Physicochemical and morphological characterization of a glass ceramic treated with different ceramic primers and post-silanization protocols

Objective: Evaluate the effect of different ceramic primers and post-silanization protocols on physicochemical and morphological characteristics of a lithium disilicate glass ceramic.

Methods: Lithium disilicate ceramic (IPS e-max CAD) plaques (6 × 10 × 2 mm) were divided into 3 groups according to the ceramic primer used: (1) Silane (RelyX Ceramic Primer-RL); (2) Silane + MDP (Clearfil Ceramic Primer Plus-CP); (3) Self-etching ceramic primer (Monobond Etch and Prime-MB). Specimens from each group were distributed into 5 sub-groups according to post-silanization protocols: (a) Treated as recommended by the manufacturer (MR), (b) MR + Additional drying with air at room temperature for 30 s (RTA), (c) MR + additional drying with hot air for 30 s (HT), (d) MR + Surface rinsing with water at room temperature for 10 s and drying with air at room temperature for 30 s (WT), and (e) Specimens were not silanized (NS). Surface free energy (SFE) was determined using static contact angles measurements with water and diiodomethane. SFE data were submitted to Friedman followed by Wilcoxon post-hoc test (α = 0.05). Morphology was analyzed using scanning electron microscopy. Elemental composition and chemical interactions were determined with X-ray photoelectron spectroscopy analysis.

Results: RL presented the highest SFE (62.4 mN/m) followed by CP (59.7 mN/m). Post-silanization protocols resulted in similar SFE, but WT and HT induced the highest water contact angles when using CP and RL. CP modified ceramics' surface morphology compared to the etched and RL treated groups. The presence of water was identified on CP treated specimen. All analyzed primers formed siloxane bonds with ceramic surface.

Significance: Ceramic primers resulted in different surface free energy and morphology, but siloxane bonds were identified for all tested solutions. HT and WT protocols should be used with RL and CP primers. MB was not influenced by the different silanization protocols.