Evaluation of Shear Bond Strength of Submicron Polycrystalline Alumina Ceramic with Different Surface Treatments and Luting Cements

Submicron polycrystalline alumina ceramic offers excellent mechanical strength and translucency, making it a promising material for pediatric crown restorations. However, due to its acid resistance and low surface energy, reliable bonding requires appropriate surface treatments and selection of compatible cement materials. This study aimed to evaluate the shear bond strength of submicron polycrystalline alumina ceramics subjected to various surface treatments and bonded with different types of luting cements. Ninety specimens were divided into three surface treatment groups: no treatment, sandblasting, and Rocatec treatment. Each group was further subdivided by cement type: glass ionomer (GI) cement (GC Fuji I), resin-modified glass ionomer (RMGI) cement (RelyX Luting 2), and self-adhesive resin cement (RelyX U200). Shear bond strength was measured using a universal testing machine, and failure modes were analyzed using scanning electron microscopy. The combination of Rocatec treatment and self-adhesive resin cement exhibited the highest bond strength. Self-adhesive resin cement demonstrated significantly higher bond strength than the other cements under all surface conditions (p < 0.017). Within the self-adhesive resin and RMGI cement groups, shear bond strength varied significantly by surface treatment (p < 0.017), while no significant difference was found in GI cement group (p > 0.017). Adhesive failures occurred only in untreated groups, whereas cohesive and mixed failures appeared exclusively in surface-treated groups. Within the limitations of this in vitro study, Rocatec treatment with self-adhesive resin cement was the most effective bonding strategy for submicron polycrystalline alumina ceramics.