Evaluation of Different Agitation Techniques on Smear Layer Formation and Dentine Erosions- An In Vitro Study

OBJECTIVE: This study was performed to assess smear layer formation and erosion after final irrigation protocols with metal and non-metal tips in the apical third of root canals. METHODS: Forty mandibular premolars were instrumented with ProTaper Gold files up to F3 and embedded in a closed silicone flask system. The teeth were subsequently cleaved and 4 sequential indentations (1 to 4 mm from the apical foramen) were prepared on the buccal root canal walls to standardize sites for environmental scanning electron microscopy (ESEM) imaging. The samples were cleaned in an ultrasonic bath and observed under ESEM (controls), reassembled and divided into four groups (n=10 each) and subjected to different final irrigation protocols; XPF Group (XP-endo Finisher) and PUI Group (passive ultrasonic irrigation) with metal tips; EA Group (EndoActivator) and MDA Group (Manual dynamic agitation) with non-metal tips. The smear layer formation and dentine erosion were evaluated using ESEM. The data were analyzed with Kruskal-Wallis test with Bonferroni correction. RESULTS: In comparison to the control groups, XPF group had significantly increased smear layer formation at 1 and 2 mm (P<0.05). PUI group had significantly higher smear layer (P<0.05) formation at 3mm while EA and MDA groups did not present with significantly higher smear layer at all levels. Erosion was significantly higher (P<0.05) in MDA, XPF and PUI groups at all levels when compared to controls while EA group presented with significantly more erosion only at 2 and 3 mm. CONCLUSION: Final irrigation protocol using EA and MDA with non-metal tips did not result in significant smear layer formation. Dentine erosion was observed after all experimental irrigation protocols.