GC EUROPE G-aenial Bond - Manual (Page 9)

9 G-ænial Bond Technical Manual
6.2 the hema-free Principle
6.2.1 Why exclude hema from the formulation? 3
hema (2-hydroxyethyl methylmethacrylate) is added to many commercially available adhesives.
adding hema provides certain benefits for those products:
• Excellent infiltration capacity of up to several millimeters into the etched dentine surface. This is
particularly useful when the dentine is deeply etched with strong acidic etching agents, such as
orthophosphoric acid or with self-etching systems with a very low ph
• HEMA helps mix hydrophobic and hydrophilic components into a single solution (avoiding a
phase separation)
• HEMA improves wetting of the adhesive on the tooth surface
• HEMA acts as a co-solvent
however, the inclusion of hema also results in some noticeable disadvantages:
• HEMA enhances water uptake from the tooth and the intra-oral environment, rendering the bond
more prone to degradation over time
• From a chemical perspective, HEMA has only one polymerizable group, reducing its polymerization
efficiency (only linear polymerization without cross-linking), thus resulting in a weaker interface
• HEMA has also been shown to retain water in the adhesive layer, which could reduce polymerisation
• HEMA has been reported in the literature as being able to induce contact allergic reactions, and
can also quickly penetrate through dental gloves.
Based on these observations, as with G-Bond, Gc decided to use a hema-free formulation for
G-ænial Bond. after application of the adhesive, water is separated from the other ingredients upon
acetone evaporation. the hema-free G-ænial Bond formulation makes it possible to avoid the
substantial amount of water that is kept within the adhesive layer in hema-containing adhesives. as
mentioned above, residual water along with the presence of hema leads to greater water sorption,
and thus weaker bond stability (Figure 4). In contrast, the long-term hydrolytic resistance and
stability of the bond will be improved when using HEMA-free G-ænial Bond adhesive. In
addition, the risk of allergic reactions associated with HEMA is avoided with G-ænial Bond.
Figure 4: Schematic representation of hydrolytic degradation of the collagen network in hema-containing bonding systems
G-ænial Bond has a ph of around 1.5, enabling the creation of a 500 nm hybrid layer. Furthermore,
the use of adequate resin monomers ensures a simultaneous demineralisation and complete
infiltration by the resin monomers into the collagen network even though no hema is present into
the composition. this in turn avoids the creation of voids at the dentine/ bond interface, thereby
decreasing the risk of nano-leakage and increasing long-term durability of the bond.
3 the science behind G-Bond, the unique concept of a hema-free adhesive; Bart Van meerbeek et al., leuven BiOmat
Research Cluster,Department of Conservative Dentistry, Catholic University of Leuven (KULeuven), Belgium, June 2009
G-aenial Bond, hema-free
Dentine
adhesive adhesive adhesive
hybrid layer hybrid layer nano-interaction
Zone
Dentine Dentine
no degradation of collagen
hema containing bonding system
hema attracts water collagen fibers degrade over time