What are crowded teeth?

Crowded teeth occur when there is not enough room in your mouth for your teeth and is one of the most frequent malocclusions (bad bites) seen in orthodontic practice. With crowded teeth, there is an inconsistency between the size of your teeth and your dental arch which houses all your teeth. This results in your teeth being positioned incorrectly in your mouth; for example, they can overlap with one another as there is not enough space for adjacent teeth.^1,2

Why is it important to acknowledge crowded teeth?

Sadly, crowded teeth can become difficult to clean, which can result in the accumulation of plaque and poor oral hygiene leading to a range of dental and medical problems such as dental cavities and possibly periodontal (gum) disease.^1,3

Understanding Crowded Teeth

Anatomy of the mouth and teeth

During your lifetime, you have two sets of teeth: 

• Primary Teeth (milk teeth)

You have 20 primary teeth that are split between your top jaw (maxilla) and your lower jaw (the mandible). When your primary teeth are lost these are replaced with your permanent teeth.⁴ 

• Permanent teeth

You have 32 permanent teeth, split evenly between your mandible and maxilla, which contain the following:⁴

• Canines
• Incisors
•  Premolars
• Molars

Compared to your permanent teeth, your primary teeth do not contain premolars but do contain molars, canines and incisors. ⁴

Common causes

• Crowded teeth are commonly caused by your genetics, with crowded teeth having a high likelihood of being passed down through families. Therefore, if your family history shows that there is a prevalence of crowded teeth, this can sadly increase your likelihood of developing crowded teeth.²
• Other causes include your permanent teeth not coming through correctly after you lose your milk (primary)  teeth or possibly losing your primary teeth too early, which causes other teeth in your mouth to evade the gap of the lost tooth/teeth.⁵ 

Which factors contribute to crowded teeth?

Genetics

Dental crowding can be attributed to genetic factors, with genetics determining your dental arch size. A smaller dental arch may make it difficult to house all your teeth, resulting in dental crowding and your teeth overlapping one another.^2,6

Tooth size and arch size discrepancies

Dental crowding can also be attributed to tooth size and dental arch discrepancies. This means that the dental arch may be too small to house all of your teeth, resulting in dental crowding. Your teeth may also be too large for your dental arch, resulting in overlapping of your teeth, and dental crowding.²

Potential complications of crowded teeth

Potential complications of crowded teeth can include the following:

• Low self-esteem: crowded teeth can cause your teeth to look crooked and misaligned, which can result in low self-esteem or possible bullying/teasing, leading to low self-esteem. This can be common if you have a child with crowded teeth as they may be subjected to teasing from other children for having crowded teeth, which may very sadly lower their self-esteem⁷
• Dental cavities: dental cavities can arise when you have crowded teeth due to them being difficult to clean, and plaque accumulating on your teeth³
• Periodontal (gum disease): periodontal disease may occur if you have crowded teeth due to plaque buildup on your teeth that has arisen due to poor cleaning and poor oral hygiene practices.³

Diagnosis of crowded teeth

Dental examination

During a dental examination, if your dentist suspects that you have crowded teeth, they will take dimensions and measurements of your teeth and your dental arch using an instrument known as a digital calliper. Crowding of the teeth is then measured as the difference between the size of your teeth and the dimensions of your dental arch.²

Imaging techniques

X-rays

Imaging techniques such as X-rays have been used to visualize the anatomy of your teeth to help aid in the diagnosis of crowded teeth. However, X-rays produce 2D photographs of a 3D object- your teeth, which can cause problems such as geometric distortion, and different structures in the mouth can be covered by others, which can make it difficult to diagnose crowded teeth.⁸

Cone-beam computed tomography (CBCT)

Moving away from 2D imaging, such as X-rays, cone beam computed tomography (CBCT) has been used in dentistry to diagnose conditions such as crowded teeth. CBCT produces high-resolution 3D images of structures in the mouth, aiding your dentist in diagnosing crowded teeth by being able to visualise the structures in your mouth better.⁸

Consultation with orthodontist

An orthodontist can help to improve the appearance of your crowded teeth. In a consultation, they can offer a treatment plan to correct your dental crowding and help you straighten your teeth. Orthodontic treatment is usually done using fixed braces to correct crowded teeth. However, there are other methods of straightening your teeth. Your exact course of treatment will depend on the severity of the crowding of your teeth.⁹ 

Treatment options

Orthodontic solution

Traditional braces

As previously discussed when diagnosing crowded teeth your dentist will do a measurement of the discrepancy between your total tooth size and the dimensions of your dental arch (which houses all of your teeth).² The discrepancy between tooth size and arch size is measured in millimetres (mm).⁷ 

• Crowded teeth can be prevented or treated using traditional braces if the crowding is measured as being mild (which is defined as a discrepancy of less than 4mm between arch size and tooth size).
• If the crowding of your teeth is moderate (between 4mm to 8mm), you may need to have a tooth or teeth removed before having traditional braces.¹⁰

Typically, traditional braces are used on your permanent teeth and are attached to each of your teeth using dental glue, with a bracket that holds a thin wire along all your teeth to help straighten them and remedy your crowded teeth.⁷

Clear aligners

Firstly, you may ask what are clear aligners?

