Biological Reasons Why Baby Teeth Fall Out


Humans lose their baby teeth as a part of natural growth and development. This process typically begins around six years of age and is triggered by a biological process known as resorption. Resorption involves the body reabsorbing the root of the baby tooth, causing it to loosen and eventually fall out. Concurrently, permanent teeth develop in the jawbone, applying pressure to the roots of the baby teeth, further contributing to their loosening. The loss of baby teeth and their replacement with permanent teeth allows for a larger, stronger set of teeth, better adapted to the dietary and speech needs of a growing individual.

The Development and Function of Baby Teeth

The first stage of oral development in humans begins with the eruption of baby teeth. This typically commences around six months of age, although there is considerable variation. By the time a child reaches three, they usually have a full set of 20 baby teeth, ten in each jaw. These teeth play a crucial role in a child’s early development.

Baby teeth facilitate the process of learning to speak and pronounce words correctly. Moreover, they act as placeholders in the jaw, ensuring there’s adequate space for the larger permanent teeth that will eventually replace them. Structurally, baby teeth have a thinner layer of enamel, the outer protective layer, compared to permanent teeth, making them more susceptible to decay.

The Biological Process of Losing Baby Teeth

The process of losing baby teeth begins with a phenomenon called resorption. This is when the body begins to reabsorb the root of the baby tooth, causing it to loosen. As the root disappears, the tooth becomes increasingly wobbly until it finally falls out. This usually starts around age six, though, as with the eruption of baby teeth, the timing can vary.

Simultaneously, permanent teeth begin to develop and push up in the jawbone, applying pressure to the roots of the baby teeth above them. This pressure also contributes to the resorption process and the ultimate dislodgement of the baby teeth.

The Emergence of Permanent Teeth

Diagram showing complete dental formula and at what age each tooth comes out

The permanent teeth start to erupt once the baby teeth have fallen out, a process that continues into late adolescence. By the age of 21, most individuals have a complete set of 32 permanent teeth, including the third molars or “wisdom teeth.”

Below is a general timeline for when you can expect each type of tooth to grow, both for baby (deciduous) teeth and permanent teeth:

Baby Teeth:

  • Central Incisors: The central incisors are usually the first teeth to erupt. The lower central incisors tend to appear around 6-10 months of age, while the upper ones come in around 8-12 months.
  • Lateral Incisors: The upper lateral incisors usually erupt around 9-13 months of age, and the lower lateral incisors appear around 10-16 months.
  • Canines (Cuspids): Baby canines typically erupt between 16-22 months of age.
  • First Molars: The first set of baby molars generally appears between 13-19 months.
  • Second Molars: The second set of baby molars typically erupt between 25-33 months.

Permanent Teeth:

  • First Molars and Central Incisors: These teeth are usually the first permanent teeth to erupt, typically appearing between 6-7 years of age.
  • Lateral Incisors: These generally appear between 7-8 years of age.
  • Canines (Cuspids): Permanent canines often erupt between 9-12 years of age.
  • Premolars (First and Second): The first and second premolars typically appear between 10-12 years of age.
  • Second Molars: These usually erupt around 11-13 years of age.
  • Third Molars (Wisdom Teeth): Wisdom teeth, if they develop and erupt, typically do so between 17-21 years of age, though this can vary significantly.

Please note that these timelines are averages and can vary from person to person. It’s also worth mentioning that girls generally tend to get their teeth a little earlier than boys.

These permanent teeth are designed to meet the demands of adult oral functions, including the need to chew harder foods and facilitate more complex speech patterns. Structurally, they are larger, stronger, and have a thicker layer of enamel compared to baby teeth.

Dental Formula

The Importance of the Tooth Loss and Replacement Process

Losing and replacing teeth is a necessary process in the development of the oral cavity. As a child grows, their jaw also expands, necessitating more substantial and numerous teeth to accommodate increasing dietary demands. Losing baby teeth and their replacement with permanent teeth is a crucial biological adaptation to these changes.

