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.& nbsp;Methods: One hundred and forty-one specimens (10 x 10 x 1.5 mm(3)) 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 (N=10): 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 (XPS) was conducted to identify carbon (C1s), nitrogen (N1s), phosphorous (P2p) and zirconium (Zr3d) peaks, from which the elemental ratios C/Zr, N/Zr and P/Zr were calculated.& nbsp;Results: Although water-rinsing removed most of the contaminants from the zirconia surface, bond strength of resin cement was significantly lower compared with the control. Phosphoric acid was ineffective and NaOCl was less reliable in restoring bond strength. The three commercial cleaners (ZirClean (TM), Ivoclean, KATANA (TM) Cleaner) out-performed the other cleaning measures and restored the bond strength of resin cement to zirconia except for the use of ZircleanT (TM) on blood-contaminated surfaces. N/Zr decreased for all cleaned specimens and P/Zr ratio increased for phosphoric acid and KATANA (TM) Cleaner groups. Differences in elemental ratios could indicate different cleaning mechanisms for the zirconia cleaners.& nbsp;Conclusion: All three commercial zirconia cleaners are effective in decontaminating saliva-contaminated or blood-contaminated zirconia and increasing the bond strength of resin cement to contaminated zirconia.& nbsp;Clinical significance: The use of water, phosphoric acid or concentrated sodium hypochorite for cleaning saliva-or blood-contaminated dental zirconia is not recommended. ZirClean (TM) works well on decontamination of saliva contaminated zirconia. Ivoclean or KATANA (TM) Cleaner are useful for decontamination of both saliva-and blood-contaminated zirconia during the intraoral try-in stage to recover the original bond strength of cementation.