Incidence of Delayed Infections after Lower Third Molar Extraction

This retrospective study aimed to verify that the onset of delayed infection after lower third molar extraction was influenced by the amount of distal space.

We evaluated 265 patients (age range 12-55 years), who had one or two mandibular third molars to be extracted. All 380 third molars were removed for orthodontic reasons, periodontal disease, or pericoronitis and were evaluated by the Pell and Gregory classification using the panoramic radiographs.

Delayed infection, characterized from purulent exudates from the alveolus and swelling, was reported in 21 extractions between 2 and 8 weeks after surgery. In 16 of the 21 cases of infection, a class III of Pell and Gregory was observed, and this anatomic condition evidenced an extremely reduced space distal to the second molar.

This study confirmed that the absence of distal space was significantly correlated with delayed infection. These data are important for proper examination of a patient because, in the case of class I or II of Pell and Gregory, a delayed infection was less likely to occur, while a class III of Pell and Gregory could indicate a greater likelihood of this type of infection.