ADHESIVE AND COHESIVE INTERFACES OF BULK-FILL FLOWABLE RESINS IN DEEP DENTIN (ABSTRACT DEFINITIVO)

OBJECTIVES: The aim of this study was to analyze bulk-fill, or heavy, resin interfaces with the pulpal dentin wall in deep cavity preparations using reflection confocal laser scanning microscopy (LEXT).METHODS: Twenty-four human third molars extracted for orthodontic were used. Class 1 preparations measuring 4mm bucco-lingually x 4mm in depth x 4 mesio-distally on the occlusal aspect, were performed using a Cavity Preparation Standardizing device (URIBE ECHEVARRIA L, 2014). Experimental groups were as follows: Group 1 (Control Group): Adper Single Bond 2 (3M-ESPE) adhesive and Z100 (3M-ESPE) composite resin, applied in 2.0mm layers following the incremental technique; Group 2: GC-Bond adhesive (GC Corporation) and Gaenial Universal Flo (GC Corporation) bulk-fill; Group 3:One Coat 7.0 adhesive (Coltène/Whaledent) and Fill Up (Coltène/Whaledent) resin; and Group 4: Prime & Bond 2.1 adhesive (Dentsply) and SureFil SDR Flow resin (Dentsply). Preparations in the latter 3 groups were bulk filled with 4mm of the corresponding material. The teeth were sectioned bucco-lingually using Isomet 1000, and polished using silicon carbide discs with decreasing grain sizes and rotating polishing pads with 0.5 µm diamond particles, for direct observation using a LEXT OLS4000 3D confocal microscope. Interfaces at the pulpal wall were determined, and mean and standard deviation were calculated. RESULTS: Interfaces in Group 1 exhibited adhesive fractures measuring 0.92 µm ±0.2. Interfaces in Group 2 showed cohesive fractures, with values similar to those observed in the control group (0.97µm ±0.15). Interfaces in Group 3 exhibited adhesive fractures (19.47µm ±5.77), and those in Group 4 also showed adhesive fractures (18.23µm ±3.25). The differences among groups were statistically significant (ANOVA: F=38.76; p<0.05). CONCLUSIONS: The obtained results allow concluding that interfaces in groups 1, 3 and 4 had adhesive fractures and no sealing of the dentinal tubules, while interfaces in group 2 showed cohesive fractures that did not affect the sealing of the dentinal tubules.