Aya Ezzat ElShimy, Omnia El-Sheihy And Maha Taymour,
ABSTRACT
Statement Of The Problem: Opposite To Silica-based Ceramics, Zirconia Has No Silica In Their Structure, So They Cannot Be Effectively Conditioned Using Hydrofluoric Acid. Zirconia Exhibits Weaker Bond Strength To Resin Than Other Types Of Ceramic Materials, So Repair Of Zirconia With Resin Composite Is Considered To Be Technique Sensitive And Questionable Procedure.
Purpose: The Aim Of This In-vitro Study Was To Assess The Effect Of Two Different Priming Agents On The Shear Bond Strength (SBS) Of Composite Resin Used To Repair Treated Zirconia Compared To Sandblasted Zirconia.
Materials and Methods: A Total Of 24 Zirconia Specimens (12 �10 �3 Mm) Were Sliced From Presintered ICE Zirkon Translucent Zirconia Blank Using An Isomet 98 Cutting Machine Then All The Specimens Were Sintered According To The Manufacturer�s Instructions. The Specimens Were Randomly Divided Into Three Groups According To The Surface Treatment Performed (n=8) : (1) Sandblasting With 110�m Al2O3 Particles (control Group); (2): Chemical Treatment With RelyX Ceramic Primer (RelyX Group); And (3): Chemical Treatment With Monobond Plus Primer (Monobond Plus Group). All Specimens Were Bonded To Two Resin Composite Cylinders With A Universal Adhesive System According To The Manufacturer�s Recommendations. The Samples Were Stored For 24 Hours In An Incubator At 37�C And 100% Humidity, Followed By Thermal Cycling (500 Cycles At 5�C And 55�C). The Shear Bond Strength Was Measured By The Universal Testing Machine With 500 N Load Cell And Speed Of 0.5 Mm/min. Two Representative Specimens Were Randomly Selected From Each Group To Be Examined Using Scanning Electron Microscope X1000 Magnification To Characterize The Surface Morphology Of Each Surface Treatment Method. Mean SBS (MPa) Were Analyzed With One-way Analysis Of Variance (ANOVA) Followed By Pair-wise Tukey�s Post-hoc Tests To Detect Significance Between Groups. Shear Strength Was Calculated Through The Equation: ( T = F (force) / A (area) ).
Results: The Sandblasted Specimens Of The Control Group Showed The Highest Mean Shear Bond Strength With A Statistically Significant Difference While The Specimens Of The RelyX Group Showed Higher Mean Shear Bond Strength Than That Of The Monobond Plus Group With Statistically Non-significant Difference Between Them. The SEM Showed That The Sandblasted Zirconia Had The Roughest Surface With Multiple And Deep Micro-irregularities. While For The RelyX And Monobond Plus Specimens, There Were Mild And Shallow Irregularities.
Conclusions: From The Findings Of Our Study, Sandblasting Of Zirconia With 110�m Alumina Particles Enhances The Shear Bond Strength Of Resin Composite Used To Repair Zirconia-cored Restorations After Chipping Of The Veneer Layer. Sandblasting Has A Better Effect On The Shear Bond Strength Compared To The Chemical Surface Treatment Of Zirconia With RelyX And Monobond Plus Primers. Both Of RelyX And Monobond Plus Primers Have Nearly The Same Effect On The Shear Bond Strength.
