Abstract
BACKGROUND: The complex and irregular morphology of prepared oval root canals poses optimal sealing in oval canals as a key endodontic challenge. To address this, this study utilized five types of standardized 3D-printed models replicating prepared anatomy of extracted teeth with oval canal, to characterize the morphological diversity of oval canals after preparation and evaluate the efficacy of three obturation techniques across different morphologies. METHODS: Five standardized 3-dimensional printed models replicating prepared oval canal morphology were produced using cone-beam computed tomography (CBCT)-derived data from sixty extracted premolars, which had undergone standardized collection, screening, and in vitro preparation procedures. Three obturation techniques (n = 15 each) were evaluated: (1) lateral condensation with AH-Plus sealer (AHP-LC), (2) continuous wave vertical compaction with AH-Plus sealer (AHP-CWC), and (3) single-cone technique with iRoot SP sealer (SP-SC). Micro-CT scanning and volumetric analyses were employed to quantify the obturation quality. Statistical analysis was performed using Mann-Whitney U test, Kruskal-Wallis H test, Dunn's test or Spearman rank's correlation depending on the experimental design. RESULTS: Micro-CT analysis revealed significant differences in the percentage of void volume (PVV) among the obturation techniques. Over the entire canal length, SP-SC demonstrated significantly lower PVV compared to AHP-LC and AHP-CWC (p < 0.01). In the apical third, canal morphology significantly influenced the PVV of AHP-CWC (p < 0.05), with a more circular cross-section (higher roundness) correlating strongly with a lower PVV (p < 0.001). No significant effects of morphology were observed in other canal segments or with the other obturation techniques. CONCLUSIONS: SP-SC achieved more complete three-dimensional adaptation regardless of morphological variations in oval canals including varied diameter ratios, isthmus and recess. Conversely, AHP-CWC's performance was significantly dependent on canal morphology in the apical third, where more circular cross-sections correlated with lower void volumes.