|Classification and external resources|
|ICD-10||K05.2 (acute), K05.3 (chronic)|
Pericoronitis (also known as operculitis, and derived from Greek peri, "around", Latin corona "crown" and -itis, meaning a disease involving inflammation), is inflammation of the soft tissues surrounding the crown of a partially erupted tooth, including the gingiva (gums) and the dental follicle. Most commonly pericoronitis occurs with a partially erupted or partially erupted and impacted mandibular third molar (lower wisdom tooth). Periocoronitis is a common dental problem, often occurring in young adults (15-24), since this is roughly the age when the wisdom teeth are erupting into the mouth.
The soft tissue covering a partially erupted molar tooth is known as an operculum. Pericoronitis may occur for several reasons, usually involving an inflammatory response in the soft tissues because bacteria, food debris and plaque have accumulated beneath the operculum, an area which can be difficult to access with normal oral hygiene methods. An upper tooth may also start to bite into the soft tissues over a lower tooth and cause inflammation.
The signs and symptoms of pericoronitis are variable. Chronic inflammation may cause few if any symptoms, whereas an acute episode of pericoronitis, often associated with the formation of a pericoronal abscess (a collection of pus within the soft tissues), can cause significant pain and swelling. Sometimes the infection can spread to other parts of the face or neck, and rarely the swelling can start to threaten the airway and the individual is treated in hospital. Food impaction causing periodontal pain and pulpitis (toothache) secondary to dental caries (tooth decay) are also possible causes of pain associated with a third molar. The treatment of acute pericoronitis is normally addressed first by cleaning the area underneath the operculum with an antiseptic solution, and with painkillers, regular hot salt water mouthwashes/mouthbaths and improved oral hygiene in the affected area. Once the acute symptoms are controlled, the underlying cause is assessed and a decision is made as to whether to remove or retain the affected tooth. Often this is related to whether the tooth will continue to grow into the mouth and reach a normal position, or whether it is stuck against another tooth, and to other factors such as the presence of decay or periodontal disease in the area. If the tooth is retained, it usually requires improved oral hygiene in the area thereafter to prevent another episode of acute pericoronitis.
The International Classification of Diseases entry for pericoronitis lists acute and chronic forms. The definition of pericoronitis is inflammation in the soft tissues surrounding the crown of a tooth. This general definition encompasses a wide spectrum of possible degrees of severity. When used unqualified, the term usually refers to an acute inflammation of the soft tissues surrounding the crown of an impacted or partially erupted third molar tooth. However, pericoronitis may affect the soft tissues surrounding the crown of any tooth, although this is less common than involvement of the lower third molar, which is a commonly impacted tooth. Transient inflammation of the soft tissues occurs immediately preceding eruption of the deciduous teeth (baby or milk teeth) in children, and this is commonly termed "teething" in infants. Acute (i.e. sudden onset and short lived, but significant, symptoms) pericoronitis is defined by some sources as "varying degrees of inflammatory involvement of the pericoronal flap and adjacent structures, as well as by systemic complications." Systemic complications refers to signs and symptoms occurring outside of the mouth, such as fever, malaise or swollen lymph nodes in the neck. Pericoronitis may also be chronic or recurrent, with repeated episodes of acute pericoronitis occurring periodically. The operculum is the flap of soft tissue that may cover an erupting or partially erupted molar, also called a pericoronal flap, or gingival flap. Operculitis is inflammation of the operculum alone, although it is often listed as a synonym of pericoronitis. The definition of pericoronitis also makes no distinction as to whether the inflammation is minor and localized to the tissues immediately surrounding the crown of a tooth, or extends into adjacent areas. Also, the inflammation may or may not be associated active infection, i.e. invasion of the soft tissues by micro-organisms, which can also be termed pericoronal infection. A feature of pericoronal infection may be the formation of a pericoronal abscess, where pus forms, or a cellulitis, both of which can spread into other regions.
Signs and symptoms
Possible signs and symptoms of acute pericoronitis depend upon the severity, and are variable. Chronic pericoronitis may cause few if any symptoms, but some signs are usually visible when the mouth is examined.
- Pain, which gets worse as the condition develops and becomes severe, The pain may be throbbing and radiate to the ear, throat, temporomandibular joint, posterior submandibular region and floor of the mouth. There may also be pain when biting. Sometimes the pain disturbs sleep.
- Tenderness, erythema (redness) and Edema (swelling) of the tissues around the involved tooth, which is usually partially erupted into the mouth. The operculum is characteristically very painful when pressure is applied.
