Compares the microleakage and nanoleakage at the interface of dentinoenamel junction (DEJ), enamel and dentin bonded with either Superbond C&B (SB), Panavia F (PN) or Valiolink II (VL) cements. Extracted human permanent molars were cross-sectioned at the middle third of coronal part to prepare 2x4x1 mm specimens with DEJ aligning in the middle, 1 mm of enamel and dentin on each side. Ninety-six specimens were divided into control and sample groups of 48 specimens. Each group was subdivided into 6 groups of 8 specimens. Samples were cemented to composite resin veneers using different resin cements: Groups 1, 4; 2, 5; 3, 6 with SB; PN; VL, respectively. All specimens were stored in distilled water at 37 oC for 24 h. All surfaces of specimens were coated with two layers of nail vanish except a cross-sectional surface for dye penetrating. Groups 1-3 were immersed in 0.5% basic fuchsin dye for 24 h prior to determine and measure the dye penetration using stereoscopy and digital micrometer. Groups 4-6 were immersed in 50% silver nitrate for 24 h and silver penetration was measured by digital micrometer and examined by stereoscopy, backscattered electron image and scanning electron microscopy attached energy dispersive X-ray spectrometer. Three control and seven sample specimens for each group were prepared to investigate DEJ and the quality of hybrid layer respectively using SEM. ANOVA and Tamhane's statistical analyses were performed. For control groups, the distance of dye penetration in dentin was significantly higher than in DEJ and enamel (p<0.01). No dye penetration in enamel was found. The distance of silver penetration in DEJ was not significantly different when compared with that in dentin but significantly higher than in enamel. Significant differences were disclosed among sample groups in microleakage and nanoleakage at the tooth-resin interface. No leakage was found at all enamel-resin interfaces. No leakage at the tooth-cement interface was observed in groups 1SB, 2PN and 4SB. Groups 3VL and 6VL had highest leakage at the resin interfaces of dentin and DEJ. After chemical modification using HCl and NaOCl solution, the thickness of hybrid layer in enamel, dentin and DEJ of SB was consistent whereas hybridized dentin were thinner in PN and VL. The results of this study suggested that the differences in components and structures influence tooth permeability. Hybridized enamel with resin could resist natural nano-permeability. Complete hybridization via dry bonding using SB could prevent leakage at resin interfaces of enamel, DEJ and dentin. Self etching and priming using PN could resist microleakage but not nanoleakage at resin interfaces of dentin and DEJ. The highest leakage indicated that wet bonding using VL could not provide reliable bonding to DEJ and dentin.
