Introduction: Apical extrusion debris (AED), an undesirable consequence of root canal instrumentation can be associated with pain / edema and may delay the periapical healing. The aim of our project was to evaluate and quantify the AED in root canal instrumented with continuous and reciprocating rotary instrumentation systems. Materials and Methods: 80 single root canal teeth without endodontic treatment were randomly divided into 4 groups (n = 20): One Shape®, Protaper NEXT®, Hyflex® EDM and WaveOne® Gold. An Eppendorf tube (ET) was weighed in advance with an analytical scale, and with an inserted tooth, it was mounted on a modified device similar to the method described by Myers & Montgomery. The root canals were instrumented and irrigated with distilled water. The instrumented teeth were removed from the ET and these were filled with distilled water up to 1.5 ml, incubated at 70°C for five days and weighed again, the difference between the initial weight and final was calculated determining the weight of debris. Data was statistically analysed using IBM SPSS Statistics 22, considering α = 0.05. Kruskal-Wallis test and post-hoc adjustment of ρ-value by Dunn-Bonferroni method was carried out. Results: There was AED in all instrumentation techniques. Statistical analysis showed significant differences in AED between the techniques used (α = 0.002). Among the WaveOne® Gold and One Shape®, techniques (α = 0.003), WaveOne® Gold and Protaper NEXT®, (α = 0.023) and WaveOne® Gold and Hyflex® EDM (α = 0.028). Conclusion: One Shape® technique presented lower AED while WaveOne® Gold technique with reciprocating movement is a major risk factor due to greater AED. The results of this study indicated that practitioners should be aware of the debris extrusion with each instrument, which could help with the decision for selection of a particular instrument. Clinical implications: The choice of root canal instrumentation system influences the extrusion of debris. Sponsorship: Micro-Mega, França, COLTÉNE e Dentsply Maillefer, Suíça. Keywords: apical extrusion debris, root canal instrumentation, continuous rotation, reciprocating movement, M-Wire, CM-Wire