- Bad taste in the mouth.
- Intra-oral halitosis.
- Formation of pus, which can be seen exuding from beneath the operculum (i.e. a pericoronal abscess), especially when pressure is applied to the operculum.
- Signs of trauma on the operculum, such as indentations of the cusps of the upper teeth, or ulceration. Rarely, the soft tissue around the crown of the involved tooth may show a similar appearance to necrotizing ulcerative gingivitis.
- Trismus (difficulty opening the mouth). Indeed, pericoronitis is one of the most common causes of temporary trismus.
- Dysphagia (difficulty swallowing).
- Cervical lymphadenitis (inflammation and swelling of the lymph nodes in the neck), especially of the submandibular nodes.
- Facial swelling, and rubor, often of the cheek that overlies the angle of the jaw.
- Pyrexia (fever).
- Leukocytosis (increased white blood cell count).
- Malaise (general feeling of being unwell).
- Loss of appetite.
Normally pericoronitis occurs in the tissues around the crown of a partially erupted mandibular third molar tooth (lower wisdom tooth). Several factors may act in combination to trigger an acute episode of pericoronitis.
The lower mandibular third molar is a commonly impacted tooth, as it is one of the last teeth to erupt into the dental arch. If the jaw is too small the wisdom tooth may erupt at an abnormal angle, e.g. mesioangularly, when it is tilted forwards. This is sometimes known colloquially as wisdom teeth "coming in sideways". Instead of erupting fully into the mouth, the tooth contacts the distal side (the side at the back) of the second molar and may be impacted in this position, i.e. it is stuck against another tooth and will not erupt any further. The partially erupted and possibly also tilted tooth remains half covered by gingival tissue (gum). The soft tissue that directly overlies the tooth is termed the operculum, or gingival flap. The operculum creates an ideal environment for the accumulation of food debris and micro-organisms (especially bacterial plaque) between it and the partially erupted tooth. This is also termed a plaque stagnation area. There is an inflammatory response in the adjacent soft tissues.
The inflammatory response causes edema (swelling) in the soft tissues directly above and around the tooth. The inflamed soft tissue, now increased in size may now be impinging on the space occupied by the upper molars during the bite. Hence, the upper molars may bite into and further traumatize the soft tissues surrounding the lower third molar. The Upper third molar will often be "over-erupted" because it has not met another tooth to bite into and keeps growing down. Teeth which have never been in a position to grind with another tooth are frequently sharp, as they have suffered no attrition (tooth wear caused by tooth to tooth contact). Trauma from the opposing tooth and swelling from the presence of bacteria beneath the operculum may become a spiraling cycle.
If bacteria begin to invade the soft tissues from the stagnation areas beneath the operculum, at this stage it is termed an active infection. Pericoronal infection is normally caused by a mixture of bacterial species that normally are present in the mouth, such as Streptococci and particularly various anaerobic species. Infection of the soft tissues may cause pus to form within an abscess, which is the body's attempt to isolate the infection. The abscess often spontaneously drains into the mouth via the area underneath the operculum, although sometimes there may be a discharging sinus tract that is in other locations in the mouth, e.g. further forward next to the other molar teeth. This may cause confusion as it appears that a different tooth is infected rather than the wisdom tooth.
The chronically inflamed soft tissues around the tooth may give few if any symptoms. A sudden, acute exacerbation of the inflammation may occur, e.g. if a piece of food gets stuck under the operculum, trapping bacteria beneath it, or if the host immune system becomes temporarily compromised (e.g. during influenza or upper respiratory tract infections, or a period of stress). In this respect, acute pericoronitis can be considered an opportunistic infection, or rather, an opportunistic exacerbation of a chronic process which is normally largely kept in check by a competent immune system.
Trismus indicates that the inflammation/infection involves the muscles of mastication (the muscles that move the jaw). Pain when biting may be caused by an upper tooth pressing into a swollen operculum over a lower tooth.
The halitosis that often accompanies pericoronitis is due to the stagnantion of food debris and bacteria underneath the operculum. The bacteria putrefy proteins in this environment and release malodorous volatile sulfur compounds. The bad taste is related the exudation of pus from beneath the flap.
