Crowded Teeth: Causes, Consequences and Correction
For adults with crowded or overlapping teeth: what crowding is, its causes, and evidence on wisdom teeth, age, cleaning and correction. In small studies of untreated adults, lower front teeth crowded more on average with age, and UK guidance cites analyses suggesting that removing impacted lower wisdom teeth is not indicated to prevent it.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
Dr Ibraheem Ijaz, principal dentist, reviewed this page. He is a General Dental Practitioner: BDS, BSc (Hons), MSc (Leeds), PG Dip Implant Dentistry, PG Cert Restorative and Aesthetic Dentistry.
What are crowded teeth?
Crowded teeth are teeth without enough room in the jaw, so they sit out of line or overlap each other.
Crowding is a form of malocclusion, meaning misaligned teeth, says MedlinePlus (US National Library of Medicine). Arch length discrepancy compares the space teeth need with the space available; Little's Irregularity Index totals lower front tooth displacement, in millimetres, across five contact points.
Why do teeth become crowded?
Teeth may crowd because of a difference between jaw and tooth size, and malocclusion is most often hereditary, MedlinePlus says.
The British Orthodontic Society (BOS) says a narrow jaw may mean there is not enough room for your teeth. MedlinePlus lists extra, lost, impacted or abnormally shaped teeth among the other causes of malocclusion.
Do wisdom teeth cause crowded teeth?
Crowding is multifactorial, says the Royal College of Surgeons of England (RCS), and wisdom teeth may play a significant role in some patients.
Its 2020 guidance says current knowledge cannot accurately identify who is at risk. Most studies suggest at least some role, which may not be clinically significant, but none isolates it from other factors, so cause and effect is difficult to establish.
The belief is that wisdom teeth coming through push the front teeth together. In a 2014 systematic review of 12 studies, most at high risk of bias, most found no correlation with more severe crowding and four described a different outcome. It said definitive conclusions cannot be drawn, but judged removal to prevent crowding not justified.
A UK trial randomised 164 adolescents after upper-arch orthodontic treatment to removal or retention of impacted wisdom teeth; 77 returned, 66 months later on average. The difference in lower front crowding was not statistically or clinically significant. Arch length shortened slightly less after removal, a statistically significant difference Cochrane calls unlikely to be clinically significant. It rates the trial at high risk of bias.
A 2024 meta-analysis of seven studies it classed as observational, all rated serious for confounding, found greater crowding with lower wisdom teeth present, significant overall and without previous orthodontic treatment, but not in people who had had it. It concluded they may contribute to crowding, and said removing them only to prevent crowding is not justified.
Two decision analyses RCS cites suggested removing impacted lower wisdom teeth is not indicated to alleviate or prevent crowding.
Do crowded teeth get worse with age?
They can. BOS says that as we get older teeth may start to move unpredictably, often showing some crossing over and increased crowding.
Lower front crowding appearing in adolescence or later is called late crowding. In 20 untreated young adults in Brazil, average Little's index rose from 4.64 mm at about 20 to 5.65 mm at about 31, and 55% increased by less than 1 mm. In 30 untreated people in Sweden with a normal bite at 13, it averaged 1.9 mm at 13, 3.5 mm at 31 and 5.0 mm at 62, when 21 remained.
The Swedish study concluded reductions in arch dimensions contribute to increasing lower front crowding, but did not test that link. The Brazilian study could not predict the rise from arch dimensions at about 20, and a 2003 US survey of 9,044 untreated people said the primary determinants of individual differences in crowding remained unidentified.
Our pages cover how teeth move and straightening teeth as an adult. If your lower front teeth start to crowd, show them to a dentist.
To ask about orthodontic treatment, book online or call 0114 288 2121.
Do crowded teeth affect cleaning and gum health?
Tooth position can make cleaning difficult: the NHS lists trouble chewing or keeping teeth clean as a reason braces may be needed.
