"One-Bottle" And Three Steps Adhesive Systems Used For Bonding Fiber Posts Into Root Canals Under Clinical Conditions: A Sem Investigation Ferrari M., Grandini S., Vichi A., Mannocci F., Lopes B., Fuzzi M. (School Of Dental Medicine, Siena, University, Italy, Private Practice, Bologna) The clinical use of three steps bonding systems in combination with resin cements and fiber posts is routinely used. Recently, the so-called ‘one-bottle’ adhesive systems were proposed to simplify the clinical bonding procedure of direct restorative dentistry. The aim of this clinical report was to evaluate the effectiveness of 3 ‘one-bottle’ and 2 three steps adhesive systems (as controls) on forming resin tags, adhesive lateral branches and hybrid layer when used to bond fiber posts under clinical condition. 50 endodontically treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed and their written consent was obtained.   The samples were randomly divided in 5 groups of ten samples each. Group 1: Scotchbond 1 in combination with Rely X ARC resin cement (3M); Group 2: One-step with C & B resin cement (Bisco), Group 3: All Bond Experimental with Post Cement HI-X (Bisco); Group 4: All Bond 2 with C & B (Bisco), and Group 5: Scotchbond Multipurpose Plus with Opal Luting Composite (3M). The adhesive systems and resin cements were used strictly following manufacturers’ instructions. The priming-adhesive solution of all ‘one-bottle’ systems was light-cured before placing the resin cement and the post. Aestheti-Plus posts (white quartz fiber posts, RTD, France) were used. A week later, the root samples were extracted and processed for SEM observations.   All the adhesive systems showed hybrid layer and resin tag and adhesive lateral branch formation. Characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals. In the apical third of the root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other two thirds. Hybrid layer morphology was well detectable and uniform in the first two thirds of root canals while in the apical third the hybrid layer was not uniformly present. No morphological differences were found between three steps and ‘one-bottle’ adhesive systems. ‘One-bottle’ systems might clinically be used for bonding fiber posts into root canal. It can be concluded that the bonding mechanism created between root canal dentin and ‘one-bottle’ systems is of the same nature of that obtained using three steps bonding systems.