Wisdom Teeth (Third Molars)

Table of Contents

1. What Wisdom Teeth Are
2. Causes and Risk Factors for Impaction
3. Symptoms
4. How Wisdom Tooth Problems Are Diagnosed
5. Pericoronitis: Infection Around a Partly Erupted Wisdom Tooth
6. Treatment
7. The Debate Over Removing Healthy Wisdom Teeth
8. Prevention
9. Recovery After Removal and Dry Socket
10. Complications
11. Warning Signs and Urgent Signs
12. Key Research Papers
13. Connections
14. Featured Videos

What Wisdom Teeth Are

Adults normally have up to 32 permanent teeth, including three molars (large back grinding teeth) on each side of the upper and lower jaw. The third molars are the last in each row, and they are the last teeth to form and come through the gum. Because they tend to appear in young adulthood, they are called wisdom teeth. Some people have all four, some have fewer, and some never develop any.

A wisdom tooth that comes fully into place, lines up with the other teeth and can be cleaned is an ordinary working molar. Problems arise when the tooth is impacted — meaning it is blocked by bone, by the tooth in front of it, or by thick gum, and cannot come fully into the mouth. A health-technology review for the United Kingdom defines impacted third molars as third molars that are blocked, by soft tissue or bone, from fully erupting through the gum, and notes that this can cause pain and disease [3].

Impaction is common. A 2024 systematic review and meta-analysis (a study that pools the results of many earlier studies) combined 98 studies covering 183,828 people. It found impacted third molars in 36.9% of people, and in 46.4% of third molars counted tooth by tooth. Rates were highest in Asia (43.1%) and lowest in Europe (24.5%), women were slightly more likely than men to have an impacted third molar (odds ratio 1.173), and lower wisdom teeth were impacted more often than upper ones [1]. An earlier clinical-evidence review quotes a figure of some 72% of Swedish people aged 20 to 30 having at least one impacted wisdom tooth [2].

Causes and Risk Factors for Impaction

A clinical-evidence review describes three reasons a wisdom tooth becomes impacted: a lack of space in the jaw, obstruction by something in its path (usually the second molar or dense bone), and an abnormal position or angle of the developing tooth [2].

• Jaw size and tooth size. When the jaw is too short from front to back for all the molars, the last tooth to arrive has nowhere to go.
• The angle of the tooth. Dentists describe impaction by angle (see the diagram): vertical, mesioangular (tilted forward toward the second molar), horizontal (lying on its side) and distoangular (tilted backward). They also describe depth — whether the tooth is covered only by gum (“soft-tissue impaction”) or partly or fully buried in bone (“bony impaction”).
• Lower jaw rather than upper. The worldwide meta-analysis found lower third molars impacted more often than upper ones [1].
• Sex and region. The same analysis found a slightly higher likelihood in women and the highest rates in Asia, though it could not show that geography itself explained the differences between studies [1].

Impaction on its own is not a disease. What matters is whether the tooth causes trouble: infection of the gum over it, decay or gum disease on the neighbouring second molar, or, less often, a cyst in the bone.

Symptoms

Many impacted wisdom teeth cause no symptoms at all and are found only on an X-ray. When they do cause problems, a clinical-evidence review describes inflammatory dental disease showing up as pain and swelling around the infected tooth, with the possibility of damage to the adjacent teeth and bone [2]. Common symptoms include:

• Pain or a dull ache at the very back of the jaw, sometimes spreading toward the ear.
• Red, swollen, tender gum behind the last visible molar.
• A bad taste or bad breath, or pus oozing from the gum flap.
• Pain on biting, often because the upper tooth bites down on the swollen gum flap over the lower wisdom tooth.
• Difficulty opening the mouth wide (called trismus), because inflammation spreads into the chewing muscles.
• Swelling of the cheek or jaw, and sometimes swollen glands under the jaw.
• Sensitivity or a cavity in the second molar, where food packs into the gap against a tilted wisdom tooth.