Clear aligners are transparent plastic ‘mouthguards’. They are designed specifically to fit over your teeth and move the teeth in a certain manner, according to your treatment plan with your orthodontist.¹¹

Similar to traditional braces, clear aligners have also been used to treat mild to moderate levels of dental crowding. Clear aligners can also be used for relapsed dental issues too, that were previously treated using a fixed brace.  You may ask: which is better, a fixed brace or a clear aligner? Sadly, research studies have not found a definite answer to this question. There is an issue that clear aligners may not produce as much tooth movement as predicted, which may hinder their ability to correct crowded teeth.¹⁰

However, the benefits of the clear aligner include that it is removable, unlike a fixed brace, and can be taken out for brushing your teeth and eating. Clear aligners are also less noticeable than fixed braces if you are concerned about the appearance of your brace/aligner, and are notably more comfortable.¹²

Lingual braces

Lingual braces are braces that are fitted behind the teeth and are commonly used by patients who do not want it to be seen that they are having their teeth straightened. Currently, approximately 10% of registered orthodontic specialists in the UK offer this treatment.¹³ 

Lingual braces are favoured among patients due to them not being able to be seen and due to them having 3D control of tooth movement, allowing your teeth to be straightened and aiding in the treatment of crowded teeth.¹⁴

Surgical interventions

Tooth extraction

There has been debate in the orthodontic community about whether or not teeth should be extracted for orthodontic treatment. However, tooth extraction can be a crucial part of the orthodontic treatment of crowded teeth as typically there is a shortage of space in the dental arch to house all of your teeth, resulting in dental crowding.^1,15

Jaw surgery (orthognathic surgery)

Surgery may also be an option in the treatment of severe crowded teeth. For example, surgical expansion of the mandible (lower jaw) can be used to treat crowding of your teeth on the lower jaw.²

Other treatment options

Interproximal reduction

Interproximal reduction is used in orthodontics to create space in your mouth for your teeth to be aligned. Interproximal reduction involves removing up to 0.5mm of enamel off the sides of your teeth to create room in your mouth for straightening your teeth. However, it is important to acknowledge that removing too much enamel from your teeth can be harmful and leave them vulnerable to decay.¹⁶ 

Expansion devices

Expansion devices include a palate expander, which widens the jaw, creating more room to house your teeth. This resolves crowded teeth and helps to avoid alternative treatments such as tooth extraction, which are not favoured by patients.¹⁷

Prevention of crowded teeth

1. Early intervention in childhood

Crowded teeth can be prevented for some in childhood using fixed braces if the crowding is described as being mild (less than 4mm).⁸

2. Regular dental checkups

You should typically have a dental checkup once every 6 months. This will allow the dentist to see if there are any dental problems (such as dental crowding), allowing them to be detected early and treatment plans to be put in place and implemented.¹⁸ 

3. Diet considerations

Studies have suggested that poor nutrition may be linked to crowded teeth, with malnutrition in animals being linked to a reduction in jaw size.¹⁹ Ensuring you have good nutrition in your diet helps to ensure that you have good oral health. Therefore you should ensure that your diet is rich in micronutrients, water, fibre, carbohydrates, proteins, and fats that all help to support your oral health.¹⁹

4. Oral exercises
   • Your resting tongue posture is believed to be important in the morphology of your jaw, and incorrect tongue posture can result in malocclusion (bad bite). Correct tongue posture is when the tip of your tongue rests behind your front teeth at the roof of your mouth, not on the floor of your mouth.²⁰ This includes eliminating habits associated with incorrect tongue posture, such as sucking or chewing on the fingers, which cause the tongue to not rest in the correct position.²¹
   • In addition, correct lip posture can reduce the occurrence of dental malocclusions and shorten the duration of orthodontic treatment for dental malocclusions.²¹ Correct lip posture is when the lips are relaxed and they hang loosely apart, or the lips touch lightly, creating a seal of the mouth.²²

Summary

Crowded teeth are defined as a malocclusion (bad bite) and occur when there is a discrepancy between your dental arch size dimensions and the size of your teeth, this can cause your teeth to overlap, giving the appearance of crowded teeth.  They are largely attributed to genetic factors, where you may inherit a smaller dental arch or larger tooth size from someone in your family. It is important to address crowded teeth as they can become difficult to clean, resulting in cavities forming and periodontal (gum disease).  

Crowded teeth can be a source of low self-esteem and possible bullying, sadly. They are usually diagnosed via scans, such as X-ray or CT scans, or via measurements taken of your dental arch and teeth to see what the discrepancy between them is. Crowded teeth can be prevented in childhood with fixed braces for mild crowding on your permanent teeth and are treated using fixed braces, clear aligners, lingual braces, tooth extraction, jaw surgery, expansion devices or interproximal reduction. You should seek professional advice from a dentist/orthodontist about possible  treatment for crowded teeth