UBC Theses and Dissertations

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UBC Theses and Dissertations

Effect of surface conditioning and storage time on the bond strength of orthodontic brackets to lithium disilicate ceramic Paxon, Jonathan


The effect of different surface conditioning procedures on bracket bond strength to lithium disilicate ceramic were investigated after 30 min, 24 h and 6 months of water storage. Brackets were bonded to 300 IPS e.max samples (Ivoclar Vivadent). Five surface conditioning procedures were tested: 15 seconds 37% H₃PO₄; 20 seconds 9.5% hydrofluoric acid (HF); 60 seconds 9.5% HF; 60 seconds 9.5% HF plus a low-viscosity enamel bonding agent; 20 seconds non-thermal plasma (NTP) only. All samples were further treated with a silane coupling agent prior to bonding with an orthodontic resin cement and were stored in distilled water at 37°C for 30 minutes, 24 hours and 6 months before testing the shear bond strength. Results showed that bond strengths increased from 30 minutes to 24 hours and then decreased at 6 months. At 30 minutes and 24 hours, HF etching for 60 seconds followed by enamel bonding agent exhibited significantly higher bond strength than all other groups. At 6 months, all groups etched with HF exhibited similar bond strengths that were significantly greater than both H₃PO₄ and NTP surface conditioning. Etching with HF resulted in increased adhesive residue on the sample surface after debonding compared to treatment with NTP or H₃PO₄. The results suggest that surface treatment with 20 to 60 second 9.5% HF etching times yields stable bond strengths, as the bond strengths did not significantly reduce after 6 months.

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Attribution-NonCommercial-NoDerivatives 4.0 International