Causes Of Crooked Teeth


Our faces are unique, and so are our teeth. Having crooked or crowded teeth can affect our appearance and confidence, with a consequence on our social interactions and overall quality of life.

So, what are crooked teeth, and what are their causes?

Crooked teeth happen when teeth are not aligned properly or not in the correct position. They can negatively impact our well-being by affecting our smile and self-esteem. Crooked teeth can also affect our speech and chewing ability and cause jaw pain. In addition, crooked teeth can lead to more severe dental problems, like tooth decay, gum disease, and tooth loss.

Let’s understand the causes of crooked teeth, their impact on health, and the available options to straighten them.


Inherited traits

Crooked teeth can be genetic; in which children are more likely to develop crooked teeth if one or both parents have similar dental issues.1

Jaw size and shape

The size and shape of a child's jaw and teeth are largely determined by genetic factors. Some children may inherit traits that can impact the alignment of their teeth, such as a small jaw or large teeth than the available space.1

Misaligned or crooked teeth occur when the jaw size is smaller than usual. If the lower jaw is smaller than the upper jaw, it leads to the overbite problem (the upper teeth protrude over the lower teeth). While if the upper jaw is smaller than the lower jaw, it results in underbite problem (the lower teeth protrude over the upper teeth).2

Developmental problems

Prenatal development

The primary or baby teeth begin forming in the 6th week of pregnancy.3 Then, continue mineralizing and building the dentin and the enamel layer around the 3rd to 4th months. Thus, the mother's diet must be adequate in all nutrients, especially phosphorous, calcium, vitamin D, and protein, to facilitate this process.

Nutritional deficiency and poor oral health during pregnancy can lead to gingival problems, such as gingivitis or periodontitis, which increase the risk of premature birth.4 Premature babies may have a wide range of dental issues, including delayed tooth growth, changes in tooth color, and crooked or out-of-place teeth.

Childhood development

Children may experience developmental issues such as jaw growth problems or craniofacial abnormalities that can impact the positioning of the teeth.1

  • Jaw growth problems can result in an underdeveloped lower jaw, overdeveloped upper jaw, or asymmetrical jaw growth. These issues can cause misalignment of the teeth, crowding, crooked teeth, or an uneven bite
  • Craniofacial abnormalities are a group of conditions that affect the skull and facial bones. These abnormalities can affect the growth and development of the teeth and jaw, resulting in misalignments of the teeth5

Tooth development

There are several stages of teeth development during childhood. Any issues during these stages can affect teeth development and result in crooked teeth or other dental problems. The baby teeth serve as placeholders for the permanent teeth that guide them into their proper position. If a baby tooth is lost too early, the surrounding teeth will shift toward the space, limiting the room for the permanent one to erupt. As a result, the permanent tooth will grow at an angle or in the wrong position, leading to crooked teeth. On the other hand, if a baby tooth is lost too late, the permanent tooth may not have enough space to come in properly, resulting in crowding or misalignment.6

Behavioural habits

Thumb sucking

Sucking on a thumb or pacifier can cause crooked teeth, particularly if the habit persists beyond the age of five. The pressure exerted by the thumb pushes the teeth out of alignment, leading to malocclusions.7

Tongue thrusting

Tongue thrusting is a habit where the tongue pushes forward against the teeth when swallowing, speaking, or at rest. This can create abnormal pressure on the teeth, which can lead to orthodontic problems.7,8

Mouth breathing

Mouth breathing causes the tongue to rest in a low position in the mouth rather than on the roof. The pressure exerted by the tongue on the mouth's roof helps to stimulate the growth and expansion of the palate. When babies breathe through their mouths instead of their nose, the tongue will not be placed properly on the mouth's roof. As a result, the palate may not develop to its full size, resulting in a narrow palate and insufficient space to accommodate the teeth.8

Trauma or injury

Facial trauma

Facial trauma, such as mouth injury, can cause teeth to shift or become displaced, resulting in misalignment and crooked teeth.9

Tooth loss

Tooth loss can cause crooked teeth, especially if the missing tooth is not replaced promptly. When a tooth is lost, the surrounding teeth may shift to fill the gap, causing them to become crooked or misaligned.10

Dental problems

Misaligned teeth

Misaligned teeth are improperly aligned teeth in the mouth, which can cause crooked or overlapping teeth, in addition to problems with speech and chewing. Misaligned teeth can also increase the risk of dental problems such as tooth decay, gum disease, and jaw problems.


Overcrowding occurs due to insufficient space in the jaw to accommodate all the adult teeth, leading to overlap or crooked teeth. Overcrowded teeth are difficult to clean properly, which increases the risk of tooth decay and gum diseases. It can also cause problems with biting and chewing.

Missing teeth

Missing teeth cause the surrounding teeth to shift into the space, leading to misalignment and an uneven bite. Over time, this can lead to crooked teeth, gaps between teeth, and other dental issues. In addition, missing teeth can also affect the jawbone, causing it to deteriorate or shrink, which further contributes to misalignment.