The transition also prepares the mouth for a diet that includes harder, tougher foods, requiring more force to chew. It is a critical phase in ensuring the overall functionality and health of the oral cavity. As such, any premature or delayed tooth loss should be evaluated by a dental professional to prevent potential complications.

Tooth Structure

The parts of a human tooth

A tooth is composed of several parts, each with specific functions:

  • Crown: The visible part of the tooth above the gum line. It’s covered with enamel, the hardest substance in the human body, which protects the tooth from decay.
  • Root: The part of the tooth below the gum line that anchors the tooth to the jawbone.
  • Enamel: The outermost layer of the tooth, composed mostly of calcium and phosphate. It’s highly mineralized and protects the tooth from physical and chemical damage.
  • Dentin: The layer beneath the enamel, less mineralized and harder than bone but softer than enamel. It protects the innermost part of the tooth, the pulp.
  • Pulp: The innermost part of the tooth, containing blood vessels and nerves. It provides nutrients to the tooth and allows for sensation.
  • Cementum: A layer of connective tissue that covers the tooth root, helping to anchor the tooth to the bone.
  • Periodontal Ligament: A tissue that helps hold the tooth in the socket, provides sensory input, and aids in tooth eruption and positioning.

Tooth Function

Each type of tooth has a specific function in the mouth related to processing food:

  • Incisors: The sharp, chisel-shaped front teeth (four upper, four lower) used for cutting food.
  • Canines: These are sharp and pointed teeth located beside the incisors used to tear food.
  • Premolars: These are larger than canines, have a flat surface with ridges, and are used to crush and grind food.
  • Molars: The flat, large teeth at the back of the mouth used for grinding and breaking down food into smaller pieces that are easier to swallow.

Disorders and Complications Related to Tooth Loss and Replacement

Despite the body’s innate ability to manage the transition from baby teeth to permanent teeth, problems can occur. These can include impacted teeth, where a tooth fails to break through the gum, or over-retained baby teeth, where baby teeth remain in place while the permanent tooth erupts alongside it.

Both conditions can cause complications such as overcrowding, misalignment, and oral discomfort. Treatment options vary depending on the severity and can range from monitoring the situation to surgical intervention.

Prevention remains the best course of action, which underscores the importance of regular dental check-ups, particularly during childhood when the dentition is transitioning. Emphasizing good oral hygiene habits from an early age is also critical. Teaching children about brushing, flossing, and the significance of a balanced diet can help ensure a smooth transition from baby teeth to permanent teeth and maintain oral health in the long run.


The loss of baby teeth and the emergence of permanent teeth is a fascinating and essential aspect of human development. This process, dictated by complex biological mechanisms, underscores the body’s remarkable ability to adapt to the changing needs of a growing individual. The transition from baby teeth to permanent teeth is not just about physical maturation, but also about preparing the child for adult functions such as consuming a varied diet and facilitating mature speech patterns.

Understanding the reasons why we lose our baby teeth helps us appreciate the complexity of our bodies and the importance of oral health. A healthy transition from baby teeth to permanent teeth can have a lasting impact on a person’s oral and general health, emphasizing the need for proper dental care from a young age. With regular dental check-ups, good oral hygiene, and a balanced diet, the journey from baby teeth to a permanent set can be a smooth ride.

Every wobbly tooth and every gap-toothed smile is a testament to the marvel of human growth and development. It serves as a biological milestone, marking the transition from childhood to adulthood, and plays a pivotal role in our ability to eat, speak, and smile confidently throughout life. Understanding this process, therefore, provides critical insights into our own development, health, and well-being.

It is also a reminder of the importance of dental health, not just in terms of maintaining a bright smile, but also in supporting overall health and quality of life. So, as we celebrate each lost baby tooth, we’re also celebrating the intricate biological processes that enable us to grow, thrive, and lead healthy lives.

Gerald Omondi
Gerald Omondi
As a writer, I have a passion for exploring a variety of topics. When I'm not putting pen to paper, I enjoy traveling and spending time with my family. As a husband and father, I understand the importance of balance and finding time for the things I love. Whether I'm delving into new subjects or spending quality time with my loved ones.


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