Most adults develop up to four third molars (“wisdom teeth”), but some people develop an additional supernumerary molar. An extra molar behind a third molar is often called a distomolar or fourth molar. A small extra tooth beside the usual molar row may be called a paramolar. So a person can appear to have five wisdom teeth, although the additional tooth is not technically a fifth normal third molar.
How many wisdom teeth do people usually have?
Wisdom teeth are the third molars, the last molars in each quadrant of the mouth. A person may develop zero to four of them. They often become visible in the late teens or twenties, but timing varies, and some remain unerupted. A panoramic X-ray can show teeth that have not come through the gum. Not everyone develops all four third molars, and missing third molars are a separate variation from having an extra tooth.
When an X-ray or examination suggests five molars in the back, a dentist first checks whether the teeth are actually third molars or whether one is supernumerary. The terms “fifth wisdom tooth” and “extra wisdom tooth” are understandable descriptions, but they can blur that distinction. Dentists use the tooth’s location and shape to classify it more precisely.
Third molars are not automatically useless or unhealthy. Some erupt in a position that can be cleaned and remain functional. Others are partly covered by gum, angled, difficult to clean or associated with disease. The same is true of a supernumerary molar: its location and condition matter more than the unusual count. For background on normal eruption timing, see our guides to when wisdom teeth erupt and when they stop growing.
What are distomolars and paramolars?
A supernumerary tooth is an additional tooth beyond the usual primary or permanent set. A distomolar is located behind a third molar; it is also sometimes called a fourth molar. A paramolar sits beside the molar row, commonly on the cheek or palate side. The location may affect whether the extra tooth erupts, remains buried in bone or overlaps with another tooth.
Some extra teeth have a familiar molar shape; others are smaller or differently shaped. An X-ray can show a hidden tooth, but a dentist interprets it together with an oral examination and the person’s dental history. An extra tooth may be mistaken for another structure or may be difficult to classify from one image alone. If you have questions about a finding, ask the dentist to point out which tooth is extra and where it sits in relation to the third molar.
Why might an extra molar develop?
The exact cause of an isolated supernumerary molar is not established. Research supports a genetic contribution to supernumerary teeth overall, but it has not identified one gene that explains every extra tooth or every location. Proposed developmental explanations include altered activity in the tissue that forms teeth, sometimes described as localized dental-lamina hyperactivity. These ideas are hypotheses, not a confirmed explanation for an individual person’s fifth molar.
It is not accurate to say that a fifth wisdom tooth is known to result from a PAX9 mutation. PAX9 is a tooth-development gene, and variants are well documented in tooth agenesis, meaning congenitally missing teeth. That does not establish PAX9 as the cause of an isolated extra wisdom tooth. Family patterns can be relevant to a dentist’s history-taking, but they do not prove a single inherited mutation.
Diet and brushing habits do not determine whether an extra tooth bud forms. Oral hygiene can affect plaque, decay and gum inflammation around a tooth that has erupted or partly erupted, but it does not create an additional tooth during development. A person should not blame themselves for an extra molar or assume that a parent passed down a specific mutation.
How rare is it to have an extra molar?
Posterior supernumerary molars are uncommon, but prevalence varies with the population studied, the age range, the definition used and whether records came from a referred dental clinic or a broader community. Studies of posterior extra molars are not the same as studies that count exactly five wisdom teeth. There is no precise global percentage for “having five wisdom teeth” that applies to every population.
For example, one retrospective study of 25,186 young patients in a referred Italian population found posterior supernumerary molars in 0.18% of subjects. Another study examined panoramic images from 10,111 non-syndromic adults in Turkey and reported distomolars in 0.26%; most of the identified distomolars in that sample were impacted. These figures describe those samples, not a person’s individual probability.
A 2026 radiographic study of 10,000 panoramic images reported distomolars in 0.37% of patients and paramolars in 0.12%. The study grouped teeth by type and position, so its results should not be presented as the prevalence of exactly five wisdom teeth. Differences between studies are a reason to give context with every number, rather than combine estimates into a universal rate.
Claims that a particular racial or ethnic group is more likely to have a fifth wisdom tooth should not be made without strong, comparable population evidence. The studies cited here sampled specific clinical populations and do not justify predicting an individual’s tooth count from a broad racial label.
What problems can an extra molar cause?
Possible effects depend on position
Many extra molars are found incidentally on dental images, and some do not cause symptoms. Others may be impacted, interfere with eruption of a nearby tooth, create a local cleaning challenge or contribute to decay or gum problems. Less commonly, a tooth may be associated with a cyst or another pathologic change. These are possibilities to assess, not outcomes that happen to everyone with an extra molar.
An extra molar can affect the local molar area, but it does not predictably push every other tooth forward or change the entire bite. Crowding and tooth movement have multiple possible causes. A dentist or orthodontist would need to examine the bite and images before connecting a particular change to a supernumerary tooth.
- Impaction: the tooth remains partly or fully within the jaw.
