Difference Between Deciduous or Milk Teeth and Permanent Teeth

Every person goes through the development of two types of dentition in life. A deciduous or primary dentition consists of milk teeth and the permanent dentition which exists for the entire life.

Both of these dentitions serve the same purpose i.e. help in chewing, swallowing and speaking. But you may ask why do we need two dentitions and how are they different from each other?


The deciduous teeth erupt at around 6 months of age in a baby and their primary role is to allow the baby to adapt to the changes in the mouth and learn to chew and swallow.

The eruption of deciduous teeth helps to transition the feeding habits of the baby. Apart from this, deciduous teeth also act as a guide for the development and alignment of the permanent teeth.

By the age of six years, the deciduous teeth start to fall out and prepare the eruption of permanent teeth.

Several factors differ in deciduous or milk teeth when compared to permanent dentition, for example, the morphology, number of teeth, structure of the teeth, etc.

Let us get straight into the article and look at the differences between deciduous and permanent dentition.

What are deciduous or milk teeth?

Deciduous teeth, otherwise called as milk teeth or baby teeth or even primary teeth, are the first set of teeth that erupt during the growth and development of a human being.

They erupt at an early age of six months after birth and remain until the age of six years. Deciduous teeth often fall out and are replaced by permanent teeth.

In some cases, where the permanent teeth haven’t erupted or are impacted, deciduous teeth can remain functional for many years. (1)

Primary teeth play a crucial part in the development of the mouth.

They maintain the arch length, act as eruption guides for permanent teeth, help in enhancing the muscular actions of the jaw and are essential for the development of a child’s food habits and speech.

What is permanent dentition?

Permanent teeth or adult teeth are the second set of teeth formed in humans. The first permanent tooth erupts at six years of age.

Permanent dentition consists of a set of 32 teeth that remain till the lifetime and function in providing support to the mouth and facial muscles, help in chewing, swallowing and speaking and improves the aesthetics of the mouth.

How are they different from one another?

There are many areas where deciduous teeth differ from permanent ones. They can be categorized into 3 criteria –


  • Deciduous teeth appear more white as compared to the permanent teeth. This is because the layer of enamel is thinner and more translucent in deciduous teeth. Permanent teeth have a relatively thicker and less translucent enamel giving it a bluish-white color.
  • The reduced thickness of the enamel makes it more permeable, and therefore, deciduous teeth are more prone to a rapid form of dental caries and cavities during sugar consumption.
  • Due to less calcification of the enamel, the effects of a fluoride treatment are also less in deciduous teeth and thus they require more dental attention as compared to the permanent teeth.


The structure of the teeth consists of several factors which differ in both the dentitions.

  • Shape – Deciduous teeth are characterized as bulbous crowns with pointed cusps. The contact area is smaller. Whereas, permanent teeth have blunt cusps and broader contact areas. (2)
  • Size – The deciduous teeth are smaller in size as compared to the permanent teeth except for the primary molars which are wider than the permanent premolars.
  • Occlusal surface – Occlusal area is narrower in deciduous teeth. Whereas, its wide in permanent teeth.
  • Pulp cavity – Pulp cavity in deciduous teeth is large and covered by less dense dentinal layer. Hence, kids are more prone to dental caries with infected pulp tissue. The pulp cavity is comparatively low and small with thicker dentin in permanent teeth.
  • Root structure – The roots in deciduous teeth are short, delicate and diverge widely. Whereas, permanent dentition has long, strong, and non-divergent roots.

Number of teeth in the dentition

There are a total of 20 teeth in deciduous dentition i.e. ten teeth per arch. They consist of two central incisors, two lateral incisors, two canines and four molars on each arch.

These teeth are set perpendicularly in the arch and start to erupt at around six months of age. These teeth eventually fall out to allow the eruption of permanent teeth.

Permanent dentition, on the other hand, consists of 32 teeth i.e. 16 teeth per arch. The types of teeth are similar to that of the deciduous dentition with an addition of two premolars in each arch.

Unlike deciduous teeth, permanent teeth are placed obliquely in the dental arch. They start to erupt at the age of six years with the exfoliation of the deciduous teeth.

What can you do to maintain healthy teeth?

Many parents don’t take care of their child’s primary teeth because of the misconception that primary teeth do not have any adverse effects on the mouth and will eventually fall out.

But this concept is not true at all. Deciduous teeth require more attention and care as they act as guides for the proper development and eruption of the permanent successors.

If the deciduous teeth are pulled or lost early, they can lead to crowding of permanent teeth. (3)

Good oral hygiene practice will help the child to learn proper technique and prepare him to take care of the permanent teeth later in life.

An excellent dental practice included brushing with a toothbrush and a toothpaste in a circular motion, twice a day.

Consult the dentist as soon as the deciduous teeth start to erupt to keep a check on the growth and development of the teeth and also to prevent dental caries.


Take away message

Now that you know that the difference between deciduous and permanent teeth, you may understand their importance in our mouth.

Both the dentitions are equally crucial for the development of our mouth and body.

Taking proper care of each dentition will help to keep the teeth healthy and free from the harmful effects of oral bacteria and dental caries.


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