Secondary Caries Susceptibility Of Teeth With Long-Term Performing Composite Restorations T. Rezwani-Kaminski*(1), P. Gaengler (1), W Kamann (1), I. Hoyer(2), R. Montag (2) (1: School Of Dental Medicine, University Of Witten/Herdecke, 2: Univ. Of Jena/Erfurt, Germany) The longevity and clinical performance of resin-based composite restorations is influenced by many material factors and especially by the individual risk of secondary caries due to marginal gap formation. Although the product generations tend to shorten and materials followed up over long-term periods are mostly out of use when evaluation is done, the qualitative assessment of these restorations gives an insight into factors related to indication and failure rate.   The aim of this study was to compare the risk of secondary caries of posterior teeth with composite restorations (Adaptic®, Concise®, Visiomolar®) over a ten- and a twenty-year period using the USPHS-compatible CPM-Index (Clinical-Photographic-Micromorphologic Coding). The C-criteria of the index refer to anatomic form, color match, surface quality, wear, marginal integrity, marginal ledge, marginal discoloration and clinical acceptance, determining secondary caries with cavitation and the need of filling replacement. The M-criteria refer to surface roughness, surface texture, marginal integrity, excess of material, marginal fracture, negative marginal ledge, marginal leakage and other filling imperfections.   The sample was selected out of the recall of a private practice and a university. 62 restorations have been longitudinally followed up over ten years and 16 restorations were reassessed after 18 and 20 years. All fillings have been rated according to the C-criteria of the CPM-Index. For the micromorphological assessment with the SEM, replicas were made using a two stage impression technique.   In the clinical and micromorphological examination all restorations exhibited marginal imperfections and a predominant rough surface. A perfect margin with no detectable clinical gaps was assessed only at baseline. Detectable marginal gaps increased during the ten-year follow-up continuously and 28.3% of 46 still functioning restorations exhibited no marginal gaps, 19.6% showed detectable gaps in fissures, 6.5% in less than one third of the circumference and 45.6% in more than one third of the filling outline. There were only four fillings after seven years and one more filling after nine years exhibiting secondary caries with the need of replacement. All 16 fillings reassessed after 18 and 20 years showed extended marginal gap formation but no secondary caries.   It is concluded that direct composite restorations can serve over a long period of time despite of poor qualitative parameters. Micromorphologic marginal deterioration and clinical gap formation does not necessarily result in a higher risk for secondary caries.