title: Dentin bonding: effect of tubule orientation on hybrid-layer formation.
abstract: In an attempt to compare the morphology of the resin-dentin interface in areas where the dentinal tubules run perpendicularly or at an angle to the cavity surface with that of areas where they run parallel to it, we studied a dentin adhesive system using transmission electron microscopy and fluorescence confocal laser scanning microscopy. The design of the study included the simulation of the normal hydrostatic pressure within the pulp and the dentinal tubules. Following acid etching of the dentinal surface with maleic acid/HEMA, the smear layer was removed, and a superficial zone was demineralized in such a way that the exposed collagenous dentin matrix retained its integrity. Confocal laser scanning microscopal investigations using primer labeled with rhodamine B showed that the penetration of the primer occurred not only vertically via surface porosities, but mainly laterally, via the dentinal tubules. The adhesive resin labeled with fluorescein completely infiltrated the demineralized layer, thereby forming a hybrid layer. The orientation of the dentinal tubules had a profound effect on the formation of the hybrid layer. In areas with perpendicular tubule orientation, the layer was 3.2 +/- 0.8 microns thick, showing solid 27.2 +/- 0.8 microns long resin tags in the dentinal tubules, and a network of tiny tags in their side-branches. In areas with parallel tubule orientation the layer was significantly thinner (1.3 +/- 0.6 microns) and resin tags were absent.
authors.affiliation: Institute of Oral Microbiology and General Immunology, University of Zurich, Switzerland. schuepba@zzmk.unizh.ch
authors.forename: P
authors.initials: P
authors.lastname: Schüpbach
authors.forename: I
authors.initials: I
authors.lastname: Krejci
authors.forename: F
authors.initials: F
authors.lastname: Lutz
mesh_terms: D000134:Acid Etching, Dental; D000269:Adhesives / Q000737:chemistry; D003094:Collagen / Q000648:ultrastructure; D001840:Dental Bonding; D003737:Dental Cavity Preparation; D003782:Dental Pulp / Q000502:physiology; D003804:Dentin / Q000502:physiology / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D019793:Fluorescein; D005456:Fluorescent Dyes; D006801:Humans; D006874:Hydrostatic Pressure; D008298:Maleates / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D016062:Porosity; D019279:Resin Cements / Q000737:chemistry*; D012235:Rhodamines; D016369:Smear Layer; D013499:Surface Properties
chemical_list: C088247:ART Bond; D000269:Adhesives; D017220:Dentin-Bonding Agents; D005456:Fluorescent Dyes; D008298:Maleates; D008689:Methacrylates; D019279:Resin Cements; D012235:Rhodamines; C005044:hydroxyethyl methacrylate; D003094:Collagen; C030272:maleic acid; C029773:rhodamine B; D019793:Fluorescein