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monomers and additives from the network. Thee polymers can be degraded by passive
hydrolysis and enzymatic degradation. The extent of enzymatic degradation depends
on the extend of cure of the resin. The ester groups are available for reaction in a more
loosely cross-linked network [22]. Most importantly the composition of monomers
determines the extent of degradation.
3.2 Masticatory Forces
In the oral environment the composite materials are subjected to relatively low repetitive masticatory or chewing forces. This continuous mechanical loads eventually
lead to degradation and initiation of cracks within the restoration. This process is
further accelerated by residual stresses and pre-existing voids induced during the
processing stage of the material [15].
3.3 Thermal and Chemical Changes
The inta oral temperature gradient caused by ingestion of different kinds of food
produces an unfavorable environment for the RBC. The coefficient of thermal expansion of these materials is not as same as the natural teeth. This in turn can induce
surface stresses leading to degradation of RBC. The changes in PH caused by the
varieties of food and beverages can affect the dental materials directly [6].
3.4 Oral Microbes
In vitro studies have shown that the presence of bacteria on the surface and its
interaction with the polymer can cause degradation and surface roughness of the
composite restorations [25].
4 Environmental Impact
At the point of origin, disposal of the waste material during the manufacturing of
resin-based composite is the first pollution event. This manufacturing waste is used
for landfill after polymerization, the verification of which is rather difficult. In dental
clinics, the excess dental composites after treatment as well as expired materials in
syringes is considered as municipal solid waste and is discarded in landfill sites.
This leads to a reaction between the landfill leachate and RBC leading to the release
of various components [40]. Landfill leachate is formed by the bacterial and fungal
T. Chandran et al.
monomers and additives from the network. Thee polymers can be degraded by passive
hydrolysis and enzymatic degradation. The extent of enzymatic degradation depends
on the extend of cure of the resin. The ester groups are available for reaction in a more
loosely cross-linked network [22]. Most importantly the composition of monomers
determines the extent of degradation.
3.2 Masticatory Forces
In the oral environment the composite materials are subjected to relatively low repetitive masticatory or chewing forces. This continuous mechanical loads eventually
lead to degradation and initiation of cracks within the restoration. This process is
further accelerated by residual stresses and pre-existing voids induced during the
processing stage of the material [15].
3.3 Thermal and Chemical Changes
The inta oral temperature gradient caused by ingestion of different kinds of food
produces an unfavorable environment for the RBC. The coefficient of thermal expansion of these materials is not as same as the natural teeth. This in turn can induce
surface stresses leading to degradation of RBC. The changes in PH caused by the
varieties of food and beverages can affect the dental materials directly [6].
3.4 Oral Microbes
In vitro studies have shown that the presence of bacteria on the surface and its
interaction with the polymer can cause degradation and surface roughness of the
composite restorations [25].
4 Environmental Impact
At the point of origin, disposal of the waste material during the manufacturing of
resin-based composite is the first pollution event. This manufacturing waste is used
for landfill after polymerization, the verification of which is rather difficult. In dental
clinics, the excess dental composites after treatment as well as expired materials in
syringes is considered as municipal solid waste and is discarded in landfill sites.
This leads to a reaction between the landfill leachate and RBC leading to the release
of various components [40]. Landfill leachate is formed by the bacterial and fungal