Abstract: Objective: To investigate the apical microleakage of iRoot BP Plus in apical barrier therapy under different apical foramen diameters and filling thicknesses of bioceramic materials. Methods: Up to 100 fresh and complete mandibular single-root premolars were collected. After root canal preparation and establishment of apical foramen models, they were divided into 2 influencing factors: 6 experimental groups (n=15) and 2 control groups (n=5). iRoot BP Plus was selected as the apical barrier filling material. Groups A, B, and C were the apical foramen diameter groups (0.5 mm, 0.7 mm, 1.0 mm); groups D, E, and F were the apical barrier material filling thickness groups (3 mm, 4 mm, 5 mm), group G was the positive control group, and group H was the negative control group. After dye penetration test was performed on the filled teeth, apical sealing ability of iRoot BP Plus in different conditions was compared. Results: In the apical foramen diameter groups, the apical microleakage values of groups B and C were greater than that of group A (P<0.001), but there was no obvious difference in leakage values between groups B and C (P>0.05). In the apical barrier material filling thickness groups, there was no obvious difference in leakage values among groups D, E, and F (P>0.05). Conclusion: When iRoot BP Plus is used as the filling material for apical barrier surgery, when the apical foramen diameter is 0.5 mm, there is no significant difference in the apical sealing effect with filling thicknesses of 3-5 mm. However, when the apical foramen diameter increases to 0.7 mm and 1.0 mm, microleakage occurs in the apical region.

Key words: iRoot BP Plus, apical barrier, microleakage