Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation

This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass‐ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne‐particle abrasion (AA). Cements were obtained from a Bis‐GMA/TEGDMA mixture filled with 60 mass% micron‐sized (1 ± 0.2 µm) or submicron‐sized (180 ± 30 µm) Ba‐Si‐Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student‐Newman‐Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA‐submicron group had lower bond strengths than the other groups. All AA‐submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb‐like aspect in the HFA‐treated ceramic, whereas the AA‐treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA‐treated compared to AA‐treated specimens. Cracks toward the bulk of the ceramic were observed in AA‐treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Microsc. Res. Tech. 77:363–367, 2014. © 2014 Wiley Periodicals, Inc.