The purpose of this study is to evaluate the effectiveness and clinical application of a chairside testing device (CTD) for evaluating root canal cleanliness. Enterococcus faecalis was cultured for this experiment, and serial dilutions were tested with the CTD and cultured on agar plates. This device provided a 0-100 Endoscore based on the sample solution's ATP and other biomarker levels. An alternative score was also provided in relative light units (RLU). Once a dilution of E. faecalis was identified with an Endoscore of 100, serial dilutions were performed to find a curve relating bacterial concentration to the Endoscore and RLU with correlations to colony-forming units (CFU). Descriptive analysis was performed to obtain the mean and SD for each sample’s serial dilutions tested in triplicate. The correlation of Endoscore and RLU to CFU was evaluated using Pearson’s correlation coefficient (PCC). PCC between CFU and the Endoscore was very high positive (average P, r = 0.9839), while CFU and RLU exhibited a high positive correlation (average P, r = 0.7760). Since this CTD does not exclusively evaluate bacteria, blood and vital tissue could affect values clinically. Within the limitations of this study, the Endocator was found to evaluate cleanliness based solely on bacterial concentration. Further research is needed to evaluate the correlation of Endoscore to clinical treatment outcomes.