Optimal cleansing of the root canal system is a prime prerequisite for long
-term success in endodontics. Recently, a new method and device were presen
ted providing "automatic" root canal cleansing without the need of endodont
ic instrumentation. Cleanliness results equivalent to or better than those
with conventional methods were achieved in considerably less time. The purp
ose of the present study was a-fold: (a) optimization of the device to make
it applicable to patients and (b) to measure its effectiveness against the
predecessor model. A total of 156 root canals of 66 freshly extracted vita
l human molars were cleansed with the new device and their cleanliness comp
ared with that of 149 canals of 52 molars cleansed previously with the firs
t apparatus. Data indicated that the smaller new machine produced equivalen
t or better cleanliness results in the root canal system using significantl
y less irrigant (NaOCl).