Why do Teeth Become Crooked (Misaligned)?
12.02.2026

What Are the Causes of Dental Crowding?

Dental crowding or misalignment is one of the oral health problems caused by teeth not being positioned where they should be. The severity of crowding can vary from person to person and may therefore require different treatment methods. In some patients, teeth may be tightly crowded, while in others they may be spaced apart with visible gaps between them.

There are many reasons why dental crowding can occur. Some of these causes are genetic. However, certain factors can be prevented at an early age. Why do teeth become crowded? What causes dental misalignment? If you have questions like these, you can read our article to find the right answers.

What Causes Dental Crowding? Why Do Teeth Become Misaligned?

If you are wondering why teeth become crowded, the answer may be genetic factors or incorrect practices. Dental crowding or misalignment may develop due to hereditary reasons, improper habits, or precautions that were not taken in time.

  • Genetic Inheritance: One of the primary causes of dental crowding is genetic factors. Genetic traits passed down from parents or previous generations can lead to misaligned teeth. Conditions involving the jaws are especially hereditary. For example, a lower jaw positioned ahead of the upper jaw may be inherited. If a child inherits a small jaw from one parent and large teeth from the other, crowding is likely to occur. Excessively small or large jaws are often genetic. Similarly, missing teeth, extra teeth, impacted canines, or the presence of a prominent labial frenum (frenulum) may be inherited and can contribute to crowding or spacing issues.
  • Premature Loss of Baby Teeth or Severe Decay: One of the most common causes of dental crowding is the early loss of primary (baby) teeth. Excessive consumption of sugary foods and poor oral hygiene can cause baby teeth to decay and be lost before their natural exfoliation time. Baby teeth act as space maintainers and guide the eruption of permanent teeth. When a baby tooth is lost prematurely, adjacent teeth may shift into the empty space. Since chewing cannot occur properly in that gap, neighboring teeth naturally drift into it. As a result, the permanent tooth developing underneath may erupt crooked, misaligned, or may even remain impacted due to lack of space. Therefore, if a baby tooth is lost prematurely for any reason, a space maintainer should be placed immediately and kept until the permanent tooth erupts.
  • Harmful Functional Habits: Regardless of age, disrupting a normally balanced oral system can lead to crowding and serious jaw problems. Habits such as nail biting, thumb sucking, biting pens, sucking the lower lip, frequently placing hands in the mouth, and swallowing disorders (infantile swallowing, simple tongue thrust, complex tongue thrust) can cause significant misalignment of the teeth and jaws. Even if orthodontic treatment corrects these issues, restarting the harmful habit can disrupt the achieved balance and cause the teeth to become crowded again. Therefore, patients and parents must be aware and work to eliminate these habits.
  • Not Using an Orthodontic Pacifier or Bottle: In infants, prolonged use of non-orthodontic pacifiers or bottles may alter the shape of the palate. Long-term pacifier or bottle use can lead to structural changes in the palate, prevent proper contact of the front teeth (anterior open bite), and cause the upper palate to become excessively deep.
  • Trauma: Trauma is another answer to the question, “Why do teeth become misaligned?” Impacts to the mouth may result in tooth loss or ankylosis (fusion of the tooth to the bone).
  • Mouth Breathing: Another cause of dental crowding is breathing through the mouth instead of the nose. Mouth breathing disrupts biological balance and negatively affects the growth of the upper jaw first, followed by the lower jaw. It may cause narrowing of the upper jaw and developmental deficiency of the lower jaw. When the lower jaw remains positioned backward, it may result in Class II orthodontic problems. Ultimately, insufficient jaw development due to mouth breathing leads to dental crowding. Additionally, mouth breathing dries the palate, which can cause redness, swelling, and even bleeding of the gums. Proper breathing should occur with the mouth closed and through the nose only. The nose not only filters the air but also conditions it—warming cold air, cooling hot air, and humidifying dry air. Mouth breathing bypasses this natural system, potentially causing unwanted effects on the throat, tonsils, and lungs. Furthermore, when the nose is not used regularly, its capacity may decrease, creating a sensation of insufficient airflow. To treat mouth breathing, the underlying cause must be identified and eliminated.

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Tülay AKKOL

Chief Dentist

Tülay AKKOL

Chief Dentist and Tülay Akkol Dental founder Tülay Akkol shares valuable insights on dental health and care, offering practical tips for everyday life. Her articles also highlight the latest innovations and developments in dentistry, helping readers stay informed about the industry's advancements.

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