GC EUROPE Unifil Bond - Manual (Page 3)

GC UniFil Bond Technical manual version 1.10, November 2005, 3/23
1.0 Introduction
The development of GC UniFil Bond is the result of GC’s commitment to
understanding and seeking solutions to the variable success parameters currently
restricting certain indications for composite resin restoratives.
While long-term success has been achieved with composite resin bonded to all
enamel surfaces, the same cannot be said for bonded composite where margins are
in dentine. Composite restoration failure often occurs at the interface between the
composite and dentine leading to staining, microbial leakage and progression of
caries.
Improvements therefore focused on solutions to the problems experienced at this
interface. The many causes of interface failure include application factors (variable
placement techniques, over etching, over drying, fluid contamination, surface
contaminants like excess acetone), site factors (variable dentin structure i.e. tubule
orientation, degree of mineralization) and stress factors (occlusal loading, tooth
flexure, polymerization shrinkage stress and variable coefficients of thermal
expansion).
GC UniFil Bond was developed seeking to provide solutions to many of these
problems and focused on three primary objectives:
• Provide strong adhesion via simple application procedures with minimal
opportunity for compromised results caused by technique variation
• Provide strong adhesion to a wide variety of dentine surfaces
Maintain an effective seal by utilizing both micromechanical interlocking and chemical
adhesion.
2.0 Currently available adhesion concepts
At present several adhesion concepts are considered for bonding to tooth surfaces.
The adhesion mechanisms are divided into three major categories
-
micromechanical interlocking
-
chemical (ion-exchange) adhesion
-
combination of above two
• Micromechanical interlocking is achieved by etching both enamel and dentine
surfaces followed by application of resin bonding systems that contain functional
monomers with both hydrophilic and hydrophobic groups. These monomers are
able to penetrate and diffuse throughout the etched dentine surface layer to form
a hybrid zone that adheres to the dentin surface. Strong micromechanical
interlocking to enamel is also achieved where the resin penetrates the
irregularities in the etched enamel surface forming micro resin tags.