Longitudinal micromorphological 15-year results of posterior composite restorations using three-dimensional scanning electron microscopy.

OBJECTIVES: Hybrid composite restorations in posterior teeth were evaluated over 15 years using the semiquantitative Clinical, Photographic and Micromorphologic (CPM) index. It was a further aim to quantitate the surface morphology by three-dimensional scanning electron microscopy (3D-SEM). METHODS: Thirty seven hybrid composite restorations (Ketac-Bond/Visio-Molar X, ESPE, Seefeld/Germany) were longitudinally followed up. Parallel to clinical assessment replicas were taken at baseline, after 1, 5, 10 and 15 years and evaluated by SEM, and profilometrical analyses of 3D-SEM data were computed. The profilometrical results were statistically analysed by ANOVA. The level of significance was set to p<0.05. RESULTS: The semiquantitative micromorphological evaluation exhibited the most considerable deterioration within the first year and up to 5 years of function. Less change was detected during the next 10 years. The profilometrical quantification showed raising depth of the negative marginal ledges with a mean of 27.2mum (range 0.6-94.5mum) after 10 years, with no statistically significant changes from 5 to 10 and 10 to 15 years. The 3D-SEM revealed marginal grooves beneath the level of the ledges (mean 34.5mum after 5 years) within the bonding zone, exposing enamel margins. Leakages, marginal fractures and surface roughness did not seriously deteriorate the quality of restorations. CONCLUSIONS: Hybrid composite restorations of Class I and II cavities surviving the first five years performed well over 15 years of function. Quantitative 3D-SEM profilometrical measurements revealed the dynamics of marginal behaviour over time. CLINICAL SIGNIFICANCE: Long-term parallel clinical and micromorphological evaluation of posterior composite restorations of Class I and Class II cavities documented the clinical safety and acceptable longevity. The longitudinal 3D micromorphologic assessment of the surface changes and of the marginal behaviour revealed deteriorating as well as improving factors hidden in clinical performance.