Biomedical Engineering Reference
In-Depth Information
Three-step
Two-step
Two-step
One-step
3
2
2
1
Acid
Acid
Solvent (=water
+ cosolvent)
(~50%)
Solvent (=water +
cosolvent)
(~50 wt%)
Mono-
methacrylates
Acidic Mono-
methacrylates
(15-30%)
Solvent (50 wt%)
Mono-
methacrylates
Dimethacrylates
(Initiator + inhibitor)
(HEMA)
Solvent
(Initiator +
inhibitor)
Initiator +
inhibitor
Mono-
methacrylates
(Filler 1-10 wt%)
Dimethacrylates
Dimethacrylates
HEMA
Dimethacrylates
HEMA
HEMA
Initiator + inhibitor
(Initiator +
inhibitor)
Initiator + inhibitor
(Filler 3-10 wt%)
(Filler 20-50 wt%)
(Filler 20-50 wt%)
Etch-and-rinse adhesives
Self-etch adhesives
FIGURE 7.9
Classification of contemporary adhesives according to Van Landuyt et al.
[16]
. Even though most adhesives
contain the same components, they may differ significantly considering the proportional amount of
ingredients. As indicated, most adhesives contain methacrylate-based monomers. The mentioned
percentages of ingredients are approximations; nevertheless a lot of variation considering the proportional
composition of adhesives exists between different products. Two-step etch-and-rinse adhesives often referred
to as “one-bottle” systems. Irrespective of the classification, each component, either primer or bonding or
self-etching adhesive can come in two bottles that need to be mixed prior to application. As such, one-step
self-etch adhesives are often subdivided in one- and two-component systems.
7.4.1
Resin monomers
Monomers are the most important components of the adhesive, which are considered the key con-
stituents of adhesives. To provide excellent bond with resin composite, monomers in the adhesive
should be similar to those of the resin composite. Two types of monomers are presented, either the
cross-linked monomers or the functional monomers. The latter are presented mainly in the self-
etching adhesives. The most cross-linking monomers, which are used in dental adhesives,
are bisphenol A-glycidyl methacrylate, urethane dimethacrylate, and triethylene glycol dimethacryl-
ate (TEGDMA), while 4-methacryloxy-ethyl trimellitate anhydride, 4-methacryloyloxy-ethyl tri-
mellitic acid, dipentaerythritol penta acrylate monophosphate, 2-(methacryloyloxyethyl) phenyl
hydrogen phosphate, and 10-methacryloyloxydecyl dihydrogen phosphate are the most used
