It may be :-

    acute 

    or chronic 

The partialy erupted or impacted mandibular third molar is the most common site of pericoronitis *

The space between the crown of the tooth and overlying  gingival flap is an ideal area for the * 

 accumulation of food debris and bacterial growth

Even in patients with no clinical signs or symptoms , the gingival flap is often chronically inflamed and infected , with various degrees of ulceration along its inner surface 

Acute inflammation involvement is a constant possibility 

An influx of inflammatory fluid and cellular exudates results in increase in the bulk of the flap which interferes with complete closer of mouth 

The flap is traumatized by contact with the opposing jaw ,and the inflammatory involvement is aggravated.

The clinical picture is that of

 

   swollen

    -with radiating pain to ear , throat

      and floor of mouth

The patient is extremely uncomfortable because of pain , a foul taste , and inability 

     to close the jaw

Swelling of the cheek in the region of the angle of the jaw 

The involvement may become localized in the form of periodontal abscess

It may spread posteriorly into the oropharyngeal area and medially to the base of the tongue making it difficult for the patient to swallow  

The treatment of pericoronitis depends on the severity of the inflammation , the advisability of retaining involved tooth .

-swabbing  with antiseptic after elevatintg 

the flap gently from the tooth with a scaler.

Antibiotic can be prescribe in severe cases.

After the acute symptoms have subsided , a determination is made as  whether the tooth is to be retained or extracted.

This decision is governed by the likelihood of further eruption into a good functional position .

Free pericoronal flaps should be removed as a preventive measures against subsequent acute involvement . 

If it is decided to retain the tooth ,the pericoronal flap is removed using periodontal knives

It is necessary to removed the distal to the tooth as well as the flap on the occlusal surface

Incising only the occlusal portion of  the flap leaves a deep distal pocket , Which invite recurrence of acute pericoronal involvement 

After the tissue is removed , a periodontal pack is applied 

The pack may be retained by bringing  it forward along the facial and lingual  Surface into the interproximal space between the second and third molar

The pack is removed after one week