Objective: The aim of the study was to clinically assess marginal fail
ures of amalgam and composite restorations. Method: Marginal defects w
ith and without clinical evidence of secondary caries were evaluated b
y practitioners pre-operatively and after the restoration had been car
efully removed. Results: Analyses of 235 amalgam and 193 composite res
torations with marginal failures showed that secondary caries was the
most frequent diagnosis resulting in replacement. The secondary caries
was predominately found along the gingival section of the restoration
. A comparison of pre-operative diagnoses of marginal discrepancies, a
nd the condition of the cavities at the site of the defects after the
restorations had been carefully removed, showed fairly good consistenc
y, but both false negative and false positive diagnoses were made. Con
clusion: The observations indicated that diagnosis of the outer lesion
of secondary caries provides a good basis for treatment planning. (C)
1997 Elsevier Science Ltd.