Microleakage of Vitrebond/P-50 Class II restorations

Thirty extracted human mandibular permanent first and second molars were used in this study. Class II preparations were made extending 1 mm below the CEJ at the mesial and 1 mm above the CEJ at the distal aspects. In 15 of the teeth Vitrebond was applied to all exposed dentin (A) while in 15 teeth the gingival floor was left exposed (B). After cure, the enamel margins were etched with H3PO4 gel and the Vitrebond surfaces were treated with Scotchbond 2. The P-50 was transferred to the approximal boxes and occlusal aspects in three increments, each compressed firmly and cured for 60 seconds. The restored teeth were stored in saline at 37 degrees C for 1 week. The teeth were thermocycled x250 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C with a dwell time of 15 seconds. The teeth were embedded in epoxy resin and five mesiodistal sections cut. Microleakage at the mesial and distal aspects were scored from 0 to 3 depending on the extent of the microleakage. The data were analyzed by the Wilcoxon 2-sample and the matched pair signed rank tests. Leakage above the CEJ was significantly less than below the CEJ and significantly reduced when Vitrebond was extended to the cavosurface margins.