The Effect of Bonding Application Between Two Layers of Composite Placed Immediately or After 15 Minutes on the Shear Strength of the Material. (In Vitro Study)

Purpose:The aim of the comparative study is to evaluate the effect of bonding application between two layers of composite placed immediately or after 15 minutes composite on the shear strength of the material. Material and Methods: The composite (PrimeDent, USA) is placed into special prepared holes on acrylic blocks with standard dimensions. Ultradent (USA) application apparatus is applied to allow the standart placement of the second layer. Shear strengths between two composite layers were measured by the testing machine (Shimadzu Autograph AG-X) and the obtained data analysed statistically. Results: Shear strength of composite in group 2 (18.6 MPa) was the highest (p 0.001). Acid etching procedure had no significant effect on shear strength of placing 15 minutes delayed second layer of composite before applying a bonding agent (p 0.05). Conclusion: Application of bonding between two layers of composite increases shear strength.