DEMONSTRATION OF A FOCUSED ION-BEAM CROSS-SECTIONING TECHNIQUE FOR ULTRASTRUCTURAL EXAMINATION OF RESIN-DENTIN INTERFACES

Objectives. Focused ion-beam (FIB) etching, commonly used as a cross-s ectioning technique for failure analysis of semiconductor devices, has recently been applied to biological tissues to expose their ultrastru cture for examination. It was the aim of this investigation to determi ne the practical utility of FIB to cross-section resin-dentin interfac es in order to morphologically evaluate the completeness of resin pene tration into the exposed collagen scaffold at the resin-dentin bond in terface. Methods, Two representative commercially available dentin adh esive systems were bonded to mid-coronal dentin. After appropriate fix ation and dehydration of the resin-bonded dentin samples, a scanned fo cused ion-beam of a few tens of nano-meters in diameter was used to cr oss-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 i nterface, hiding its actual ultrastructure, probably due to a heat-eff ect with possible recrystallization. Further studies of FIB are needed to optimize its usefulness for resin-dentin interface examinations an d other biological tissue applications. Significance, Complete resin s aturation of the demineralized dentin surface-layer has been claimed t o be the key factor for a long-lasting resin-dentin bond. A ''clean'' artifact-free micro-cross-sectioning technique may provide indisputabl e ultra-structural information about the depth of resin penetration in to the demineralized zone. Such a test would be useful in the developm ent of dentin adhesive systems.