- Local eruption or alignment issue: the extra tooth may affect a nearby molar or its path.
- Cleaning difficulty: a partly erupted tooth or tight space can be harder to keep clean.
- Decay or gum inflammation: risk depends on access for cleaning and the condition of the surrounding tissues.
- Uncommon pathology: imaging may reveal a cystic change or another finding that needs assessment.
Persistent pain, swelling, bad taste, drainage or difficulty opening the mouth warrants dental advice. Facial swelling with fever, difficulty swallowing or difficulty breathing needs urgent professional care. Symptoms do not tell you by themselves whether an extra tooth is present; examination is needed. Our overview of wisdom-tooth pain and article on possible eruption symptoms provide related context, but they are not a substitute for diagnosis.
How do dentists find and assess it?
Two-dimensional images are often enough to start
A dentist may notice an extra tooth during an examination or on radiographs taken for a clinical reason. Panoramic radiography is commonly used to view the jaws and identify unerupted or unusually positioned molars. The dentist considers the tooth’s location, eruption status, relationship to neighboring roots and surrounding bone, symptoms, oral hygiene access and any changes on prior images.
Three-dimensional cone-beam computed tomography (CBCT) is not automatically needed for every extra molar. It may be considered when a more detailed view would change diagnosis or treatment planning—for example, when the tooth’s relationship to a nerve, sinus or adjacent root is unclear. Current dental imaging recommendations emphasize selecting images for the individual clinical question and using CBCT only when its additional information is justified.
- Review the finding: identify whether the tooth is a third molar or an additional tooth, and note its position.
- Check the surrounding area: assess eruption, neighboring teeth, gum health and any symptoms.
- Compare images when available: determine whether the tooth or nearby structures have changed.
- Choose only useful imaging: use a 3-D scan when the extra detail is expected to affect care.
Does an extra wisdom tooth need to be removed?
Observation can be a reasonable plan
No—not just because it exists. Management may involve observation or removal, depending on the tooth’s position, whether it is causing or threatening disease, how it affects neighboring teeth, how easily it can be monitored, and the risks of surgery. An asymptomatic tooth without concerning changes may be monitored when a dentist judges that the potential harms of removal outweigh the expected benefit.
Removal may be considered when there is pain or infection attributable to the tooth, decay or periodontal disease that cannot be managed predictably, damage or interference involving an adjacent tooth, a cystic change, or a meaningful problem with eruption or planned orthodontic care. The decision is individualized; the presence of a supernumerary tooth does not make surgery inevitable. Ask the dentist what specific finding supports treatment and what could happen if the tooth is monitored.
Extraction has its own possible harms, which vary with anatomy and the person’s health. The clinician can explain the expected benefits, surgical risks, alternatives and follow-up in the particular case. A second opinion from an oral surgeon may help if the tooth is near important structures or the recommended procedure is complex. Do not use a general article or a population statistic to decide whether your own tooth should be removed.
For more background on how dentists think about third molars, see our articles on potential issues with retained wisdom teeth, why third molars emerge later and wisdom-tooth positions. Those general resources describe ordinary third molars; they do not determine treatment for an additional tooth.
Does one extra tooth mean a person has a syndrome?
A single isolated distomolar does not automatically mean that a person has a syndrome or a broader health condition. Multiple supernumerary teeth are more likely than one isolated posterior extra molar to prompt a clinician to ask about other dental or developmental findings and family history. Even then, the pattern needs clinical interpretation; the tooth count alone does not establish a diagnosis.
Genetic testing is not routinely implied by one extra molar. A clinician may consider referral when there are multiple unusual findings, a strong family pattern or other medical reasons. Most people with one extra posterior molar will not need a genetic explanation to decide how the tooth should be monitored or treated.
Questions to ask at a dental visit
If a dental image shows an extra molar, these questions can help turn the finding into a clear plan:
- Which tooth is extra, and is it a distomolar or paramolar?
- Is it erupted, partly erupted or completely impacted?
- Is there evidence of decay, gum disease, a cyst or pressure on another tooth?
- Would a new image or CBCT change the diagnosis or treatment plan?
- What are the benefits and risks of monitoring compared with removal?
- If we monitor it, what symptoms or imaging changes should prompt earlier review?
If the tooth is not causing a problem, ask how often follow-up is appropriate for your situation. If it is causing symptoms, tell the clinician when they began and whether there is swelling, fever, drainage or a change in how you bite. Bring prior X-rays if they are available so the dentist can compare the same area over time.
Common questions
Takeaway
Yes, a person can appear to have a fifth wisdom tooth, but dentists usually classify it as a supernumerary molar such as a distomolar. These teeth are uncommon, and studies report different rates because their populations and definitions vary. The exact cause of one isolated extra molar is not established; PAX9 is not a proven explanation. Many extra molars are discovered on X-rays without symptoms. Whether to monitor or remove one depends on its position, symptoms, nearby structures and clinical findings—not simply on having five molars at the back of the mouth.