidence for a difference by sex
  for the first primary molars, but there appears
  to be no answer for the question
• Why does the first molar have a different
  pattern of sexual dimorphism?

10
2 YEARS

• The primary maxillary canine erupts at a mean age
  of 19 months and the mandibular canines at 20
  months.
• The primary second mandibular molar erupts at a
  mean age of 27 months with evidence that there is
  difference between boys and girls.
• The primary maxillary second molar follows at a
  mean age of 29 months.

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• The predominant sequence of eruption of the
  primary teeth in the individual jaw is
• central incisor (A), lateral incisor (B), first
  molar (D), canine (C), and second molar (E),
• Variations in that order may be due to reversals
  of central and lateral incisors, first molar and
  lateral incisor. or eruption of two teeth at the
  same time.
• Jaw reversals in eruption of canines and first
  molars have been found to be important in
  increasing the variety of sequences

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• When differences according to jaws are
  considered, we may see that
• The lateral incisor. first molar. and canine tend
  to erupt earlier in the maxilla than in the
  mandible.
• Characteristic order in about a third of the
  children is AB D C E

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• The completed primary dentition may show evidence
  of bruxing wear, especially of the anterior
  teeth.
• Spacing of the teeth may be beneficial for the
  subsequent eruption of the permanent successors.

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• The premature loss of primary teeth because of
  caries may not only reflect an unfortunate lack
  of knowledge as to the course of the disease but
  also establishes a negative attitude about
  preventing dental caries in the adult dentition.
• Loss of primary teeth may lead to lack of space
  for the permanent dentition.

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• It is sometimes assumed by lay persons that the
  loss of primary teeth, which are sometimes
  referred to as "baby teeth" or "milk teeth is of
  little consequence because they are only
  temporary.

16

• the primary teeth are in use and contributing to
  the health and well-being of the individual
  during the first years of greatest development,
  physically and mentally.

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Premature loss of primary teeth, retention of
primary teeth, congenital absence of teeth,
dental anomalies, and insufficient space are
considered important factors in the initiation
and development of an abnormal occlusion.
Premature loss of primary teeth from dental
neglect is likely to cause a loss of arch length
with consequent tendency for crowding of the
permanent dentition.
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• The transition from primary to permanent
  dentition begins about 6 years of age with the
  eruption of the first permanent molars.
• The timing of the shedding of the primary teeth
  has an effect on the emergence of the permanent
  teeth, i.e., early shedding of primary teeth
  advances the emergence of the permanent teeth

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3 YEARS 4 YEARS
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5 YEARS 6 YEARS
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7 YEARS 8 YEARS