Composite resin-Tooth interface as seen through an acetate paper peel: A transmitted light microscopic observation

Background: Optimum marginal seal is a key success in restorative dentistry. Lack of this may lead to microleakage. The aim of this study was to observe the characteristic features of the composite resin-tooth interface under transmitted light microscope using acetate paper peel technique and to determine its feasibility in microleakage evaluation. Materials and Methods: Standardized class I cavity was prepared and restored with Filtek Z350 XT composite resin on three extracted human maxillary premolars. The occlusal surface of one of the restored premolars was made flat and the other two premolars were sectioned buccolingually and a flat surface was obtained. All the three samples were embedded in epoxy resin, polished, etched with 37% phosphoric acid, washed with distilled water and then dried. Acetone was flooded onto the prepared surface and a pre-cut acetate film was placed onto it. As the acetone evaporated, the film gets settled down to take the shape of micro relief produced by etching. The film was left over to dry for 15-20 min. The film was gently peeled off and mounted on a glass slide with a cover slip and observed under transmitted light microscope at different magnifications. Results: At lower magnification (×4), the intricate details of the composite resin-tooth interface could be observed, but the formation of resin tags and a thick dark band of hybrid layer was clearly visible only at higher magnification (×40). Furthermore, the interfacial gap between the restoration-tooth interfaces could be measured at ×40 magnification. Conclusions: This technique is an efficient way to study the interfacial space between the restoration and the tooth but by measuring the interfacial gap at a particular point it would be difficult to comment on the microleakage aspect.