Microscopy investigations. Techniques, results, limitations

This paper critically reviews current microscopy techniques that are used to image resin-dentin interfaces and more in particular to investigate the process of hybridization and resin-tag formation. A short description of the four most commonly used microscopy techniques with their necessary specimen-preparation methodology is provided along with a discussion of their possibilities, limitations and potential artifact formation. With this critical appraisal on microscopy techniques available to study adhesive interfaces, it is hoped to encourage the use of high-resolution analytical tools to further elucidate the mechanisms of bonding at the ultra-structural level. Besides ultra-morphologic characterization, more research should be devoted to study the chemical and physical properties of resin-dentin bonds. The final objective of such fundamental research should be to establish a more durable and reliable adhesive restorative technique.