Effect of 9% Hydrofluoric Acid Gel Hot-Etching Surface Treatment on Shear Bond Strength of Resin Cements to Zirconia Ceramics

Abstract

Background and Objectives: There is no consensus regarding the surface treatment method for achieving optimal bonding strength between zirconia and resin cements. We evaluated the effect of hot-etching with 9% hydrofluoric acid (HF) gel using the Zirconia Etchant Cloud System on zirconia surfaces and the consequent shear bond strength (SBS) of different resin cements to such surface-treated zirconia ceramics. Materials and Methods: Forty-five zirconia specimens were randomly assigned to surface-treatment groups (n = 15/group): no treatment (control, CT); sandblasting with 110-μm Al2O3 at an air pressure of 1 bar for 10 s (SB); hot-etching with 9% HF gel (HE). Post-treatment, specimens were examined using scanning electron microscopy (SEM) and surface roughness (SR) analysis. After treatment, self-adhesive resin cements (Maxcem Elite, MAZIC Cem, RelyX U200, 3M ESPE: Maplewood, MN, USA) were bonded to zirconia specimens, which were stored in distilled water at 37 °C for 24 h. All specimens were then subjected to SBS testing, using a universal testing machine, until failure. Data were analyzed using one-way analysis of variance and Tukey’s post hoc test (α = 0.05). Results: In the SEM images, roughness was greater in SB than in HE specimens. Ra and Rt values were highest in SB, followed by HE, and CT specimens. HE specimens showed significantly higher SBS values than CT or SB specimens (p < 0.05). MAZIC Cem cement, with 10-methacryloyloxydcyl dihydrogen phosphate yielded the highest SBS values. Conclusions: Hot-etching with 9% HF gel in a safe shell formed uniformly small, defined holes on the zirconia surface and achieved significantly higher SBS values than sandblasting (p < 0.05). Zirconia prostheses can be bonded micromechanically with resin cement, without the deterioration of properties due to t-m transformation, using chemical acid etching with the Zirconia Etchant Cloud System.

The Shear Bond Strength of Resin-Based Luting Cement to Zirconia Ceramics after Different Surface Treatments

“…Sales et al [21], who also used the Zircos-E system for their research. Similar differences between sandblasted samples and those additionally etched with a strong acid solutions were also observed in other studies [12,23,24]. Proper surface treatments may promote the micromechanical interlocking of resin cement by creating fitting roughness and increasing surface energy [11,[25][26][27].…”

Evaluation of Shear Bond Strength of Multilayered Zirconia and Lithium Disilicate Ceramic to Resin Cement

“…This method involves air abrasion systems that emit a flow of air mixed with aluminum oxide (Al2O3) particles, which are used to abrade surfaces (16,17) . Particle diameter of 50 μm was found to give optimum results as concluded by some authors (18) . This mechanism relies on loosening the contaminated layers, creating surface irregularities and porosities, thus allowing the adhesive to interlock mechanically into these pores (16,19) .…”

“…Although sandblasting is used extensively as the mechanical method for increasing the zirconia's surface roughness, however, its effectiveness was influenced by several factors such as the abrasive particle size, the timing and the distance used for spraying the substrate (18) . Specifically, when huge grains are being used for closely-spraying the zirconia, the latter mechanical strength and qualities degrade, also microscopic fissures (21) occur as a result of the intense thermal shock that causes the zirconia phase to change from tetragonal phase to monoclinic phase.…”

“…Specifically, when huge grains are being used for closely-spraying the zirconia, the latter mechanical strength and qualities degrade, also microscopic fissures (21) occur as a result of the intense thermal shock that causes the zirconia phase to change from tetragonal phase to monoclinic phase. Such a transition significantly affects the zirconia restorations' long-EVALUATION OF SHEAR BOND STRENGTH OF MULTILAYERED ZIRCONIA AND LITHIUM (1479) term mechanical stability and permanent fracture resistance (18,21) . However, some evidences showed that resin cement infiltrates these cracks, thereby reinforcing the ceramic.…”

“…Other authors stated that silanization will not make a difference in the bond durability (25) . Acid etching has the benefit of consistently roughening the material's surface without imposing any force on it, which eliminates the possibility of material chipping (26) , other than avoiding phase transformation, acid etching showed other advantages superior to sandblasting like the compatibility with resin cements containing MDP, the phosphate monomer of MDP chemically bonds with the hydroxyl groups on the etched zirconia surface, also the roughened surface created by HF acid treatment allowed the micro-mechanical retention of the cement, as well as corroding the zirconia surface exposing more reactive sites for chemical bonding with the resin cement, further enhancing the bond strength and durability (18) . Shear and microtensile bond strength testing are commonly utilized methods in restorative dentistry and dental materials research to compare products and techniques (27) .…”