Demonstration of a focused ion-beam cross-sectioning technique for ultrastructural examination of resin-dentin interfaces.
OBJECTIVE
focused ion-beam (FIB) etching, commonly used as a cross-sectioning technique for failure analysis of semiconductor devices, has recently been applied to biological tissues to expose their ultrastructure for examination. It was the aim of this investigation to determine the practical utility of FIB to cross-section resin-dentin interfaces in order to morphologically evaluate the completeness of resin penetration into the exposed collagen scaffold at the resin-dentin bond interface.


METHODS
Two representative commercially available dentin adhesive systems were bonded to mid-coronal dentin. After appropriate fixation and dehydration of the resin-bonded dentin samples, a scanned focused ion-beam of a few tens of nano-meters in diameter was used to cross=section the resin-dentin interface. Examination of the interfacial ultrastructure was accomplished using a field-emission SEM.


RESULTS
Results indicate possible artifact production at the cross-sectioned interface, hiding its actual ultrastructure, probably due to a heat-effect with possible recrystallization. Further studies of FIB are needed to optimize its usefulness for resin-dentin interface examinations and other biological tissue applications.


CONCLUSIONS
Complete resin saturation of the demineralized dentin surface-layer has been claimed to be the key factor for a long-lasting resin-dentin bond. A "clean" artifact-free micro-cross-sectioning technique may provide indisputable ultra-structural information about the depth of resin penetration into the demineralized zone. Such a test would be useful in the development of dentin adhesive systems.
Van Meerbeek
B
B
Clinical Research Facility, University of Texas Health Science Center at San Antonio, Texas, USA.
Conn
L J
LJ
Duke
E S
ES
Schraub
D
D
Ghafghaichi
F
F
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D016591:Histocytological Preparation Techniques; D006801:Humans; D007477:Ions; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D019279:Resin Cements; D013499:Surface Properties
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D007477:Ions; D008689:Methacrylates; C088316:Optibond Dual Cure; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; D017438:Bisphenol A-Glycidyl Methacrylate