Role of phosphate-buffered saline on push-out bond strength of MTA Flow™ and Biodentine™ after acid challenge: An in vitro study

CONTEXT: The physical and chemical properties of root repair materials are adversely affected when placed in areas of inflammation with acidic pH. AIM: To evaluate the role of phosphate-buffered saline (PBS– pH 7.4) on push-out bond strength (POBS) of MTA flow and Biodentine (BD) after acid challenge with butyric acid buffered solution (BABS– pH 5.4). SUBJECTS AND METHODS: Eighty mid-root dentin slices (2 mm thick; 1.3 mm lumen diameter) were prepared and were divided into two groups (n = 40) based on the type of material used for filling lumen: Group 1-MTA Flow and Group 2-BD. Each group was again divided into four subgroups (n = 10) based on the duration of exposure to storage media: (a) 3 days in PBS, (b) 3 days in BABS, (c) 3 days in BABS followed by 30 days in PBS, and (d) 33 days in PBS. POBS was then measured using the universal strength testing machine. STATISTICAL ANALYSIS USED: Statistical analysis was performed with one-way analysis of variance and post hoc test using SPSS software version 23.0. RESULTS: Group 1b and 2b showed significantly lower bond strength values. No significant difference was observed between Group 1b and Group 1c (P > 0.05), whereas highly significant POBS values were observed between Group 2b and Group 2c (P = 0.000). Among all the tested groups, Group 2d showed the highest POBS values. CONCLUSION: On storage in PBS after acid challenge, BD attained the highest POBS values while no significant difference was observed in MTA Flow.