# Narrative Review on Methods of Activating Irrigation Liquids for Root Canal Treatment
## 4 Irrigants Activation Techniques
### Other Activation Systems  
On the market, there are special devices available, designated for the activation of irrigants. Among them, we can enlist pressure systems (EndoVac, Kerr Endodontics, Gilbert, AZ, USA; Rinsendo, Durr Dental, Biettigheim, Germany) or sound-wave-based system (EndoAcivator, Dentsply Maillefer, Ballaigues, Switzerland; EDDY, VDW, Munchen, Germany; Ripissonic, Medidenta International Inc., Woodside, NY, USA; SAF, ReDent, Ra'anana, Israel).  
EndoVac uses negative irrigation pressure. It results in the canceling of the vapor lock effect and provides better cleaning at a depth of 1 mm from the working length in comparison to irrigation with a syringe and needle [78]. The apical negative pressure irrigation technique was shown to be the most effective in delivering the irrigant up to the working length in mature permanent teeth [79]. After irrigation with the EndoVac system patients less frequently complained about post-treatment pain, compared to the irrigation with a needle [80]. It might be linked to the fact that using EndoVac limits the occurrence of pushing the irrigant through the canal to the tissues surrounding the apex, in juxtaposition with Manual Dynamic Agitation (MDA) or UA [81,82]. Moreover, EndoVac is more effective in the removal of the smear layer than MDA. It is mainly because it removes the vapor lock effect more efficiently and better cleansing of the apical area [61]. The efficiency of root canal processing is greater with using UA, but EndoVac is much safer in terms of the potential pushing of irrigants through the apex to apical tissues [83]. This system requires minimal apical preparation measuring 35/0.04 [72].  
RinsEndo (Durr Dental, Bietigheim, Germany) is a hydrodynamic irrigation system that utilizes pressure-sucking technology [82]. It is characterized by greater penetration depth of the irrigants in comparison with using a syringe and needle. However, it bears a greater risk of pushing the irrigant through the apical foramen [84]. The efficiency of cleansing root canals is better with RinsEndo in comparison with using a syringe and needle but worse when compared to MDA [62]. There are studies regarding the presence of broken tools inside the root canal which is unremovable. In that scope, pressure instruments were proven to be the best choice for irrigation. They possessed better permeability of NaOCI than UD or EndoActivator. It may ensure better microbiological control despite the difficulty of tool breakage [85].  
The endoActivator system ([PERSON], Ballaigues, Switzerland) is a soundwave-based system equipped with a non-cutting tip from synthetic material for activation of the irrigant. The tip does not cause shaving of the dentin which prevents further widening of the canals. It is possible to use many types of tips depending on the size of the root canal. They must be adjusted in the way that the tip moves freely in the canal up to 2 mm before the working length [86]. EndoActivator might be utilized to activate the solution of EDTA [87].  
EDDY (VDW, Munchen, Germany) is a tip made of elastic polyamide fiber activated with the air ultrasonic tip, designated to work in a frequency range of 5000-6000 Hz. A flexible working tip is safe for root canal walls and causes no damage to dentin compared to UA sharp tips [88]. Sonic activation (with EDDY of EndoActivator) and PUI are better choices for removing debris than irrigation without activation with a syringe in straight root canals. Moreover, EDDY and PUI removed the smear layer more efficiently than manual activation [89]. The study shows that EDDY can be also more effective than PUI at removing antibiotic pasts from the root canal [90]. One must bear in mind, that patients subjected to irrigation with EDDY complained about post-treatment pain more frequently than a group of patients treated with MDA. It might be related to the much more frequent pushing of irrigants through the apical foramen caused by using EDDY [50].