Micro-CT analysis of calcium silicate-based cements in simulated acidic and neutral environments: a comparative study

This in vitro investigation aimed to examine the physical characteristics of three calcium silicate-based cements—Neo MTA Plus, Biodentine, and MTA Repair HP—when used as root canal filling materials under diverse environmental conditions, employing micro-computed tomography (micro-CT) analysis. A total of 144 extracted human maxillary anterior teeth were sectioned to produce standardized root canals. These canals were then randomly distributed into 12 groups ( n = 12) according to the type of material used, the method of placement (either manual or ultrasonic), and the storage environment (acidic or phosphate-buffered saline [PBS]). Phosphate-buffered saline (PBS, pH ≈ 7.4) served as the neutral comparison condition referred to in the title. The materials were inserted into the prepared canals and underwent micro-CT scanning both before and after a 7-day exposure to the designated environments. The resulting changes in volume, density, and porosity were measured. Data normality was assessed with the Shapiro–Wilk test. As the data were non-parametric, Kruskal–Wallis and Dunn’s post hoc tests were used ( p < 0.05). Under acidic conditions, a trend toward structural changes was observed in all tested materials. Biodentine exhibited a greater tendency toward volume reduction compared to the other materials; however, these differences were not statistically significant ( p > 0.05). Increased porosity was noted under acidic conditions, particularly in Biodentine, whereas specimens stored in phosphate-buffered saline (PBS) showed minimal changes. No statistically significant differences were detected between the acidic and PBS conditions; however, several baseline-to-post-incubation comparisons showed statistically significant differences according to Dunn’s post hoc test. Within the limitations of this study, calcium silicate-based materials showed a tendency toward structural changes under acidic conditions, although these were not always statistically significant. Biodentine exhibited a greater tendency for change compared to the other materials, while placement technique had no significant effect.