Microbial Microleakage In 4 Single- And Multi-Component Dental Adhesives In Vitro S. Preussker*, W. Klimm, R. Koch (Department Of Conservative Dentistry And Institute Of Informatics And Biometrics, University Clinic Carl Gustav Carus, Dresden, Germany) The aim of this study was to compare the microbial microleakage of composite restorations with single-component dental adhesives (groups 1, 3, 5, 7) and multi-component dental adhesives (groups 2, 4, 6, 8) using an in vitro microbial test system (Klimm et al. 1996). 94 mixed standardized Class V cavities of human caries-free extracted premolars were filled with different composite-adhesive systems using one-layer (groups 1, 2, 3, 4) and two-layer technique (groups 5, 6, 7, 8). After thermocycling (5 to 550C, 5000 cycles) and incubation in broth culture of S. mutans and Lactobacillus acidophilus for 8 weeks, decalcification and staining (Brown and Brenn) degree of microbial microleakage was analyzed by light microscopy. The degree of microbial microleakage of marginal gaps was very low in all groups (predominantly single microorganisms at the cavity wall). There were no significant differences in the degree of microbial microleakage between single- and multi-component adhesives of different manufacturers. The groups 1 and 2 showed a significantly higher degree of microbial microleakage than the groups 3 and 4 (two way nonparametric test with global α=0.05, Brunner and Langer 1999). The groups 5 and 6 showed a significantly lower degree of microbial microleakage than the groups 7 and 8 (U test, Bonferroni-adjustment p<0.001). The single- and multi- component dental adhesives are equivalent with regard to microbial microleakage in vitro.     Microbial microleakage Groups Mean of degree Differences (U test, a=0.05) 1 Scotchbond™ 1/Z100™ 1.01 - 2 Scotchbond™ Multi-Purpose/Z100™ 0.94 - 3 Syntac® Single-Component™ / Tetric® Flow 0.92 - 4 Syntac® / Tetric® Flow 0.85 - 5 OptiBond Solo™ / XRV™ Herculite® 0.68 - 6 OptiBond™ FL / XRV™ Herculite® 0.77 - 7 Solobond M/ Arabesk® Top 0,97 - 8 Solobond Plus/ Arabesk® Top 0,99 - - no significant difference