Effectiveness of various procedures and instruments used in root canal treatment for reducing bacterial growth (in vitro comparison)

: In this study root canal preparation methods and instruments were compared by using forty extracted upper first bicuspids. The trepanated and extirpated teeth were sterilised in an autoclave, inoculated with Enterococcus faecalis and incubated for 24 hours at 37 degrees C. The teeth were divided into 5 groups as follows: those treated with K-file and K-file Nitiflex (step back technique, 1st, 2nd groups), with K-reamer (standard technique, 3rd group), those rinsed only with sterile saline solution (4th group), and those left untouched after incubation (5th group). Bacterial samples were taken before and after preparation and were inoculated onto special E67 plates. The plates were evaluated after 24 hours of incubation. It was concluded that the number of the bacteria could be significantly reduced with rinsing and mechanical preparation. There was no significant difference as to the efficacy of the preparation procedures or instruments applied.