Relative Retention of bonded Bruxzir restoration to Dentin: Function of different surface treatment

Objectives: The efficacy of cementing Bruxzir restorations to dentin as a method of crown retention is contingent on the interplay between the primers, cements and the restorative material’s surface characteristics within an applied clinical situation.The purpose of this study was to evaluate the relative retention of BruxZir^® Shaded Solid Zirconia restorations to dentin with different surface treatments.
Methods: A total of 80 BruxZir^® Shaded Zirconia restorations and corresponding human molar preparation were milled with VHF–BruxZir and HASS mini mill respectively with cement gap of 80 µm. Specimens (n=10) were randomly distributed in 8 experimental groups distinguished by surface treatment, primer, and adhesive cement. Prepared molars embedded in polymerized acrylic resin had uniform occlusal and axial reduction of 1.5-2mm with 20 degree taper.Experimental groups were either sandblasted (50µm, 80Psi) after sintering or treated with ultra-pure silica solution (1µm) before sintering and sandblasted after sintering.The restorations were primed with Clearfil^™Ceramic Primer (Kuraray Noritake Dental Inc.; New York, N.Y.) or Monobond Plus (Ivoclar Vivadent; Amherst, N.Y.) and cemented with RelyX Unicem (3M ESPE, Maplewood, Minnesota),Panavia F2.0 (Kuraray) or Multilink Automix (Ivoclar Vivadent) according to manufacturer’s recommendations. Cemented specimens were stored for 24 hours in deionized water (37°C). The mean retention force and stress for specimens were measured for all groups with a universal testing machine (0.5 mm/min crosshead speed), and data was analyzed (α=0.05) using the One-Way ANOVA procedure and Tukey-Kramer post hoc test.
Results: A statistically significant difference (p≤0.001) of mean retention force and stress values was found between groups treated with silica solution, sandblasted with alumina and cemented with a resin-based cement (Multilink Automix).
Conclusions: Within limitations of this study, the surface treatment and primer application plays an important role in the retention of BruxZir crowns cemented to dentin using different resin-based cements.