Symptoms often come and go in flare-ups, particularly with a partly erupted lower wisdom tooth.

How Wisdom Tooth Problems Are Diagnosed

Dentists diagnose wisdom tooth problems by looking at and feeling the area at the back of the mouth, and by X-ray. The usual X-ray is a panoramic radiograph — a single wide image that shows all the teeth, both jaws and the canal in the lower jaw that carries the inferior alveolar nerve (the nerve that gives feeling to the lower teeth, lower lip and chin).

The X-ray shows the angle and depth of the tooth, how many roots it has, whether it is damaging the second molar, and whether the roots sit close to the nerve canal. A 2017 systematic review looked at seven warning signs on panoramic X-rays — such as darkening of the root where it crosses the canal, interruption of the white line that outlines the canal, and diversion of the canal around the root. When none of these signs were present, the chance of a nerve injury after surgery was low (negative predictive values of 95.9% to 97.7%), but the review concluded that the absence of signs added too little information to rule out the risk. When diversion of the canal, interruption of the white line or darkening of the root was present, the review judged that enough to flag a raised risk of nerve injury [11].

When a panoramic image shows the roots overlapping the nerve canal, surgeons often order a cone-beam computed tomography (CBCT) scan, a three-dimensional X-ray of the jaw, to see the exact relationship before planning surgery. Pericoronitis itself is diagnosed mainly by its appearance: swollen, tender gum over a partly erupted tooth.

Pericoronitis: Infection Around a Partly Erupted Wisdom Tooth

Pericoronitis means inflammation of the soft tissue around the crown of a partly erupted tooth, almost always a lower wisdom tooth. A 2024 review describes it as most often diagnosed in young adults aged 20 to 29, more often in women, and caused by bacteria and food debris collecting under the operculum — the flap of gum partly covering the tooth. Symptoms it lists are localised pain, gum swelling, trismus and sometimes pus discharge [7].

The angle of the tooth matters. A study of 432 impacted lower wisdom teeth in 262 patients in Shanghai found pericoronitis was the main symptom overall. Teeth covered only by gum and standing vertically were most associated with pericoronitis; forward-tilted (mesioangular) teeth sitting less deep carried a greater risk of decay on the back of the second molar; and forward-tilted or horizontal teeth sitting deeper in the bone were more likely to cause gum and bone disease behind the second molar. Decay and gum disease of the second molar became more common in older patients [6].

How pericoronitis is treated

Dentists first treat pericoronitis locally: flushing out the space under the gum flap with saline or an antiseptic rinse, cleaning away debris, and sometimes relieving the upper tooth that bites on the flap. A review of the evidence-based guidance recommends local therapy over antibiotics, with antibiotics reserved for severe cases. Its systematic review of actual practice found the opposite: almost 75% of surveyed dentists prescribed antibiotics for pericoronitis, more than half of patients received them, and amoxicillin and metronidazole were the most prescribed. The authors describe this as abundant and unnecessary antibiotic use that feeds antimicrobial resistance [8].

A 2022 systematic review searched for controlled trials of systemic antibiotics (pills or injections) for pericoronitis or periodontal abscess and found not a single randomised or non-randomised controlled trial assessing their benefits and harms in adults [9]. In practice, antibiotics are generally kept for pericoronitis with fever, spreading swelling or difficulty opening the mouth.

Because pericoronitis tends to return while the gum flap remains, the longer-term options are removing the flap (operculectomy), removing the tooth, or coronectomy (described under Treatment). The 2024 pericoronitis review notes that operculectomy suits patients with good oral hygiene and a well-angled tooth, while extraction removes the source of inflammation for good but carries a higher risk of inferior alveolar nerve damage and more discomfort after surgery [7].

