F03.
Recognize the adverse effects that may result when dental composite restorations
do not bond adequately to etched enamel.
Poor bonding initially results in a white line in the region where a bond
failure has occurred. The white line is caused by a mismatch in refractive index
between tooth and composite materials (both with a refractive index in the range
of 1.5 - 1.6) and air present in the gap (refractive index of air is around
1.0). As the gap ages, more and more pigments present in oral fluids enter the
gap and induce marginal discolorations. These discolorations are often brownish.
The color change does not necessary mean that there is a carious lesion present,
but many clinicians misdiagnose the situation at this point in time and replace
the restorations. It is also possible that microorganisms may enter the gap and
induce caries (wall lesions). Depending on the design of the restoration and how
it is retained, enamel debonding can also result in a loss of the restoration.
