Methods: Resin-dentin bonded specimens were prepared using one of two material combinations (Syntac adhesive systeme + Tetric Ceram Cavifil; Prime & Bond NT + Spectrum TPH). The specimens (Prime & Bond NT + Tetric Ceram Cavifil: n = 52; Syntac adhesive system + Spectrum TPH: n = 57) were subjected to a modified microtensile bond strength test (stick width and dephts 300 ƒÝm). Before fracturing the sticks, the occurence of nanoleakage (grade 0 to 3) was determined undestructively under a confocal laser scanning microscope having dyed the specimens with rhodamine B as a fluorescent dye for one hour before. A possible influence of Rhodamine B on £gTBS was tested by comparing two groups of specimens; one group with, and the other group without the fluorescent dye. The specimens were kept humid through the whole experiments.
Results: Rhodamine-B-Isothiocyanate did not have any influence on bond strength (30.4°"13.6N no dye, 30.5°"11.5N with dye, n=25, p=0.869). For the influence of nanoleakage on £gTBS with Prime & Bond NT the Spearman correlation coefficient was r2=0.04 (n=52, p=0.781). For the Syntac adhesive system the Spearman correlation coefficient was r2=-0.074 (p=0.601).
Conclusion: It is concluded that neither preparing specimens with Rhodamine-B-Isothiocyanate nor the presence of nanoleakage has any influence on tensile bond strength.