The patented RDT3 / RDT3-NX handpiece heads by ReDent Nova are the only existing handpiece heads that provide the combined motion of vertical vibration and rotation required for proper operation of the SAF. The head contains a clutch mechanism that inactivates the rotational motion when the file is engaged in the canal. The use of imitation handpiece heads other than the original RDT3 may prevent proper functioning, damage the files, and/or compromise the treatment.
The file’s effective, main mode of operation, is vertical vibration. The motor should be operated at 5,000 rpm, which are converted by the handpiece head to 5,000 in-and-out vibrations per minute. These vibrations, combined with a pecking motion by the operator, serve to circumferentially remove dentin from the canal walls while providing also a gentle scrubbing motion and agitation of the irrigant.
The added rotation motion is very slow and almost torque-less. It only serves to repeatedly shift the file’s circular position when entering the root canal during treatment. The rotation motion is not meant to remove any dentin, and only occurs when the file is not engaged with the canal walls. Continuous in-and-out hand pecking motions are required during operation of the SAF and are essential for the circular repositioning of the file to take place. Each out-bound stroke of the pecking motion should reach far enough coronally to disengage the file and allow it to rotate. Such rotation can be observed by the movement of the colored stripe on the rubber stopper. When inserted into the canal, with the in-bound motion, the file should stop rotating but keep vibrating.
Please note: the file should never rotate when engaged with the canal walls. If it does rotate while inside the canal, either (1) the diameter of the file is too small for that given canal (i.e. 1.5 mm diameter file rather than the 2.0 mm diameter file in a wide canal); (2) the pressure applied to the file by the operator was too high and caused file buckling inside the canal; or, more rarely, (3) the RDT3 head clutch mechanism malfunctioned. If the file rotates in the canal for any of these reasons - immediately remove it from the canal.
Please note that the rotation speed should be controlled by stretching / loosening the irrigation tube that is connected to the file, which does not affect the vibration at all. Continuous re-use of the irrigation tubes may reduce their flexibility and thus their ability to control the rotation speed. Periodical replacement of the irrigation tubes is advised.
Markedly fast rotation or excessive pressure applied by the operator may cause unnecessary mechanical damage to the file. The irrigation tube must always be connected to the file during treatment, even when the continuous irrigation has been turned off for any reason (see below), in order to limit and control the rotation speed.
At the beginning of the clinical procedure, make sure that both vibration and rotation function properly. The lack of any of the two functions may lead to improper operation and may indicate a malfunction of the RDT3 handpiece head, which should be reported immediately to an authorized technician. Avoid operating a malfunctioning handpiece head.
