Abstract: BACKGROUND: In recent years, bioceramic materials have become the preferred materials for retrograde apical filling due to their excellent biocompatibility and sealing properties. The bioceramic materials C-Root BP and iRoot BP Plus both exhibit excellent biocompatibility and sealing properties.
OBJECTIVE: To compare the apical sealing performance and resistance strength of C-Root BP and iRoot BP Plus materials in vitro. 
METHODS: From June 2022 to June 2024, 56 freshly extracted single detached teeth at the Department of Stomatology, Shijiazhuang Second Hospital due to orthodontics or periodontal disease were collected and randomly divided into four groups. The iRoot BP Plus group (n=16) and C-Root BP group (n=16) were respectively treated with iRoot BP Plus and C-Root BP materials for root tip filling. The positive control group (n=16) was treated with distilled water for root tip filling, while the negative control group (n=8) was not treated with root tip filling and only underwent routine root canal preparation and disinfection. Dye penetration method was used to detect the apical sealing. A root canal bacterial leakage model was made in vitro, and bacterial microleakage was evaluated. The adhesion strength between the filling material and dentin was measured by wafer extrusion test, and the fracture form was observed under a microscope. 
RESULTS AND CONCLUSION: (1) After 7 days of dye staining, the dye penetration length of the positive control group was greater than that of the iRoot BP Plus group and C-Root BP group (P < 0.05). There was no significant difference in dye penetration length between the iRoot BP Plus group and the C-Root BP group (P > 0.05). (2) After 90 days of cultivation, the incidence of bacterial microleakage in the positive control group was higher than that in the iRoot BP Plus group and C-Root BP group (P < 0.05), while there was no significant difference in the incidence of bacterial microleakage between the iRoot BP Plus group and C-Root BP group (P > 0.05). (3) The adhesion strength between the filling material and dentin in the C-Root BP group was greater than that in the iRoot BP Plus group (P < 0.05), and there was no significant difference in the fracture surface pattern between the two groups (P > 0.05). (4) These findings indicate that the use of C-Root BP and iRoot BP Plus materials for root tip filling can produce similar root tip sealing effects, and the fracture mode is also basically the same. However, C-Root BP material has good adhesion strength.

Key words: C-Root BP, iRoot BP Plus, retrograde root tip filling, apical sealing, resistance strength, bacteria, root canal treatment, biomaterial