Treatment

Treatment depends on whether the wisdom tooth is causing disease. A United Kingdom health-technology assessment notes that guidance from the National Institute for Health and Care Excellence (NICE) states that an impacted third molar with pathological changes is to be removed [3], and a 2018 review describes a broad consensus for removal when a third molar is linked to infection, unrestorable decay, cysts, tumours, or destruction of neighbouring teeth and bone [5].

Watchful waiting (retention)

A wisdom tooth that is not causing disease can be left in place and checked at regular dental visits, with an X-ray from time to time. The Cochrane review on this question states that if the decision is made to keep these teeth, clinical assessment at regular intervals is advisable to catch problems early [4].

Extraction

A wisdom tooth that has come fully through the gum can often be removed like any other tooth. An impacted one usually needs surgical extraction: the surgeon lifts a flap of gum, removes some bone around the tooth, and often cuts the tooth into pieces so it can come out through a smaller opening. The procedure is done under local anaesthetic (numbing injection), with or without sedation, or under general anaesthetic. Third molar surgery is one of the most common operations in oral surgery.

Coronectomy

When the roots lie very close to the inferior alveolar nerve, surgeons may perform a coronectomy: they remove only the crown (the top part) of the tooth and deliberately leave the roots in the bone, so the nerve is not disturbed. The roots heal over with bone. A 2025 meta-analysis of 34 studies covering 7,115 wisdom teeth in 4,477 patients compared coronectomy with full extraction:

• Coronectomy cut the risk of inferior alveolar nerve injury sharply (relative risk 0.1) and also lowered the risk of lingual nerve injury (relative risk 0.2) and dry socket (relative risk 0.4).
• There was no significant difference in infection after surgery.
• The trade-off: 3.63% needed a second operation, 2.66% had roots that later became exposed, and 2.79% of coronectomies failed [12].

Coronectomy is generally used only for healthy roots; a tooth with an infected pulp or decay reaching the roots is not suitable, because infected root material left behind can cause later problems.

Pain relief and recovery medicines

Pain after wisdom tooth surgery is usually managed with over-the-counter anti-inflammatory painkillers such as ibuprofen, sometimes combined with paracetamol (acetaminophen). Some surgeons give a single dose of a corticosteroid such as dexamethasone around the time of surgery to reduce swelling.

Antibiotics around surgery

Whether to give antibiotics to prevent infection after removal of a lower wisdom tooth is debated. A 2024 network meta-analysis of 16 randomised trials (2,158 patients, 2,428 lower third molars) found antibiotics did reduce dry socket and surgical-site infection, but 25 patients needed to be treated to prevent one dry socket, and 18 to prevent one infection. The authors judged this number high, and wrote that prescribing needs to weigh each patient’s general health and individual infection risk [15]. A 2022 scoping review concluded that the literature does not support routine preventive antibiotics for dry socket [14].

The Debate Over Removing Healthy Wisdom Teeth

For decades, many people had wisdom teeth removed before they caused any trouble — called prophylactic (preventive) removal. Whether this helps is one of the longest-running debates in dentistry, and the best available reviews conclude that the evidence is thin.

What the Cochrane review found

The 2020 Cochrane review on removing versus keeping symptom-free, disease-free impacted wisdom teeth found only two usable studies. One cohort study of 416 healthy men aged 24 to 84 found very low-certainty evidence that keeping such teeth may be linked to more gum disease (periodontitis) on the neighbouring second molar in the long term, and not enough evidence to show any difference in decay. One randomised trial in teenagers who had already had orthodontic treatment found no evidence that removing wisdom teeth had a clinically meaningful effect on crowding of the dental arch after five years. No study measured quality of life. The review concluded that there is insufficient evidence to determine whether these teeth are better removed or kept, and that the patient’s own values together with clinical judgement guide a shared decision [4].

