A NOVEL NONINSTRUMENTED TECHNIQUE FOR CLEANSING THE ROOT-CANAL SYSTEM

The aim of this study was to develop a machine to clean root canals wi thout conventional instruments. This goal was achieved with a device w hich was able to develop controlled cavitation in the root canal. Unde r reduced pressure, alternating pressure fields generated microscopic and macroscopic cavitation bubbles. Subsequently, these vapor-filled c avitation bubbles collapsed, creating hydrodynamic turbulence. These t wo phenomena allowed the irrigant to penetrate the canal system and th en be exchanged with new irrigant. To test the cleaning ability of the device 79 freshly extracted vital molars with 222 root canals were co llected. The control group (27 molars, 73 canals) was prepared with th e step-back technique using NaOCl (3%) as an irrigant. The three test groups (52 molars, 149 canals) were prepared with the new machine usin g 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. Ov erall, the treatment with NaOCl (2 and 3%) resulted in similar or bett er cleanliness in all three root sections when comparing machine and h and instrumentation. In curved canals, however, the apical one third w as also significantly cleaner when using the machine and 3% NaOCl than with hand instrumentation. This in vitro study shows that it is possi ble to clean a root canal system by a noninstrumented technique as wel l as by conventional hand instrumentation.