INTRODUCTION
Composite resins have been widely used in both posterior
and anterior restorations since their first introduction
to the dental field. When compared to the
porcelain veneers and ceramic crowns, resin composite
restorations are still plagued with several significant
drawbacks despite continual improvements1,2).
Besides polymerization shrinkage and secondary caries,
plaque accumulation and color stability are some
of their major problems too3).
Discoloration of composite resins can be induced
internally or externally. In visible light-cured composite
resin system, camphorquinone is generally
used as the photoinitiator. However, if curing is inadequate,
unconverted camphorquinone will cause a
yellowish discoloration. Further, other components
of the photoinitiator system - namely tertiary aromatic
or aliphatic amines which act as so-called
synergists or accelerators, they also tend to cause
yellow or brown discoloration under the influence of
light or heat4). These are internally induced
discolorations which are permanent and which are related
to polymer quality, filler type and amount, as
well as the synergist added to the photoinitiator system5-7).
As dental practitioners cannot interfere in
nor meddle with the content of composite resins, internal
discoloration depends on the manufacturer’s
formulations, except due to improper light curing.
In the oral environment, be it superficial degradation
or a slight penetration and adsorption of
staining agents at the superficial layer of composite
resins, it can cause discoloration of the surface or
subsurface of resin restorations8).
INTRODUCTION
Composite resins have been widely used in both posterior
and anterior restorations since their first introduction
to the dental field. When compared to the
porcelain veneers and ceramic crowns, resin composite
restorations are still plagued with several significant
drawbacks despite continual improvements1,2).
Besides polymerization shrinkage and secondary caries,
plaque accumulation and color stability are some
of their major problems too3).
Discoloration of composite resins can be induced
internally or externally. In visible light-cured composite
resin system, camphorquinone is generally
used as the photoinitiator. However, if curing is inadequate,
unconverted camphorquinone will cause a
yellowish discoloration. Further, other components
of the photoinitiator system - namely tertiary aromatic
or aliphatic amines which act as so-called
synergists or accelerators, they also tend to cause
yellow or brown discoloration under the influence of
light or heat4). These are internally induced
discolorations which are permanent and which are related
to polymer quality, filler type and amount, as
well as the synergist added to the photoinitiator system5-7).
As dental practitioners cannot interfere in
nor meddle with the content of composite resins, internal
discoloration depends on the manufacturer’s
formulations, except due to improper light curing.
In the oral environment, be it superficial degradation
or a slight penetration and adsorption of
staining agents at the superficial layer of composite
resins, it can cause discoloration of the surface or
subsurface of resin restorations8).
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