title: Paper point transfer of minimal numbers of microorganisms from a prepared canal in vitro.
abstract: A strain of Str. faecalis resistant to 2 mg./c.c. streptomycin was developed, and serial dilutions of known quantities of the organism were introduced into prepared root canals of extracted teeth. The canals were cultured with sterile dry paper points, incubated in tubes of thioglycollate media containing 2 mg./c.c. streptomycin at 37 degrees C. These tubes were checked for growth at 24-hour intervals for 7 days. Some tubes yielded growth on the first day, while those with greater dilutions of sample took 7 days. All samples with bacteria did yield growth by the seventh day. At the time of transfer of the organism into the prepared root canals, an identical sample of suspended organisms were spread on pour plates of brain-heart infusion broth containing 2 mg./c.c. streptomycin. After incubation at 37 degrees C. for 24 hours, the numbers of colonies were counted in order to determine the exact number of organisms in each serial dilution. Taking a culture after introduction of sterile distilled water into a canal and evaluation of the culture at the time of the scheduled filling appointment are recommended clinical procedures.
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000302:isolation & purification*; D010209:Paper; D012390:Root Canal Therapy