Plaque is the primary cause of gum inflammation and periodontitis, a 2007 review says, and plaque-retaining conditions result in localised gingivitis, which rarely progresses to periodontal disease.
A 2008 systematic review, of studies of weak overall quality, found greater malocclusion went with more severe periodontal disease, which may depend on oral health status, and said association does not necessarily mean causation. It found no reliable evidence on orthodontic treatment's effects on gum health, with low-quality evidence suggesting small detrimental effects, and said its results do not warrant recommending treatment to prevent future gum problems, except for specific unusual malocclusions. A 2018 study of US men associated certain front tooth crowding and irregularity with periodontal disease progression.
Our page on cleaning between your teeth covers floss and interdental brushes. If crowding makes your teeth hard to clean, show them to a dentist.
How can crowded teeth be corrected?
Most alignment problems are minor and do not require treatment, MedlinePlus says.
It says treatments may include braces or other appliances, with clear aligners in some people; tooth extraction if overcrowding is part of the problem; repairing rough or irregular teeth; and, in rare cases, jaw surgery. Our pages on fixed braces and whether aligners suit severe crowding give more detail.
Can crowded teeth be fixed without extraction?
Sometimes. BOS says it may be possible to avoid extractions when there is crowding, but no advice applies to all patients.
Arch expansion can sometimes create space, BOS says, but is not always feasible or the most suitable approach, and there are limits to the space created. Interproximal reduction removes a very thin sliver of enamel from the sides of the teeth for some space, which is not possible or effective for all patients, particularly with a lot of crowding.
Extractions are necessary in some adults, BOS says, and for many people with more severe crowding may be inevitable to get the most stable result. Straightening severely crowded teeth without them risks pushing teeth outside the bone, causing later gum recession.
BOS treats claims of treatment without extractions, especially before an assessment, with considerable caution. A decision can only follow a detailed case assessment.
What are the limits of correcting crowding?
Teeth tend to move back after treatment. BOS calls this relapse, one of the most common problems.
It says wearing retainers long term can reduce age changes. If your teeth shift after treatment, show them to a dentist.
Does Deepcar Dental Care treat crowded teeth?
Yes. Orthodontic treatment at Deepcar Dental Care is for adults only, and mild to moderate crowding and spacing are among the problems treated.
Extraction and complex cases are assessed case by case; some need braces or a combined approach. Options offered include fixed metal, ceramic and lingual braces and clear aligners. See orthodontics at Deepcar Dental Care.
Frequently asked questions
How is the severity of crowding graded?
By how far teeth are displaced at contact points, among other features. The Index of Orthodontic Treatment Need, for adult teeth, puts displacements of 2 to 4 mm at grade 3, borderline need, and over 4 mm at grade 4, need treatment.
Should wisdom teeth come out before orthodontic treatment?
Royal College of Surgeons of England guidance says extracting wisdom teeth for orthodontic purposes is rare, though they should be considered during treatment planning. It adds that crowding at the back of the mouth, particularly the lower arch, may increase impaction risk, where a tooth gets stuck.
Can teeth crowd after wisdom teeth are removed?
Removal may not prevent late crowding, a 2024 meta-analysis says. It found less crowding with lower wisdom teeth missing or removed, but not after orthodontic treatment, in studies all rated serious for confounding. In a 2014 review of 12 studies, most at high risk of bias, most found no difference by wisdom tooth status and four a different outcome.
Does removing a sliver of enamel cause decay?
Limited evidence suggests not. The British Orthodontic Society says decay rates after interproximal reduction are no higher than in normal teeth, but plaque can collect more readily if the surface is not smoothed and polished. A 2022 review of 8 low to very low quality studies found no increase.
Do upper teeth crowd with age too?
In one small Swedish study of untreated people with a normal bite, both arches lost space on average. Among the 21 followed from 13 to 62, the upper arch lost 1.9 mm and the lower arch 3.1 mm.
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