Original Analysis of the effects of apical backfilling depth on apical sealing of different root canal filling qualities and morphologies

Purpose: The aim of this study was to evaluate the effects of apical back -filling depth on the apical sealing of different root canal filling qualities and morphologies.Methods: 3D-printed root canals (A: round, B: oval, C: long oval, D: flat) were used and divided into subgroups by root canal filling quality (a: good, b: poor, c: nonfilling) and backfilling depth (3 mm, 5 mm). A glucose microleakage device was used to measure leakage. Results: (1) 3-mm iRoot BP Plus was filled at the apex, and no obvious leakage occurred in the good root canal filling group, which was sig-nificantly smaller than that in the poor/nonfilling groups (P < 0.05). Under good root canal filling conditions in groups A, B, C, and D, no obvious leakage was observed. Under poor/nonfilling root canal filling conditions, there was significant leakage; A and B (P > 0.05) and C and D were com-pared (P < 0.05). (2) Apical backfilling with 5-mm iRoot BP Plus showed no significant leakage in the poor root canal filling groups with the four morphologies.Conclusion: 3-mm iRoot BP Plus was filled at the apex, root canal fill-ing was poor, apical sealing was poor, and root canal morphology affected apical sealing. Apical backfilling with 5-mm iRoot BP Plus improved apical sealing under poor root canal filling conditions, and apical sealing was unaffected by root canal morphology.