Micromorphological evaluation of posterior composite restorations - a 10-year report

The summarized scanning electron microscopic-supported micromorphologic data of a 10-year longitudinal clinical study of GIC/Hybrid composite posterior restorations is reported. The aim of this study was to compare the results to USPHS-compatible clinical criteria of the CPM index and to analyse the deterioration pattern and the success rate. Out of a total of 194 Class I and Class II fillings 46 restorations were at baseline, after 1, 3, 5, 7 and 10 years. The restorations were micromorphologically examined using gold-sputtered replicas and coded according to the M-criteria of the CPM index. The features for surface roughness, surface texture, marginal integrity, excess of material, marginal fracture, loss of material, marginal leakage and other filling imperfections were assessed. Eighteen fillings showed perfect margins, rapidly deteriorating after the first year of service. Despite poor micromorphologic marginal conditions all restorations retained optimal functional characteristics. Parallel longitudinal micromorphologic and clinical assessment of posterior GIC/Composite restorations revealed fine structure and deterioration patterns of the tooth-biomaterial interface. The layer-technique using GIC as dentine replacement and resin-based composite as enamel replacement results, according to previous biocompatibility testing, and clinical data, in optimal pulp protection and correct anatomic form over a 10-year period. The myth of the need for perfect marginal integrity requires further discussion.