Pericoronal infection may remain localized in the tissues around the crown or spread into adjacent potential spaces. Acute pericoronitis is often responsible for the spread of infection to areas of the neck or face. As such, the infection may result in an obvious facial swelling, or even compromise the airway depending upon the direction of spread. Pus in the region of the lower third molar may spread in any one of several directions and involve potential spaces. This is unpredictable and mostly related to local anatomic factors such as muscle attachments. Possible potential spaces which may become involved with a spreading pericoronal infection include the sublingual space, submandibular space, parapharyngeal space, pterygomandibular space, infratemporal space, submasseteric space and buccal space. Ludwig's angina is bilateral infection involving the submandibular and sublingual spaces. This is a serious condition because the airway can become compressed by the swelling. It is a rare complication of pericoronitis.
Chronic pericoronitis may be the etiology for the development of paradental cyst, an inflammatory odontogenic cyst. Areas of chronic pericoronitis may cause the radiographic appearance of the local bone to become more radiopaque than surrounding bone. An area of ulceration may develop on the operculum in the long term, which resembles necrotizing ulcerative gingivitis. The presence of supernumerary teeth (extra teeth) makes pericoronitis more likely.
The diagnosis is usually clinical, but it is not always straightforward. Severe swelling and restricted mouth opening may prevent examination of the area. For pericoronal infection to occur, there must always be some communication between the tooth and the oral cavity. However, the wisdom tooth may be so buried by soft tissue that it is not visible in the mouth, and careful examination with a dental probe immediately behind the second molar may be needed to discover the communication.
The wisdom teeth are often hard to keep free of dental plaque due to their posterior position in the mouth and also because impacted teeth create areas which are difficult to access due to their angulation. Dental caries (tooth decay) of the wisdom tooth and of the distal surface of the second molar is common. Tooth decay may cause pulpitis (toothache) to occur in the same region, and this may cause pulp necrosis and the formation of a periapical abscess associated with either tooth. Food can also become stuck between the wisdom tooth and the tooth infront, termed food packing, and cause acute inflammation in a periodontal pocket when the bacteria become trapped. A periodontal abscess may even form by this mechanism. In these cases the pain will not be due to pericoronitis, even though signs of chronic pericoronitis may be also evident around the partially erupted wisdom tooth. Pain associated with temporomandibular pain dysfunction and myofascial pain also often occurs in the same region. They are easily missed diagnoses in the presence of mild and chronic pericoronitis, and the latter may not be contributing greatly to the individual's pain. It is rare for pericoronitis to occur in association with both lower third molars at the same time, despite the fact that many young people will have both lower wisdom teeth partially erupted. Therefore bilateral pain from the lower third molar region is unlikely to be caused by pericoronitis and more likely to be muscular in origin.
Sometimes a "migratory abscess" of the buccal sulcus occurs with pericoronal infection, where pus from the lower third molar region tracks forwards in the submucosal plane, between the body of the mandible and the attachment of the buccinator muscle to the mandible. In this scenario, pus may start to spontaneously discharge via an intra-oral sinus located over the mandibular second or first molar, or even the second premolar. This may cause diagnostic confusion and even lead to dental treatment being carried out on the wrong tooth.
Radiographs are of little benefit in the diagnosis of acute pericoronitis except to rule out pulpitis or another cause of the pain. However, often they are needed to properly assess the position and status of the wisdom teeth, necessary information upon which the choice of treatment is made.
Prevention of pericoronitis can be achieved by removing impacted third molars before they erupt into the mouth, although as not all impacted third molars develop pericoronitis it may or may not be an unnecessary procedure. Prophylactic operculectomy carried out before the first attack of acute pericoronitis has also been described. If the individual has reached their twenties without any attack of pericoronitis, it becomes substantially less likely one will occur thereafter. Wisdom teeth that are still completely buried within the bone are likely to remain there the rest of the individual's life without causing any pathology, although rarely an odontogenic cyst may form.
Management of acute pericoronitis
People usually only attend a dentist when an acute exacerbation of pericoronitis occurs, since there will usually have been few if any symptoms present before this development. Traditionally, acute pericoronitis is treated before the underlying cause is addressed. Often, this will be a decision about whether to retain or remove the causative tooth. There are many arguments for this approach. The main reason is the surgical principle that generally, surgery should not be performed in an area of acute infection for fear of disseminating the infection into the surrounding tissues (e.g. osteomyelitis or cellulitis) and causing an infected surgical site which interferes with healing. The logic of delaying extraction of wisdom teeth in the presence of acute pericoronal infection has more recently been challenged, as it is been shown that immediate extraction gives faster resolution of the infection, decreased pain, and an earlier return of function and oral intake, and that the risk of spreading the infection is low. However, delayed extraction of a wisdom tooth until the symptoms of acute pericoronitis resolve remains a very common practise among oral surgeons. Other reasons for delaying extraction in the presence of infection and acute pericoronitis are more practical, e.g.:
- Reduced efficiency of local anesthetics caused by the acidic environment of infected tissues, meaning that more local anesthetic may be needed, or even that the procedure is not totally pain free.
