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3 D micro‐ CT analysis of the interface voids associated with T hermafil root fillings used with AH P lus or a flowable MTA sealer
Author(s) -
Gandolfi M. G.,
Parrilli A. P.,
Fini M.,
Prati C.,
Dummer P. M. H.
Publication year - 2013
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.1365-2591.2012.02124.x
Subject(s) - mineral trioxide aggregate , materials science , root canal , gutta percha , premolar , chemistry , dentistry , molar , medicine
Aim To investigate nondestructively the percentage of 3 D voids and marginal gaps in a pre‐defined interface volume of interest ( VOI ) within root fillings produced by T hermafil O bturators with either a hydrophobic epoxy‐resin‐based sealer ( AH P lus) or a hydrophilic flowable calcium‐silicate sealer [mineral trioxide aggregate ( MTA ) F low]. Methodology Sixteen single root canals from extracted premolar teeth were prepared with P ro T aper rotary instruments, randomly allocated into two groups ( n = 8) and filled with size 30 T hermafil O bturators in association with AH P lus or MTA F low sealers. The filled roots were stored at 37 °C in 5 mL of H ank's balanced salt solution ( HBSS ) used to represent body fluids and scanned after 7 days and 6 months using a high‐resolution micro‐ CT . From each root, images of 3000 sections were analysed in 3 D and binarized using a high‐resolution micro‐ CT (4‐μ resolution). The 3 D distribution of voids (porosity and marginal gaps) at the gutta‐percha‐sealer‐dentine interface was detected through a threshold grey level and expressed as percentage of the 40‐μ‐thick pre‐defined interface VOI (20 μ of interface dentine and 20 μ of gutta‐percha/sealer). A method of analysis based on the root canal segmentation was used, and coronal, middle and apical thirds considered separately. The percentage of 3 D void volume was compared statistically using one‐way anova (significance for P < 0.05). Environmental S canning E lectron M icroscope with E nergy D ispersive X ‐ray ( ESEM ‐ EDX ) analysis was performed on the surface of both sealers after soaking in HBSS . Results Micro‐ CT detected gaps at the dentine‐sealer interface in both groups. Void volumes wider than 10.21 μm 3 with 1.35 μm diameter were detected. Cul‐de‐sac‐type voids (blind pores) and through‐and‐through voids (continuous pores) were discriminated. The apical thirds had a significantly lower 3 D void volume ( P < 0.05) than the middle and coronal thirds. The 3 D void volume reduced significantly ( P < 0.05) over time. ESEM ‐ EDX analysis revealed that MTA Flow sealer created a dense apatite layer after 7 days of immersion in HBSS , whilst only sparse calcium phosphate deposits were detected on AH P lus even after 28 days. Conclusions Micro‐ CT proved to be a powerful nondestructive 3 D analysis tool for visualizing the porous internal microstructure of dental/endodontic materials at the interface with dentine. The proportion of voids was least in the apical third of root canals. Voids reduced over time in the presence of simulated body fluid.