The clinical definition of Pericoronitis
An operculum (green arrow) is a soft tissue which may directly partially cover an erupting third molar tooth. Pericoronitis is a recurrent inflammation with swelling and pus around a partially erupted tooth or fully erupted the third molar which inadequate space in the lower arch, or failure to erupt completely often as a result of limited space for eruption, or a non-ideal angle of tooth eruption causing tooth impaction

OPG radiographic shows pericoronitis around the 3rd lower right & left molar teeth (48 & 38).
Caries on the second lower right, 3rd lower left, and upper left molar teeth (47, 38, 28) as a result of chronic food impaction.

Causes of pericoronitis
Operculum creates a closed space which promotes the accumulation of food debris and stagnation of plaque micro-organisms. This triggers an inflammatory response in the adjacent soft tissues and eventually the whole periodontium around the affected tooth. Sometimes the pericoronal infection can spread into the potential adjacent tissue spaces including the sublingual space, submandibular space, parapharyngeal space, pterygomandibular space, infratemporal space, and buccal space. This may cause an acute spread of infection into the neck or face causing facial swelling, or even airway compromise called Ludwig's angina.
Signs and symptoms of pericoronitis
The signs and symptoms of pericoronitis variably depend upon the extent and severity of pericoronal tissue involvement in form of:
  • Pain and tenderness which may be throbbing and radiate to the ear, throat, temporomandibular joint, posterior submandibular region and floor of the mouth. When the inflamed pericoronal tissues interfere with chewing, the pain exacerbates during mouth closure and eating.
  • Erythema (redness) and oedema (swelling) of the pericoronal tissues.
  • Formation and exudation of pus from operculum cause pericoronal abscess and bad taste called halitosis.
  • The sharp cusps of the opposing tooth can cause indentations and ulceration by repeating traumatisation on the operculum.
  • The infection-induced inflammation of the muscles of mastication can cause difficulty in mouth opening called trismus, and in swallowing called Dysphagia
  • Cervical lymphadenitis (inflammation and swelling of the lymph nodes in the neck), especially of the submandibular nodes.
  • Facial swelling of the cheek that overlies the angle of the jaw.
  • Pyrexia (fever) can be caused by increased white blood cell production (Leukocytosis).
  • Malaise (general feeling of being unwell).
  • Loss of appetite.
Inadequate cleaning of the operculum space allows stagnation of accumulated debris, and plaque bacteria as a result of compromised access. Pericoronal infection caused by a mixture of bacterial species can result in abscess formation, and when left untreated, the abscess can spontaneously drain. In chronic pericoronitis, drainage may happen through an approximal sinus tract.
Features of pericoronitis
  • Inflamed operculum covering partially erupted lower third molar, with an accumulation of food debris and bacteria underneath
  • Mesio-angulated partially erupted mandibular third molar,
  • Dental caries and periodontal defects, caused by food packing and poor access to oral hygiene methods
  • The upper third molar has over-erupted due to lack of opposing tooth contact and may start to traumatically occlude into the operculum over the lower third molar. Un-opposed teeth are usually sharp because they have not been blunted by another tooth (attrition).
Pericoronitis Temporomandibular joint disorder
Swelling and tenderness of operculum and around the wisdom tooth Dull, aching pain around face, around the ear, angle of the jaw (masseter), and inside the mouth behind upper wisdom tooth (lateral pterygoid)
Bad taste Headaches
Disturbed sleep Does not disturb sleep
Poorly responsive to analgesics Responds to analgesics
Possibly limited mouth opening (trismus) Possibly trismus, joint noises (e.g. clicking upon opening) and deviation of the mandible