What happens to wisdom teeth that are kept

The United Kingdom health-technology assessment found no head-to-head trials. In the studies it did find, between 5.5% and 31.4% of retained symptom-free impacted lower wisdom teeth were later extracted, the spread depending on whether follow-up lasted one or five years. Two published cost studies found no economic evidence to support preventive removal, while the assessment’s own model, built on observational data, suggested preventive removal might be the more cost-effective strategy. The authors stressed that evidence on effectiveness is lacking [3].

The case made for earlier removal

A 2018 review takes the opposite side. It reports that nearly half of impacted third molars are associated with some form of disease, most often decay (20%) and gum disease (17%), and that only 31% of third molars remain by age 38. It argues that preventive removal at a young age is justified, because surgery becomes more complex and complications more frequent with age [5]. A study of 1,116 extracted third molars in Oman likewise found that older age and the need to remove bone were linked to more complications [10].

In short: removal of a wisdom tooth that is causing disease is broadly agreed on; removal of a healthy, symptom-free one remains a judgement call in which the research leaves room for both choices.

Prevention

Nothing is known to prevent a wisdom tooth from becoming impacted, since that depends on jaw size and the tooth’s angle as it develops. What can be reduced is the damage an impacted or partly erupted tooth causes:

• Cleaning the back of the mouth. Plaque and food collecting under the gum flap and in the gap behind the second molar drive both pericoronitis and second-molar decay. A small-headed or single-tuft toothbrush reaches this area more easily than a standard brush.
• Rinsing the gum flap. Warm salt-water rinses are a traditional home measure for flushing debris from under the operculum.
• Regular check-ups with X-rays. Decay on the back of the second molar and early bone loss often cause no pain until they are advanced, and the Cochrane review describes regular clinical assessment as the safeguard when wisdom teeth are kept [4].
• Not smoking, since smoking worsens gum disease and is studied as a risk factor for problems after extraction.

Recovery After Removal and Dry Socket

After surgery, a blood clot forms in the empty socket. That clot protects the bone and is the scaffold on which new gum and bone grow. Pain, swelling and stiffness of the jaw are normal and usually peak around the second or third day, then settle over about a week. Standard after-care instructions given by oral surgeons include biting on gauze to stop bleeding, keeping the head raised, not rinsing hard or spitting forcefully on the first day, soft food, and gentle salt-water rinses from the next day.

Dry socket (alveolar osteitis)

Dry socket happens when the clot breaks down or is lost too early, leaving bone exposed. The 2022 Cochrane review describes it as severe pain developing two to three days after extraction, with or without bad breath, in a socket that may be partly or completely empty of clot. It occurs in about 1% to 5% of routine extractions but up to 30% of surgically removed third molars [13].

The same review found moderate-certainty evidence that chlorhexidine (an antiseptic) reduces dry socket: rinsing with 0.12% or 0.2% chlorhexidine before and for 24 hours after extraction cut the odds of dry socket (odds ratio 0.38), and placing 0.2% chlorhexidine gel in the socket did likewise (odds ratio 0.44). Chlorhexidine rinses were linked to minor side effects such as altered taste, tooth staining and mouth irritation [13]. A 2022 scoping review warns that chlorhexidine placed inside the socket carries a serious risk of anaphylaxis (a severe allergic reaction) and reports that saline irrigation and eugenol pastes — eugenol being the main aromatic compound of clove oil — have been shown to be cheap and effective preventive alternatives. It identified impaired immune response, surgical technique and age as significant risk factors, and found conflicting evidence on smoking and sex [14].

Dry socket is treated by gently rinsing the socket, then packing it with a soothing dressing, often one containing eugenol, and by pain relief. It is very painful but it is not an infection, and it heals, usually within one to two weeks.

Complications

Complications of leaving a problem wisdom tooth

• Repeated pericoronitis, which can occasionally spread into the spaces of the face and neck.
• Decay of the second molar on the side facing the wisdom tooth, sometimes deep enough to lose that tooth [6].
• Gum and bone loss behind the second molar [6].
• Cysts (fluid-filled sacs) and, rarely, tumours growing from the tissue around the crown of a buried tooth, and resorption (wearing away) of the neighbouring root [4].

