Association of odor from infected root canal analyzed by an electronic nose with isolated bacteria

Infected root canals usually cause foul odor. On sensory testing, objective evaluation of the odor is difficult because of the subjectivity of the examiner. In this study, the odor of the canal content was analyzed by an electronic nose. Moreover, association of the odor with culturable bacteria isolated from the root canal was examined. The median of the odor index (indicating odor quantity) in nonvital teeth group was significantly higher than that in vital teeth. When Prevotella, Porphyromonas, Fusobacterium, or Bacteroides was detected, the value of the odor index and the strength of smell representation (indicating odor quality) for hydrogen sulfide and ammonia were higher than when these bacteria were not present. Relationship between odor analysis data, clinical symptoms, and isolated bacterial species was seen, thus suggesting that the electronic nose is useful for objective evaluation of root canal odor.