Fissure removal and needle scraping for evaluation of the bacteria in occlusal fissures of human teeth.

The bacterial counts obtained with a needle-scrape method for collecting plaque samples from human occlusal fissures with incipient caries were compared with the microflora remaining in the fissures as determined with a fissure removal method. Scraping of six fissures with a sterile needle recovered only 18.2% of the total recovered fissure flora. The needle-scrape method failed to detect specific cariogenic bacteria which were present in four of the fissures. Treatment of nine fissures with an antibacterial solution demonstrated that the needle method failed to detect viable bacteria in eight of the fissures which were subsequently shown to contain bacteria by fissure removal. The commonly used needle-scraping method does not appear adequate for studies on the effect of antimicrobial agents on fissure plaque.