- There may be limited mouth opening, making oral surgery difficult if not impossible during the acute phase.
- People with acute pericoronitis are typically younger individuals with little experience of oral surgery. They will be more able to cope with the dental extraction when they are rested, eating well and are not in severe pain.
- Allows time to take dental radiographs and plan the procedure.
- Emergency appointments to see a dentist or oral surgeon are usually of short duration, e.g. 15 minutes, which often is not long enough to take a history, take radiographs, make a diagnosis and carry out definitive treatment.
Given the above, it is common practice for dentists to prescribe antibiotics and arrange for a second appointment when the infection is more suppressed and treatment is easier to carry out. The problem with this method is that frequently people will not attend again when they are pain free, largely due to a lack of understanding that antibiotics are a temporary solution for the infection, which will inevitably return in time, and also due to a reluctance to have oral surgery. This can lead to some people developing a pattern of attending only when they are in pain ("irregular attendance"), receiving a course of antibiotics and then never having their infection correctly treated, which becomes chronic. Antibiotics are not without their risks, mainly the development of antibiotic resistance which is a major problem, meaning that the infecting organisms are exposed to selective evolutionary pressure and adapt to their environment, e.g. utilizing a different metabolic pathway that renders antibiotics ineffective. This can be a significant problem if a life threatening condition subsequently develops which requires antibiotics to treat in hospital. Some dentists therefore only prescribe antibiotics where this is absolutely necessary, and advise the individual with acute pericoronitis to have definitive treatment as soon as possible, based on the logic that this approach is more in the persons best interests than using antibiotics and delaying treatment.
Acute pericoronitis is managed by local measures and oral analgesics. Local measures are first carried out by the dentist and then later by the person themselves in the following days at home. Firstly, the area underneath the operculum is gently irrigated with warm saline solution. This removes debris and inflammatory exudate. Sometimes dentists use other irrigants, such as solutions containing hydrogen peroxide, chlorhexidine or other antiseptics. Debridement (removal of plaque, calculus and food debris) is usually carried out with periodontal instruments, e.g. an ultrasonic scaler. The occlusion is analysed to determine if an opposing upper tooth is biting into the operculum. If it is, then sometimes the sharp points on the tooth (the cusps) are smoothed with a dental drill. This can be done without any anesthetic as no pain is caused. Usually a radiograph is taken to determine the position of the involved tooth, its relationship to the tooth infront, the upper opposing tooth, and any other factors such the presence of periodontal disease or dental caries on these teeth. The home care involves regular use (e.g. every two hours) of hot salt water mouthwashes/mouth baths.
Acute pericoronitis may also involve a pericoronal abscesss, a collection of pus in the tissues which is under pressure and causes pain. The management of this is very similar, with the added stage of draining the pus if possible. A local anesthetic may be given, although sometimes it is not needed. Often drainage occurs during the initial irrigation under the operculum. Otherwise, a small incision inside the mouth may be needed to allow the pus to drain out of the tissues. Once an abscess is drained, usually a significant portion of the pain disappears immediately, because pain was the result of pressure exerted by the trapped pus on surrounding tissues.
If there are systemic signs and symptoms, such as facial or neck swelling, cervical lymphadenitis, fever or malaise, a course of oral antibiotics is often prescribed, usually from the penicillin group, or if there is allergy to penicillin, clindamycin as an alternative. Sometimes metronidazole is given in combination with penicillin. If there is dysphagia or dyspnoea (difficulty swallowing or breathing), then this usually means there is a severe infection and an emergency admission to hospital is appropriate where intravenous medications and fluids can be administered and the threat to the airway monitored. Sometimes semi-emergency surgery may be arranged to drain a swelling that is threatening the airway.
Management following acute phase
Treatment following the acute phase is based largely around the decision as to whether the offending tooth is to be retained or extracted. Several factors contribute to this decision, including whether the tooth is in such a position that it may continue to erupt and reach a functional position or remain partially erupted and half-buried in soft tissue. Teeth which are impacted, e.g. tilted into the side of another tooth, will not erupt any further, and after the age of 25 complete eruption of a partially erupted tooth is unlikely. Teeth which have caused multiple episodes of acute pericoronitis are more likely to benefit from removal. Impacted teeth may also cause other problems apart from pericoronitis, such as resorption of the roots of the tooth it is impacted against (occasionally), or tooth decay or localized gum disease caused by the difficult access to oral hygiene methods. Sometimes if the opposing tooth is over-erupted and the lower tooth is going to be extracted, this too is extracted.