Complications of removal

A ten-year review of 1,116 third molars removed under general anaesthetic at a hospital in Oman found complications during surgery in 3.7% — including fracture of the upper jaw’s back corner (tuberosity), broken roots, bleeding and soft-tissue injury — and after surgery in 8.3%. The most common after-surgery problem was sensory nerve injury (7.2%), which was temporary in 41 patients and permanent in 4. Most complications were minor; older age and the need to remove bone raised the risk [10]. Other recognised complications include dry socket, infection, damage to the neighbouring tooth, and, after upper wisdom tooth removal, an opening between the mouth and the sinus.

Nerve injury

Two nerves run close to lower wisdom teeth: the inferior alveolar nerve inside the jawbone, which supplies feeling to the lower lip, chin and lower teeth, and the lingual nerve on the tongue side of the jaw, which supplies feeling and taste to the side of the tongue. Injury causes numbness, tingling or, in some people, burning pain in those areas. Most injuries recover over weeks to months. A 2019 review describes the long-term effects of the injuries that do not recover as possibly including persistent sensory loss, chronic pain and depression, states that full recovery is not commonly achieved with current treatments, and describes coronectomy as proven effective at reducing inferior alveolar nerve injury [16].

Warning Signs and Urgent Signs

Signs that point to a wisdom tooth problem

• Pain, swelling or a bad taste at the very back of the jaw that keeps coming back.
• A swollen gum flap over a partly erupted tooth that hurts when the upper teeth bite down.
• Food packing and pain or sensitivity in the last visible molar.
• Stiffness and difficulty opening the mouth.

Signs after removal that are not part of normal healing

• Pain that gets worse after day two or three instead of easing, often spreading to the ear, with an empty-looking socket — the typical pattern of dry socket [13].
• Bleeding that keeps soaking gauze after several hours of firm pressure.
• Swelling that grows after the third day, pus, or fever — signs of infection.
• Numbness of the lip, chin or tongue that is still present the day after surgery, when the anaesthetic has long worn off.

Signs of a spreading infection, which can be life-threatening

Swelling that spreads to the floor of the mouth or neck, difficulty swallowing or breathing, or high fever with a tooth infection are signs of a spreading infection, which can be life-threatening. Other signs emergency services treat as urgent:

• Swelling under the tongue that lifts it, or a hard, tense swelling under the jaw.
• Drooling, a muffled voice, or being unable to lie flat because breathing gets harder.
• Severe difficulty opening the mouth (trismus) with fever.
• Swelling spreading quickly over hours, or swelling reaching the eye.
• Fever, chills, a racing heart, confusion or extreme weakness — signs the infection may have entered the bloodstream (sepsis).

