Repairability of a packable resin-based composite using different adhesives

Purpose: To compare the repair potential of a packable composite (Filtek P60) to that of a conventional hybrid composite (Pertac II) using three different adhesives: an unfilled resin (EBS-Multi), a one-bottle, acetone-based adhesive (One-Step), and a self-etching adhesive (Prompt L-Pop). Materials and Methods: 30 composite disks (ø = 8 mm) of each composite material were fabricated, light-cured, and stored in 37°C for 7 days. The specimens were polished to 600-grit, sandblasted (CoJet-System), silanated, and randomly assigned to three groups (n=10). EBS-Multi, One-Step, and Prompt L-Pop were applied to each composite and cured. Pertac II was applied in a #5 gelatin capsule and light-cured. As controls, Pertac II was applied to freshly cured Filtek P60 and Pertac II specimens, with no additional surface treatment. Specimens were loaded in shear using an Instron testing machine at a crosshead speed of 5 mm/minute, 24 hours after bonding, and the peak shear force at failure was converted to MPa (force/area). Results: ANOVA showed a significant difference in means at P< 0.001. Tukey's test was used for pairwise comparisons. Mean SBS (±SD, MPa) were: P60/control: 25.2 (3.0); P60/EBS-Multi: 18.0 (2.3); P60/One-Step: 16.7 (2.3); P60/Prompt: 10.5 (3.3); Pertac/control: 25.5 (3.6); Pertac/EBS-Multi: 18.8 (3.0); Pertac/One-Step: 18.8 (2.4); Pertac/Prompt: 9.7 (3.5). Repair strengths were all significantly less than their respective controls, and repairs made using Prompt L-Pop had significantly lower mean strengths than the repairs made with EBS-Multi and One-Step (P< 0.05).