If the tooth is to be kept, usually long term maintenance by the individual is needed to keep the area clean and prevent further acute episodes of inflammation. A variety of specialized oral hygiene methods are available to deal with hard to reach areas of the mouth, including small headed tooth brushes, interdental brushes, electronic irrigators and dental floss. Sometimes the soft tissues over the crown of the involved tooth are removed to expose more the tooth and remove the plaque stagnation area.
In some cases, removal of the tooth may not be necessary with meticulous oral hygiene to prevent build up of plaque in the area. Occasional increased symptoms can be managed with hot salt water mouth baths as required until the inflammation subsides again.
This is a minor surgical procedure where the inflamed soft tissue is removed from around the crown of the tooth, and can be done with a normal surgical scalpel, with electrocautery, or with lasers. Caustic agents such as trichloracetic acid can be used to reduce the soft tissue around the crown of the tooth, although this is now largely historical since it risked damage to any soft tissue it came into contact with. Complete removal the soft tissue behind as well as on top of the partially erupted tooth is required. This leaves an area that is easy to keep clean, and will not lead to plaque build up with return of soft tissue inflammation. This option is only appropriate if the wisdom tooth is not to be extracted. In reality this procedure is rarely carried out, although some mainstream textbooks describe it. Pericoronitis is usually managed either with conservative measures or by extracting the tooth. Other sources state that operculectomy is often ineffective.
If the tooth is to be extracted, this can be carried out under local anesthetic and with the person awake, or under sedation, or under general anesthetic. Depending on the position of the tooth, this may be a straightforward or more complex procedure, where an incision is placed in the mouth and surgical burs are used to remove portions of bone that are holding the tooth in, and also to divide the tooth into sections so it can be removed more easily. The latter scenario involves sutures (stitches) to replace the soft tissues in a position for healing, and the area where the tooth was and the bone removed eventually fills in with bone during the healing. Extraction of teeth which are involved in pericoronitis carries a higher risk of dry socket, a painful complication which results in delayed healing. The anxiety of the individual towards oral surgery is a common reason for carrying this procedure out under general anesthetic. If a general anesthetic is required, in order to reduce the overall number of general anesthetics used, each of which carries its own risk, then other teeth which are likely to require extraction in the future are often extracted during the same procedure. This especially applies to cases where there is a similarly impacted and partially erupted wisdom tooth on the other side of the mouth which has yet to cause any acute problems.
Historically many lower wisdom teeth that were not in an ideal position were surgically removed in order to prevent problems like pericoronitis. It became apparent that the majority of impacted lower third molars would cause little or no problems during the individual's lifetime. In modern practice, oral surgeons tend to only remove wisdom teeth that develop problems, or those that are likely to develop problems, in cases where the benefits of removing the tooth outweigh the potential risks of leaving it in place or the possible complications associated with the procedure. However, removal of impacted wisdom teeth remains one of most common surgical procedures, and recurrent episodes of significant pericoronitis is the most common reason it is undertaken. In the UK, the National Institute for Health and Clinical Excellence (the body which advises best practice for the National Health Service) published guidelines for the removal of wisdom teeth in 2000. These guidelines advised that the routine prophylactic removal of pathology free third molars should be discontinued, and that a single episode of acute pericoronitis, unless especially severe, did not constitute an indication for tooth extraction, but that a second episode was an indication. This was intended to avoid the unnecessary removal of wisdom teeth that may only cause a single instance of acute pericoronitis, and then erupt further and/or be manageable with oral hygiene methods. A systematic review in 2012 investigating the possible preventative benefits of removal of symptom-free, impacted wisdom teeth in adults found no evidence for this practise. The review also concluded that prevention of late lower incisor tooth crowding, a commonly cited reason for removing symptom free and impacted wisdom teeth, also had no evidence.
However, many mainstream dental textbooks state that impacted wisdom teeth should generally be removed unless otherwise contraindicated, and this should be done earlier rather than later because their removal may become more difficult with advancing age. Research has also shown that there is a significant geographic variation in the views of both dentists and patients as to whether wisdom teeth should be removed.
