Micro‐XRD and nanoindentation investigation of bioceramics for dental pulp therapy

Abstract

Therapeutic bioceramics for dental pulp treatment are an area of active research. This study investigated the phases in two commonly used bioceramics and depth of dentin remineralization after application of these bioceramics. Cavities in non‐carious third molars were filled with ProRoot White mineral trioxide aggregate (MTA) (Dentsply Tulsa Dental), EndoSequence Root Repair Material (Brasseler USA) and with calcium hydroxide (Dycal, Dentsply Caulk) serving as a control. Specimens were immersed in simulated body fluid (SBF) for 3 months, and Micro‐X‐ray diffraction (Micro‐XRD) analyses were performed on the bioceramics two minutes after placement and at seven subsequent intervals. After three months in SBF, specimens were subjected to nanoindentation testing. Micro‐XRD revealed the presence of dicalcium silicate, tricalcium silicate, tricalcium aluminate and calcium sulphate in both bioceramics. Opacifying agents bismuth oxide and zirconia were also detected in ProRoot White MTA and EndoSequence Root Repair Material, respectively. There was no evidence for the silicate gel matrix that forms during setting of these bioceramics. Nanoindentation testing revealed that at <17 µm from the interface, the nanohardness of dentin in specimens filled with Dycal was lower than for EndoSequence and ProRoot White MTA, whereas at 21–97 µm from the interface, there was no significant difference in nanohardness of dentin filled with any material.