Influence of air-particle deposition protocols on the surface topography and adhesion of resin cement to zirconia

Abstract

Objectives. This study evaluated the influence of air-particle abrasion protocols on the surface roughness (SR) of zirconia and the shear bond strength (SBS) of dual-polymerized resin cement to this ceramic. Materials and methods. Sintered zirconia blocks (n = 115) (Lava, 3M ESPE) were embedded in acrylic resin and polished. The specimens were divided according to the ‘particle type' (Al: 110 µm Al₂O₃; Si: 110 µm SiO₂) and ‘pressure' factors (2.5 or 3.5 bar) (n = 3 per group): (a) Control (no air-abrasion); (b) Al2.5; (c) Si2.5; (d) Al3.5; (e) Si3.5. SR (Ra) was measured 3-times from each specimen after 20 s of air-abrasion (distance: 10 mm) using a digital optical profilometer. Surface topography was evaluated under SEM analyses. For the SBS test, ‘particle type', ‘pressure' and ‘thermocycling' (TC) factors were considered (n = 10; n = 10 per group): Control (no air-abrasion); Al2.5; Si2.5; Al3.5; Si3.5; Control_TC; Al2.5_TC; Si2.5_TC; Al3.5_TC; Si3.5_TC. After silane application, resin cement (Panavia F2.0) was bonded and polymerized. Specimens were thermocycled (6.000 cycles, 5–55°C) and subjected to SBS (1 mm/min). Data were analyzed using ANOVA, Tukey's and Dunnett tests (5%). Results. ‘Particle' (p = 0.0001) and ‘pressure' (p = 0.0001) factors significantly affected the SR. All protocols significantly increased the SR (Al2.5: 0.45 ± 0.02; Si2.5: 0.39 ± 0.01; Al3.5: 0.80 ± 0.01; Si3.5: 0.64 ± 0.01 µm) compared to the control group (0.16 ± 0.01 µm). For SBS, only ‘particle' factor significantly affected the results (p = 0.015). The SiO₂ groups presented significantly higher SBS results than Al₂O₃ (Al2.5: 4.78 ± 1.86; Si2.5: 7.17 ± 2.62; Al3.5: 4.97 ± 3.74; Si3.5: 9.14 ± 4.09 MPa) and the control group (3.67 ± 3.0 MPa). All TC specimens presented spontaneous debondings. SEM analysis showed that Al₂O₃ created damage in zirconia in the form of grooves, different from those observed with SiO₂ groups. Conclusions. Air-abrasion with 110 µm Al₂O₃ resulted in higher roughness, but air-abrasion protocols with SiO₂ promoted better adhesion.

Key Words::

• Adhesion
• aluminum oxide
• roughness
• scanning electron microscopy
• shear strength
• silicon dioxide
• yttria stabilized tetragonal zirconia

Acknowledgement

This study was previously presented at the 28^th Annual Meeting of the Brazilian Society of Dental Research (SBPqO) on 6 September 2011.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.