Improving the bonding stability between resin cements and zirconia-based ceramic using different surface treatments

Bonding stability between resin cements and zirconia-based ceramics is a critical concern in dental restorations. While prior research has shown that surface treatments can influence bond strength, no prior work had resolved how specific combinations of abrasion and primers affect long-term performance. Established knowledge includes the role of surface roughness and chemical primers in enhancing adhesion. However, the specific effects of alumina or silica-modified alumina abrasion on MDP-based or self-adhesive resin cements remain unclear. This gap motivated a closer examination of how different surface treatments interact with various resin cements. The study aimed to address this uncertainty by comparing multiple treatment combinations. No previous studies had directly compared the effects of silane and MDP-based primers on zirconia surfaces. The need for a detailed comparison of these treatments led to the current investigation.

The study aimed to assess how different surface treatments influence the bond strength between zirconia and two types of resin cements. Specifically, it sought to determine whether airborne-particle abrasion with alumina or silica-modified alumina particles, combined with primers, could improve bonding stability. The motivation stemmed from the lack of clarity regarding which treatment combinations yield the most durable bonds. The study focused on evaluating the immediate and long-term effects of these treatments. It also aimed to compare the performance of MDP-based and self-adhesive resin cements under the same conditions. The researchers wanted to identify which treatment method provides the most consistent bond strength after thermocycling. The goal was to provide evidence-based guidance for clinical applications involving zirconia restorations. This study fills a specific gap in the literature on zirconia bonding protocols.

The study evaluated five surface treatments applied to zirconia specimens. These included no treatment, airborne-particle abrasion with alumina particles, alumina abrasion plus MDP-based primer, silica-modified alumina abrasion plus silane, and silica-modified alumina abrasion plus silane and MDP-based primer. Surface roughness (Ra) was measured using a contact profilometer. Resin cement cylinders were bonded to the treated zirconia surfaces. A microshear test was conducted using a wire loop to apply a parallel load until debonding occurred. The bond strength was measured before and after thermocycling between 5°C and 55°C for 3,000 cycles. Statistical analysis included one-way and two-way ANOVA followed by Tukey post hoc tests. This approach allowed for a detailed comparison of bond strength across treatment groups.

The SS and SSP treatments produced the highest surface roughness values, with P < .001. The SS surface treatment achieved the highest immediate bond strength for both resin cements. After thermocycling, the SA resin cement showed higher bond strength values regardless of the surface treatment. The SS treatment with SA cement had the highest post-thermocycling bond strength at 10.0 MPa. The self-adhesive resin cement demonstrated greater stability after thermocycling compared to the MDP-based cement. The combination of silica-modified alumina abrasion and silane provided immediate benefits but lost strength after thermocycling. The addition of an MDP-based primer to the SS treatment reduced the bond strength after thermocycling. These findings suggest that the choice of cement and surface treatment significantly affects bond durability.

The SS treatment provided the highest immediate bond strength for both resin cements. However, after thermocycling, the SA cement showed greater stability regardless of the surface treatment. The self-adhesive resin cement proved more durable under thermal stress. The SS treatment combined with SA cement achieved the highest post-thermocycling bond strength. The addition of an MDP-based primer to the SS treatment reduced long-term bond strength. The study supports the use of self-adhesive resin cements with surface roughening methods. The results suggest that thermocycling significantly impacts bond strength stability. These findings align with the authors' claim that cement type and surface treatment are key factors in bonding performance.