Periodontopathic bacteria and salivary microbes before and after extraction of partly erupted third molars

This study examines the effect of extraction of third molars on suspected periodontopathogenic microbes, salivary acidogenic bacteria, and yeasts. The subjects were 39 healthy conscripts aged 20.2 yr, with symptom-free, partly erupted mandibular third molars. Microbial samples were taken from the mandibular third molar pericoronal space and from the adjacent gingival pocket of the second molar. The samples were stained by Gram's and Giemsa's methods and studied under a light microscope. Stimulated saliva was collected for assessing mutans streptococci, lactobacilli, and yeast counts by chair-side kits. All partly erupted third molars were extracted from 20 test subjects; 19 control subjects were left untreated. Microbial samplings were repeated 2 and 5 months postoperatively. Results showed that at base line the total number of Gram-negative bacteria, Gram-negative rods, and spirochetes was significantly higher at the third molar than at the second molar sites. The extraction of the third molars caused a significant decrease in the percentage of these bacteria at the second molar sites. High counts of salivary mutans streptococci (CFU > or = 10(6)) and lactobacilli (CFU > or = 10(5)) were also significantly less frequent after the operations. Yeast counts were not affected by the extractions. Thus, partly erupted third molars may harbor a periodontally pathogenic microflora and increase the number of salivary acidogenic microbes.