Medical conditions

Cleft lip and palate

Cleft lip and palate are congenital conditions occur when the tissues that form the lip or palate do not completely fuse during fetal development, leading to an opening in the lip or palate. Children with cleft lip or palate experience dental issues, including misaligned teeth, gaps between teeth, crooked teeth, and problems with their bite.11

Down syndrome

Children with Down syndrome are prone to have a small jaw, large tongue, and undersized, crooked, and irregularly shaped teeth.12 The smaller jaw can lead to crowding and misalignment of the teeth. While; the large tongue can affect the position of the teeth and lead to malocclusion. In addition, undersized and irregularly shaped teeth can contribute to other dental problems.

Ehlers-danlos syndrome

A group of inherited disorders that affect the connective tissues in the body, including those in the teeth and gums. People with EDS may experience dental problems, like crooked or crowded teeth and malocclusion.13,14

Lifestyle factors

Poor nutrition

Poor nutrition can contribute to crooked teeth in several ways:15

  • Malnutrition: A diet that lacks essential vitamins and minerals affects teeth and jaw development, leading to misalignment and other dental issues
  • High sugar intake: High sugar diet increases the risk of tooth decay, which can lead to the loss of teeth and contribute to crooked teeth
  • Soft food diet: A diet that consists of only soft and processed foods can lead to weaker jaw muscles and a lack of stimulation to the teeth, causing them to shift and become misaligned

Smoking and tobacco use

Smoking and tobacco use negatively affects oral health. The nicotine and other chemicals in tobacco products can cause gum disease and damage the bone and soft tissues that support teeth, leading to tooth loss and misalignment.16,17 Additionally, smokers are more likely to have a dry mouth, which can lead to a buildup of bacteria in the mouth and an increased risk of tooth decay and gum disease.

Alcohol consumption

Excessive Alcohol consumption decreases saliva production, leading to dry mouth and increasing the risk of tooth decay and gum disease. In addition, excessive alcohol consumption affects calcium absorption and vitamin D metabolism, which decreases bone density and affects teeth development, leading to misalignment and crooked teeth.18

How to Straighten Crooked Teeth

Fortunately, several options are available to address crooked teeth and straighten them. Orthodontic treatment, such as braces or clear aligners, can help shift teeth into the correct position.2 A palatal expander is also used to correct crooked teeth in children that have a small mouth. It works by gradually widening the jaw to create more space for teeth to align properly. In some cases, tooth extraction or surgery may be necessary to create more space in the mouth.


Crooked teeth can negatively affect our appearance, self-esteem, oral hygiene, speech, and chewing. They can have various causes, including genetics, jaw alignment, and childhood habits like thumb sucking or tongue thrusting. Several options are available to treat crooked teeth. However, it is advisable to consult a dental professional if you have concerns about the alignment of your teeth. They can determine the best course of treatment to help you achieve a healthy and beautiful smile.


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  2. Agbim COA, Koutroulis I. Dental emergencies involving oral hardware. In: Koutroulis I, Tsarouhas N, Lin RJ, Posner JC, Seneff M, Shesser R, editors. Emergency Management of the Hi‐Tech Patient in Acute and Critical Care [Internet]. 1st ed. Wiley; 2021 [cited 2023 Mar 21]. p. 209–14. Available from:
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  9. Gadre KS, Kumar B, Gadre DP. Panfacial fractures. In: Bonanthaya K, Panneerselvam E, Manuel S, Kumar VV, Rai A, editors. Oral and Maxillofacial Surgery for the Clinician [Internet]. Singapore: Springer Nature; 2021 [cited 2023 Mar 21]. p. 1283–302. Available from:
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  11. Alois CI, Ruotolo RA. An overview of cleft lip and palate. JAAPA [Internet]. 2020 Dec [cited 2023 Mar 21];33(12):17. Available from:
  12. Sáenz-Torres ME, Rincón-Méndez AY. Families’ experiences in oral health care of Down Syndrome children from a foundation in Bucaramanga, Colombia. Revista Facultad de Odontología Universidad de Antioquia [Internet]. 2020 Aug 24 [cited 2023 Mar 21];32(2):33–41. Available from:
  13. Lepperdinger U, Zschocke J, Kapferer-Seebacher I. Oral manifestations of Ehlers-Danlos syndromes. Am J Med Genet C Semin Med Genet. 2021 Dec;187(4):520–6.
  14. Kapferer-Seebacher I, Schnabl D, Zschocke J, Pope FM. Dental manifestations of ehlers-danlos syndromes: a systematic review. Acta Derm Venereol. 2020 Mar 25;100(7):adv00092.
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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Mayasah Al-Nema

PhD Pharmaceutical Sciences – MSc Pharmaceutical Chemistry – BSc Pharmacy, UCSI University, Malaysia

Mayasah is a skilled and experienced scientific researcher and writer with over seven years of experience in writing scientific articles and books. In addition to her expertise in research, she has three years of experience as a teaching assistant at UCSI University, providing her with valuable insights into effective teaching practices. Mayasah has participated in numerous international conferences, where she has presented her research findings to peers and colleagues. She is also a respected peer-reviewer for three prominent scientific journals, providing expert analysis and feedback on articles submitted for publication.

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