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Oral Anatomy
 
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The Primary Set of Dentition
 
    The primary set of teeth (milk teeth, baby teeth) numbers twenty in all, both in the upper arch and lower arch (ten in each arch). There are no Premolars and third molars in the primary set. The primary set also differs in size with the permanent set.     If you have keenly observed your babies, then first ever teeth to emerge in the oral cavity is the lower central incisor, normally at 6-61/2 months old. The table below shows the sequence of eruption of the primary set. When a child is aged 2-21/2 years, all the temporary teeth are expected to be erupted. years, and some of them are in use from the very early age of 6 months (when the firs baby teeth erupts) until the age of 12 years (when the last of the baby teeth are exfoliated.) This tender age are the years when the development of the child is very much needed. Also, the premature loss of a baby teeth will greatly affect the alignment of the coming permanent teeth, and subsequently will cause initiation of an abnormal occlusion. Did you know that, save for the permanent molars, the primary dentition serves as a guide for the developing 
Below is a table showing the sequence of eruption of the Primary Dentition: 
Tooth
(Maxillary)
Root Length
(mm.)
Crown length
(mm.)
Eruption
(in months)
Central Incisor
10
6.0
7 1/2
Lateral Incisor
11.4
5.6
8
Canine
13.5
6.5
16-20
First Molar
10
5.1
12-16
Second Molar
11
5.7
20-30
 
Tooth
(Mandibular)
Root Length
(mm.)
Crown length
(mm.)
Eruption
(in months)
Central Incisor
9.0
5.0
6 1/2
Lateral Incisor
10
5.2
7
Canine
11.5
6.0
16-20
First Molar
9.8
6.0
12-16
Second Molar
11.3
5.5
20-30
 
Fig.4-2. A panoramic x-ray of a 7 year-old child. One can notice the complex mix of the permanent and the primary teeth at this stage. The developing permanent teeth up to 2nd premolar are called succedaneous teeth because they succeed their corresponding primary teeth. Permanent molars are not considered succedaneous teeth.
 
    I find this part of the tour rather a delicate one. People usually think of the baby teeth or the milk teeth as just really temporary and should not be given serious attention.  All of the baby teeth are in use from the early age of 2 years until the age of 7  permanent teeth to erupt to their proper places? Usually, a premature loss of a primary teeth will cause the succeeding permanent teeth to wander either lingually (towards the tongue or the palate) or bucally, labially (towards the cheek or lip).
 
 

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