Two sets of teeth in a lifetime
They are the first set of teeth we have and there are
altogether 20 of them. They usually start to erupt from
around the age of six months until 3 years of age.
At the age of 6, they sequentially erupt to replace the
deciduous teeth which become loose and shed.
Deciduous teeth: Space retainer for permanent teeth
• Normally, underneath the root of each deciduous tooth, there is a developing
permanent successor tooth.
• When it is time for the permanent
successor tooth to erupt, the root of
the deciduous tooth will resorb and
the deciduous tooth will become
loose. The place is then taken up by
its permanent successor tooth.
• Deciduous tooth retains the space for its permanent successor tooth.
No tooth is dispensable
If the second deciduous molar is lost early due to tooth decay, the consequences can
• The premature loss of deciduous molar tooth is problematic
The second deciduous molar is
The first permanent
molar (6-year molar)
The permanent tooth is crowded
out of the arch when it erupts
Since the first permanent molar erupts
behind the second deciduous molar at the
age of 6, the space of the lost second
deciduous molar will gradually close up as
the first permanent molar moves forward.
Later, when the second permanent premolar erupts
to replace the second deciduous molar, the
permanent tooth will either be crowded out of the
dental arch or be impacted and is unable to erupt,
leading to poor alignment of the teeth.
˙ The poor alignment of teeth will affect the bite.
It is difficult to clean the crowded area. Dental plaque bacteria and food debris
will easily accumulate between
teeth, increasing the chance of
inflammation and tooth decay.
˙ Surgical removal may be required if the permanent tooth cannot erupt.
Don't remove the deciduous incisors (front teeth)
Some parents thought that the lower d