title: Nanoleakage within the hybrid layer: a correlative FEISEM/TEM investigation.
abstract: The aim of this study was to compare the nanoleakage patterns of the resin-dentin interfaces of three dentin bonding systems at both TEM and field emission in lens SEM (FEI-SEM) levels. A standardized smear layer was created with 180-grit silicon carbide paper (SiC) on dentin disks obtained from 18 noncarious human third molars. Specimens were randomly divided into three groups and bonded with a two-step total etching adhesive (Single Bond, SB), a two-step, self-etching adhesive (Clearfil SE BOND, SEB), and a one-step, self-etching adhesive (XENO III, XEIII). Nanoleakage was evaluated by using an ammoniacal silver-nitrate solution. Specimens were processed for TEM and FEI-SEM observation. The TEM of SB revealed silver deposits in adhesive and hybrid layers (HL). High-magnification FEI-SEM micrographs clearly identified these deposits as spherical clusters mainly associated with nonembedded collagen fibrils. TEM and FEI-SEM examination of SEB revealed some clusters of silver deposits within porosities and small channels of the HL. Additional silver deposits were observed between the peritubular dentin walls and the resin tags. XEIII revealed very fine and diffuse silver grains throughout the entire HL. SEM visualization of nanoleakage at a high level of resolution has not been previously described. FEI-SEM technology supported the TEM visualization with three-dimensional morphological data of the relations between the HL constituents and nanoleakage. The results of the present study confirm the hypothesis that both total- and self-etch adhesives are not able to fully infiltrate the dentin substrate.
authors.affiliation: Department of SAU&FAL, University of Bologna, Bologna, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Suppa
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Ruggeri
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mazzotti
authors.forename: Carlo
authors.initials: C
authors.lastname: Prati
authors.forename: Stefano
authors.initials: S
authors.lastname: Chersoni
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Lenarda
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D000134:Acid Etching, Dental; D001672:Biocompatible Materials / Q000737:chemistry; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D003094:Collagen / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods; D003738:Dental Cements / Q000737:chemistry*; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D008963:Molar / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D017655:Silicon Compounds / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D017554:Carbon Compounds, Inorganic; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D017655:Silicon Compounds; D014867:Water; D012834:Silver; D003094:Collagen; C022088:silicon carbide