(PR23) Effectiveness of Different Cleaning Measures on the Bonding of Resin Cement to Saliva-Contaminated or Blood-Contaminated Zirconia

Objective: To investigate the effectiveness of different cleaning measures on the bonding of resin cement to saliva- or blood-contaminated zirconia.

Methods: 141 specimens were fabricated from KATANA^TM zirconia blocks and contaminated with human saliva or sheep blood. Six cleaning measures were examined: water-rinse, H₃PO₄, 5.25% NaOCl, ZirClean^TM, Ivoclean and KATANA^TM Cleaner. Tensile bond strength was evaluated for 13 groups: six cleaning measures against two contaminations (12 experimental groups) and one uncontaminated control group. Scanning electron microscopy was used to observe the control and water-rinsed specimen surfaces. X-ray photoelectron spectroscopy was conducted to identify carbon, nitrogen, phosphorous and zirconium peaks from which the elemental ratios C/Zr, N/Zr and P/Zr were calculated.

Results: Although water-rinsing removed most of the contaminants from the zirconia surface, the bond strength of resin cement was significantly lower compared with the control. The three commercial cleaners outperformed the other cleaning measures and restored the bond strength of resin cement to zirconia except for Zirclean^TM on blood-contaminated surfaces. Phosphoric acid was ineffective and NaOCl was less reliable in restoring bond strength. The ratio of N/Zr decreased for all cleaned specimens and P/Zr ratio increased for H₃PO₄ and KATANA^TM Cleaner.

Conclusion: All three commercial zirconia cleaners are effective in decontaminating saliva- or blood-contaminated zirconia and increasing the bond strength of resin cement to contaminated zirconia. The use of water, phosphoric acid or concentrated sodium hypochlorite for cleaning saliva- or blood-contaminated dental zirconia is not recommended.