Marginal Adaptability of Harvard MTA and Biodentine Used as Root-End Filling Material: A Comparative SEM Study

The proper selection of bioactive root-end material is one of the main prognostic factors for the successful healing outcome of apical microsurgery (AMS). The aim of the present in vitro study was to evaluate and compare the marginal adaptability of a novel calcium silicate cement (CSC), Harvard MTA Universal, and Biodentine used as root-end filling materials. The endodontic treatment of 20 extracted human maxillary central incisors was performed. The apicoectomy was simulated, and root-end cavities were prepared ultrasonically using universal retrotips. Teeth were randomly assigned into two equal groups (n = 10) according to the retrofilling cement used: Group 1-Harvard MTA Universal and Group 2-Biodentine. The specimens were stored in relative humidity for 48 h and sectioned longitudinally. The data were processed and analyzed statistically. Harvard MTA exhibited a significantly lower mean gap width (1.16 ± 0.37 µm) than Biodentine (2.48 ± 0.38 µm) (<i>p</i> < 0.05), indicating a more intimate interfacial adaptation. Additionally, the phenomenon of material penetration into the dentinal tubules was observed only in the Harvard MTA group. Within the limitations of this in vitro study, Harvard MTA Universal demonstrated better interfacial properties than Biodentine when applied as a root-end filling material. This novel biomaterial could be regarded as a promising alternative for earlier calcium silicate cements in the context of AMS goals. <b>Clinical relevance:</b> The quality of marginal adaptation is a determinative feature for the clinical performance of CSCs and the long-term prognosis of AMS.