Effectiveness of irrigation systems for removing intracanal medication isthmuses in 3D-printed molars replicas

This study evaluated the effectiveness of four irrigation techniques used during root canal treatment [conventional irrigation (CU), Irriflex (IF), Easy Clean (EC), and passive ultrasonic irrigation (PUI)] in removing calcium hydroxide-based and calcium silicate-based intracanal medications from the isthmus of mesial root canals in 3D-printed mandibular molar replicas. A mandibular molar with presence of an isthmus in the mesial roots and moderate curvature was instrumented with Reciproc R40.06, scanned by Micro Computed Tomography (micro-CT), and used as model to create 64 standardized translucent resin replicas. The mesial roots and isthmus areas were filled with Ultracal XS or Bio-C Temp and scanned again. After 7 days, replicas were reinstrumented and subjected to the irrigation protocols, followed by micro-CT analysis of medication removal. The percentage of remaining intracanal medication volume was analyzed using a t-test. The percentage of medication removed in the isthmus area was also calculated and analyzed using two-way ANOVA (p < 0.05) to evaluate the effects of different factors, followed by Tukey's post hoc test for multiple comparisons. PUI promoted the highest removal of Ultracal XS in percentage (98.2 ± 2.28) (p < 0.05), with no differences among the other techniques. For Bio-C Temp, all protocols performed similarly. PUI showed similar performance for both medications, while the other techniques removed Bio-C Temp more effectively than Ultracal XS.