Modern dentalceramic is the esthetic material of choice and has contributed greatly to the increased demand on cosmetic indirect restorations. Adhesive cementation of glass-ceramic restorations with a composite resin of optimum physical properties can withstand higher masticatory forces and has demonstrated improved clinical performance1. Bonding of indirect ceramic restorations to tooth structure involves the luting agent to interact with two different surfaces i.e. enamel/dentin and ceramic. As compared to other ceramics lithium disilicateceramics offer enhanced flexural
1. Conservative Dental Science Department, College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj, Saudi Arabia.
Corresponding author: “Zaid A. Al Jeaidi” < email@example.com >
JPDA Vol. 25 No. 02 April-June 2016 75
strength and fracture toughness2. Some investigators, due to improved mechanical properties, have also used LD ceramics for 3 unit bridges3,4.
As conditioning of tooth surface is a standard protocol for adhesive bonding, similar is the importance of conditioning the ceramic bonding surface for predictable adhesion. Hydrofluoric acid, as a surface treatment has a long term proven track record of favorable clinical outcome5. Similarly, for the formation of a durable chemical bond, silane application is recommended6,7. And many authors consider treatment of ceramic surface both with HF acid and silane as indispensable5,8-10.
In a recent study by Canay et al., 11 spectroscopic analyses showed formation of crystalline precipitates on the etched ceramic surfaces in the form of Na, K, Ca & Al by-products. These by-products of HF acid etch are readily insoluble in water and possibly contaminate the ceramic bonding surface. In
MATERIAL AND METHODS
The methodology of this study is similar to our previously published paper20. Briefly, 30 blocks of lithium disilicate ceramic (IvoclarVivadent) measuring 4x6x8 mm of were prepared, grit blasted with alumina (70μm glass beads, finished with 240-1200 grit SiC) and cleansed in ultrasonic bath for 10 minutes.
A total of 20 ceramic blocks were etched using 9.5% HF acid for 90 seconds and rinsed with water for 20 seconds (sec) for removal of HF acid. 10 ceramic blocks were left un-etched to be used as negative controls (Group A). All the experimental ceramic specimens were divided into the following three groups (A,B and C) depending on the surface treatments.
The prepared ceramic blocks were subjected to following surface treatment:
Group A: LD ceramic blocks no HF acid etch Silane (S) application (5 minutes) Group B: LD ceramic blocks HF acid etch Rinse with water (20 secs) Silane (S) application (5 minutes)
Group C: LD ceramic blocks HF acid etch Rinse with water (20 secs) Post etch cleaning (37.5%
phosphoric acid (H3PO4)with agitation for 1 min, water rinse 20 sec and ultrasonic cleaning (US) for 5 min in distilled water bath) Silane (S) application (5 minutes).
An adhesive (Optibond FL, Kerr) was applied to all the surface treated ceramic blocks. Composite blocks (Hybrid filler) (4x6x8 mm) of same dimensions as ceramic blocks were fabricated using a rubber (Aquasil, putty) copy mould of ceramic blocks. Composite and ceramic blocks were bonded using a 10 sec load application of 1 kilogram and light cured (LED) for 160 sec (650 mWcm-2). The bonded composite- ceramic blocks were sectioned using slow speed diamond wheel saw (Isomet 1000) at a constant speed of 500 rpm at 250 g force. Specimen sticks of 1mm2 cross section (non trimming technique) were produced and stored for 24 hours in normal saline. Hundred specimen for each group were randomly selected for microtensile testing. The specimens were attached to the tester jaws using cyanoacrylate adhesive and loaded to failure under tension at a crosshead speed of 0.5mm/min using a microtensile tester. The means of μ-tbs were analyzed with one way ANOVA. Details of the materials and equipment used in the study are presented as appendix A
محتويات مواقع أعضاء هيئة التدريس بما فيها من نصوص وملفات وصور وأبحاث وأية مواد أخرى هي مسئولية عضو هيئة التدريس بالكامل بصفته صاحب الموقع وبما له من صلاحية مطلقة في الإضافة والحذف، وتخلي الجامعة مسئوليتها عن محتويات تلك المواقع.
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