Comparison of two devices for root canal cleansing by the noninstrumentation technology.

Optimal cleansing of the root canal system is a prime prerequisite for long-term success in endodontics. Recently, a new method and device were presented providing "automatic" root canal cleansing without the need of endodontic instrumentation. Cleanliness results equivalent to or better than those with conventional methods were achieved in considerably less time. The purpose of the present study was 2-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 vital human molars were cleansed with the new device and their cleanliness compared with that of 149 canals of 52 molars cleansed previously with the first apparatus. Data indicated that the smaller new machine produced equivalent or better cleanliness results in the root canal system using significantly less irrigant (NaOCl).

A novel noninstrumented technique for cleansing the root canal system.

The aim of this study was to develop a machine to clean root canals without conventional instruments. This goal was achieved with a device which was able to develop controlled cavitation in the root canal. Under reduced pressure, alternating pressure fields generated microscopic and macroscopic cavitation bubbles. Subsequently, these vapor-filled cavitation bubbles collapsed, creating hydrodynamic turbulence. These two phenomena allowed the irrigant to penetrate the canal system and then be exchanged with new irrigant. To test the cleaning ability of the device 79 freshly extracted vital molars with 222 root canals were collected. The control group (27 molars, 73 canals) was prepared with the step-back technique using NaOCl (3%) as an irrigant. The three test groups (52 molars, 149 canals) were prepared with the new machine using NaOCl (1, 2, or 3%). The treatment time ranged from 16 to 32 min in the hand group and from 10 to 15 min in the machine groups. The teeth were then prepared histologically and examined by light microscopy. Overall, the treatment with NaOCl (2 and 3%) resulted in similar or better cleanliness in all three root sections when comparing machine and hand instrumentation. In curved canals, however, the apical one third was also significantly cleaner when using the machine and 3% NaOCl than with hand instrumentation. This in vitro study shows that it is possible to clean a root canal system by a noninstrumented technique as well as by conventional hand instrumentation.