Development of primary dentition /certified fixed orthodontic courses by Indian dental academy

DEVELOPMEN
T OF
DENTITION

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


1.PRE-DENTAL PERIOD
(Birth- 6 months)
a. Gum pads
b. Precociously erupted primary teeth
2. DECIDUOUS DENTITION PERIOD
(6 months- 6 years)
3. MIXED DENTITION PERIOD
(6 years- 12 years)
4. PERMANENT DENTITION PERIOD
(12 years onwards)

1. PRE-DENTAL PERIOD- Birth- 6 months
a.GUM PADSThe alveolar processes at the time of birth are known as gum pads


The gum pads are pink, firm and resilient
and are covered by a dense layer of
fibrous periosteum.
Upper gum pad : Horse shoe shaped
Lower gum pad : ‘U’ shaped
Develop in 2 parts:
a. Labio-buccal portion
b. Lingual portion
The 2 portions are separated by a
groove called DENTAL GROOVE

a. LABIO-BUCCAL PORTIONDifferentiates first and grows more
rapidly.
Divided into 10 segments by grooves
called TRANSVERSE GROOVES.
Each segment consist of one
developing tooth sac.
The transverse groove between canine
and 1st deciduous molar is called the
LATERAL SULCUS.


b. LINGUAL PORTION
 Differentiates later.
 Remains relatively smooth.

The upper and lower gum pads are
separated from the palate and the floor
of the mouth respectively by a groove
called GINGIVAL GROOVE.


RELATIONSHIP OF
GUM PADS.


Upper gum pad is wider and longer than the
lower gum pad . Thus when approximated,
complete overjet present all around.
Anterior open bite present at rest with contact
only in the deciduous 1st molar region.
 Tongue protrudes anteriorly through
this space- helps in suckling
 Permits eruption of lower incisors without
impingement on upper gum pad.
Lateral sulcus of mandibular arch is normally
distal to that of maxillary arch.

b. PRECOCIOUSLY ERUPTED PRIMARY TEETH1.NATAL TEETH Teeth that are present at the time of birth are called natal
teeth.
 Usually mandibular incisors.
 Show familial tendency.


2.NEO-NATAL TEETHTeeth that erupt during 1st month of age
are called neonatal teeth.
Mostly seen in mandibular incisor region
and show familial tendency.


DEVELOPMENT OF PRIMARY DENTITION Initiation of primary tooth buds occurs during 6
weeks of intrauterine life.
 Primary teeth begin to erupt at about 6 months
of age.
 Eruption of all primary teeth is completed by
24- 30 months of age


ERUPTION AGE AND SEQUENCE OF
DECIDUOUS DENTITION SEQUENCE:

A- B- D- C- E

The mandibular central incisors are the 1st to erupt at around
6-7 months of age.
- Timing of tooth eruption is highly variable.
- A variation of 3 months from the mean age has been
acceptable as normal.

ERUPTION AGES OF PRIMARY
TEETH
ARCH

TOOTH

MONTHS

MAXILLARY

A

10 (08-12)

B

11 (09-13)

C

19 (16-22)

D

16 (14-18)

E

29 (25-33)

A

O8 (06-10)

B

13 (10-16)

C

20 (17-23)

D

16 (14-18)

E

27 (24-30)

MANDIBULAR

Source –Wheelers 8th edition.


NORMAL FEATURES OF PRIMARY DENTITION1. PHYSIOLOGICAL SPACES/ DEVELOPMENTAL SPACES:


Usually seen in deciduous dentition to accommodate the
larger permanent teeth in the jaws.



Absence of spacing in deciduous dentition is an indication
that crowding of teeth may occur in permanent dentition.


2. PRIMATE / SIMIAN / ANTHROPOID SPACES Present mesial to deciduous maxillary canine and distal to
mandibular canine.
 Commonly seen in primates.
 Help in interdigitation of opposing canines.
 Used for EARLY MOLAR SHIFT.


3.ALMOST VERTICAL INCLINATION OF
INCISORS

4.SHALLOW OVERJET AND OVERBITE


TERMINAL PLANE RELATIONSHIPThe mesio- distal relation between the distal surfaces of the upper and
lower 2nd deciduous molars is called the TERMINAL PLANE

BAUME’S CLASSIFICATION
a. FLUSH TERMINAL PLANE – (76%)
- Distal surfaces of the upper and lower 2nd deciduous molars
are in the same vertical plane.
- This is regarded as normal relation in deciduous dentition.


b. MESIAL STEP- (14%)
Distal surface of mandibular deciduous 2nd molar
is mesial to the distal surface of maxillary
deciduous 2nd molar.


c. DISTAL STEP- (10%)
Distal surface of mandibular deciduous 2nd molar
is more distal than the distal surface of maxillary
2nd molar.


The primary dentition is usually established by 3
years of age.
Between 3-6 years , the dental arch is relatively
stable and very few changes occur in the
dentition in this period.
The deciduous dentition period lasts for 6 years
of age till the eruption of permanent 1st molars
which marks the beginning of the mixed dentition
period.

Maturation of oral functions
New born infants are obligatory nasal
breathers, at a later period breathing through
mouth becomes a physiologically possible.
Once airway is established, next physiologic
priority is to obtain milk.
It is accomplished by 2 maneuvers1. Suckling. (not sucking)
 2. Swallowing.


Maturation of oral function has a gradient
from front to back.
Suckling reflex normally disappears during 1 st
year of life.

Development of primary dentition /certified fixed orthodontic courses by Indian dental academy

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Development of primary dentition /certified fixed orthodontic courses by Indian dental academy