The goal of endodontic treatment is to eliminate the pathogenic effects of bacteria in the root canal system of the teeth. Treatment approaches include chemomechanical cleaning and filling to prevent the microorganisms from infecting and reinfecting the canals and the periradicular tissues after treatment Many irrigation devices have been developed to improve the irrigant delivery throughout the root canal by using sonic or ultrasonic energy. Recently, SLP endoactivator was introduced. It consists of an ergonomic, cordless, contrangled sonic motor that works at 3000 cpm and 18000 cpm.  Diode lasers exhibit high water transmission, that allows them  to interact with the microorganisms located in the deeper layers of dentinal tubules.A recent study showed that 940nm diode laser has extremely high bactericidal effect on Enterococcus faecalis. Trunatomy needle is a double side vented needle that provides a balanced volume of irrigation solution for greater control throughout the canal .Adenosine Triphosphate is the universal energy carrier in all living systems mediating intracellular energy transfer and enabling cells to store and transport chemical energy.  Endocator is the chair side technique to assess the microbial load in the root canal system during endodontic treatment. Bioluminescent ATP assays takes advantage of  firefly luciferase enzymatic reaction, that uses ATP  from viable cells to generate the photons of light. Present study is to evaluate the effectiveness of three different irrigation activation mechanisms, trunatomy needle irrigation, SLP endoactivator and laser diode in disinfecting the root canals during root canal treatment using Endocator. A total of 150 patients were recruited according to the inclusion criteria, from the outpatient department and after taking the informed consent, treatment protocols were performed after randomization using Sequentially Numbered Opaque Sealed Envelope (SNOSE) method. Microbial load in the root canal was evalauted using ATP testing method (Endocator).

Present in vivo study evaluated antimicrobial efficacy of three different irrigation activation techniques—CNI using TN, SA using SLP-EA, and LAI using 980 nm DL in reducing microbial load of pulp necrosis. Microbial reduction is quantitatively assessed using ATP-based bioluminescence assay serving as reliable indicator of viable bacterial activity within canal. A cohort of 150 patients with multirooted maxillary and mandibular teeth of pulp necrosis are included and randomly allocated into three groups (n = 50 each) using SNOSE technique. Standardized BMP is performed using ProTaper Ultimate rotary files, followed by irrigation and activation using 2 ml of 5.25% NaOCl for 2 minutes followed by 1 ml of 17% EDTA for 1 minute and 2 ml of 5.25% NaOCl for 2 minutes. ATP readings are recorded post instrumentation and post irrigation to evaluate reduction in microbial activity.

Evidence demonstrated that all three irrigation techniques resulted in a substantial reduction in ATP levels from post-instrumentation to post-irrigation stages (p < .001), confirming effectiveness of irrigation.

However, intergroup analysis showed notable differences in efficacy among techniques. DL group exhibited lowest post-irrigation ATP values, followed by SLP-EA group, while TN group showed comparatively higher residual ATP levels. Mean percentage reduction in ATP values is highest in DL group (93.06%), followed by SLP-EA group (88.00%), and least in TN group (74.63%).

Statistical analysis using ANOVA and post hoc tests revealed significant differences between TN and SLP-EA groups, as well as between TN and DL groups (p < .05), indicating superior antimicrobial efficacy of activation techniques over CNI. However, no statistically significant difference is observed between SLP- EA and DL groups (p > .05), suggesting comparable effectiveness between these two advanced irrigation techniques. Findings highlight importance of irrigant activation in enhancing disinfection, particularly in complex anatomical regions such as apical thirds, isthmuses, and lateral canals, where CNI may be less effective.

Superior performance of DL may result from its photothermal and photomechanical effects enhancing bacterial elimination and improving penetration of irrigants into dentinal tubules. Similarly, effectiveness of SA using SLP-EA can be explained by acoustic streaming and cavitation effects promoting better irrigant flow and disruption of biofilms.

Despite enhanced efficacy of DL, lack of statistically significant difference between DL and SLP-EA suggests that SA can serve as a clinically viable and cost-effective alternative to laser systems.

Therefore it can be concluded that ATP Endocator can be considered as a reliable chairside tool in assessing microbial load of root canal system.