Key Research Papers

1. Pinto AC, Francisco H, Marques D, Martins JNR, Caramês J. Worldwide Prevalence and Demographic Predictors of Impacted Third Molars-Systematic Review with Meta-Analysis. J Clin Med. 2024;13(24). PubMed PMID: 39768456
2. Dodson TB, Susarla SM. Impacted wisdom teeth. BMJ Clin Evid. 2014;2014. PubMed PMID: 25170946
3. Hounsome J, Pilkington G, Mahon J, Boland A, Beale S, Kotas E, et al. Prophylactic removal of impacted mandibular third molars: a systematic review and economic evaluation. Health Technol Assess. 2020;24(30):1-116. PubMed PMID: 32589125
4. Ghaeminia H, Nienhuijs ME, Toedtling V, Perry J, Tummers M, Hoppenreijs TJ, et al. Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth. Cochrane Database Syst Rev. 2020;5(5):CD003879. PubMed PMID: 32368796
5. Shoshani-Dror D, Shilo D, Ginini JG, Emodi O, Rachmiel A. Controversy regarding the need for prophylactic removal of impacted third molars: An overview. Quintessence Int. 2018;49(8):653-662. PubMed PMID: 30109309
6. Ye ZX, Qian WH, Wu YB, Yang C. Pathologies associated with the mandibular third molar impaction. Sci Prog. 2021;104(2):368504211013247. PubMed PMID: 33913399
7. Rolek A, Pławecki P. Comprehensive management of pericoronitis in lower third molars: extraction, operculectomy, and coronectomy approaches. Wiad Lek. 2024;77(7):1514-1516. PubMed PMID: 39241154
8. Schmidt J, Kunderova M, Pilbauerova N, Kapitan M. A Review of Evidence-Based Recommendations for Pericoronitis Management and a Systematic Review of Antibiotic Prescribing for Pericoronitis among Dentists: Inappropriate Pericoronitis Treatment Is a Critical Factor of Antibiotic Overuse in Dentistry. Int J Environ Res Public Health. 2021;18(13). PubMed PMID: 34202699
9. Leroy R, Bourgeois J, Verleye L, Toma S. Should systemic antibiotics be prescribed in periodontal abscesses and pericoronitis? A systematic review of the literature. Eur J Oral Sci. 2022;130(4):e12884. PubMed PMID: 35781706
10. Sayed N, Bakathir A, Pasha M, Al-Sudairy S. Complications of Third Molar Extraction: A retrospective study from a tertiary healthcare centre in Oman. Sultan Qaboos Univ Med J. 2019;19(3):e230-e235. PubMed PMID: 31728221
11. Su N, van Wijk A, Berkhout E, Sanderink G, De Lange J, Wang H, et al. Predictive Value of Panoramic Radiography for Injury of Inferior Alveolar Nerve After Mandibular Third Molar Surgery. J Oral Maxillofac Surg. 2017;75(4):663-679. PubMed PMID: 28041843
12. Kang FW, Yuan XR, Li GC, Yang YFZ, Zhang XM, Hou GY. Coronectomy in Lower Third Molar Surgery: A Systematic Review and Meta-Analysis. J Oral Maxillofac Surg. 2025;83(5):601-615. PubMed PMID: 39956152
13. Daly BJ, Sharif MO, Jones K, Worthington HV, Beattie A. Local interventions for the management of alveolar osteitis (dry socket). Cochrane Database Syst Rev. 2022;9(9):CD006968. PubMed PMID: 36156769
14. Ghosh A, Aggarwal VR, Moore R. Aetiology, Prevention and Management of Alveolar Osteitis-A Scoping Review. J Oral Rehabil. 2022;49(1):103-113. PubMed PMID: 34625985
15. Camps-Font O, Sábado-Bundó H, Toledano-Serrabona J, Valmaseda-de-la-Rosa N, Figueiredo R, Valmaseda-Castellón E. Antibiotic prophylaxis in the prevention of dry socket and surgical site infection after lower third molar extraction: a network meta-analysis. Int J Oral Maxillofac Surg. 2024;53(1):57-67. PubMed PMID: 37612199
16. Leung YY. Management and prevention of third molar surgery-related trigeminal nerve injury: time for a rethink. J Korean Assoc Oral Maxillofac Surg. 2019;45(5):233-240. PubMed PMID: 31728330

PubMed Topic Searches

1. PubMed: impacted third molar
2. PubMed: pericoronitis
3. PubMed: prophylactic removal of third molars
4. PubMed: coronectomy
5. PubMed: dry socket after third molar surgery

Connections

• Dentistry & Oral Health
• Tooth Decay (Dental Caries)
• Gum Disease
• Periodontitis
• Halitosis (Chronic Bad Breath)
• TMJ Disorder
• Oral Microbiome
• Tooth Abscess (Dental Abscess)
• Tooth Sensitivity (Dentin Hypersensitivity)
• Clove
• Trigeminal Neuralgia
• Sinusitis
• Peritonsillar Abscess
• Cellulitis
• Sepsis

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