Role of cold atmospheric plasma alone or combined with conventional surface treatments on shear bond strength of 3Y-TZP and 5YSZ ceramics bonded with composite resin

Objective: To evaluate the role of cold atmospheric plasma (CAP), alone or in combination with conventional surface treatments, on the shear bond strength (SBS) and failure mode of 3Y-TZP and 5YSZ ceramics bonded to composite resin using two adhesive protocols. Materials and methods: A total of 200 zirconia specimens (3Y-TZP and 5YSZ) were assigned to five surface-treatment groups: No treatment (control), airborne-particle abrasion (APA), CAP, APA + CAP, and hydrofluoric acid (HF) + CAP. Each group was further divided according to the use of a primer. The zirconia specimens were bonded to composite resin using a self-adhesive cement. After artificial aging, SBS testing and failure-mode analysis were performed. Data were analyzed using appropriate parametric tests (α = 0.05). Results: Compared with the control group, surface treatments significantly improved SBS (p < 0.001). Applying self-adhesive cement with surface primer further improved SBS (p < 0.001). Different yttria contents of zirconia materials did not impact SBS (p > 0.05). There was no benefit to combining APA and CAP or CAP and HF. Failure modes were predominantly adhesive in the control group and mixed on treated zirconia surfaces. Conclusions: CAP provides bond strength comparable to APA while potentially minimizing surface damage, supporting its use as a conservative surface-treatment option. Additional combined or aggressive surface treatments do not offer further clinical benefit for bonding zirconia restorations.