Acute pericoronitis
Acute pericoronitis with significant signs and symptoms is defined as afflicting the pericoronal and adjacent tissue structures, and systemic complications such as fever, malaise or swollen lymph nodes in the neck.
Chronic pericoronitis
Chronic pericoronitis with recurrent episodes of semi-acute pericoronitis causing a few symptoms.
When food gets impacted between the wisdom tooth and the adjacent causing acute periodontal inflammation or abscess.
In conjunction with pericoronitis, dental caries in the affected wisdom tooth and /or distal surface of the second molar leading to acute or chronic pulpitis (toothache) and eventually when untreated to pulp necrosis and periapical abscess in the affected tooth.
Severe swelling and restricted mouth opening may limit the examination of the area. Radiographs can be used to rule out other causes of pain and to properly assess the prognosis for the further eruption of the affected tooth.
A migratory abscess refers to the expansion of pericoronal infection and pus on the buccal aspect of the lower third molar region in the submucosal plane, the space confined to the body of the mandible and the buccinator muscle to the attachment. Consequently, an intra-oral sinus formation may spontaneously discharge the pus exudate.
Prevention of pericoronitis
Prevention of pericoronitis can be achieved by removing the impacted third molars before they erupt into the mouth, or through pre-emptive operculectomy. However, the new guidelines advise against any preemptive elective removal of asymptomatic, disease-free impacted wisdom teeth prior to orthodontic treatment which prevents pericoronitis.
Management of chronic pericoronitis
An efficient treatment should address the source of the inflammation through improved oral hygiene and /or by removal of the plaque accumulation areas through tooth extraction or gingival resection. Undertaking an immediate treatment may prevent over-consumption of antibiotics hence the emergence of the antibiotic-resistance bacterial strains.
Management of acute pericoronitis
When possible, immediate definitive treatment of acute pericoronitis is recommended because surgical treatment has been shown to resolve the spread of the infection and pain, with a quicker return of function.
The surgical approach may at times be deferred in an area with acute infection. In such an instance, analgesics and antibiotics should primarily be prescribed for the following reasons:
  • To avoid causing an infected surgical site with delayed healing (e.g. osteomyelitis or cellulitis).
  • To avoid a reduced efficiency of local anaesthetics caused by the acidic environment of infected tissues.
  • To resolve the limited mouth opening to enable the performance of oral surgery.
  • To improve patient compliance as a result of the pain-free period.
  • To allow for adequate planning and timing.
Therefore, the following steps may be taken before the surgery
  • Gentle irrigation of the area underneath the operculum to remove debris and inflammatory exudate with warm saline, hydrogen peroxide, chlorhexidine or other antiseptic solutions.
  • Debridement of plaque, calculus and food debris with periodontal instruments.
  • A small incision can be made to allow drainage.
  • Cusp grinding of the opposing tooth which bites into the affected operculum can eliminate the source of trauma.
Home care may involve regular use of hot salt water mouthwashes/mouth baths. A randomized clinical trial found green tea mouth rinse effectively in controlling pain and trismus in acute cases of pericoronitis.
Following treatment, 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. Common antibiotics used are from the β-lactam antibiotic group, clindamycin and metronidazole.
The presence of dysphagia or dyspnoea (difficulty swallowing or breathing) may indicate a severe neck infection and required an emergency admission to hospital to administer intravenous medications and to monitor the threatened airway. Sometimes semi-emergency surgical drainage is advocated to drain a swelling that is threatening the airway.
Once the plaque stagnation area is removed either through further complete tooth eruption or tooth removal then pericoronitis will likely never return. A non-impacted tooth may continue to erupt, reaching a position which eliminates the operculum. A transient and mild pericoronal inflammation often continues while this tooth eruption completes. With adequate space for sustained improved oral hygiene methods, pericoronitis may never return. However, when relying on just oral hygiene for impacted and partially erupted teeth, chronic pericoronitis with occasional acute exacerbation can be expected.
Definitive treatment
Dental infections such as a pericoronal abscess can develop into sepsis and be life-threatening in persons who have neutropenia. Even in people with normal immune function, pericoronitis may cause a spreading infection into the potential spaces of the head and neck.
Rarely, the spread of infection from pericoronitis may compress the airway and require hospital treatment (e.g. Ludwig's angina), although the majority of cases of pericoronitis are localized to the tooth. Other potential complications of a spreading pericoronal abscess include peritonsillar abscess formation or cellulitis.
Chronic pericoronitis may be the aetiology for the development of paradental cyst, an inflammatory odontogenic cyst.
Oral hygiene
In some cases, removal of the tooth may not be necessary with meticulous oral hygiene to prevent the accumulation of plaque in the area. Long term maintenance is needed to keep the operculum clean in order to 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 toothbrushes, interdental brushes, electronic irrigators and dental floss.
The affected tooth must be exposed to the oral cavity, which can be difficult to detect if the exposure is hidden beneath thick tissue or behind an adjacent tooth.
To preventing plaque accumulation and subsequent inflammation, and create an area easy to keep clean, the affected pericoronal soft tissue should be excised using electrocautery or a soft-tissue laser.
Tooth extraction
Sometimes operculectomy is not an effective treatment, and removal of the associated tooth will eliminate the plaque stagnation area, and thus eliminate any further episodes of pericoronitis.
Removal is indicated when the involved tooth will not erupt any further due to impaction or ankylosis; if extensive work would be required to restore structural damage; or to allow improved oral hygiene. Sometimes the opposing tooth is also extracted if no longer required.
Extraction of teeth which are involved in pericoronitis carries a higher risk of dry socket, a painful complication which results in delayed healing.