Evaluation of the push-out bonding strength of four different calcium silicate-based bioactive simulants in sterile and contaminated environments at different time intervals in vitro

Objective: The aim of this in vitro study was to evaluate the push-out bond strength of four different calcium silicate-based cements (Biodentine™ [Septodont, France], MTA Angelus [Angelus, Brazil], NeoMTA 2, and NeoPutty [Avalon Biomed, USA]) at different time intervals (1st, 7th, and 28th days) in both blood-contaminated and non-contaminated environments, and to examine the fracture types resulting from the tests under a stereomicroscope. Materials and Methods: In this in vitro study, 1 mm-thick dentin discs were prepared from single-rooted mandibular premolars and maxillary central incisors. Four artificial perforations (1,0 mm in diameter) were created in each disc. Half of the discs were kept sterile, while the other half were contaminated with a lysed sheep blood–agar mixture. The four different cements were prepared in accordance with manufacturers' instructions and applied into the perforation sites. Samples were divided into eight groups: Biodentine™ non-contaminated (BD-NC), Biodentine™ blood-contaminated (BD-C), MTA Angelus non-contaminated (aMTA-NC), MTA Angelus blood-contaminated (aMTA-C), NeoMTA 2 non-contaminated (NMTA-NC), NeoMTA 2 blood-contaminated (NMTA-C), NeoPutty non-contaminated (Putty-NC), and NeoPutty blood-contaminated (Putty-C). All samples were incubated at 37 °C and 95–100% humidity for 1, 7, and 28 days. Push-out bond strength testing was performed using a universal testing machine, and the recorded force values were normalized to the bonding area and expressed in megapascals (MPa). The data were statistically analyzed, and the significance level was set at p<0,05. Results: Among all groups and time points, the highest mean bond strength was recorded in the BD-NC group, while the lowest was observed in the NMTA-C group. The mean bond strength values for BD-NC were 4,97 ± 0,80 MPa, 6,32 ± 1,20 MPa, and 6,74 ± 0,36 MPa on days 1, 7, and 28, respectively. In the NMTA-C group, the respective values were 1,34 ± 0,21 MPa, 1,45 ± 0,45 MPa, and 1,81 ± 0,33 MPa. Blood contamination significantly reduced bond strength (p<0,05), and adhesive failure was notably more frequent in the contaminated groups. Conclusion: The bond strength of the tested materials increased over time; however, in the presence of contamination, this strength was markedly reduced—especially in the late-setting cements. Due to its rapid setting time and high biomineralization capacity, Biodentine™ was the least affected by contamination. In contrast, the bond strength performance of Angelus MTA, NeoMTA 2, and NeoPutty significantly decreased under contaminated conditions.