Influence of multimode universal adhesives and zirconia primer application techniques on zirconia repair Bruno Seabra, MSc, a Sofia Arantes-Oliveira, PhD, b and Jaime Portugal, PhD c Faculty of Dental Medicine, University of Lisbon, Lisbon, Portugal Statement of problem. More information is needed on the efficacy of the new universal adhesives and on the best 10-methacryloyloxydecyl dihydrogen phosphate- (MDP)-containing primer protocol to promote adhesion to zirconia. Purpose. The aim of this study was to evaluate the influence of 2 new multimode MDP-containing adhesives and several application protocols of a zirconia primer on the shear bond strength (SBS) of composite resin to zirconia. Material and methods. Sixty zirconia (3Y-TZP) blocks were abraded (50 mm Al 2 O 3 ) and divided into 6 experimental groups (n¼10): one Z-Prime Plus coat without light polymerization; one Z-Prime Plus light-polymerized coat; two Z-Prime Plus coats without light polymerization; two Z-Prime Plus light-polymerized coats; All-Bond Universal; and ScotchBond Universal Adhesive. Multimode adhesives were applied according to the manufacturers’ recommendations. After composite resin (Filtek Z250) light polymerization, the specimens were stored in distilled water (37  C/48 hours) and tested in shear (1 mm/min). Failure mode was classified as adhesive or mixed. Statistical analysis of the SBS data was performed with 1-way ANOVA followed by the Student-Newman-Keuls post hoc tests. Nonparametric tests (Kruskal-Wallis) were used to analyze the failure mode data (a¼.05). Results. The ScotchBond Universal Adhesive, All-Bond Universal, and two Z-Prime Plus light-polymerized coats groups showed a higher mean SBS than the other experimental groups (P<.05). The 3 groups with the lowest mean SBS registered 100% of adhesive failures. Conclusions. The new multimode adhesives tested were effective in promoting adhesion between composite resin and zirconia. Z-Prime Plus should be applied in 2 light-polymerized coats to promote SBS values similar to those of the new multimode adhesives. (J Prosthet Dent 2014;-:---) Clinical Implications New multimode MDP-containing adhesives are simple and effective in achieving adhesion between composite resin and zirconia. In the last decade, zirconia has been increasingly used in dentistry because of its excellent biocompatibility, superior mechanical properties, and the high demand for metal-free and esthetic restorations. 1-4 However, despite the recent introduction of more translucent monolithic systems, zirconia is still more opaque than traditional ceramics. To achieve superior esthetics, zirconia is widely used as a core material veneered by a stratified feldspathic ceramic. 5,6 Many studies designed to evaluate the clinical performance of zirconia restorations have shown a high success rate after 2 to 5 years in function. 7-10 Nevertheless, the interface between the core and the veneer is one of the weakest points of this type of restoration, and in some restorations, chipping has exposed the underlying zirconia. 11,12 The repair or replacement of the restoration is determined by the Presented at the 46th Meeting of the Continental European Division, International Association of Dental Research (IADR), Florence, Italy, September 2013. a Assistant Professor, Department of Dental Materials and Imagiology. b Associate Professor and Head, Department of Geriatric Dentistry. c Associate Professor and Head, Department of Dental Materials. Seabra et al