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Bond strengths of repaired laboratory composites using three surface treatments and three primers
Cynthia P Trajtenberg1, John M Powers
1Department of Restorative Dentistry and Biomaterials, University of Texas Dental Branch at Houston, 6516 M.D. Anderson Blvd., Room 493, Houston, TX 77030-3402, USA. Cynthia.Trajtenberg@uth.tmc.edu
Purpose:
To determine the in vitro bond strength of three laboratory composites repaired with their corresponding direct repair composites using various combinations of surface treatments and primers.
Methods:
The effects of three surface treatments (600-grit as a control, air abrasion with 50-microm Al2O3 particles and 8% hydrofluoric acid etching) and three primers with different formulations [Artglass Liquid (resin/silane), Sculpture Thinning Liquid (resin), and Targis Wetting Agent (silane)] were studied on three laboratory composites (Artglass, Targis and Sculpture). Specimens were stored for 24 hours at 37 degrees C and 100% relative humidity. Tensile bond strengths were determined on an Instron universal testing machine at a crosshead speed of 0.5 mm/minute at room temperature, keeping the specimens moist throughout the testing procedure.
Results:
Three-way analysis of variance (SuperANOVA) indicated that in general, 8% hydrofluoric acid produced the highest bond strengths when used to prepare the three laboratory composites. Either 8% hydrofluoric acid or air abrasion with Al2O3 particles produced the strongest repair bond strengths for Tetric Ceram when used with the resin/silane primer (Artglass Liquid) with values ranging from 36.9 to 39.6 MPa., respectively, as did the combination of hydrofluoric acid and the silane primer (Targis Wetting Agent) 38.2 MPa. The 8% hydrofluoric acid produced the highest bond strengths when used to prepare Artglass and Sculpture and used with the resin/silane primer, 32.9 and 38.7 MPa, respectively. Most bond failures (65%) were adhesive between the laboratory and repair composites, followed by cohesive failures in the laboratory composite with Artglass/Charisma and Targis/Tetric Ceram; and cohesive in the repair composite with Sculpture/Sculpt-It. Overall, the resin/silane primer produced the highest repair bond strengths for Al2O3- and hydrofluoric acid-treated composites.
Clinical Significance:
Air abrasion and hydrofluoric acid etching offer acceptable bond strengths for laboratory composites repaired with direct repair composites. Repair bond strengths are enhanced by the application of a resin/silane primer.
