Investigation on the effect of blood contamination of calcium silicate-based pulp capping materials hardened at different times on shear bond strength

The aim of this thesis study is to examine the effect of blood contamination of MTA and Biodentine, which are widely used in the market, on shear bond strength (SBS) with a self-etch adhesive resin, after different hardening times (24, 48, 72 and 96 hours). For this study, slots with a diameter of 5 mm and a height of 2 mm were prepared in 192 acrylic blocks. Half of the slots were filled with ProRoot MTA and the other half were filled with Biodentine which was prepared according to the manufacturer's instructions. MTA and Biodentine groups were divided into 4 groups according to 4 different hardening times (24, 48, 72 and 96 hours) and stored at 37°C and 100% humidity. The groups formed with different hardening times of each pulp capping material were divided into 2 subgroups (n:12) with and without contamination. In uncontaminated groups, after each hardening time, a self-etch adhesive resin (Clearfil Liner Bond, Kuraray Inc.) and a resin-based composite (Filtek P60, 3M ESPE) were applied on the samples according to the manufacturer's instructions and polymerised with light. In the contaminated groups, after each harderning time, the sample surfaces were contaminated with blood for 20 seconds, and then washed with water. After they were dried with cotton pellets, adhesive resin and resin composite were applied on them. The shear bond strength values of the materials were measured by using a universal testing machine. The data were subjected to a 2-way ANOVA test analysis. SEM images were taken from one sample for each group and surface changes were examined. According to the findings of this study, in the uncontaminated MTA and Biodentine groups, there was no significant difference in the bond strength values of each material among 24, 48, 72 and 96 hours hardening times (p>0.05). ProRoot MTA showed statistically higher shear bond strength than Biodentine in the 72 and 96 hour uncontaminated groups (p<0.05). Blood contamination caused a significant decrease in the shear bonding values of ProRoot MTA and Biodentine compared to the uncontaminated groups (p<0.05). In the 96 hour contaminated groups, ProRoot MTA showed statistically higher shear bond strength than Biodentine (p<0.05). In addition, with the prolonged hardening times of MTA (72 and 96 hours), SBS values were close to clinically acceptable bond strength values in blood-contaminated groups. In this study, it was determined that blood contamination reduces the shear bond strength of pulp capping materials. Therefore, it is recommended to keep the hardening times of the capping materials long and to take clinical measures to prevent blood contamination as much as possible before restorative treatments are performed. Keywords: Biodentine, Blood Contamination, Calcium Silicate Based Capping Materials, MTA, Pulp Capping