The prognosis largely depends upon whether the condition is treated, and if the causative tooth erupts into a functional position. A transient and mild pericoronal inflammation often occurs in the soft tissues around teeth as they finish erupting fully. If the tooth reaches a position where there is no overlying gum flap, and where the space between it and the tooth infront is accessible to oral hygiene methods, then pericoronitis will likely never return. Similarly, pericoronoitis will not return if the involved tooth is removed, although it may occur at a different site in the mouth, e.g. the wisdom tooth on the other side. This new occurrence is independent of the earlier condition and how it is managed. However, chronic pericoronitis with occasional acute exacerbations can often be expected in teeth which are in an impacted, partially erupted position and will not erupt any further. Dental infections such as pericoronitis can develop into septicemia and be life threatening in persons who have neutropenia. Even in people with normal immune function, pericoronitis may sometimes cause a spreading infection into the potential spaces of the head and neck, and potentially threaten the airway and require hospital treatment, although the majority of cases of pericoronitis are localized to the tooth.
Pericoronitis usually occurs in young adults, around the time when wisdom teeth are erupting into the mouth.
- Douglass AB, Douglass JM (2003 Feb 1). "Common dental emergencies.". American family physician 67 (3): 511–6. PMID 12588073.
- Fragiskos, Fragiskos D. (2007). Oral surgery. Berlin: Springer. p. 122. ISBN 978-3-540-25184-2.
- Carranza's clinical periodontology (11th ed.). St. Louis, Mo.: Elsevier/Saunders. 2012. pp. 103, 133, 440. ISBN 978-1-4377-0416-7.
- CA Bartzokas and GW Smith, ed. (1998). Managing Infections: Decision-making Options in Clinical Practice. Informa Health Care. p. 157. ISBN 1-85996-171-1. Retrieved 2008-05-31.
- Nguyen DH, Martin, JT (2008 Mar 15). "Common dental infections in the primary care setting.". American family physician 77 (6): 797–802. PMID 18386594.
- Laskaris, George (2003). Color Atlas of Oral Diseases. Thieme. p. 176. ISBN 1-58890-138-6. Retrieved 2008-05-31.
- Neville BW, Damm DD, Allen CA, Bouquot JE. (2002). Oral & maxillofacial pathology (2nd ed.). Philadelphia: W.B. Saunders. pp. 73,129,133,153,154,590,608. ISBN 0721690033.
- Wray D, Stenhouse D, Lee D, Clark AJE (2003). Textbook of general and oral surgery. Edinburgh [etc.]: Churchill Livingstone. pp. 220–222. ISBN 0443070830.
- Cawson RA, Odell EW (2002). Cawson's essentials of oral pathology and oral medicine (7th ed.). Edinburgh: Churchill Livingstone. pp. 82,166. ISBN 9780443071058.
- Soames JV, Southam JC (1999). Oral pathology (3rd ed.). Oxford: Oxford Univ. Press. p. 114. ISBN 0192628941.
- Hupp JR, Ellis E, Tucker MR (2008). Contemporary oral and maxillofacial surgery (5th ed.). St. Louis, Mo.: Mosby Elsevier. ISBN 9780323049030.
- Odell EW (2010). Clinical problem solving in dentistry (3rd ed.). Edinburgh: Churchill Livingstone. pp. 151–153. ISBN 9780443067846.
- Johri, A; Piecuch, JF (2011 Nov). "Should teeth be extracted immediately in the presence of acute infection?". Oral and maxillofacial surgery clinics of North America 23 (4): 507–11, v. doi:10.1016/j.coms.2011.07.003. PMID 21982602.
- Samaranayake, Lakshman P. (2009). Essential microbiology for dentistry. Elseveier. p. 71. ISBN 978-0702041679.
- Kravitz, ND; Kusnoto, B (2008 Apr). "Soft-tissue lasers in orthodontics: an overview.". American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 133 (4 Suppl): S110–4. doi:10.1016/j.ajodo.2007.01.026. PMID 18407017.
- "TA1: Guidance on the Extraction of Wisdom Teeth". National Institute of Clinical Excellence. Retrieved 3 April 2013.
- Mettes, TD; Ghaeminia, H; Nienhuijs, ME; Perry, J; van der Sanden, WJ; Plasschaert, A (2012 Jun 13). "Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth.". Cochrane database of systematic reviews (Online) 6: CD003879. doi:10.1002/14651858.CD003879.pub3. PMID 22696337.
- Zadik, Y; Levin, L (2007 Apr). "Decision making of Israeli, East European, and South American dental school graduates in third molar surgery: is there a difference?". Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons 65 (4): 658–62. doi:10.1016/j.joms.2006.09.002. PMID 17368360.