###### Abstract  
This study evaluated the efficacy of a multisonic technology for the debridement of vital and necrotic pulp tissues in freshly extracted human mandibular molar teeth. Twelve teeth with a diagnosis of symptomatic irreversible pulpitis (SIP) and twelve teeth with a diagnosis of pulp necrosis with symptomatic apical periodontitis (SAP) were extracted. The GentleWave(r) procedure was performed on 10 teeth from each group. Four non-treated teeth served as histologic controls. Histological consecutive 5 um sections were obtained from the apical, middle, and coronal portion of the canals. The canals were evaluated for the presence of pulpal debris and bacteria. **Results:** In nine out of the ten specimens with SIP, no pulpal debris was detected in any portion of the canals. In the necrotic pulp group, eight out of the ten specimens had no detectable pulpal debris in any portion of the canal spaces. No bacteria were detected in the main canals, isthmuses, or lateral canals, but were detected deep within the dental tubules in 10 specimens. **Conclusions:** This study demonstrated that the multisonic technology was effective at removing vital and necrotic pulp tissue as well as bacteria from the root canal system, including inaccessible areas. NaOC; EDTA; multisonication; root canal debridement +
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discussed the anatomical variation of the teeth and mechanical preparation through a meta-analysis and concluded that neither ultrasonic irrigation nor conventional positive pressure techniques are 100% effective. [PERSON] et al. [13] and [PERSON] [26] reported side effects such as alteration of the original canal anatomy and instrument fracture. In addition, it has been demonstrated that the efficacy of irrigation is correlated with the penetration depth of the needle [24] and that the vapor lock phenomenon can decrease irrigation efficiency [27]. A system using multisonic technology has recently been introduced (GentleWave(r)). The technology uses a combination of broad-spectrum acoustic energy, advanced fluid dynamics, and accelerated chemistry to debride and disinfect the root canal system with minimal instrumentation. The mechanism of action allows efficient delivery of energy to all anatomical areas of the root canal system, including difficult to reach areas such as isthmuses, fins, lateral canals, and anastomoses [28]. The GentleWave System consists of a console and a sterile single-use procedure instrument (PI). The console degasses the procedure fluids which helps prevent vapor lock and then dilutes the procedure fluids to the desired concentrations (3% NaOCl and 8% EDTA). The technology allows use of lower concentrations of NaOCl and EDTA than traditional root canal therapy. In addition, the console delivers approximately 50 mL of procedure fluid per minute that ensures that fresh procedure fluid is continuously delivered to the root canal system which creates accelerated chemistry. When the high-pressure fluid jet flows through the procedure instrument, the jet of fluid interacts with the stationary fluid in the pulp chamber to generate a shear force which produces a cavitation cloud. The cavitation cloud consists of thousands of microbubbles which implode to create broad spectrum acoustic energy that travels into the root canal system. The degassed fluids also help prevent the damping of the acoustic energy as it moves through the root canal system. In addition, the fluid jet generates vortical flow which helps refresh the procedure fluids and produces negative pressure at the apices of the root canals which minimizes fluid extrusion [29]. The combination of broad-spectrum acoustic energy, advanced fluid dynamics, and accelerated chemistry leads to increased dissolution of organic matter, including pulp tissue and biofilm. [PERSON] et al. [30] have reported on the effectiveness of multisonic technology in removing hard tissue debris, and others have evaluated gutta-percha and sealer removal using this system [31].