Fiber posts bonding to root canal dentin after ethanol drying

Aim. To verify by SEM the influence of root canal walls ethanol drying in promoting the adhesion of fiber posts. Methodology. Thirty extracted human maxillary incisors with an av- erage length of 22±1 mm were prepared with Revo-S Ni-Ti instru- ments (MicroMega, France) and shaped to ISO size 25 and .06 taper. All root canals were irrigated with 5% NaOCl and 17% EDTA solu- tions. The samples were obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Germany) using the continuous wave warm vertical compaction technique. After a week the post space were pre- pared. All the specimens were randomly divided into two groups: in group 1 post space was etched and bonded with All Bond 3 (Bisco Inc. USA), in group 2 it was etched, dried with ethanol and bonded with the same adhesive system. Then a D.T. Light Post (Bisco Inc., USA) was placed using the same dual-cured resin cement (Duo Link, Bisco Inc. USA) and the same restorative protocol. Restored samples were longitudinally sectioned and prepared for SEM observation in order to evaluate the characteristics of the interfaces between root dentin, resin cement and fiber posts at coronal, middle and apical third. Eachsection was observed separately by two investigators and the inci- dence of gaps was recorded and scored (0: no gaps; 1: gap no longer than 200 μm; 2: gap between 200 and 500 μm; 3: gap longer than 500 μm) in order to perform statistical analysis. Results. All the interfaces between resin cement and fiber post were free of gaps. The interfaces between resin cement and root dentin showed significant differences (P<0.05): 58% of samples dried with ethanol showed presence of voids/bubbles and gaps at cement-den- tin interface. Conclusions. Ethanol drying seems to be not effective in improving the adhesion of fiber posts into root canal.