Investigation of infectious organisms causing pericoronitis of the mandibular third molar

Abstract

Purpose: The purpose of the study was to identify the most frequently encountered pyogenic organisms involved in pericoronitis to permit more targeted antibiotic therapy.

Patients and methods: Pericoronal pockets of mandibular third molars from 37 patients showing symptoms of acute, severe pericoronitis were sampled and subjected to microbiologic analysis, including primary evaluation by phase-contrast microscopy. To avoid overgrowth with faster-growing, less fastidious organisms, specimens were cultured on a wide variety of selective media (supporting growth of fastidious bacteria, protozoa, and fungi).

Results: Microscopic examination indicated spirochetes in 55% and fusiform bacteria in 84% of the samples. A total of 441 microorganisms were isolated and identified from the 37 cultured samples. Besides obligate anaerobic bacteria, including various Actinomyces and Prevotella species, a predominantly facultative anaerobic microflora was cultivated, that is, Streptococcus milleri group (78% of samples), Stomatococcus mucilaginosus (71%), and Rothia dentocariosa (57%).

Conclusion: It was concluded that the Streptococci milleri group bacteria, well-known for their ability to cause suppurative infections, are most likely involved in the pathogenesis of acute severe pericoronitis of the lower third molar.