RESUMEN
Objective: To compare the amount of extruded debris in primary molars after manual instrumentation or WaveOne system. Material and Methods: Twenty-five primary molar roots with mild and moderate root angulation (between 10 to 20º), having at least two thirds of root length, no pathological reabsorption (internal or external) or furcation perforation, were selected for this study. Roots were standardized at 6 mm in length, inserted and stabilized in individual acrylic resin blocks with random distribution into two groups: G1 (n=12): Instrumentation with crown-down manual technique; and G2 (n=13): instrumentation with WaveOne system. Blocks with roots were weighed before and after instrumentation, allowing the calculation of extruded debris using both mechanical preparations. Data analysis was performed by Bioestat 4.0 statistical software using Mann Whitney test. Results: The mean weight of extruded debris in manual instrumentation and WaveOne system have no significant difference (p=0.8704). Conclusion: Manual crown-down instrumentation or WaveOne system does not influence the amount of extruded debris after mechanical preparation, suggesting that both techniques were effective in canals clean causing similar extrused debris, however more studies with largest sample should be done to better validate this evidence.